// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <inttypes.h>
#include "util.h"
#include "string2.h"
#include <sys/param.h>
#include <sys/types.h>
#include <byteswap.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <linux/compiler.h>
#include <linux/list.h>
#include <linux/kernel.h>
#include <linux/bitops.h>
#include <linux/stringify.h>
#include <sys/stat.h>
#include <sys/utsname.h>
#include <linux/time64.h>
#include <dirent.h>

#include "evlist.h"
#include "evsel.h"
#include "header.h"
#include "memswap.h"
#include "../perf.h"
#include "trace-event.h"
#include "session.h"
#include "symbol.h"
#include "debug.h"
#include "cpumap.h"
#include "pmu.h"
#include "vdso.h"
#include "strbuf.h"
#include "build-id.h"
#include "data.h"
#include <api/fs/fs.h>
#include "asm/bug.h"
#include "tool.h"
#include "time-utils.h"
#include "units.h"

#include "sane_ctype.h"

/*
 * magic2 = "PERFILE2"
 * must be a numerical value to let the endianness
 * determine the memory layout. That way we are able
 * to detect endianness when reading the perf.data file
 * back.
 *
 * we check for legacy (PERFFILE) format.
 */
static const char *__perf_magic1 = "PERFFILE";
static const u64 __perf_magic2    = 0x32454c4946524550ULL;
static const u64 __perf_magic2_sw = 0x50455246494c4532ULL;

#define PERF_MAGIC      __perf_magic2

const char perf_version_string[] = PERF_VERSION;

struct perf_file_attr {
        struct perf_event_attr  attr;
        struct perf_file_section        ids;
};

struct feat_fd {
        struct perf_header      *ph;
        int                     fd;
        void                    *buf;   /* Either buf != NULL or fd >= 0 */
        ssize_t                 offset;
        size_t                  size;
        struct perf_evsel       *events;
};

void perf_header__set_feat(struct perf_header *header, int feat)
{
        set_bit(feat, header->adds_features);
}

void perf_header__clear_feat(struct perf_header *header, int feat)
{
        clear_bit(feat, header->adds_features);
}

bool perf_header__has_feat(const struct perf_header *header, int feat)
{
        return test_bit(feat, header->adds_features);
}

static int __do_write_fd(struct feat_fd *ff, const void *buf, size_t size)
{
        ssize_t ret = writen(ff->fd, buf, size);

        if (ret != (ssize_t)size)
                return ret < 0 ? (int)ret : -1;
        return 0;
}

static int __do_write_buf(struct feat_fd *ff,  const void *buf, size_t size)
{
        /* struct perf_event_header::size is u16 */
        const size_t max_size = 0xffff - sizeof(struct perf_event_header);
        size_t new_size = ff->size;
        void *addr;

        if (size + ff->offset > max_size)
                return -E2BIG;

        while (size > (new_size - ff->offset))
                new_size <<= 1;
        new_size = min(max_size, new_size);

        if (ff->size < new_size) {
                addr = realloc(ff->buf, new_size);
                if (!addr)
                        return -ENOMEM;
                ff->buf = addr;
                ff->size = new_size;
        }

        memcpy(ff->buf + ff->offset, buf, size);
        ff->offset += size;

        return 0;
}

/* Return: 0 if succeded, -ERR if failed. */
int do_write(struct feat_fd *ff, const void *buf, size_t size)
{
        if (!ff->buf)
                return __do_write_fd(ff, buf, size);
        return __do_write_buf(ff, buf, size);
}

/* Return: 0 if succeded, -ERR if failed. */
static int do_write_bitmap(struct feat_fd *ff, unsigned long *set, u64 size)
{
        u64 *p = (u64 *) set;
        int i, ret;

        ret = do_write(ff, &size, sizeof(size));
        if (ret < 0)
                return ret;

        for (i = 0; (u64) i < BITS_TO_U64(size); i++) {
                ret = do_write(ff, p + i, sizeof(*p));
                if (ret < 0)
                        return ret;
        }

        return 0;
}

/* Return: 0 if succeded, -ERR if failed. */
int write_padded(struct feat_fd *ff, const void *bf,
                 size_t count, size_t count_aligned)
{
        static const char zero_buf[NAME_ALIGN];
        int err = do_write(ff, bf, count);

        if (!err)
                err = do_write(ff, zero_buf, count_aligned - count);

        return err;
}

#define string_size(str)                                                \
        (PERF_ALIGN((strlen(str) + 1), NAME_ALIGN) + sizeof(u32))

/* Return: 0 if succeded, -ERR if failed. */
static int do_write_string(struct feat_fd *ff, const char *str)
{
        u32 len, olen;
        int ret;

        olen = strlen(str) + 1;
        len = PERF_ALIGN(olen, NAME_ALIGN);

        /* write len, incl. \0 */
        ret = do_write(ff, &len, sizeof(len));
        if (ret < 0)
                return ret;

        return write_padded(ff, str, olen, len);
}

static int __do_read_fd(struct feat_fd *ff, void *addr, ssize_t size)
{
        ssize_t ret = readn(ff->fd, addr, size);

        if (ret != size)
                return ret < 0 ? (int)ret : -1;
        return 0;
}

static int __do_read_buf(struct feat_fd *ff, void *addr, ssize_t size)
{
        if (size > (ssize_t)ff->size - ff->offset)
                return -1;

        memcpy(addr, ff->buf + ff->offset, size);
        ff->offset += size;

        return 0;

}

static int __do_read(struct feat_fd *ff, void *addr, ssize_t size)
{
        if (!ff->buf)
                return __do_read_fd(ff, addr, size);
        return __do_read_buf(ff, addr, size);
}

static int do_read_u32(struct feat_fd *ff, u32 *addr)
{
        int ret;

        ret = __do_read(ff, addr, sizeof(*addr));
        if (ret)
                return ret;

        if (ff->ph->needs_swap)
                *addr = bswap_32(*addr);
        return 0;
}

static int do_read_u64(struct feat_fd *ff, u64 *addr)
{
        int ret;

        ret = __do_read(ff, addr, sizeof(*addr));
        if (ret)
                return ret;

        if (ff->ph->needs_swap)
                *addr = bswap_64(*addr);
        return 0;
}

static char *do_read_string(struct feat_fd *ff)
{
        u32 len;
        char *buf;

        if (do_read_u32(ff, &len))
                return NULL;

        buf = malloc(len);
        if (!buf)
                return NULL;

        if (!__do_read(ff, buf, len)) {
                /*
                 * strings are padded by zeroes
                 * thus the actual strlen of buf
                 * may be less than len
                 */
                return buf;
        }

        free(buf);
        return NULL;
}

/* Return: 0 if succeded, -ERR if failed. */
static int do_read_bitmap(struct feat_fd *ff, unsigned long **pset, u64 *psize)
{
        unsigned long *set;
        u64 size, *p;
        int i, ret;

        ret = do_read_u64(ff, &size);
        if (ret)
                return ret;

        set = bitmap_alloc(size);
        if (!set)
                return -ENOMEM;

        bitmap_zero(set, size);

        p = (u64 *) set;

        for (i = 0; (u64) i < BITS_TO_U64(size); i++) {
                ret = do_read_u64(ff, p + i);
                if (ret < 0) {
                        free(set);
                        return ret;
                }
        }

        *pset  = set;
        *psize = size;
        return 0;
}

static int write_tracing_data(struct feat_fd *ff,
                              struct perf_evlist *evlist)
{
        if (WARN(ff->buf, "Error: calling %s in pipe-mode.\n", __func__))
                return -1;

        return read_tracing_data(ff->fd, &evlist->entries);
}

static int write_build_id(struct feat_fd *ff,
                          struct perf_evlist *evlist __maybe_unused)
{
        struct perf_session *session;
        int err;

        session = container_of(ff->ph, struct perf_session, header);

        if (!perf_session__read_build_ids(session, true))
                return -1;

        if (WARN(ff->buf, "Error: calling %s in pipe-mode.\n", __func__))
                return -1;

        err = perf_session__write_buildid_table(session, ff);
        if (err < 0) {
                pr_debug("failed to write buildid table\n");
                return err;
        }
        perf_session__cache_build_ids(session);

        return 0;
}

static int write_hostname(struct feat_fd *ff,
                          struct perf_evlist *evlist __maybe_unused)
{
        struct utsname uts;
        int ret;

        ret = uname(&uts);
        if (ret < 0)
                return -1;

        return do_write_string(ff, uts.nodename);
}

static int write_osrelease(struct feat_fd *ff,
                           struct perf_evlist *evlist __maybe_unused)
{
        struct utsname uts;
        int ret;

        ret = uname(&uts);
        if (ret < 0)
                return -1;

        return do_write_string(ff, uts.release);
}

static int write_arch(struct feat_fd *ff,
                      struct perf_evlist *evlist __maybe_unused)
{
        struct utsname uts;
        int ret;

        ret = uname(&uts);
        if (ret < 0)
                return -1;

        return do_write_string(ff, uts.machine);
}

static int write_version(struct feat_fd *ff,
                         struct perf_evlist *evlist __maybe_unused)
{
        return do_write_string(ff, perf_version_string);
}

static int __write_cpudesc(struct feat_fd *ff, const char *cpuinfo_proc)
{
        FILE *file;
        char *buf = NULL;
        char *s, *p;
        const char *search = cpuinfo_proc;
        size_t len = 0;
        int ret = -1;

        if (!search)
                return -1;

        file = fopen("/proc/cpuinfo", "r");
        if (!file)
                return -1;

        while (getline(&buf, &len, file) > 0) {
                ret = strncmp(buf, search, strlen(search));
                if (!ret)
                        break;
        }

        if (ret) {
                ret = -1;
                goto done;
        }

        s = buf;

        p = strchr(buf, ':');
        if (p && *(p+1) == ' ' && *(p+2))
                s = p + 2;
        p = strchr(s, '\n');
        if (p)
                *p = '\0';

