LXR linux/tools/perf/util/strbuf.c

   1// SPDX-License-Identifier: GPL-2.0
   2#include "debug.h"
   3#include "util.h"
   4#include <linux/kernel.h>
   5#include <errno.h>
   6
   7/*
   8 * Used as the default ->buf value, so that people can always assume
   9 * buf is non NULL and ->buf is NUL terminated even for a freshly
  10 * initialized strbuf.
  11 */
  12char strbuf_slopbuf[1];
  13
  14int strbuf_init(struct strbuf *sb, ssize_t hint)
  15{
  16        sb->alloc = sb->len = 0;
  17        sb->buf = strbuf_slopbuf;
  18        if (hint)
  19                return strbuf_grow(sb, hint);
  20        return 0;
  21}
  22
  23void strbuf_release(struct strbuf *sb)
  24{
  25        if (sb->alloc) {
  26                zfree(&sb->buf);
  27                strbuf_init(sb, 0);
  28        }
  29}
  30
  31char *strbuf_detach(struct strbuf *sb, size_t *sz)
  32{
  33        char *res = sb->alloc ? sb->buf : NULL;
  34        if (sz)
  35                *sz = sb->len;
  36        strbuf_init(sb, 0);
  37        return res;
  38}
  39
  40int strbuf_grow(struct strbuf *sb, size_t extra)
  41{
  42        char *buf;
  43        size_t nr = sb->len + extra + 1;
  44
  45        if (nr < sb->alloc)
  46                return 0;
  47
  48        if (nr <= sb->len)
  49                return -E2BIG;
  50
  51        if (alloc_nr(sb->alloc) > nr)
  52                nr = alloc_nr(sb->alloc);
  53
  54        /*
  55         * Note that sb->buf == strbuf_slopbuf if sb->alloc == 0, and it is
  56         * a static variable. Thus we have to avoid passing it to realloc.
  57         */
  58        buf = realloc(sb->alloc ? sb->buf : NULL, nr * sizeof(*buf));
  59        if (!buf)
  60                return -ENOMEM;
  61
  62        sb->buf = buf;
  63        sb->alloc = nr;
  64        return 0;
  65}
  66
  67int strbuf_addch(struct strbuf *sb, int c)
  68{
  69        int ret = strbuf_grow(sb, 1);
  70        if (ret)
  71                return ret;
  72
  73        sb->buf[sb->len++] = c;
  74        sb->buf[sb->len] = '\0';
  75        return 0;
  76}
  77
  78int strbuf_add(struct strbuf *sb, const void *data, size_t len)
  79{
  80        int ret = strbuf_grow(sb, len);
  81        if (ret)
  82                return ret;
  83
  84        memcpy(sb->buf + sb->len, data, len);
  85        return strbuf_setlen(sb, sb->len + len);
  86}
  87
  88static int strbuf_addv(struct strbuf *sb, const char *fmt, va_list ap)
  89{
  90        int len, ret;
  91        va_list ap_saved;
  92
  93        if (!strbuf_avail(sb)) {
  94                ret = strbuf_grow(sb, 64);
  95                if (ret)
  96                        return ret;
  97        }
  98
  99        va_copy(ap_saved, ap);
 100        len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
 101        if (len < 0)
 102                return len;
 103        if (len > strbuf_avail(sb)) {
 104                ret = strbuf_grow(sb, len);
 105                if (ret)
 106                        return ret;
 107                len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap_saved);
 108                va_end(ap_saved);
 109                if (len > strbuf_avail(sb)) {
 110                        pr_debug("this should not happen, your vsnprintf is broken");
 111                        return -EINVAL;
 112                }
 113        }
 114        return strbuf_setlen(sb, sb->len + len);
 115}
 116
 117int strbuf_addf(struct strbuf *sb, const char *fmt, ...)
 118{
 119        va_list ap;
 120        int ret;
 121
 122        va_start(ap, fmt);
 123        ret = strbuf_addv(sb, fmt, ap);
 124        va_end(ap);
 125        return ret;
 126}
 127
 128ssize_t strbuf_read(struct strbuf *sb, int fd, ssize_t hint)
 129{
 130        size_t oldlen = sb->len;
 131        size_t oldalloc = sb->alloc;
 132        int ret;
 133
 134        ret = strbuf_grow(sb, hint ? hint : 8192);
 135        if (ret)
 136                return ret;
 137
 138        for (;;) {
 139                ssize_t cnt;
 140
 141                cnt = read(fd, sb->buf + sb->len, sb->alloc - sb->len - 1);
 142                if (cnt < 0) {
 143                        if (oldalloc == 0)
 144                                strbuf_release(sb);
 145                        else
 146                                strbuf_setlen(sb, oldlen);
 147                        return cnt;
 148                }
 149                if (!cnt)
 150                        break;
 151                sb->len += cnt;
 152                ret = strbuf_grow(sb, 8192);
 153                if (ret)
 154                        return ret;
 155        }
 156
 157        sb->buf[sb->len] = '\0';
 158        return sb->len - oldlen;
 159}
 160