/*
 * (C) Copyright 2000-2010
 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 *
 * (C) Copyright 2008
 * Guennadi Liakhovetski, DENX Software Engineering, lg@denx.de.
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#define _GNU_SOURCE

#include <compiler.h>
#include <errno.h>
#include <env_flags.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <linux/stringify.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dirent.h>

#ifdef MTD_OLD
# include <stdint.h>
# include <linux/mtd/mtd.h>
#else
# define  __user        /* nothing */
# include <mtd/mtd-user.h>
#endif

#include <mtd/ubi-user.h>

#include "fw_env_private.h"
#include "fw_env.h"

struct env_opts default_opts = {
#ifdef CONFIG_FILE
        .config_file = CONFIG_FILE
#endif
};

#define DIV_ROUND_UP(n, d)      (((n) + (d) - 1) / (d))

#define min(x, y) ({                            \
        typeof(x) _min1 = (x);                  \
        typeof(y) _min2 = (y);                  \
        (void) (&_min1 == &_min2);              \
        _min1 < _min2 ? _min1 : _min2; })

struct envdev_s {
        const char *devname;            /* Device name */
        long long devoff;               /* Device offset */
        ulong env_size;                 /* environment size */
        ulong erase_size;               /* device erase size */
        ulong env_sectors;              /* number of environment sectors */
        uint8_t mtd_type;               /* type of the MTD device */
        int is_ubi;                     /* set if we use UBI volume */
};

static struct envdev_s envdevices[2] =
{
        {
                .mtd_type = MTD_ABSENT,
        }, {
                .mtd_type = MTD_ABSENT,
        },
};
static int dev_current;

#define DEVNAME(i)    envdevices[(i)].devname
#define DEVOFFSET(i)  envdevices[(i)].devoff
#define ENVSIZE(i)    envdevices[(i)].env_size
#define DEVESIZE(i)   envdevices[(i)].erase_size
#define ENVSECTORS(i) envdevices[(i)].env_sectors
#define DEVTYPE(i)    envdevices[(i)].mtd_type
#define IS_UBI(i)     envdevices[(i)].is_ubi

#define CUR_ENVSIZE ENVSIZE(dev_current)

static unsigned long usable_envsize;
#define ENV_SIZE      usable_envsize

struct env_image_single {
        uint32_t        crc;    /* CRC32 over data bytes    */
        char            data[];
};

struct env_image_redundant {
        uint32_t        crc;    /* CRC32 over data bytes    */
        unsigned char   flags;  /* active or obsolete */
        char            data[];
};

enum flag_scheme {
        FLAG_NONE,
        FLAG_BOOLEAN,
        FLAG_INCREMENTAL,
};

struct environment {
        void                    *image;
        uint32_t                *crc;
        unsigned char           *flags;
        char                    *data;
        enum flag_scheme        flag_scheme;
};

static struct environment environment = {
        .flag_scheme = FLAG_NONE,
};

static int HaveRedundEnv = 0;

static unsigned char active_flag = 1;
/* obsolete_flag must be 0 to efficiently set it on NOR flash without erasing */
static unsigned char obsolete_flag = 0;

#define DEFAULT_ENV_INSTANCE_STATIC
#include <env_default.h>

#define UBI_DEV_START "/dev/ubi"
#define UBI_SYSFS "/sys/class/ubi"
#define UBI_VOL_NAME_PATT "ubi%d_%d"

static int is_ubi_devname(const char *devname)
{
        return !strncmp(devname, UBI_DEV_START, sizeof(UBI_DEV_START) - 1);
}

static int ubi_check_volume_sysfs_name(const char *volume_sysfs_name,
                                       const char *volname)
{
        char path[256];
        FILE *file;
        char *name;
        int ret;

        strcpy(path, UBI_SYSFS "/");
        strcat(path, volume_sysfs_name);
        strcat(path, "/name");

        file = fopen(path, "r");
        if (!file)
                return -1;

        ret = fscanf(file, "%ms", &name);
        fclose(file);
        if (ret <= 0 || !name) {
                fprintf(stderr,
                        "Failed to read from file %s, ret = %d, name = %s\n",
                        path, ret, name);
                return -1;
        }

        if (!strcmp(name, volname)) {
                free(name);
                return 0;
        }
        free(name);

        return -1;
}

static int ubi_get_volnum_by_name(int devnum, const char *volname)
{
        DIR *sysfs_ubi;
        struct dirent *dirent;
        int ret;
        int tmp_devnum;
        int volnum;

        sysfs_ubi = opendir(UBI_SYSFS);
        if (!sysfs_ubi)
                return -1;

#ifdef DEBUG
        fprintf(stderr, "Looking for volume name \"%s\"\n", volname);
#endif

        while (1) {
                dirent = readdir(sysfs_ubi);
                if (!dirent)
                        return -1;

                ret = sscanf(dirent->d_name, UBI_VOL_NAME_PATT,
                             &tmp_devnum, &volnum);
                if (ret == 2 && devnum == tmp_devnum) {
                        if (ubi_check_volume_sysfs_name(dirent->d_name,
                                                        volname) == 0)
                                return volnum;
                }
        }

        return -1;
}

static int ubi_get_devnum_by_devname(const char *devname)
{
        int devnum;
        int ret;

        ret = sscanf(devname + sizeof(UBI_DEV_START) - 1, "%d", &devnum);
        if (ret != 1)
                return -1;

        return devnum;
}

static const char *ubi_get_volume_devname(const char *devname,
                                          const char *volname)
{
        char *volume_devname;
        int volnum;
        int devnum;
        int ret;

        devnum = ubi_get_devnum_by_devname(devname);
        if (devnum < 0)
                return NULL;

        volnum = ubi_get_volnum_by_name(devnum, volname);
        if (volnum < 0)
                return NULL;

        ret = asprintf(&volume_devname, "%s_%d", devname, volnum);
        if (ret < 0)
                return NULL;