        /* squash extra space characters (branding string) */
        p = s;
        while (*p) {
                if (isspace(*p)) {
                        char *r = p + 1;
                        char *q = r;
                        *p = ' ';
                        while (*q && isspace(*q))
                                q++;
                        if (q != (p+1))
                                while ((*r++ = *q++));
                }
                p++;
        }
        ret = do_write_string(ff, s);
done:
        free(buf);
        fclose(file);
        return ret;
}

static int write_cpudesc(struct feat_fd *ff,
                       struct perf_evlist *evlist __maybe_unused)
{
        const char *cpuinfo_procs[] = CPUINFO_PROC;
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(cpuinfo_procs); i++) {
                int ret;
                ret = __write_cpudesc(ff, cpuinfo_procs[i]);
                if (ret >= 0)
                        return ret;
        }
        return -1;
}


static int write_nrcpus(struct feat_fd *ff,
                        struct perf_evlist *evlist __maybe_unused)
{
        long nr;
        u32 nrc, nra;
        int ret;

        nrc = cpu__max_present_cpu();

        nr = sysconf(_SC_NPROCESSORS_ONLN);
        if (nr < 0)
                return -1;

        nra = (u32)(nr & UINT_MAX);

        ret = do_write(ff, &nrc, sizeof(nrc));
        if (ret < 0)
                return ret;

        return do_write(ff, &nra, sizeof(nra));
}

static int write_event_desc(struct feat_fd *ff,
                            struct perf_evlist *evlist)
{
        struct perf_evsel *evsel;
        u32 nre, nri, sz;
        int ret;

        nre = evlist->nr_entries;

        /*
         * write number of events
         */
        ret = do_write(ff, &nre, sizeof(nre));
        if (ret < 0)
                return ret;

        /*
         * size of perf_event_attr struct
         */
        sz = (u32)sizeof(evsel->attr);
        ret = do_write(ff, &sz, sizeof(sz));
        if (ret < 0)
                return ret;

        evlist__for_each_entry(evlist, evsel) {
                ret = do_write(ff, &evsel->attr, sz);
                if (ret < 0)
                        return ret;
                /*
                 * write number of unique id per event
                 * there is one id per instance of an event
                 *
                 * copy into an nri to be independent of the
                 * type of ids,
                 */
                nri = evsel->ids;
                ret = do_write(ff, &nri, sizeof(nri));
                if (ret < 0)
                        return ret;

                /*
                 * write event string as passed on cmdline
                 */
                ret = do_write_string(ff, perf_evsel__name(evsel));
                if (ret < 0)
                        return ret;
                /*
                 * write unique ids for this event
                 */
                ret = do_write(ff, evsel->id, evsel->ids * sizeof(u64));
                if (ret < 0)
                        return ret;
        }
        return 0;
}

static int write_cmdline(struct feat_fd *ff,
                         struct perf_evlist *evlist __maybe_unused)
{
        char buf[MAXPATHLEN];
        u32 n;
        int i, ret;

        /* actual path to perf binary */
        ret = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
        if (ret <= 0)
                return -1;

        /* readlink() does not add null termination */
        buf[ret] = '\0';

        /* account for binary path */
        n = perf_env.nr_cmdline + 1;

        ret = do_write(ff, &n, sizeof(n));
        if (ret < 0)
                return ret;

        ret = do_write_string(ff, buf);
        if (ret < 0)
                return ret;

        for (i = 0 ; i < perf_env.nr_cmdline; i++) {
                ret = do_write_string(ff, perf_env.cmdline_argv[i]);
                if (ret < 0)
                        return ret;
        }
        return 0;
}

#define CORE_SIB_FMT \
        "/sys/devices/system/cpu/cpu%d/topology/core_siblings_list"
#define THRD_SIB_FMT \
        "/sys/devices/system/cpu/cpu%d/topology/thread_siblings_list"

struct cpu_topo {
        u32 cpu_nr;
        u32 core_sib;
        u32 thread_sib;
        char **core_siblings;
        char **thread_siblings;
};

static int build_cpu_topo(struct cpu_topo *tp, int cpu)
{
        FILE *fp;
        char filename[MAXPATHLEN];
        char *buf = NULL, *p;
        size_t len = 0;
        ssize_t sret;
        u32 i = 0;
        int ret = -1;

        sprintf(filename, CORE_SIB_FMT, cpu);
        fp = fopen(filename, "r");
        if (!fp)
                goto try_threads;

        sret = getline(&buf, &len, fp);
        fclose(fp);
        if (sret <= 0)
                goto try_threads;

        p = strchr(buf, '\n');
        if (p)
                *p = '\0';

        for (i = 0; i < tp->core_sib; i++) {
                if (!strcmp(buf, tp->core_siblings[i]))
                        break;
        }
        if (i == tp->core_sib) {
                tp->core_siblings[i] = buf;
                tp->core_sib++;
                buf = NULL;
                len = 0;
        }
        ret = 0;

try_threads:
        sprintf(filename, THRD_SIB_FMT, cpu);
        fp = fopen(filename, "r");
        if (!fp)
                goto done;

        if (getline(&buf, &len, fp) <= 0)
                goto done;

        p = strchr(buf, '\n');
        if (p)
                *p = '\0';

        for (i = 0; i < tp->thread_sib; i++) {
                if (!strcmp(buf, tp->thread_siblings[i]))
                        break;
        }
        if (i == tp->thread_sib) {
                tp->thread_siblings[i] = buf;
                tp->thread_sib++;
                buf = NULL;
        }
        ret = 0;
done:
        if(fp)
                fclose(fp);
        free(buf);
        return ret;
}

static void free_cpu_topo(struct cpu_topo *tp)
{
        u32 i;

        if (!tp)
                return;

        for (i = 0 ; i < tp->core_sib; i++)
                zfree(&tp->core_siblings[i]);

        for (i = 0 ; i < tp->thread_sib; i++)
                zfree(&tp->thread_siblings[i]);

        free(tp);
}

static struct cpu_topo *build_cpu_topology(void)
{
        struct cpu_topo *tp = NULL;
        void *addr;
        u32 nr, i;
        size_t sz;
        long ncpus;
        int ret = -1;
        struct cpu_map *map;

        ncpus = cpu__max_present_cpu();

        /* build online CPU map */
        map = cpu_map__new(NULL);
        if (map == NULL) {
                pr_debug("failed to get system cpumap\n");
                return NULL;
        }

        nr = (u32)(ncpus & UINT_MAX);

        sz = nr * sizeof(char *);
        addr = calloc(1, sizeof(*tp) + 2 * sz);
        if (!addr)
                goto out_free;

        tp = addr;
        tp->cpu_nr = nr;
        addr += sizeof(*tp);
        tp->core_siblings = addr;
        addr += sz;
        tp->thread_siblings = addr;

        for (i = 0; i < nr; i++) {
                if (!cpu_map__has(map, i))
                        continue;

                ret = build_cpu_topo(tp, i);
                if (ret < 0)
                        break;
        }

out_free:
        cpu_map__put(map);
        if (ret) {
                free_cpu_topo(tp);
                tp = NULL;
        }
        return tp;
}

static int write_cpu_topology(struct feat_fd *ff,
                              struct perf_evlist *evlist __maybe_unused)
{
        struct cpu_topo *tp;
        u32 i;
        int ret, j;

        tp = build_cpu_topology();
        if (!tp)
                return -1;

        ret = do_write(ff, &tp->core_sib, sizeof(tp->core_sib));
        if (ret < 0)
                goto done;

        for (i = 0; i < tp->core_sib; i++) {
                ret = do_write_string(ff, tp->core_siblings[i]);
                if (ret < 0)
                        goto done;
        }
        ret = do_write(ff, &tp->thread_sib, sizeof(tp->thread_sib));
        if (ret < 0)
                goto done;

        for (i = 0; i < tp->thread_sib; i++) {
                ret = do_write_string(ff, tp->thread_siblings[i]);
                if (ret < 0)
                        break;
        }

        ret = perf_env__read_cpu_topology_map(&perf_env);
        if (ret < 0)
                goto done;

        for (j = 0; j < perf_env.nr_cpus_avail; j++) {
                ret = do_write(ff, &perf_env.cpu[j].core_id,
                               sizeof(perf_env.cpu[j].core_id));
                if (ret < 0)
                        return ret;
                ret = do_write(ff, &perf_env.cpu[j].socket_id,
                               sizeof(perf_env.cpu[j].socket_id));
                if (ret < 0)
                        return ret;
        }
done:
        free_cpu_topo(tp);
        return ret;
}



static int write_total_mem(struct feat_fd *ff,
                           struct perf_evlist *evlist __maybe_unused)
{
        char *buf = NULL;
        FILE *fp;
        size_t len = 0;
        int ret = -1, n;
        uint64_t mem;

        fp = fopen("/proc/meminfo", "r");
        if (!fp)
                return -1;

        while (getline(&buf, &len, fp) > 0) {
                ret = strncmp(buf, "MemTotal:", 9);
                if (!ret)
                        break;
        }
        if (!ret) {
                n = sscanf(buf, "%*s %"PRIu64, &mem);
                if (n == 1)
                        ret = do_write(ff, &mem, sizeof(mem));
        } else
                ret = -1;
        free(buf);
        fclose(fp);
        return ret;
}

static int write_topo_node(struct feat_fd *ff, int node)
{
        char str[MAXPATHLEN];
        char field[32];
        char *buf = NULL, *p;
        size_t len = 0;
        FILE *fp;
        u64 mem_total, mem_free, mem;
        int ret = -1;

        sprintf(str, "/sys/devices/system/node/node%d/meminfo", node);
        fp = fopen(str, "r");
        if (!fp)
                return -1;

        while (getline(&buf, &len, fp) > 0) {
                /* skip over invalid lines */
                if (!strchr(buf, ':'))
                        continue;
                if (sscanf(buf, "%*s %*d %31s %"PRIu64, field, &mem) != 2)
                        goto done;
                if (!strcmp(field, "MemTotal:"))
                        mem_total = mem;
                if (!strcmp(field, "MemFree:"))
                        mem_free = mem;
        }