#ifdef DEBUG
        fprintf(stderr, "Found ubi volume \"%s:%s\" -> %s\n",
                devname, volname, volume_devname);
#endif

        return volume_devname;
}

static void ubi_check_dev(unsigned int dev_id)
{
        char *devname = (char *)DEVNAME(dev_id);
        char *pname;
        const char *volname = NULL;
        const char *volume_devname;

        if (!is_ubi_devname(DEVNAME(dev_id)))
                return;

        IS_UBI(dev_id) = 1;

        for (pname = devname; *pname != '\0'; pname++) {
                if (*pname == ':') {
                        *pname = '\0';
                        volname = pname + 1;
                        break;
                }
        }

        if (volname) {
                /* Let's find real volume device name */
                volume_devname = ubi_get_volume_devname(devname, volname);
                if (!volume_devname) {
                        fprintf(stderr, "Didn't found ubi volume \"%s\"\n",
                                volname);
                        return;
                }

                free(devname);
                DEVNAME(dev_id) = volume_devname;
        }
}

static int ubi_update_start(int fd, int64_t bytes)
{
        if (ioctl(fd, UBI_IOCVOLUP, &bytes))
                return -1;
        return 0;
}

static int ubi_read(int fd, void *buf, size_t count)
{
        ssize_t ret;

        while (count > 0) {
                ret = read(fd, buf, count);
                if (ret > 0) {
                        count -= ret;
                        buf += ret;

                        continue;
                }

                if (ret == 0) {
                        /*
                         * Happens in case of too short volume data size. If we
                         * return error status we will fail it will be treated
                         * as UBI device error.
                         *
                         * Leave catching this error to CRC check.
                         */
                        fprintf(stderr, "Warning: end of data on ubi volume\n");
                        return 0;
                } else if (errno == EBADF) {
                        /*
                         * Happens in case of corrupted volume. The same as
                         * above, we cannot return error now, as we will still
                         * be able to successfully write environment later.
                         */
                        fprintf(stderr, "Warning: corrupted volume?\n");
                        return 0;
                } else if (errno == EINTR) {
                        continue;
                }

                fprintf(stderr, "Cannot read %u bytes from ubi volume, %s\n",
                        (unsigned int)count, strerror(errno));
                return -1;
        }

        return 0;
}

static int ubi_write(int fd, const void *buf, size_t count)
{
        ssize_t ret;

        while (count > 0) {
                ret = write(fd, buf, count);
                if (ret <= 0) {
                        if (ret < 0 && errno == EINTR)
                                continue;

                        fprintf(stderr, "Cannot write %u bytes to ubi volume\n",
                                (unsigned int)count);
                        return -1;
                }

                count -= ret;
                buf += ret;
        }

        return 0;
}

static int flash_io (int mode);
static int parse_config(struct env_opts *opts);

#if defined(CONFIG_FILE)
static int get_config (char *);
#endif

static char *skip_chars(char *s)
{
        for (; *s != '\0'; s++) {
                if (isblank(*s))
                        return s;
        }
        return NULL;
}

static char *skip_blanks(char *s)
{
        for (; *s != '\0'; s++) {
                if (!isblank(*s))
                        return s;
        }
        return NULL;
}

/*
 * s1 is either a simple 'name', or a 'name=value' pair.
 * s2 is a 'name=value' pair.
 * If the names match, return the value of s2, else NULL.
 */
static char *envmatch(char *s1, char *s2)
{
        if (s1 == NULL || s2 == NULL)
                return NULL;

        while (*s1 == *s2++)
                if (*s1++ == '=')
                        return s2;
        if (*s1 == '\0' && *(s2 - 1) == '=')
                return s2;
        return NULL;
}

/**
 * Search the environment for a variable.
 * Return the value, if found, or NULL, if not found.
 */
char *fw_getenv (char *name)
{
        char *env, *nxt;

        for (env = environment.data; *env; env = nxt + 1) {
                char *val;

                for (nxt = env; *nxt; ++nxt) {
                        if (nxt >= &environment.data[ENV_SIZE]) {
                                fprintf (stderr, "## Error: "
                                        "environment not terminated\n");
                                return NULL;
                        }
                }
                val = envmatch (name, env);
                if (!val)
                        continue;
                return val;
        }
        return NULL;
}

/*
 * Search the default environment for a variable.
 * Return the value, if found, or NULL, if not found.
 */
char *fw_getdefenv(char *name)
{
        char *env, *nxt;

        for (env = default_environment; *env; env = nxt + 1) {
                char *val;

                for (nxt = env; *nxt; ++nxt) {
                        if (nxt >= &default_environment[ENV_SIZE]) {
                                fprintf(stderr, "## Error: "
                                        "default environment not terminated\n");
                                return NULL;
                        }
                }
                val = envmatch(name, env);
                if (!val)
                        continue;
                return val;
        }
        return NULL;
}

/*
 * Print the current definition of one, or more, or all
 * environment variables
 */
int fw_printenv(int argc, char *argv[], int value_only, struct env_opts *opts)
{
        int i, rc = 0;

        if (value_only && argc != 1) {
                fprintf(stderr,
                        "## Error: `-n' option requires exactly one argument\n");
                return -1;
        }

        if (!opts)
                opts = &default_opts;

        if (fw_env_open(opts))
                return -1;

        if (argc == 0) {                /* Print all env variables  */
                char *env, *nxt;
                for (env = environment.data; *env; env = nxt + 1) {
                        for (nxt = env; *nxt; ++nxt) {
                                if (nxt >= &environment.data[ENV_SIZE]) {
                                        fprintf (stderr, "## Error: "
                                                "environment not terminated\n");
                                        return -1;
                                }
                        }