        fclose(fp);
        fp = NULL;

        ret = do_write(ff, &mem_total, sizeof(u64));
        if (ret)
                goto done;

        ret = do_write(ff, &mem_free, sizeof(u64));
        if (ret)
                goto done;

        ret = -1;
        sprintf(str, "/sys/devices/system/node/node%d/cpulist", node);

        fp = fopen(str, "r");
        if (!fp)
                goto done;

        if (getline(&buf, &len, fp) <= 0)
                goto done;

        p = strchr(buf, '\n');
        if (p)
                *p = '\0';

        ret = do_write_string(ff, buf);
done:
        free(buf);
        if (fp)
                fclose(fp);
        return ret;
}

static int write_numa_topology(struct feat_fd *ff,
                               struct perf_evlist *evlist __maybe_unused)
{
        char *buf = NULL;
        size_t len = 0;
        FILE *fp;
        struct cpu_map *node_map = NULL;
        char *c;
        u32 nr, i, j;
        int ret = -1;

        fp = fopen("/sys/devices/system/node/online", "r");
        if (!fp)
                return -1;

        if (getline(&buf, &len, fp) <= 0)
                goto done;

        c = strchr(buf, '\n');
        if (c)
                *c = '\0';

        node_map = cpu_map__new(buf);
        if (!node_map)
                goto done;

        nr = (u32)node_map->nr;

        ret = do_write(ff, &nr, sizeof(nr));
        if (ret < 0)
                goto done;

        for (i = 0; i < nr; i++) {
                j = (u32)node_map->map[i];
                ret = do_write(ff, &j, sizeof(j));
                if (ret < 0)
                        break;

                ret = write_topo_node(ff, i);
                if (ret < 0)
                        break;
        }
done:
        free(buf);
        fclose(fp);
        cpu_map__put(node_map);
        return ret;
}

/*
 * File format:
 *
 * struct pmu_mappings {
 *      u32     pmu_num;
 *      struct pmu_map {
 *              u32     type;
 *              char    name[];
 *      }[pmu_num];
 * };
 */

static int write_pmu_mappings(struct feat_fd *ff,
                              struct perf_evlist *evlist __maybe_unused)
{
        struct perf_pmu *pmu = NULL;
        u32 pmu_num = 0;
        int ret;

        /*
         * Do a first pass to count number of pmu to avoid lseek so this
         * works in pipe mode as well.
         */
        while ((pmu = perf_pmu__scan(pmu))) {
                if (!pmu->name)
                        continue;
                pmu_num++;
        }

        ret = do_write(ff, &pmu_num, sizeof(pmu_num));
        if (ret < 0)
                return ret;

        while ((pmu = perf_pmu__scan(pmu))) {
                if (!pmu->name)
                        continue;

                ret = do_write(ff, &pmu->type, sizeof(pmu->type));
                if (ret < 0)
                        return ret;

                ret = do_write_string(ff, pmu->name);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

/*
 * File format:
 *
 * struct group_descs {
 *      u32     nr_groups;
 *      struct group_desc {
 *              char    name[];
 *              u32     leader_idx;
 *              u32     nr_members;
 *      }[nr_groups];
 * };
 */
static int write_group_desc(struct feat_fd *ff,
                            struct perf_evlist *evlist)
{
        u32 nr_groups = evlist->nr_groups;
        struct perf_evsel *evsel;
        int ret;

        ret = do_write(ff, &nr_groups, sizeof(nr_groups));
        if (ret < 0)
                return ret;

        evlist__for_each_entry(evlist, evsel) {
                if (perf_evsel__is_group_leader(evsel) &&
                    evsel->nr_members > 1) {
                        const char *name = evsel->group_name ?: "{anon_group}";
                        u32 leader_idx = evsel->idx;
                        u32 nr_members = evsel->nr_members;

                        ret = do_write_string(ff, name);
                        if (ret < 0)
                                return ret;

                        ret = do_write(ff, &leader_idx, sizeof(leader_idx));
                        if (ret < 0)
                                return ret;

                        ret = do_write(ff, &nr_members, sizeof(nr_members));
                        if (ret < 0)
                                return ret;
                }
        }
        return 0;
}

/*
 * default get_cpuid(): nothing gets recorded
 * actual implementation must be in arch/$(SRCARCH)/util/header.c
 */
int __weak get_cpuid(char *buffer __maybe_unused, size_t sz __maybe_unused)
{
        return -1;
}

static int write_cpuid(struct feat_fd *ff,
                       struct perf_evlist *evlist __maybe_unused)
{
        char buffer[64];
        int ret;

        ret = get_cpuid(buffer, sizeof(buffer));
        if (!ret)
                goto write_it;

        return -1;
write_it:
        return do_write_string(ff, buffer);
}

static int write_branch_stack(struct feat_fd *ff __maybe_unused,
                              struct perf_evlist *evlist __maybe_unused)
{
        return 0;
}

static int write_auxtrace(struct feat_fd *ff,
                          struct perf_evlist *evlist __maybe_unused)
{
        struct perf_session *session;
        int err;

        if (WARN(ff->buf, "Error: calling %s in pipe-mode.\n", __func__))
                return -1;

        session = container_of(ff->ph, struct perf_session, header);

        err = auxtrace_index__write(ff->fd, &session->auxtrace_index);
        if (err < 0)
                pr_err("Failed to write auxtrace index\n");
        return err;
}

static int cpu_cache_level__sort(const void *a, const void *b)
{
        struct cpu_cache_level *cache_a = (struct cpu_cache_level *)a;
        struct cpu_cache_level *cache_b = (struct cpu_cache_level *)b;

        return cache_a->level - cache_b->level;
}

static bool cpu_cache_level__cmp(struct cpu_cache_level *a, struct cpu_cache_level *b)
{
        if (a->level != b->level)
                return false;

        if (a->line_size != b->line_size)
                return false;

        if (a->sets != b->sets)
                return false;

        if (a->ways != b->ways)
                return false;

        if (strcmp(a->type, b->type))
                return false;

        if (strcmp(a->size, b->size))
                return false;

        if (strcmp(a->map, b->map))
                return false;

        return true;
}

static int cpu_cache_level__read(struct cpu_cache_level *cache, u32 cpu, u16 level)
{
        char path[PATH_MAX], file[PATH_MAX];
        struct stat st;
        size_t len;

        scnprintf(path, PATH_MAX, "devices/system/cpu/cpu%d/cache/index%d/", cpu, level);
        scnprintf(file, PATH_MAX, "%s/%s", sysfs__mountpoint(), path);

        if (stat(file, &st))
                return 1;

        scnprintf(file, PATH_MAX, "%s/level", path);
        if (sysfs__read_int(file, (int *) &cache->level))
                return -1;

        scnprintf(file, PATH_MAX, "%s/coherency_line_size", path);
        if (sysfs__read_int(file, (int *) &cache->line_size))
                return -1;

        scnprintf(file, PATH_MAX, "%s/number_of_sets", path);
        if (sysfs__read_int(file, (int *) &cache->sets))
                return -1;

        scnprintf(file, PATH_MAX, "%s/ways_of_associativity", path);
        if (sysfs__read_int(file, (int *) &cache->ways))
                return -1;

        scnprintf(file, PATH_MAX, "%s/type", path);
        if (sysfs__read_str(file, &cache->type, &len))
                return -1;

        cache->type[len] = 0;
        cache->type = rtrim(cache->type);

        scnprintf(file, PATH_MAX, "%s/size", path);
        if (sysfs__read_str(file, &cache->size, &len)) {
                free(cache->type);
                return -1;
        }

        cache->size[len] = 0;
        cache->size = rtrim(cache->size);

        scnprintf(file, PATH_MAX, "%s/shared_cpu_list", path);
        if (sysfs__read_str(file, &cache->map, &len)) {
                free(cache->map);
                free(cache->type);
                return -1;
        }

        cache->map[len] = 0;
        cache->map = rtrim(cache->map);
        return 0;
}

static void cpu_cache_level__fprintf(FILE *out, struct cpu_cache_level *c)
{
        fprintf(out, "L%d %-15s %8s [%s]\n", c->level, c->type, c->size, c->map);
}

static int build_caches(struct cpu_cache_level caches[], u32 size, u32 *cntp)
{
        u32 i, cnt = 0;
        long ncpus;
        u32 nr, cpu;
        u16 level;

        ncpus = sysconf(_SC_NPROCESSORS_CONF);
        if (ncpus < 0)
                return -1;

        nr = (u32)(ncpus & UINT_MAX);

        for (cpu = 0; cpu < nr; cpu++) {
                for (level = 0; level < 10; level++) {
                        struct cpu_cache_level c;
                        int err;

                        err = cpu_cache_level__read(&c, cpu, level);
                        if (err < 0)
                                return err;

                        if (err == 1)
                                break;

                        for (i = 0; i < cnt; i++) {
                                if (cpu_cache_level__cmp(&c, &caches[i]))
                                        break;
                        }

                        if (i == cnt)
                                caches[cnt++] = c;
                        else
                                cpu_cache_level__free(&c);

                        if (WARN_ONCE(cnt == size, "way too many cpu caches.."))
                                goto out;
                }
        }
 out:
        *cntp = cnt;
        return 0;
}

#define MAX_CACHES 2000

static int write_cache(struct feat_fd *ff,
                       struct perf_evlist *evlist __maybe_unused)
{
        struct cpu_cache_level caches[MAX_CACHES];
        u32 cnt = 0, i, version = 1;
        int ret;

        ret = build_caches(caches, MAX_CACHES, &cnt);
        if (ret)
                goto out;

        qsort(&caches, cnt, sizeof(struct cpu_cache_level), cpu_cache_level__sort);

        ret = do_write(ff, &version, sizeof(u32));
        if (ret < 0)
                goto out;

        ret = do_write(ff, &cnt, sizeof(u32));
        if (ret < 0)
                goto out;

        for (i = 0; i < cnt; i++) {
                struct cpu_cache_level *c = &caches[i];

                #define _W(v)                                   \
                        ret = do_write(ff, &c->v, sizeof(u32)); \
                        if (ret < 0)                            \
                                goto out;

                _W(level)
                _W(line_size)
                _W(sets)
                _W(ways)
                #undef _W

                #define _W(v)                                           \
                        ret = do_write_string(ff, (const char *) c->v); \
                        if (ret < 0)                                    \
                                goto out;

                _W(type)
                _W(size)
                _W(map)
                #undef _W
        }

out:
        for (i = 0; i < cnt; i++)
                cpu_cache_level__free(&caches[i]);
        return ret;
}

static int write_stat(struct feat_fd *ff __maybe_unused,
                      struct perf_evlist *evlist __maybe_unused)
{
        return 0;
}

static int write_sample_time(struct feat_fd *ff,
                             struct perf_evlist *evlist)
{
        int ret;

        ret = do_write(ff, &evlist->first_sample_time,
                       sizeof(evlist->first_sample_time));
        if (ret < 0)
                return ret;

        return do_write(ff, &evlist->last_sample_time,
                        sizeof(evlist->last_sample_time));
}


static int memory_node__read(struct memory_node *n, unsigned long idx)
{
        unsigned int phys, size = 0;
        char path[PATH_MAX];
        struct dirent *ent;
        DIR *dir;

#define for_each_memory(mem, dir)                                       \
        while ((ent = readdir(dir)))                                    \
                if (strcmp(ent->d_name, ".") &&                         \
                    strcmp(ent->d_name, "..") &&                        \
                    sscanf(ent->d_name, "memory%u", &mem) == 1)

        scnprintf(path, PATH_MAX,
                  "%s/devices/system/node/node%lu",
                  sysfs__mountpoint(), idx);

        dir = opendir(path);
        if (!dir) {
                pr_warning("failed: cant' open memory sysfs data\n");
                return -1;
        }

        for_each_memory(phys, dir) {
                size = max(phys, size);
        }

        size++;

        n->set = bitmap_alloc(size);
        if (!n->set) {
                closedir(dir);
                return -ENOMEM;
        }

        bitmap_zero(n->set, size);
        n->node = idx;
        n->size = size;

        rewinddir(dir);

        for_each_memory(phys, dir) {
                set_bit(phys, n->set);
        }

        closedir(dir);
        return 0;
}

static int memory_node__sort(const void *a, const void *b)
{
        const struct memory_node *na = a;
        const struct memory_node *nb = b;

        return na->node - nb->node;
}

static int build_mem_topology(struct memory_node *nodes, u64 size, u64 *cntp)
{
        char path[PATH_MAX];
        struct dirent *ent;
        DIR *dir;
        u64 cnt = 0;
        int ret = 0;

        scnprintf(path, PATH_MAX, "%s/devices/system/node/",
                  sysfs__mountpoint());

        dir = opendir(path);
        if (!dir) {
                pr_debug2("%s: could't read %s, does this arch have topology information?\n",
                          __func__, path);
                return -1;
        }

        while (!ret && (ent = readdir(dir))) {
                unsigned int idx;
                int r;

                if (!strcmp(ent->d_name, ".") ||
                    !strcmp(ent->d_name, ".."))
                        continue;

                r = sscanf(ent->d_name, "node%u", &idx);
                if (r != 1)
                        continue;

                if (WARN_ONCE(cnt >= size,
                              "failed to write MEM_TOPOLOGY, way too many nodes\n"))
                        return -1;

                ret = memory_node__read(&nodes[cnt++], idx);
        }

        *cntp = cnt;
        closedir(dir);

        if (!ret)
                qsort(nodes, cnt, sizeof(nodes[0]), memory_node__sort);

        return ret;
}

#define MAX_MEMORY_NODES 2000

/*
 * The MEM_TOPOLOGY holds physical memory map for every
 * node in system. The format of data is as follows:
 *
 *  0 - version          | for future changes
 *  8 - block_size_bytes | /sys/devices/system/memory/block_size_bytes
 * 16 - count            | number of nodes
 *
 * For each node we store map of physical indexes for
 * each node:
 *
 * 32 - node id          | node index
 * 40 - size             | size of bitmap
 * 48 - bitmap           | bitmap of memory indexes that belongs to node
 */
static int write_mem_topology(struct feat_fd *ff __maybe_unused,
                              struct perf_evlist *evlist __maybe_unused)
{
        static struct memory_node nodes[MAX_MEMORY_NODES];
        u64 bsize, version = 1, i, nr;
        int ret;

        ret = sysfs__read_xll("devices/system/memory/block_size_bytes",
                              (unsigned long long *) &bsize);
        if (ret)
                return ret;

        ret = build_mem_topology(&nodes[0], MAX_MEMORY_NODES, &nr);
        if (ret)
                return ret;

        ret = do_write(ff, &version, sizeof(version));
        if (ret < 0)
                goto out;

        ret = do_write(ff, &bsize, sizeof(bsize));
        if (ret < 0)
                goto out;

        ret = do_write(ff, &nr, sizeof(nr));
        if (ret < 0)
                goto out;

        for (i = 0; i < nr; i++) {
                struct memory_node *n = &nodes[i];

                #define _W(v)                                           \
                        ret = do_write(ff, &n->v, sizeof(n->v));        \
                        if (ret < 0)                                    \
                                goto out;

                _W(node)
                _W(size)

                #undef _W

                ret = do_write_bitmap(ff, n->set, n->size);
                if (ret < 0)
                        goto out;
        }

out:
        return ret;
}

static void print_hostname(struct feat_fd *ff, FILE *fp)
{
        fprintf(fp, "# hostname : %s\n", ff->ph->env.hostname);
}

static void print_osrelease(struct feat_fd *ff, FILE *fp)
{
        fprintf(fp, "# os release : %s\n", ff->ph->env.os_release);
}

static void print_arch(struct feat_fd *ff, FILE *fp)
{
        fprintf(fp, "# arch : %s\n", ff->ph->env.arch);
}

static void print_cpudesc(struct feat_fd *ff, FILE *fp)
{
        fprintf(fp, "# cpudesc : %s\n", ff->ph->env.cpu_desc);
}

static void print_nrcpus(struct feat_fd *ff, FILE *fp)
{
        fprintf(fp, "# nrcpus online : %u\n", ff->ph->env.nr_cpus_online);
        fprintf(fp, "# nrcpus avail : %u\n", ff->ph->env.nr_cpus_avail);
}

static void print_version(struct feat_fd *ff, FILE *fp)
{
        fprintf(fp, "# perf version : %s\n", ff->ph->env.version);
}

static void print_cmdline(struct feat_fd *ff, FILE *fp)
{
        int nr, i;

        nr = ff->ph->env.nr_cmdline;

        fprintf(fp, "# cmdline : ");

        for (i = 0; i < nr; i++)
                fprintf(fp, "%s ", ff->ph->env.cmdline_argv[i]);
        fputc('\n', fp);
}

static void print_cpu_topology(struct feat_fd *ff, FILE *fp)
{
        struct perf_header *ph = ff->ph;
        int cpu_nr = ph->env.nr_cpus_avail;
        int nr, i;
        char *str;

        nr = ph->env.nr_sibling_cores;
        str = ph->env.sibling_cores;

        for (i = 0; i < nr; i++) {
                fprintf(fp, "# sibling cores   : %s\n", str);
                str += strlen(str) + 1;
        }

        nr = ph->env.nr_sibling_threads;
        str = ph->env.sibling_threads;

        for (i = 0; i < nr; i++) {
                fprintf(fp, "# sibling threads : %s\n", str);
                str += strlen(str) + 1;
        }

        if (ph->env.cpu != NULL) {
                for (i = 0; i < cpu_nr; i++)
                        fprintf(fp, "# CPU %d: Core ID %d, Socket ID %d\n", i,
                                ph->env.cpu[i].core_id, ph->env.cpu[i].socket_id);
        } else
                fprintf(fp, "# Core ID and Socket ID information is not available\n");
}

static void free_event_desc(struct perf_evsel *events)
{
        struct perf_evsel *evsel;

        if (!events)
                return;

        for (evsel = events; evsel->attr.size; evsel++) {
                zfree(&evsel->name);
                zfree(&evsel->id);
        }

        free(events);
}

static struct perf_evsel *read_event_desc(struct feat_fd *ff)
{
        struct perf_evsel *evsel, *events = NULL;
        u64 *id;
        void *buf = NULL;
        u32 nre, sz, nr, i, j;
        size_t msz;

        /* number of events */
        if (do_read_u32(ff, &nre))
                goto error;

        if (do_read_u32(ff, &sz))
                goto error;

        /* buffer to hold on file attr struct */
        buf = malloc(sz);
        if (!buf)
                goto error;

        /* the last event terminates with evsel->attr.size == 0: */
        events = calloc(nre + 1, sizeof(*events));
        if (!events)
                goto error;

        msz = sizeof(evsel->attr);
        if (sz < msz)
                msz = sz;

        for (i = 0, evsel = events; i < nre; evsel++, i++) {
                evsel->idx = i;