                        printf ("%s\n", env);
                }
                fw_env_close(opts);
                return 0;
        }

        for (i = 0; i < argc; ++i) {    /* print a subset of env variables */
                char *name = argv[i];
                char *val = NULL;

                val = fw_getenv(name);
                if (!val) {
                        fprintf (stderr, "## Error: \"%s\" not defined\n", name);
                        rc = -1;
                        continue;
                }

                if (value_only) {
                        puts(val);
                        break;
                }

                printf("%s=%s\n", name, val);
        }

        fw_env_close(opts);

        return rc;
}

int fw_env_flush(struct env_opts *opts)
{
        int ret;

        if (!opts)
                opts = &default_opts;

        /*
         * Update CRC
         */
        *environment.crc = crc32(0, (uint8_t *) environment.data, ENV_SIZE);

        /* write environment back to flash */
        if (flash_io(O_RDWR)) {
                fprintf(stderr,
                        "Error: can't write fw_env to flash\n");
                        return -1;
        }

        return 0;
}


/*
 * Set/Clear a single variable in the environment.
 * This is called in sequence to update the environment
 * in RAM without updating the copy in flash after each set
 */
int fw_env_write(char *name, char *value)
{
        int len;
        char *env, *nxt;
        char *oldval = NULL;
        int deleting, creating, overwriting;

        /*
         * search if variable with this name already exists
         */
        for (nxt = env = environment.data; *env; env = nxt + 1) {
                for (nxt = env; *nxt; ++nxt) {
                        if (nxt >= &environment.data[ENV_SIZE]) {
                                fprintf(stderr, "## Error: "
                                        "environment not terminated\n");
                                errno = EINVAL;
                                return -1;
                        }
                }
                if ((oldval = envmatch (name, env)) != NULL)
                        break;
        }

        deleting = (oldval && !(value && strlen(value)));
        creating = (!oldval && (value && strlen(value)));
        overwriting = (oldval && (value && strlen(value)));

        /* check for permission */
        if (deleting) {
                if (env_flags_validate_varaccess(name,
                    ENV_FLAGS_VARACCESS_PREVENT_DELETE)) {
                        printf("Can't delete \"%s\"\n", name);
                        errno = EROFS;
                        return -1;
                }
        } else if (overwriting) {
                if (env_flags_validate_varaccess(name,
                    ENV_FLAGS_VARACCESS_PREVENT_OVERWR)) {
                        printf("Can't overwrite \"%s\"\n", name);
                        errno = EROFS;
                        return -1;
                } else if (env_flags_validate_varaccess(name,
                    ENV_FLAGS_VARACCESS_PREVENT_NONDEF_OVERWR)) {
                        const char *defval = fw_getdefenv(name);

                        if (defval == NULL)
                                defval = "";
                        if (strcmp(oldval, defval)
                            != 0) {
                                printf("Can't overwrite \"%s\"\n", name);
                                errno = EROFS;
                                return -1;
                        }
                }
        } else if (creating) {
                if (env_flags_validate_varaccess(name,
                    ENV_FLAGS_VARACCESS_PREVENT_CREATE)) {
                        printf("Can't create \"%s\"\n", name);
                        errno = EROFS;
                        return -1;
                }
        } else
                /* Nothing to do */
                return 0;

        if (deleting || overwriting) {
                if (*++nxt == '\0') {
                        *env = '\0';
                } else {
                        for (;;) {
                                *env = *nxt++;
                                if ((*env == '\0') && (*nxt == '\0'))
                                        break;
                                ++env;
                        }
                }
                *++env = '\0';
        }

        /* Delete only ? */
        if (!value || !strlen(value))
                return 0;

        /*
         * Append new definition at the end
         */
        for (env = environment.data; *env || *(env + 1); ++env);
        if (env > environment.data)
                ++env;
        /*
         * Overflow when:
         * "name" + "=" + "val" +"\0\0"  > CUR_ENVSIZE - (env-environment)
         */
        len = strlen (name) + 2;
        /* add '=' for first arg, ' ' for all others */
        len += strlen(value) + 1;

        if (len > (&environment.data[ENV_SIZE] - env)) {
                fprintf (stderr,
                        "Error: environment overflow, \"%s\" deleted\n",
                        name);
                return -1;
        }

        while ((*env = *name++) != '\0')
                env++;
        *env = '=';
        while ((*++env = *value++) != '\0')
                ;

        /* end is marked with double '\0' */
        *++env = '\0';

        return 0;
}

/*
 * Deletes or sets environment variables. Returns -1 and sets errno error codes:
 * 0      - OK
 * EINVAL - need at least 1 argument
 * EROFS  - certain variables ("ethaddr", "serial#") cannot be
 *          modified or deleted
 *
 */
int fw_env_set(int argc, char *argv[], struct env_opts *opts)
{
        int i;
        size_t len;
        char *name, **valv;
        char *oldval;
        char *value = NULL;
        int valc;
        int ret;

        if (!opts)
                opts = &default_opts;

        if (argc < 1) {
                fprintf(stderr, "## Error: variable name missing\n");
                errno = EINVAL;
                return -1;
        }

        if (fw_env_open(opts)) {
                fprintf(stderr, "Error: environment not initialized\n");
                return -1;
        }

        name = argv[0];
        valv = argv + 1;
        valc = argc - 1;

        if (env_flags_validate_env_set_params(name, valv, valc) < 0) {
                fw_env_close(opts);
                return -1;
        }

        len = 0;
        for (i = 0; i < valc; ++i) {
                char *val = valv[i];
                size_t val_len = strlen(val);

                if (value)
                        value[len - 1] = ' ';
                oldval = value;
                value = realloc(value, len + val_len + 1);
                if (!value) {
                        fprintf(stderr,
                                "Cannot malloc %zu bytes: %s\n",
                                len, strerror(errno));
                        free(oldval);
                        return -1;
                }

                memcpy(value + len, val, val_len);
                len += val_len;
                value[len++] = '\0';
        }

        fw_env_write(name, value);

        free(value);

        ret = fw_env_flush(opts);
        fw_env_close(opts);