                /*
                 * must read entire on-file attr struct to
                 * sync up with layout.
                 */
                if (__do_read(ff, buf, sz))
                        goto error;

                if (ff->ph->needs_swap)
                        perf_event__attr_swap(buf);

                memcpy(&evsel->attr, buf, msz);

                if (do_read_u32(ff, &nr))
                        goto error;

                if (ff->ph->needs_swap)
                        evsel->needs_swap = true;

                evsel->name = do_read_string(ff);
                if (!evsel->name)
                        goto error;

                if (!nr)
                        continue;

                id = calloc(nr, sizeof(*id));
                if (!id)
                        goto error;
                evsel->ids = nr;
                evsel->id = id;

                for (j = 0 ; j < nr; j++) {
                        if (do_read_u64(ff, id))
                                goto error;
                        id++;
                }
        }
out:
        free(buf);
        return events;
error:
        free_event_desc(events);
        events = NULL;
        goto out;
}

static int __desc_attr__fprintf(FILE *fp, const char *name, const char *val,
                                void *priv __maybe_unused)
{
        return fprintf(fp, ", %s = %s", name, val);
}

static void print_event_desc(struct feat_fd *ff, FILE *fp)
{
        struct perf_evsel *evsel, *events;
        u32 j;
        u64 *id;

        if (ff->events)
                events = ff->events;
        else
                events = read_event_desc(ff);

        if (!events) {
                fprintf(fp, "# event desc: not available or unable to read\n");
                return;
        }

        for (evsel = events; evsel->attr.size; evsel++) {
                fprintf(fp, "# event : name = %s, ", evsel->name);

                if (evsel->ids) {
                        fprintf(fp, ", id = {");
                        for (j = 0, id = evsel->id; j < evsel->ids; j++, id++) {
                                if (j)
                                        fputc(',', fp);
                                fprintf(fp, " %"PRIu64, *id);
                        }
                        fprintf(fp, " }");
                }

                perf_event_attr__fprintf(fp, &evsel->attr, __desc_attr__fprintf, NULL);

                fputc('\n', fp);
        }

        free_event_desc(events);
        ff->events = NULL;
}

static void print_total_mem(struct feat_fd *ff, FILE *fp)
{
        fprintf(fp, "# total memory : %llu kB\n", ff->ph->env.total_mem);
}

static void print_numa_topology(struct feat_fd *ff, FILE *fp)
{
        int i;
        struct numa_node *n;

        for (i = 0; i < ff->ph->env.nr_numa_nodes; i++) {
                n = &ff->ph->env.numa_nodes[i];

                fprintf(fp, "# node%u meminfo  : total = %"PRIu64" kB,"
                            " free = %"PRIu64" kB\n",
                        n->node, n->mem_total, n->mem_free);

                fprintf(fp, "# node%u cpu list : ", n->node);
                cpu_map__fprintf(n->map, fp);
        }
}

static void print_cpuid(struct feat_fd *ff, FILE *fp)
{
        fprintf(fp, "# cpuid : %s\n", ff->ph->env.cpuid);
}

static void print_branch_stack(struct feat_fd *ff __maybe_unused, FILE *fp)
{
        fprintf(fp, "# contains samples with branch stack\n");
}

static void print_auxtrace(struct feat_fd *ff __maybe_unused, FILE *fp)
{
        fprintf(fp, "# contains AUX area data (e.g. instruction trace)\n");
}

static void print_stat(struct feat_fd *ff __maybe_unused, FILE *fp)
{
        fprintf(fp, "# contains stat data\n");
}

static void print_cache(struct feat_fd *ff, FILE *fp __maybe_unused)
{
        int i;

        fprintf(fp, "# CPU cache info:\n");
        for (i = 0; i < ff->ph->env.caches_cnt; i++) {
                fprintf(fp, "#  ");
                cpu_cache_level__fprintf(fp, &ff->ph->env.caches[i]);
        }
}

static void print_pmu_mappings(struct feat_fd *ff, FILE *fp)
{
        const char *delimiter = "# pmu mappings: ";
        char *str, *tmp;
        u32 pmu_num;
        u32 type;

        pmu_num = ff->ph->env.nr_pmu_mappings;
        if (!pmu_num) {
                fprintf(fp, "# pmu mappings: not available\n");
                return;
        }

        str = ff->ph->env.pmu_mappings;

        while (pmu_num) {
                type = strtoul(str, &tmp, 0);
                if (*tmp != ':')
                        goto error;

                str = tmp + 1;
                fprintf(fp, "%s%s = %" PRIu32, delimiter, str, type);

                delimiter = ", ";
                str += strlen(str) + 1;
                pmu_num--;
        }

        fprintf(fp, "\n");

        if (!pmu_num)
                return;
error:
        fprintf(fp, "# pmu mappings: unable to read\n");
}

static void print_group_desc(struct feat_fd *ff, FILE *fp)
{
        struct perf_session *session;
        struct perf_evsel *evsel;
        u32 nr = 0;

        session = container_of(ff->ph, struct perf_session, header);

        evlist__for_each_entry(session->evlist, evsel) {
                if (perf_evsel__is_group_leader(evsel) &&
                    evsel->nr_members > 1) {
                        fprintf(fp, "# group: %s{%s", evsel->group_name ?: "",
                                perf_evsel__name(evsel));

                        nr = evsel->nr_members - 1;
                } else if (nr) {
                        fprintf(fp, ",%s", perf_evsel__name(evsel));

                        if (--nr == 0)
                                fprintf(fp, "}\n");
                }
        }
}

static void print_sample_time(struct feat_fd *ff, FILE *fp)
{
        struct perf_session *session;
        char time_buf[32];
        double d;

        session = container_of(ff->ph, struct perf_session, header);

        timestamp__scnprintf_usec(session->evlist->first_sample_time,
                                  time_buf, sizeof(time_buf));
        fprintf(fp, "# time of first sample : %s\n", time_buf);

        timestamp__scnprintf_usec(session->evlist->last_sample_time,
                                  time_buf, sizeof(time_buf));
        fprintf(fp, "# time of last sample : %s\n", time_buf);

        d = (double)(session->evlist->last_sample_time -
                session->evlist->first_sample_time) / NSEC_PER_MSEC;

        fprintf(fp, "# sample duration : %10.3f ms\n", d);
}

static void memory_node__fprintf(struct memory_node *n,
                                 unsigned long long bsize, FILE *fp)
{
        char buf_map[100], buf_size[50];
        unsigned long long size;

        size = bsize * bitmap_weight(n->set, n->size);
        unit_number__scnprintf(buf_size, 50, size);

        bitmap_scnprintf(n->set, n->size, buf_map, 100);
        fprintf(fp, "#  %3" PRIu64 " [%s]: %s\n", n->node, buf_size, buf_map);
}

static void print_mem_topology(struct feat_fd *ff, FILE *fp)
{
        struct memory_node *nodes;
        int i, nr;

        nodes = ff->ph->env.memory_nodes;
        nr    = ff->ph->env.nr_memory_nodes;

        fprintf(fp, "# memory nodes (nr %d, block size 0x%llx):\n",
                nr, ff->ph->env.memory_bsize);

        for (i = 0; i < nr; i++) {
                memory_node__fprintf(&nodes[i], ff->ph->env.memory_bsize, fp);
        }
}

static int __event_process_build_id(struct build_id_event *bev,
                                    char *filename,
                                    struct perf_session *session)
{
        int err = -1;
        struct machine *machine;
        u16 cpumode;
        struct dso *dso;
        enum dso_kernel_type dso_type;

        machine = perf_session__findnew_machine(session, bev->pid);
        if (!machine)
                goto out;

        cpumode = bev->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;

        switch (cpumode) {
        case PERF_RECORD_MISC_KERNEL:
                dso_type = DSO_TYPE_KERNEL;
                break;
        case PERF_RECORD_MISC_GUEST_KERNEL:
                dso_type = DSO_TYPE_GUEST_KERNEL;
                break;
        case PERF_RECORD_MISC_USER:
        case PERF_RECORD_MISC_GUEST_USER:
                dso_type = DSO_TYPE_USER;
                break;
        default:
                goto out;
        }

        dso = machine__findnew_dso(machine, filename);
        if (dso != NULL) {
                char sbuild_id[SBUILD_ID_SIZE];

                dso__set_build_id(dso, &bev->build_id);

                if (dso_type != DSO_TYPE_USER) {
                        struct kmod_path m = { .name = NULL, };

                        if (!kmod_path__parse_name(&m, filename) && m.kmod)
                                dso__set_module_info(dso, &m, machine);
                        else
                                dso->kernel = dso_type;

                        free(m.name);
                }

                build_id__sprintf(dso->build_id, sizeof(dso->build_id),
                                  sbuild_id);
                pr_debug("build id event received for %s: %s\n",
                         dso->long_name, sbuild_id);
                dso__put(dso);
        }

        err = 0;
out:
        return err;
}

static int perf_header__read_build_ids_abi_quirk(struct perf_header *header,
                                                 int input, u64 offset, u64 size)
{
        struct perf_session *session = container_of(header, struct perf_session, header);
        struct {
                struct perf_event_header   header;
                u8                         build_id[PERF_ALIGN(BUILD_ID_SIZE, sizeof(u64))];
                char                       filename[0];
        } old_bev;
        struct build_id_event bev;
        char filename[PATH_MAX];
        u64 limit = offset + size;

        while (offset < limit) {
                ssize_t len;

                if (readn(input, &old_bev, sizeof(old_bev)) != sizeof(old_bev))
                        return -1;

                if (header->needs_swap)
                        perf_event_header__bswap(&old_bev.header);

                len = old_bev.header.size - sizeof(old_bev);
                if (readn(input, filename, len) != len)
                        return -1;

                bev.header = old_bev.header;

                /*
                 * As the pid is the missing value, we need to fill
                 * it properly. The header.misc value give us nice hint.
                 */
                bev.pid = HOST_KERNEL_ID;
                if (bev.header.misc == PERF_RECORD_MISC_GUEST_USER ||
                    bev.header.misc == PERF_RECORD_MISC_GUEST_KERNEL)
                        bev.pid = DEFAULT_GUEST_KERNEL_ID;

                memcpy(bev.build_id, old_bev.build_id, sizeof(bev.build_id));
                __event_process_build_id(&bev, filename, session);

                offset += bev.header.size;
        }

        return 0;
}

static int perf_header__read_build_ids(struct perf_header *header,
                                       int input, u64 offset, u64 size)
{
        struct perf_session *session = container_of(header, struct perf_session, header);
        struct build_id_event bev;
        char filename[PATH_MAX];
        u64 limit = offset + size, orig_offset = offset;
        int err = -1;

        while (offset < limit) {
                ssize_t len;

                if (readn(input, &bev, sizeof(bev)) != sizeof(bev))
                        goto out;

                if (header->needs_swap)
                        perf_event_header__bswap(&bev.header);

                len = bev.header.size - sizeof(bev);
                if (readn(input, filename, len) != len)
                        goto out;
                /*
                 * The a1645ce1 changeset:
                 *
                 * "perf: 'perf kvm' tool for monitoring guest performance from host"
                 *
                 * Added a field to struct build_id_event that broke the file
                 * format.
                 *
                 * Since the kernel build-id is the first entry, process the
                 * table using the old format if the well known
                 * '[kernel.kallsyms]' string for the kernel build-id has the
                 * first 4 characters chopped off (where the pid_t sits).
                 */
                if (memcmp(filename, "nel.kallsyms]", 13) == 0) {
                        if (lseek(input, orig_offset, SEEK_SET) == (off_t)-1)
                                return -1;
                        return perf_header__read_build_ids_abi_quirk(header, input, offset, size);
                }

                __event_process_build_id(&bev, filename, session);

                offset += bev.header.size;
        }
        err = 0;
out:
        return err;
}

/* Macro for features that simply need to read and store a string. */
#define FEAT_PROCESS_STR_FUN(__feat, __feat_env) \
static int process_##__feat(struct feat_fd *ff, void *data __maybe_unused) \
{\
        ff->ph->env.__feat_env = do_read_string(ff); \
        return ff->ph->env.__feat_env ? 0 : -ENOMEM; \
}

FEAT_PROCESS_STR_FUN(hostname, hostname);
FEAT_PROCESS_STR_FUN(osrelease, os_release);
FEAT_PROCESS_STR_FUN(version, version);
FEAT_PROCESS_STR_FUN(arch, arch);
FEAT_PROCESS_STR_FUN(cpudesc, cpu_desc);
FEAT_PROCESS_STR_FUN(cpuid, cpuid);

static int process_tracing_data(struct feat_fd *ff, void *data)
{
        ssize_t ret = trace_report(ff->fd, data, false);

        return ret < 0 ? -1 : 0;
}

static int process_build_id(struct feat_fd *ff, void *data __maybe_unused)
{
        if (perf_header__read_build_ids(ff->ph, ff->fd, ff->offset, ff->size))
                pr_debug("Failed to read buildids, continuing...\n");
        return 0;
}

static int process_nrcpus(struct feat_fd *ff, void *data __maybe_unused)
{
        int ret;
        u32 nr_cpus_avail, nr_cpus_online;

        ret = do_read_u32(ff, &nr_cpus_avail);
        if (ret)
                return ret;

        ret = do_read_u32(ff, &nr_cpus_online);
        if (ret)
                return ret;
        ff->ph->env.nr_cpus_avail = (int)nr_cpus_avail;
        ff->ph->env.nr_cpus_online = (int)nr_cpus_online;
        return 0;
}

static int process_total_mem(struct feat_fd *ff, void *data __maybe_unused)

{
        u64 total_mem;
        int ret;

        ret = do_read_u64(ff, &total_mem);
        if (ret)
                return -1;
        ff->ph->env.total_mem = (unsigned long long)total_mem;
        return 0;
}

static struct perf_evsel *
perf_evlist__find_by_index(struct perf_evlist *evlist, int idx)
{
        struct perf_evsel *evsel;

        evlist__for_each_entry(evlist, evsel) {
                if (evsel->idx == idx)
                        return evsel;
        }

        return NULL;
}

static void
perf_evlist__set_event_name(struct perf_evlist *evlist,
                            struct perf_evsel *event)
{
        struct perf_evsel *evsel;

        if (!event->name)
                return;

        evsel = perf_evlist__find_by_index(evlist, event->idx);
        if (!evsel)
                return;

        if (evsel->name)
                return;

        evsel->name = strdup(event->name);
}

static int
process_event_desc(struct feat_fd *ff, void *data __maybe_unused)
{
        struct perf_session *session;
        struct perf_evsel *evsel, *events = read_event_desc(ff);

        if (!events)
                return 0;

        session = container_of(ff->ph, struct perf_session, header);

        if (session->data->is_pipe) {
                /* Save events for reading later by print_event_desc,
                 * since they can't be read again in pipe mode. */
                ff->events = events;
        }

        for (evsel = events; evsel->attr.size; evsel++)
                perf_evlist__set_event_name(session->evlist, evsel);

        if (!session->data->is_pipe)
                free_event_desc(events);

        return 0;
}

static int process_cmdline(struct feat_fd *ff, void *data __maybe_unused)
{
        char *str, *cmdline = NULL, **argv = NULL;
        u32 nr, i, len = 0;

        if (do_read_u32(ff, &nr))
                return -1;

        ff->ph->env.nr_cmdline = nr;

        cmdline = zalloc(ff->size + nr + 1);
        if (!cmdline)
                return -1;

        argv = zalloc(sizeof(char *) * (nr + 1));
        if (!argv)
                goto error;

        for (i = 0; i < nr; i++) {
                str = do_read_string(ff);
                if (!str)
                        goto error;

                argv[i] = cmdline + len;
                memcpy(argv[i], str, strlen(str) + 1);
                len += strlen(str) + 1;
                free(str);
        }
        ff->ph->env.cmdline = cmdline;
        ff->ph->env.cmdline_argv = (const char **) argv;
        return 0;

error:
        free(argv);
        free(cmdline);
        return -1;
}

static int process_cpu_topology(struct feat_fd *ff, void *data __maybe_unused)
{
        u32 nr, i;
        char *str;
        struct strbuf sb;
        int cpu_nr = ff->ph->env.nr_cpus_avail;
        u64 size = 0;
        struct perf_header *ph = ff->ph;

        ph->env.cpu = calloc(cpu_nr, sizeof(*ph->env.cpu));
        if (!ph->env.cpu)
                return -1;

        if (do_read_u32(ff, &nr))
                goto free_cpu;

        ph->env.nr_sibling_cores = nr;
        size += sizeof(u32);
        if (strbuf_init(&sb, 128) < 0)
                goto free_cpu;

        for (i = 0; i < nr; i++) {
                str = do_read_string(ff);
                if (!str)
                        goto error;

                /* include a NULL character at the end */
                if (strbuf_add(&sb, str, strlen(str) + 1) < 0)
                        goto error;
                size += string_size(str);
                free(str);
        }
        ph->env.sibling_cores = strbuf_detach(&sb, NULL);

        if (do_read_u32(ff, &nr))
                return -1;

        ph->env.nr_sibling_threads = nr;
        size += sizeof(u32);

        for (i = 0; i < nr; i++) {
                str = do_read_string(ff);
                if (!str)
                        goto error;

                /* include a NULL character at the end */
                if (strbuf_add(&sb, str, strlen(str) + 1) < 0)
                        goto error;
                size += string_size(str);
                free(str);
        }
        ph->env.sibling_threads = strbuf_detach(&sb, NULL);

        /*
         * The header may be from old perf,
         * which doesn't include core id and socket id information.
         */
        if (ff->size <= size) {
                zfree(&ph->env.cpu);
                return 0;
        }

        for (i = 0; i < (u32)cpu_nr; i++) {
                if (do_read_u32(ff, &nr))
                        goto free_cpu;

                ph->env.cpu[i].core_id = nr;

                if (do_read_u32(ff, &nr))
                        goto free_cpu;

                if (nr != (u32)-1 && nr > (u32)cpu_nr) {
                        pr_debug("socket_id number is too big."
                                 "You may need to upgrade the perf tool.\n");
                        goto free_cpu;
                }

                ph->env.cpu[i].socket_id = nr;
        }

        return 0;

error:
        strbuf_release(&sb);
free_cpu:
        zfree(&ph->env.cpu);
        return -1;
}

static int process_numa_topology(struct feat_fd *ff, void *data __maybe_unused)
{
        struct numa_node *nodes, *n;
        u32 nr, i;
        char *str;

        /* nr nodes */
        if (do_read_u32(ff, &nr))
                return -1;

        nodes = zalloc(sizeof(*nodes) * nr);
        if (!nodes)
                return -ENOMEM;

        for (i = 0; i < nr; i++) {
                n = &nodes[i];

                /* node number */
                if (do_read_u32(ff, &n->node))
                        goto error;

                if (do_read_u64(ff, &n->mem_total))
                        goto error;

                if (do_read_u64(ff, &n->mem_free))
                        goto error;

                str = do_read_string(ff);
                if (!str)
                        goto error;

                n->map = cpu_map__new(str);
                if (!n->map)
                        goto error;

                free(str);
        }
        ff->ph->env.nr_numa_nodes = nr;
        ff->ph->env.numa_nodes = nodes;
        return 0;

error:
        free(nodes);
        return -1;
}

static int process_pmu_mappings(struct feat_fd *ff, void *data __maybe_unused)
{
        char *name;
        u32 pmu_num;
        u32 type;
        struct strbuf sb;

        if (do_read_u32(ff, &pmu_num))
                return -1;

        if (!pmu_num) {
                pr_debug("pmu mappings not available\n");
                return 0;
        }

        ff->ph->env.nr_pmu_mappings = pmu_num;
        if (strbuf_init(&sb, 128) < 0)
                return -1;

        while (pmu_num) {
                if (do_read_u32(ff, &type))
                        goto error;

                name = do_read_string(ff);
                if (!name)
                        goto error;

                if (strbuf_addf(&sb, "%u:%s", type, name) < 0)
                        goto error;
                /* include a NULL character at the end */
                if (strbuf_add(&sb, "", 1) < 0)
                        goto error;

                if (!strcmp(name, "msr"))
                        ff->ph->env.msr_pmu_type = type;

                free(name);
                pmu_num--;
        }
        ff->ph->env.pmu_mappings = strbuf_detach(&sb, NULL);
        return 0;

error:
        strbuf_release(&sb);
        return -1;
}

static int process_group_desc(struct feat_fd *ff, void *data __maybe_unused)
{
        size_t ret = -1;
        u32 i, nr, nr_groups;
        struct perf_session *session;
        struct perf_evsel *evsel, *leader = NULL;
        struct group_desc {
                char *name;
                u32 leader_idx;
                u32 nr_members;
        } *desc;

        if (do_read_u32(ff, &nr_groups))
                return -1;

        ff->ph->env.nr_groups = nr_groups;
        if (!nr_groups) {
                pr_debug("group desc not available\n");
                return 0;
        }

        desc = calloc(nr_groups, sizeof(*desc));
        if (!desc)
                return -1;

        for (i = 0; i < nr_groups; i++) {
                desc[i].name = do_read_string(ff);
                if (!desc[i].name)
                        goto out_free;

                if (do_read_u32(ff, &desc[i].leader_idx))
                        goto out_free;

                if (do_read_u32(ff, &desc[i].nr_members))
                        goto out_free;
        }