        return ret;
}

/*
 * Parse  a file  and configure the u-boot variables.
 * The script file has a very simple format, as follows:
 *
 * Each line has a couple with name, value:
 * <white spaces>variable_name<white spaces>variable_value
 *
 * Both variable_name and variable_value are interpreted as strings.
 * Any character after <white spaces> and before ending \r\n is interpreted
 * as variable's value (no comment allowed on these lines !)
 *
 * Comments are allowed if the first character in the line is #
 *
 * Returns -1 and sets errno error codes:
 * 0      - OK
 * -1     - Error
 */
int fw_parse_script(char *fname, struct env_opts *opts)
{
        FILE *fp;
        char dump[1024];        /* Maximum line length in the file */
        char *name;
        char *val;
        int lineno = 0;
        int len;
        int ret = 0;

        if (!opts)
                opts = &default_opts;

        if (fw_env_open(opts)) {
                fprintf(stderr, "Error: environment not initialized\n");
                return -1;
        }

        if (strcmp(fname, "-") == 0)
                fp = stdin;
        else {
                fp = fopen(fname, "r");
                if (fp == NULL) {
                        fprintf(stderr, "I cannot open %s for reading\n",
                                 fname);
                        return -1;
                }
        }

        while (fgets(dump, sizeof(dump), fp)) {
                lineno++;
                len = strlen(dump);

                /*
                 * Read a whole line from the file. If the line is too long
                 * or is not terminated, reports an error and exit.
                 */
                if (dump[len - 1] != '\n') {
                        fprintf(stderr,
                        "Line %d not corrected terminated or too long\n",
                                lineno);
                        ret = -1;
                        break;
                }

                /* Drop ending line feed / carriage return */
                dump[--len] = '\0';
                if (len && dump[len - 1] == '\r')
                        dump[--len] = '\0';

                /* Skip comment or empty lines */
                if (len == 0 || dump[0] == '#')
                        continue;

                /*
                 * Search for variable's name,
                 * remove leading whitespaces
                 */
                name = skip_blanks(dump);
                if (!name)
                        continue;

                /* The first white space is the end of variable name */
                val = skip_chars(name);
                len = strlen(name);
                if (val) {
                        *val++ = '\0';
                        if ((val - name) < len)
                                val = skip_blanks(val);
                        else
                                val = NULL;
                }

#ifdef DEBUG
                fprintf(stderr, "Setting %s : %s\n",
                        name, val ? val : " removed");
#endif

                if (env_flags_validate_type(name, val) < 0) {
                        ret = -1;
                        break;
                }

                /*
                 * If there is an error setting a variable,
                 * try to save the environment and returns an error
                 */
                if (fw_env_write(name, val)) {
                        fprintf(stderr,
                        "fw_env_write returns with error : %s\n",
                                strerror(errno));
                        ret = -1;
                        break;
                }

        }

        /* Close file if not stdin */
        if (strcmp(fname, "-") != 0)
                fclose(fp);

        ret |= fw_env_flush(opts);

        fw_env_close(opts);

        return ret;
}

/**
 * environment_end() - compute offset of first byte right after environemnt
 * @dev - index of enviroment buffer
 * Return:
 *  device offset of first byte right after environemnt
 */
off_t environment_end(int dev)
{
        /* environment is block aligned */
        return DEVOFFSET(dev) + ENVSECTORS(dev) * DEVESIZE(dev);
}

/*
 * Test for bad block on NAND, just returns 0 on NOR, on NAND:
 * 0    - block is good
 * > 0  - block is bad
 * < 0  - failed to test
 */
static int flash_bad_block(int fd, uint8_t mtd_type, loff_t blockstart)
{
        if (mtd_type == MTD_NANDFLASH) {
                int badblock = ioctl(fd, MEMGETBADBLOCK, &blockstart);

                if (badblock < 0) {
                        perror ("Cannot read bad block mark");
                        return badblock;
                }

                if (badblock) {
#ifdef DEBUG
                        fprintf (stderr, "Bad block at 0x%llx, skipping\n",
                                (unsigned long long)blockstart);
#endif
                        return badblock;
                }
        }

        return 0;
}

/*
 * Read data from flash at an offset into a provided buffer. On NAND it skips
 * bad blocks but makes sure it stays within ENVSECTORS (dev) starting from
 * the DEVOFFSET (dev) block. On NOR the loop is only run once.
 */
static int flash_read_buf (int dev, int fd, void *buf, size_t count,
                           off_t offset)
{
        size_t blocklen;        /* erase / write length - one block on NAND,
                                   0 on NOR */
        size_t processed = 0;   /* progress counter */
        size_t readlen = count; /* current read length */
        off_t block_seek;       /* offset inside the current block to the start
                                   of the data */
        loff_t blockstart;      /* running start of the current block -
                                   MEMGETBADBLOCK needs 64 bits */
        int rc;

        blockstart = (offset / DEVESIZE (dev)) * DEVESIZE (dev);

        /* Offset inside a block */
        block_seek = offset - blockstart;

        if (DEVTYPE(dev) == MTD_NANDFLASH) {
                /*
                 * NAND: calculate which blocks we are reading. We have
                 * to read one block at a time to skip bad blocks.
                 */
                blocklen = DEVESIZE (dev);

                /* Limit to one block for the first read */
                if (readlen > blocklen - block_seek)
                        readlen = blocklen - block_seek;
        } else {
                blocklen = 0;
        }

        /* This only runs once on NOR flash */
        while (processed < count) {
                rc = flash_bad_block(fd, DEVTYPE(dev), blockstart);
                if (rc < 0)             /* block test failed */
                        return -1;

                if (blockstart + block_seek + readlen > environment_end(dev)) {
                        /* End of range is reached */
                        fprintf (stderr,
                                 "Too few good blocks within range\n");
                        return -1;
                }

                if (rc) {               /* block is bad */
                        blockstart += blocklen;
                        continue;
                }

                /*
                 * If a block is bad, we retry in the next block at the same
                 * offset - see env/nand.c::writeenv()
                 */
                lseek (fd, blockstart + block_seek, SEEK_SET);

                rc = read (fd, buf + processed, readlen);
                if (rc != readlen) {
                        fprintf (stderr, "Read error on %s: %s\n",
                                 DEVNAME (dev), strerror (errno));
                        return -1;
                }
#ifdef DEBUG
                fprintf(stderr, "Read 0x%x bytes at 0x%llx on %s\n",
                        rc, (unsigned long long) blockstart + block_seek,
                        DEVNAME(dev));
#endif
                processed += readlen;
                readlen = min (blocklen, count - processed);
                block_seek = 0;
                blockstart += blocklen;
        }

        return processed;
}

/*
 * Write count bytes from begin of environment, but stay within
 * ENVSECTORS(dev) sectors of
 * DEVOFFSET (dev). Similar to the read case above, on NOR and dataflash we
 * erase and write the whole data at once.
 */
static int flash_write_buf(int dev, int fd, void *buf, size_t count)
{
        void *data;
        struct erase_info_user erase;
        size_t blocklen;        /* length of NAND block / NOR erase sector */
        size_t erase_len;       /* whole area that can be erased - may include
                                   bad blocks */
        size_t erasesize;       /* erase / write length - one block on NAND,
                                   whole area on NOR */
        size_t processed = 0;   /* progress counter */
        size_t write_total;     /* total size to actually write - excluding
                                   bad blocks */
        off_t erase_offset;     /* offset to the first erase block (aligned)
                                   below offset */
        off_t block_seek;       /* offset inside the erase block to the start
                                   of the data */
        loff_t blockstart;      /* running start of the current block -
                                   MEMGETBADBLOCK needs 64 bits */
        int rc;

        /*
         * For mtd devices only offset and size of the environment do matter
         */
        if (DEVTYPE(dev) == MTD_ABSENT) {
                blocklen = count;
                erase_len = blocklen;

                blockstart = DEVOFFSET(dev);
                block_seek = 0;
                write_total = blocklen;
        } else {
                blocklen = DEVESIZE(dev);

                erase_offset = DEVOFFSET(dev);

                /* Maximum area we may use */
                erase_len = environment_end(dev) - erase_offset;

                blockstart = erase_offset;

                /* Offset inside a block */
                block_seek = DEVOFFSET(dev) - erase_offset;

                /*
                 * Data size we actually write: from the start of the block
                 * to the start of the data, then count bytes of data, and
                 * to the end of the block
                 */
                write_total = ((block_seek + count + blocklen - 1) /
                                                        blocklen) * blocklen;
        }

        /*
         * Support data anywhere within erase sectors: read out the complete
         * area to be erased, replace the environment image, write the whole
         * block back again.
         */
        if (write_total > count) {
                data = malloc (erase_len);
                if (!data) {
                        fprintf (stderr,
                                 "Cannot malloc %zu bytes: %s\n",
                                 erase_len, strerror (errno));
                        return -1;
                }

                rc = flash_read_buf(dev, fd, data, write_total, erase_offset);
                if (write_total != rc)
                        return -1;

#ifdef DEBUG
                fprintf(stderr, "Preserving data ");
                if (block_seek != 0)
                        fprintf(stderr, "0x%x - 0x%lx", 0, block_seek - 1);
                if (block_seek + count != write_total) {
                        if (block_seek != 0)
                                fprintf(stderr, " and ");
                        fprintf(stderr, "0x%lx - 0x%lx",
                                (unsigned long) block_seek + count,
                                (unsigned long) write_total - 1);
                }
                fprintf(stderr, "\n");
#endif
                /* Overwrite the old environment */
                memcpy (data + block_seek, buf, count);
        } else {
                /*
                 * We get here, iff offset is block-aligned and count is a
                 * multiple of blocklen - see write_total calculation above
                 */
                data = buf;
        }

        if (DEVTYPE(dev) == MTD_NANDFLASH) {
                /*
                 * NAND: calculate which blocks we are writing. We have
                 * to write one block at a time to skip bad blocks.
                 */
                erasesize = blocklen;
        } else {
                erasesize = erase_len;
        }

        erase.length = erasesize;

        /* This only runs once on NOR flash and SPI-dataflash */
        while (processed < write_total) {
                rc = flash_bad_block(fd, DEVTYPE(dev), blockstart);
                if (rc < 0)             /* block test failed */
                        return rc;

                if (blockstart + erasesize > environment_end(dev)) {
                        fprintf (stderr, "End of range reached, aborting\n");
                        return -1;
                }

                if (rc) {               /* block is bad */
                        blockstart += blocklen;
                        continue;
                }

                if (DEVTYPE(dev) != MTD_ABSENT) {
                        erase.start = blockstart;
                        ioctl(fd, MEMUNLOCK, &erase);
                        /* These do not need an explicit erase cycle */
                        if (DEVTYPE(dev) != MTD_DATAFLASH)
                                if (ioctl(fd, MEMERASE, &erase) != 0) {
                                        fprintf(stderr,
                                                "MTD erase error on %s: %s\n",
                                                DEVNAME(dev), strerror(errno));
                                        return -1;
                                }
                }

                if (lseek (fd, blockstart, SEEK_SET) == -1) {
                        fprintf (stderr,
                                 "Seek error on %s: %s\n",
                                 DEVNAME (dev), strerror (errno));
                        return -1;
                }