        /*
         * Rebuild group relationship based on the group_desc
         */
        session = container_of(ff->ph, struct perf_session, header);
        session->evlist->nr_groups = nr_groups;

        i = nr = 0;
        evlist__for_each_entry(session->evlist, evsel) {
                if (evsel->idx == (int) desc[i].leader_idx) {
                        evsel->leader = evsel;
                        /* {anon_group} is a dummy name */
                        if (strcmp(desc[i].name, "{anon_group}")) {
                                evsel->group_name = desc[i].name;
                                desc[i].name = NULL;
                        }
                        evsel->nr_members = desc[i].nr_members;

                        if (i >= nr_groups || nr > 0) {
                                pr_debug("invalid group desc\n");
                                goto out_free;
                        }

                        leader = evsel;
                        nr = evsel->nr_members - 1;
                        i++;
                } else if (nr) {
                        /* This is a group member */
                        evsel->leader = leader;

                        nr--;
                }
        }

        if (i != nr_groups || nr != 0) {
                pr_debug("invalid group desc\n");
                goto out_free;
        }

        ret = 0;
out_free:
        for (i = 0; i < nr_groups; i++)
                zfree(&desc[i].name);
        free(desc);

        return ret;
}

static int process_auxtrace(struct feat_fd *ff, void *data __maybe_unused)
{
        struct perf_session *session;
        int err;

        session = container_of(ff->ph, struct perf_session, header);

        err = auxtrace_index__process(ff->fd, ff->size, session,
                                      ff->ph->needs_swap);
        if (err < 0)
                pr_err("Failed to process auxtrace index\n");
        return err;
}

static int process_cache(struct feat_fd *ff, void *data __maybe_unused)
{
        struct cpu_cache_level *caches;
        u32 cnt, i, version;

        if (do_read_u32(ff, &version))
                return -1;

        if (version != 1)
                return -1;

        if (do_read_u32(ff, &cnt))
                return -1;

        caches = zalloc(sizeof(*caches) * cnt);
        if (!caches)
                return -1;

        for (i = 0; i < cnt; i++) {
                struct cpu_cache_level c;

                #define _R(v)                                           \
                        if (do_read_u32(ff, &c.v))\
                                goto out_free_caches;                   \

                _R(level)
                _R(line_size)
                _R(sets)
                _R(ways)
                #undef _R

                #define _R(v)                                   \
                        c.v = do_read_string(ff);               \
                        if (!c.v)                               \
                                goto out_free_caches;

                _R(type)
                _R(size)
                _R(map)
                #undef _R

                caches[i] = c;
        }

        ff->ph->env.caches = caches;
        ff->ph->env.caches_cnt = cnt;
        return 0;
out_free_caches:
        free(caches);
        return -1;
}

static int process_sample_time(struct feat_fd *ff, void *data __maybe_unused)
{
        struct perf_session *session;
        u64 first_sample_time, last_sample_time;
        int ret;

        session = container_of(ff->ph, struct perf_session, header);

        ret = do_read_u64(ff, &first_sample_time);
        if (ret)
                return -1;

        ret = do_read_u64(ff, &last_sample_time);
        if (ret)
                return -1;

        session->evlist->first_sample_time = first_sample_time;
        session->evlist->last_sample_time = last_sample_time;
        return 0;
}

static int process_mem_topology(struct feat_fd *ff,
                                void *data __maybe_unused)
{
        struct memory_node *nodes;
        u64 version, i, nr, bsize;
        int ret = -1;

        if (do_read_u64(ff, &version))
                return -1;

        if (version != 1)
                return -1;

        if (do_read_u64(ff, &bsize))
                return -1;

        if (do_read_u64(ff, &nr))
                return -1;

        nodes = zalloc(sizeof(*nodes) * nr);
        if (!nodes)
                return -1;

        for (i = 0; i < nr; i++) {
                struct memory_node n;

                #define _R(v)                           \
                        if (do_read_u64(ff, &n.v))      \
                                goto out;               \

                _R(node)
                _R(size)

                #undef _R

                if (do_read_bitmap(ff, &n.set, &n.size))
                        goto out;

                nodes[i] = n;
        }

        ff->ph->env.memory_bsize    = bsize;
        ff->ph->env.memory_nodes    = nodes;
        ff->ph->env.nr_memory_nodes = nr;
        ret = 0;

out:
        if (ret)
                free(nodes);
        return ret;
}

struct feature_ops {
        int (*write)(struct feat_fd *ff, struct perf_evlist *evlist);
        void (*print)(struct feat_fd *ff, FILE *fp);
        int (*process)(struct feat_fd *ff, void *data);
        const char *name;
        bool full_only;
        bool synthesize;
};

#define FEAT_OPR(n, func, __full_only) \
        [HEADER_##n] = {                                        \
                .name       = __stringify(n),                   \
                .write      = write_##func,                     \
                .print      = print_##func,                     \
                .full_only  = __full_only,                      \
                .process    = process_##func,                   \
                .synthesize = true                              \
        }

#define FEAT_OPN(n, func, __full_only) \
        [HEADER_##n] = {                                        \
                .name       = __stringify(n),                   \
                .write      = write_##func,                     \
                .print      = print_##func,                     \
                .full_only  = __full_only,                      \
                .process    = process_##func                    \
        }

/* feature_ops not implemented: */
#define print_tracing_data      NULL
#define print_build_id          NULL

#define process_branch_stack    NULL
#define process_stat            NULL


static const struct feature_ops feat_ops[HEADER_LAST_FEATURE] = {
        FEAT_OPN(TRACING_DATA,  tracing_data,   false),
        FEAT_OPN(BUILD_ID,      build_id,       false),
        FEAT_OPR(HOSTNAME,      hostname,       false),
        FEAT_OPR(OSRELEASE,     osrelease,      false),
        FEAT_OPR(VERSION,       version,        false),
        FEAT_OPR(ARCH,          arch,           false),
        FEAT_OPR(NRCPUS,        nrcpus,         false),
        FEAT_OPR(CPUDESC,       cpudesc,        false),
        FEAT_OPR(CPUID,         cpuid,          false),
        FEAT_OPR(TOTAL_MEM,     total_mem,      false),
        FEAT_OPR(EVENT_DESC,    event_desc,     false),
        FEAT_OPR(CMDLINE,       cmdline,        false),
        FEAT_OPR(CPU_TOPOLOGY,  cpu_topology,   true),
        FEAT_OPR(NUMA_TOPOLOGY, numa_topology,  true),
        FEAT_OPN(BRANCH_STACK,  branch_stack,   false),
        FEAT_OPR(PMU_MAPPINGS,  pmu_mappings,   false),
        FEAT_OPN(GROUP_DESC,    group_desc,     false),
        FEAT_OPN(AUXTRACE,      auxtrace,       false),
        FEAT_OPN(STAT,          stat,           false),
        FEAT_OPN(CACHE,         cache,          true),
        FEAT_OPR(SAMPLE_TIME,   sample_time,    false),
        FEAT_OPR(MEM_TOPOLOGY,  mem_topology,   true),
};

struct header_print_data {
        FILE *fp;
        bool full; /* extended list of headers */
};

static int perf_file_section__fprintf_info(struct perf_file_section *section,
                                           struct perf_header *ph,
                                           int feat, int fd, void *data)
{
        struct header_print_data *hd = data;
        struct feat_fd ff;

        if (lseek(fd, section->offset, SEEK_SET) == (off_t)-1) {
                pr_debug("Failed to lseek to %" PRIu64 " offset for feature "
                                "%d, continuing...\n", section->offset, feat);
                return 0;
        }
        if (feat >= HEADER_LAST_FEATURE) {
                pr_warning("unknown feature %d\n", feat);
                return 0;
        }
        if (!feat_ops[feat].print)
                return 0;

        ff = (struct  feat_fd) {
                .fd = fd,
                .ph = ph,
        };

        if (!feat_ops[feat].full_only || hd->full)
                feat_ops[feat].print(&ff, hd->fp);
        else
                fprintf(hd->fp, "# %s info available, use -I to display\n",
                        feat_ops[feat].name);

        return 0;
}

int perf_header__fprintf_info(struct perf_session *session, FILE *fp, bool full)
{
        struct header_print_data hd;
        struct perf_header *header = &session->header;
        int fd = perf_data__fd(session->data);
        struct stat st;
        int ret, bit;

        hd.fp = fp;
        hd.full = full;

        ret = fstat(fd, &st);
        if (ret == -1)
                return -1;

        fprintf(fp, "# captured on    : %s", ctime(&st.st_ctime));

        fprintf(fp, "# header version : %u\n", header->version);
        fprintf(fp, "# data offset    : %" PRIu64 "\n", header->data_offset);
        fprintf(fp, "# data size      : %" PRIu64 "\n", header->data_size);
        fprintf(fp, "# feat offset    : %" PRIu64 "\n", header->feat_offset);

        perf_header__process_sections(header, fd, &hd,
                                      perf_file_section__fprintf_info);

        if (session->data->is_pipe)
                return 0;

        fprintf(fp, "# missing features: ");
        for_each_clear_bit(bit, header->adds_features, HEADER_LAST_FEATURE) {
                if (bit)
                        fprintf(fp, "%s ", feat_ops[bit].name);
        }

        fprintf(fp, "\n");
        return 0;
}

static int do_write_feat(struct feat_fd *ff, int type,
                         struct perf_file_section **p,
                         struct perf_evlist *evlist)
{
        int err;
        int ret = 0;

        if (perf_header__has_feat(ff->ph, type)) {
                if (!feat_ops[type].write)
                        return -1;

                if (WARN(ff->buf, "Error: calling %s in pipe-mode.\n", __func__))
                        return -1;