#ifdef DEBUG
                fprintf(stderr, "Write 0x%llx bytes at 0x%llx\n",
                        (unsigned long long) erasesize,
                        (unsigned long long) blockstart);
#endif
                if (write (fd, data + processed, erasesize) != erasesize) {
                        fprintf (stderr, "Write error on %s: %s\n",
                                 DEVNAME (dev), strerror (errno));
                        return -1;
                }

                if (DEVTYPE(dev) != MTD_ABSENT)
                        ioctl(fd, MEMLOCK, &erase);

                processed  += erasesize;
                block_seek = 0;
                blockstart += erasesize;
        }

        if (write_total > count)
                free (data);

        return processed;
}

/*
 * Set obsolete flag at offset - NOR flash only
 */
static int flash_flag_obsolete (int dev, int fd, off_t offset)
{
        int rc;
        struct erase_info_user erase;

        erase.start  = DEVOFFSET (dev);
        erase.length = DEVESIZE (dev);
        /* This relies on the fact, that obsolete_flag == 0 */
        rc = lseek (fd, offset, SEEK_SET);
        if (rc < 0) {
                fprintf (stderr, "Cannot seek to set the flag on %s \n",
                         DEVNAME (dev));
                return rc;
        }
        ioctl (fd, MEMUNLOCK, &erase);
        rc = write (fd, &obsolete_flag, sizeof (obsolete_flag));
        ioctl (fd, MEMLOCK, &erase);
        if (rc < 0)
                perror ("Could not set obsolete flag");

        return rc;
}

static int flash_write (int fd_current, int fd_target, int dev_target)
{
        int rc;

        switch (environment.flag_scheme) {
        case FLAG_NONE:
                break;
        case FLAG_INCREMENTAL:
                (*environment.flags)++;
                break;
        case FLAG_BOOLEAN:
                *environment.flags = active_flag;
                break;
        default:
                fprintf (stderr, "Unimplemented flash scheme %u \n",
                         environment.flag_scheme);
                return -1;
        }

#ifdef DEBUG
        fprintf(stderr, "Writing new environment at 0x%llx on %s\n",
                DEVOFFSET (dev_target), DEVNAME (dev_target));
#endif

        if (IS_UBI(dev_target)) {
                if (ubi_update_start(fd_target, CUR_ENVSIZE) < 0)
                        return 0;
                return ubi_write(fd_target, environment.image, CUR_ENVSIZE);
        }

        rc = flash_write_buf(dev_target, fd_target, environment.image,
                             CUR_ENVSIZE);
        if (rc < 0)
                return rc;

        if (environment.flag_scheme == FLAG_BOOLEAN) {
                /* Have to set obsolete flag */
                off_t offset = DEVOFFSET (dev_current) +
                        offsetof (struct env_image_redundant, flags);
#ifdef DEBUG
                fprintf(stderr,
                        "Setting obsolete flag in environment at 0x%llx on %s\n",
                        DEVOFFSET (dev_current), DEVNAME (dev_current));
#endif
                flash_flag_obsolete (dev_current, fd_current, offset);
        }

        return 0;
}

static int flash_read (int fd)
{
        int rc;

        if (IS_UBI(dev_current)) {
                DEVTYPE(dev_current) = MTD_ABSENT;

                return ubi_read(fd, environment.image, CUR_ENVSIZE);
        }

        rc = flash_read_buf(dev_current, fd, environment.image, CUR_ENVSIZE,
                            DEVOFFSET(dev_current));
        if (rc != CUR_ENVSIZE)
                return -1;

        return 0;
}

static int flash_io (int mode)
{
        int fd_current, fd_target, rc, dev_target;

        /* dev_current: fd_current, erase_current */
        fd_current = open (DEVNAME (dev_current), mode);
        if (fd_current < 0) {
                fprintf (stderr,
                         "Can't open %s: %s\n",
                         DEVNAME (dev_current), strerror (errno));
                return -1;
        }

        if (mode == O_RDWR) {
                if (HaveRedundEnv) {
                        /* switch to next partition for writing */
                        dev_target = !dev_current;
                        /* dev_target: fd_target, erase_target */
                        fd_target = open (DEVNAME (dev_target), mode);
                        if (fd_target < 0) {
                                fprintf (stderr,
                                         "Can't open %s: %s\n",
                                         DEVNAME (dev_target),
                                         strerror (errno));
                                rc = -1;
                                goto exit;
                        }
                } else {
                        dev_target = dev_current;
                        fd_target = fd_current;
                }

                rc = flash_write (fd_current, fd_target, dev_target);

                if (fsync(fd_current) &&
                    !(errno == EINVAL || errno == EROFS)) {
                        fprintf (stderr,
                                 "fsync failed on %s: %s\n",
                                 DEVNAME (dev_current), strerror (errno));
                }

                if (HaveRedundEnv) {
                        if (fsync(fd_target) &&
                            !(errno == EINVAL || errno == EROFS)) {
                                fprintf (stderr,
                                         "fsync failed on %s: %s\n",
                                         DEVNAME (dev_current), strerror (errno));
                        }

                        if (close (fd_target)) {
                                fprintf (stderr,
                                        "I/O error on %s: %s\n",
                                        DEVNAME (dev_target),
                                        strerror (errno));
                                rc = -1;
                        }
                }
        } else {
                rc = flash_read (fd_current);
        }

exit:
        if (close (fd_current)) {
                fprintf (stderr,
                         "I/O error on %s: %s\n",
                         DEVNAME (dev_current), strerror (errno));
                return -1;
        }

        return rc;
}

/*
 * Prevent confusion if running from erased flash memory
 */
int fw_env_open(struct env_opts *opts)
{
        int crc0, crc0_ok;
        unsigned char flag0;
        void *addr0 = NULL;

        int crc1, crc1_ok;
        unsigned char flag1;
        void *addr1 = NULL;

        int ret;

        struct env_image_single *single;
        struct env_image_redundant *redundant;

        if (!opts)
                opts = &default_opts;

        if (parse_config(opts))         /* should fill envdevices */
                return -EINVAL;

        addr0 = calloc(1, CUR_ENVSIZE);
        if (addr0 == NULL) {
                fprintf(stderr,
                        "Not enough memory for environment (%ld bytes)\n",
                        CUR_ENVSIZE);
                ret = -ENOMEM;
                goto open_cleanup;
        }

        /* read environment from FLASH to local buffer */
        environment.image = addr0;

        if (HaveRedundEnv) {
                redundant = addr0;
                environment.crc         = &redundant->crc;
                environment.flags       = &redundant->flags;
                environment.data        = redundant->data;
        } else {
                single = addr0;
                environment.crc         = &single->crc;
                environment.flags       = NULL;
                environment.data        = single->data;
        }

        dev_current = 0;
        if (flash_io(O_RDONLY)) {
                ret = -EIO;
                goto open_cleanup;
        }

        crc0 = crc32 (0, (uint8_t *) environment.data, ENV_SIZE);

        crc0_ok = (crc0 == *environment.crc);
        if (!HaveRedundEnv) {
                if (!crc0_ok) {
                        fprintf (stderr,
                                "Warning: Bad CRC, using default environment\n");
                        memcpy(environment.data, default_environment, sizeof default_environment);
                }
        } else {
                flag0 = *environment.flags;

                dev_current = 1;
                addr1 = calloc(1, CUR_ENVSIZE);
                if (addr1 == NULL) {
                        fprintf(stderr,
                                "Not enough memory for environment (%ld bytes)\n",
                                CUR_ENVSIZE);
                        ret = -ENOMEM;
                        goto open_cleanup;
                }
                redundant = addr1;

                /*
                 * have to set environment.image for flash_read(), careful -
                 * other pointers in environment still point inside addr0
                 */
                environment.image = addr1;
                if (flash_io(O_RDONLY)) {
                        ret = -EIO;
                        goto open_cleanup;
                }

                /* Check flag scheme compatibility */
                if (DEVTYPE(dev_current) == MTD_NORFLASH &&
                    DEVTYPE(!dev_current) == MTD_NORFLASH) {
                        environment.flag_scheme = FLAG_BOOLEAN;
                } else if (DEVTYPE(dev_current) == MTD_NANDFLASH &&
                           DEVTYPE(!dev_current) == MTD_NANDFLASH) {
                        environment.flag_scheme = FLAG_INCREMENTAL;
                } else if (DEVTYPE(dev_current) == MTD_DATAFLASH &&
                           DEVTYPE(!dev_current) == MTD_DATAFLASH) {
                        environment.flag_scheme = FLAG_BOOLEAN;
                } else if (DEVTYPE(dev_current) == MTD_UBIVOLUME &&
                           DEVTYPE(!dev_current) == MTD_UBIVOLUME) {
                        environment.flag_scheme = FLAG_INCREMENTAL;
                } else if (DEVTYPE(dev_current) == MTD_ABSENT &&
                           DEVTYPE(!dev_current) == MTD_ABSENT &&
                           IS_UBI(dev_current) == IS_UBI(!dev_current)) {
                        environment.flag_scheme = FLAG_INCREMENTAL;
                } else {
                        fprintf (stderr, "Incompatible flash types!\n");
                        ret = -EINVAL;
                        goto open_cleanup;
                }

                crc1 = crc32 (0, (uint8_t *) redundant->data, ENV_SIZE);

                crc1_ok = (crc1 == redundant->crc);
                flag1 = redundant->flags;

                if (crc0_ok && !crc1_ok) {
                        dev_current = 0;
                } else if (!crc0_ok && crc1_ok) {
                        dev_current = 1;
                } else if (!crc0_ok && !crc1_ok) {
                        fprintf (stderr,
                                "Warning: Bad CRC, using default environment\n");
                        memcpy (environment.data, default_environment,
                                sizeof default_environment);
                        dev_current = 0;
                } else {
                        switch (environment.flag_scheme) {
                        case FLAG_BOOLEAN:
                                if (flag0 == active_flag &&
                                    flag1 == obsolete_flag) {
                                        dev_current = 0;
                                } else if (flag0 == obsolete_flag &&
                                           flag1 == active_flag) {
                                        dev_current = 1;
                                } else if (flag0 == flag1) {
                                        dev_current = 0;
                                } else if (flag0 == 0xFF) {
                                        dev_current = 0;
                                } else if (flag1 == 0xFF) {
                                        dev_current = 1;
                                } else {
                                        dev_current = 0;
                                }
                                break;
                        case FLAG_INCREMENTAL:
                                if (flag0 == 255 && flag1 == 0)
                                        dev_current = 1;
                                else if ((flag1 == 255 && flag0 == 0) ||
                                         flag0 >= flag1)
                                        dev_current = 0;
                                else /* flag1 > flag0 */
                                        dev_current = 1;
                                break;
                        default:
                                fprintf (stderr, "Unknown flag scheme %u \n",
                                         environment.flag_scheme);
                                return -1;
                        }
                }

                /*
                 * If we are reading, we don't need the flag and the CRC any
                 * more, if we are writing, we will re-calculate CRC and update
                 * flags before writing out
                 */
                if (dev_current) {
                        environment.image       = addr1;
                        environment.crc         = &redundant->crc;
                        environment.flags       = &redundant->flags;
                        environment.data        = redundant->data;
                        free (addr0);
                } else {
                        environment.image       = addr0;
                        /* Other pointers are already set */
                        free (addr1);
                }
#ifdef DEBUG
                fprintf(stderr, "Selected env in %s\n", DEVNAME(dev_current));
#endif
        }
        return 0;

open_cleanup:
        if (addr0)
                free(addr0);

        if (addr1)
                free(addr0);

        return ret;
}

/*
 * Simply free allocated buffer with environment
 */
int fw_env_close(struct env_opts *opts)
{
        if (environment.image)
                free(environment.image);

        environment.image = NULL;

        return 0;
}

static int check_device_config(int dev)
{
        struct stat st;
        int32_t lnum = 0;
        int fd, rc = 0;