                (*p)->offset = lseek(ff->fd, 0, SEEK_CUR);

                err = feat_ops[type].write(ff, evlist);
                if (err < 0) {
                        pr_debug("failed to write feature %s\n", feat_ops[type].name);

                        /* undo anything written */
                        lseek(ff->fd, (*p)->offset, SEEK_SET);

                        return -1;
                }
                (*p)->size = lseek(ff->fd, 0, SEEK_CUR) - (*p)->offset;
                (*p)++;
        }
        return ret;
}

static int perf_header__adds_write(struct perf_header *header,
                                   struct perf_evlist *evlist, int fd)
{
        int nr_sections;
        struct feat_fd ff;
        struct perf_file_section *feat_sec, *p;
        int sec_size;
        u64 sec_start;
        int feat;
        int err;

        ff = (struct feat_fd){
                .fd  = fd,
                .ph = header,
        };

        nr_sections = bitmap_weight(header->adds_features, HEADER_FEAT_BITS);
        if (!nr_sections)
                return 0;

        feat_sec = p = calloc(nr_sections, sizeof(*feat_sec));
        if (feat_sec == NULL)
                return -ENOMEM;

        sec_size = sizeof(*feat_sec) * nr_sections;

        sec_start = header->feat_offset;
        lseek(fd, sec_start + sec_size, SEEK_SET);

        for_each_set_bit(feat, header->adds_features, HEADER_FEAT_BITS) {
                if (do_write_feat(&ff, feat, &p, evlist))
                        perf_header__clear_feat(header, feat);
        }

        lseek(fd, sec_start, SEEK_SET);
        /*
         * may write more than needed due to dropped feature, but
         * this is okay, reader will skip the mising entries
         */
        err = do_write(&ff, feat_sec, sec_size);
        if (err < 0)
                pr_debug("failed to write feature section\n");
        free(feat_sec);
        return err;
}

int perf_header__write_pipe(int fd)
{
        struct perf_pipe_file_header f_header;
        struct feat_fd ff;
        int err;

        ff = (struct feat_fd){ .fd = fd };

        f_header = (struct perf_pipe_file_header){
                .magic     = PERF_MAGIC,
                .size      = sizeof(f_header),
        };

        err = do_write(&ff, &f_header, sizeof(f_header));
        if (err < 0) {
                pr_debug("failed to write perf pipe header\n");
                return err;
        }

        return 0;
}

int perf_session__write_header(struct perf_session *session,
                               struct perf_evlist *evlist,
                               int fd, bool at_exit)
{
        struct perf_file_header f_header;
        struct perf_file_attr   f_attr;
        struct perf_header *header = &session->header;
        struct perf_evsel *evsel;
        struct feat_fd ff;
        u64 attr_offset;
        int err;

        ff = (struct feat_fd){ .fd = fd};
        lseek(fd, sizeof(f_header), SEEK_SET);

        evlist__for_each_entry(session->evlist, evsel) {
                evsel->id_offset = lseek(fd, 0, SEEK_CUR);
                err = do_write(&ff, evsel->id, evsel->ids * sizeof(u64));
                if (err < 0) {
                        pr_debug("failed to write perf header\n");
                        return err;
                }
        }

        attr_offset = lseek(ff.fd, 0, SEEK_CUR);

        evlist__for_each_entry(evlist, evsel) {
                f_attr = (struct perf_file_attr){
                        .attr = evsel->attr,
                        .ids  = {
                                .offset = evsel->id_offset,
                                .size   = evsel->ids * sizeof(u64),
                        }
                };
                err = do_write(&ff, &f_attr, sizeof(f_attr));
                if (err < 0) {
                        pr_debug("failed to write perf header attribute\n");
                        return err;
                }
        }

        if (!header->data_offset)
                header->data_offset = lseek(fd, 0, SEEK_CUR);
        header->feat_offset = header->data_offset + header->data_size;

        if (at_exit) {
                err = perf_header__adds_write(header, evlist, fd);
                if (err < 0)
                        return err;
        }

        f_header = (struct perf_file_header){
                .magic     = PERF_MAGIC,
                .size      = sizeof(f_header),
                .attr_size = sizeof(f_attr),
                .attrs = {
                        .offset = attr_offset,
                        .size   = evlist->nr_entries * sizeof(f_attr),
                },
                .data = {
                        .offset = header->data_offset,
                        .size   = header->data_size,
                },
                /* event_types is ignored, store zeros */
        };

        memcpy(&f_header.adds_features, &header->adds_features, sizeof(header->adds_features));

        lseek(fd, 0, SEEK_SET);
        err = do_write(&ff, &f_header, sizeof(f_header));
        if (err < 0) {
                pr_debug("failed to write perf header\n");
                return err;
        }
        lseek(fd, header->data_offset + header->data_size, SEEK_SET);

        return 0;
}

static int perf_header__getbuffer64(struct perf_header *header,
                                    int fd, void *buf, size_t size)
{
        if (readn(fd, buf, size) <= 0)
                return -1;

        if (header->needs_swap)
                mem_bswap_64(buf, size);

        return 0;
}

int perf_header__process_sections(struct perf_header *header, int fd,
                                  void *data,
                                  int (*process)(struct perf_file_section *section,
                                                 struct perf_header *ph,
                                                 int feat, int fd, void *data))
{
        struct perf_file_section *feat_sec, *sec;
        int nr_sections;
        int sec_size;
        int feat;
        int err;

        nr_sections = bitmap_weight(header->adds_features, HEADER_FEAT_BITS);
        if (!nr_sections)
                return 0;

        feat_sec = sec = calloc(nr_sections, sizeof(*feat_sec));
        if (!feat_sec)
                return -1;

        sec_size = sizeof(*feat_sec) * nr_sections;

        lseek(fd, header->feat_offset, SEEK_SET);

        err = perf_header__getbuffer64(header, fd, feat_sec, sec_size);
        if (err < 0)
                goto out_free;

        for_each_set_bit(feat, header->adds_features, HEADER_LAST_FEATURE) {
                err = process(sec++, header, feat, fd, data);
                if (err < 0)
                        goto out_free;
        }
        err = 0;
out_free:
        free(feat_sec);
        return err;
}

static const int attr_file_abi_sizes[] = {
        [0] = PERF_ATTR_SIZE_VER0,
        [1] = PERF_ATTR_SIZE_VER1,
        [2] = PERF_ATTR_SIZE_VER2,
        [3] = PERF_ATTR_SIZE_VER3,
        [4] = PERF_ATTR_SIZE_VER4,
        0,
};

/*
 * In the legacy file format, the magic number is not used to encode endianness.
 * hdr_sz was used to encode endianness. But given that hdr_sz can vary based
 * on ABI revisions, we need to try all combinations for all endianness to
 * detect the endianness.
 */
static int try_all_file_abis(uint64_t hdr_sz, struct perf_header *ph)
{
        uint64_t ref_size, attr_size;
        int i;

        for (i = 0 ; attr_file_abi_sizes[i]; i++) {
                ref_size = attr_file_abi_sizes[i]
                         + sizeof(struct perf_file_section);
                if (hdr_sz != ref_size) {
                        attr_size = bswap_64(hdr_sz);
                        if (attr_size != ref_size)
                                continue;

                        ph->needs_swap = true;
                }
                pr_debug("ABI%d perf.data file detected, need_swap=%d\n",
                         i,
                         ph->needs_swap);
                return 0;
        }
        /* could not determine endianness */
        return -1;
}

#define PERF_PIPE_HDR_VER0      16

static const size_t attr_pipe_abi_sizes[] = {
        [0] = PERF_PIPE_HDR_VER0,
        0,
};

/*
 * In the legacy pipe format, there is an implicit assumption that endiannesss
 * between host recording the samples, and host parsing the samples is the
 * same. This is not always the case given that the pipe output may always be
 * redirected into a file and analyzed on a different machine with possibly a
 * different endianness and perf_event ABI revsions in the perf tool itself.
 */
static int try_all_pipe_abis(uint64_t hdr_sz, struct perf_header *ph)
{
        u64 attr_size;
        int i;

        for (i = 0 ; attr_pipe_abi_sizes[i]; i++) {
                if (hdr_sz != attr_pipe_abi_sizes[i]) {
                        attr_size = bswap_64(hdr_sz);
                        if (attr_size != hdr_sz)
                                continue;

                        ph->needs_swap = true;
                }
                pr_debug("Pipe ABI%d perf.data file detected\n", i);
                return 0;
        }
        return -1;
}

bool is_perf_magic(u64 magic)
{
        if (!memcmp(&magic, __perf_magic1, sizeof(magic))
                || magic == __perf_magic2
                || magic == __perf_magic2_sw)
                return true;

        return false;
}

static int check_magic_endian(u64 magic, uint64_t hdr_sz,
                              bool is_pipe, struct perf_header *ph)
{
        int ret;

        /* check for legacy format */
        ret = memcmp(&magic, __perf_magic1, sizeof(magic));
        if (ret == 0) {
                ph->version = PERF_HEADER_VERSION_1;
                pr_debug("legacy perf.data format\n");
                if (is_pipe)
                        return try_all_pipe_abis(hdr_sz, ph);

                return try_all_file_abis(hdr_sz, ph);
        }
        /*
         * the new magic number serves two purposes:
         * - unique number to identify actual perf.data files
         * - encode endianness of file
         */
        ph->version = PERF_HEADER_VERSION_2;

        /* check magic number with one endianness */
        if (magic == __perf_magic2)
                return 0;

        /* check magic number with opposite endianness */
        if (magic != __perf_magic2_sw)
                return -1;

        ph->needs_swap = true;

        return 0;
}

int perf_file_header__read(struct perf_file_header *header,
                           struct perf_header *ph, int fd)
{
        ssize_t ret;