        /* Fills in IS_UBI(), converts DEVNAME() with ubi volume name */
        ubi_check_dev(dev);

        fd = open(DEVNAME(dev), O_RDONLY);
        if (fd < 0) {
                fprintf(stderr,
                        "Cannot open %s: %s\n",
                        DEVNAME(dev), strerror(errno));
                return -1;
        }

        rc = fstat(fd, &st);
        if (rc < 0) {
                fprintf(stderr, "Cannot stat the file %s\n",
                        DEVNAME(dev));
                goto err;
        }

        if (IS_UBI(dev)) {
                rc = ioctl(fd, UBI_IOCEBISMAP, &lnum);
                if (rc < 0) {
                        fprintf(stderr, "Cannot get UBI information for %s\n",
                                DEVNAME(dev));
                        goto err;
                }
        } else if (S_ISCHR(st.st_mode)) {
                struct mtd_info_user mtdinfo;
                rc = ioctl(fd, MEMGETINFO, &mtdinfo);
                if (rc < 0) {
                        fprintf(stderr, "Cannot get MTD information for %s\n",
                                DEVNAME(dev));
                        goto err;
                }
                if (mtdinfo.type != MTD_NORFLASH &&
                    mtdinfo.type != MTD_NANDFLASH &&
                    mtdinfo.type != MTD_DATAFLASH &&
                    mtdinfo.type != MTD_UBIVOLUME) {
                        fprintf(stderr, "Unsupported flash type %u on %s\n",
                                mtdinfo.type, DEVNAME(dev));
                        goto err;
                }
                DEVTYPE(dev) = mtdinfo.type;
                if (DEVESIZE(dev) == 0)
                        /* Assume the erase size is the same as the env-size */
                        DEVESIZE(dev) = ENVSIZE(dev);
        } else {
                uint64_t size;
                DEVTYPE(dev) = MTD_ABSENT;
                if (DEVESIZE(dev) == 0)
                        /* Assume the erase size to be 512 bytes */
                        DEVESIZE(dev) = 0x200;

                /*
                 * Check for negative offsets, treat it as backwards offset
                 * from the end of the block device
                 */
                if (DEVOFFSET(dev) < 0) {
                        rc = ioctl(fd, BLKGETSIZE64, &size);
                        if (rc < 0) {
                                fprintf(stderr, "Could not get block device size on %s\n",
                                        DEVNAME(dev));
                                goto err;
                        }

                        DEVOFFSET(dev) = DEVOFFSET(dev) + size;
#ifdef DEBUG
                        fprintf(stderr, "Calculated device offset 0x%llx on %s\n",
                                DEVOFFSET(dev), DEVNAME(dev));
#endif
                }
        }

        if (ENVSECTORS(dev) == 0)
                /* Assume enough sectors to cover the environment */
                ENVSECTORS(dev) = DIV_ROUND_UP(ENVSIZE(dev), DEVESIZE(dev));

        if (DEVOFFSET(dev) % DEVESIZE(dev) != 0) {
                fprintf(stderr, "Environment does not start on (erase) block boundary\n");
                errno = EINVAL;
                return -1;
        }

        if (ENVSIZE(dev) > ENVSECTORS(dev) * DEVESIZE(dev)) {
                fprintf(stderr, "Environment does not fit into available sectors\n");
                errno = EINVAL;
                return -1;
        }

err:
        close(fd);
        return rc;
}

static int parse_config(struct env_opts *opts)
{
        int rc;

        if (!opts)
                opts = &default_opts;

#if defined(CONFIG_FILE)
        /* Fills in DEVNAME(), ENVSIZE(), DEVESIZE(). Or don't. */
        if (get_config(opts->config_file)) {
                fprintf(stderr, "Cannot parse config file '%s': %m\n",
                        opts->config_file);
                return -1;
        }
#else
        DEVNAME (0) = DEVICE1_NAME;
        DEVOFFSET (0) = DEVICE1_OFFSET;
        ENVSIZE (0) = ENV1_SIZE;

        /* Set defaults for DEVESIZE, ENVSECTORS later once we
         * know DEVTYPE
         */
#ifdef DEVICE1_ESIZE
        DEVESIZE (0) = DEVICE1_ESIZE;
#endif
#ifdef DEVICE1_ENVSECTORS
        ENVSECTORS (0) = DEVICE1_ENVSECTORS;
#endif

#ifdef HAVE_REDUND
        DEVNAME (1) = DEVICE2_NAME;
        DEVOFFSET (1) = DEVICE2_OFFSET;
        ENVSIZE (1) = ENV2_SIZE;

        /* Set defaults for DEVESIZE, ENVSECTORS later once we
         * know DEVTYPE
         */
#ifdef DEVICE2_ESIZE
        DEVESIZE (1) = DEVICE2_ESIZE;
#endif
#ifdef DEVICE2_ENVSECTORS
        ENVSECTORS (1) = DEVICE2_ENVSECTORS;
#endif
        HaveRedundEnv = 1;
#endif
#endif
        rc = check_device_config(0);
        if (rc < 0)
                return rc;

        if (HaveRedundEnv) {
                rc = check_device_config(1);
                if (rc < 0)
                        return rc;

                if (ENVSIZE(0) != ENVSIZE(1)) {
                        fprintf(stderr,
                                "Redundant environments have unequal size");
                        return -1;
                }
        }

        usable_envsize = CUR_ENVSIZE - sizeof(uint32_t);
        if (HaveRedundEnv)
                usable_envsize -= sizeof(char);

        return 0;
}

#if defined(CONFIG_FILE)
static int get_config (char *fname)
{
        FILE *fp;
        int i = 0;
        int rc;
        char dump[128];
        char *devname;

        fp = fopen (fname, "r");
        if (fp == NULL)
                return -1;

        while (i < 2 && fgets (dump, sizeof (dump), fp)) {
                /* Skip incomplete conversions and comment strings */
                if (dump[0] == '#')
                        continue;

                rc = sscanf(dump, "%ms %lli %lx %lx %lx",
                            &devname,
                            &DEVOFFSET(i),
                            &ENVSIZE(i),
                            &DEVESIZE(i),
                            &ENVSECTORS(i));

                if (rc < 3)
                        continue;

                DEVNAME(i) = devname;

                /* Set defaults for DEVESIZE, ENVSECTORS later once we
                 * know DEVTYPE
                 */

                i++;
        }
        fclose (fp);

        HaveRedundEnv = i - 1;
        if (!i) {                       /* No valid entries found */
                errno = EINVAL;
                return -1;
        } else
                return 0;
}
#endif