/*
 * (C) Copyright 2000-2008
 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 *
 * (C) Copyright 2008
 * Guennadi Liakhovetski, DENX Software Engineering, lg@denx.de.
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <errno.h>
#include <fcntl.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>

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

#include "fw_env.h"

#define CMD_GETENV      "fw_printenv"
#define CMD_SETENV      "fw_setenv"

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

struct envdev_s {
        char devname[16];               /* Device name */
        ulong 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 */
};

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 CONFIG_ENV_SIZE ENVSIZE(dev_current)

#define ENV_SIZE      getenvsize()

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 XMK_STR(x)      #x
#define MK_STR(x)       XMK_STR(x)

static char default_environment[] = {
#if defined(CONFIG_BOOTARGS)
        "bootargs=" CONFIG_BOOTARGS "\0"
#endif
#if defined(CONFIG_BOOTCOMMAND)
        "bootcmd=" CONFIG_BOOTCOMMAND "\0"
#endif
#if defined(CONFIG_RAMBOOTCOMMAND)
        "ramboot=" CONFIG_RAMBOOTCOMMAND "\0"
#endif
#if defined(CONFIG_NFSBOOTCOMMAND)
        "nfsboot=" CONFIG_NFSBOOTCOMMAND "\0"
#endif
#if defined(CONFIG_BOOTDELAY) && (CONFIG_BOOTDELAY >= 0)
        "bootdelay=" MK_STR (CONFIG_BOOTDELAY) "\0"
#endif
#if defined(CONFIG_BAUDRATE) && (CONFIG_BAUDRATE >= 0)
        "baudrate=" MK_STR (CONFIG_BAUDRATE) "\0"
#endif
#ifdef  CONFIG_LOADS_ECHO
        "loads_echo=" MK_STR (CONFIG_LOADS_ECHO) "\0"
#endif
#ifdef  CONFIG_ETHADDR
        "ethaddr=" MK_STR (CONFIG_ETHADDR) "\0"
#endif
#ifdef  CONFIG_ETH1ADDR
        "eth1addr=" MK_STR (CONFIG_ETH1ADDR) "\0"
#endif
#ifdef  CONFIG_ETH2ADDR
        "eth2addr=" MK_STR (CONFIG_ETH2ADDR) "\0"
#endif
#ifdef  CONFIG_ETH3ADDR
        "eth3addr=" MK_STR (CONFIG_ETH3ADDR) "\0"
#endif
#ifdef  CONFIG_ETH4ADDR
        "eth4addr=" MK_STR (CONFIG_ETH4ADDR) "\0"
#endif
#ifdef  CONFIG_ETH5ADDR
        "eth5addr=" MK_STR (CONFIG_ETH5ADDR) "\0"
#endif
#ifdef  CONFIG_ETHPRIME
        "ethprime=" CONFIG_ETHPRIME "\0"
#endif
#ifdef  CONFIG_IPADDR
        "ipaddr=" MK_STR (CONFIG_IPADDR) "\0"
#endif
#ifdef  CONFIG_SERVERIP
        "serverip=" MK_STR (CONFIG_SERVERIP) "\0"
#endif
#ifdef  CONFIG_SYS_AUTOLOAD
        "autoload=" CONFIG_SYS_AUTOLOAD "\0"
#endif
#ifdef  CONFIG_ROOTPATH
        "rootpath=" MK_STR (CONFIG_ROOTPATH) "\0"
#endif
#ifdef  CONFIG_GATEWAYIP
        "gatewayip=" MK_STR (CONFIG_GATEWAYIP) "\0"
#endif
#ifdef  CONFIG_NETMASK
        "netmask=" MK_STR (CONFIG_NETMASK) "\0"
#endif
#ifdef  CONFIG_HOSTNAME
        "hostname=" MK_STR (CONFIG_HOSTNAME) "\0"
#endif
#ifdef  CONFIG_BOOTFILE
        "bootfile=" MK_STR (CONFIG_BOOTFILE) "\0"
#endif
#ifdef  CONFIG_LOADADDR
        "loadaddr=" MK_STR (CONFIG_LOADADDR) "\0"
#endif
#ifdef  CONFIG_PREBOOT
        "preboot=" CONFIG_PREBOOT "\0"
#endif
#ifdef  CONFIG_CLOCKS_IN_MHZ
        "clocks_in_mhz=" "1" "\0"
#endif
#if defined(CONFIG_PCI_BOOTDELAY) && (CONFIG_PCI_BOOTDELAY > 0)
        "pcidelay=" MK_STR (CONFIG_PCI_BOOTDELAY) "\0"
#endif
#ifdef  CONFIG_EXTRA_ENV_SETTINGS
        CONFIG_EXTRA_ENV_SETTINGS
#endif
        "\0"            /* Termimate struct environment data with 2 NULs */
};

static int flash_io (int mode);
static char *envmatch (char * s1, char * s2);
static int env_init (void);
static int parse_config (void);

#if defined(CONFIG_FILE)
static int get_config (char *);
#endif
static inline ulong getenvsize (void)
{
        ulong rc = CONFIG_ENV_SIZE - sizeof (long);

        if (HaveRedundEnv)
                rc -= sizeof (char);
        return rc;
}

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

        if (env_init ())
                return NULL;

        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;
}

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

        if (env_init ())
                return -1;

        if (argc == 1) {                /* Print all env variables  */
                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);
                }
                return 0;
        }

        if (strcmp (argv[1], "-n") == 0) {
                n_flag = 1;
                ++argv;
                --argc;
                if (argc != 2) {
                        fprintf (stderr, "## Error: "
                                "`-n' option requires exactly one argument\n");
                        return -1;
                }
        } else {
                n_flag = 0;
        }

        for (i = 1; i < argc; ++i) {    /* print single env variables   */
                char *name = argv[i];
                char *val = NULL;

                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;
                                }
                        }
                        val = envmatch (name, env);
                        if (val) {
                                if (!n_flag) {
                                        fputs (name, stdout);
                                        putc ('=', stdout);
                                }
                                puts (val);
                                break;
                        }
                }
                if (!val) {
                        fprintf (stderr, "## Error: \"%s\" not defined\n", name);
                        rc = -1;
                }
        }

        return rc;
}

/*
 * 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_setenv (int argc, char *argv[])
{
        int i, len;
        char *env, *nxt;
        char *oldval = NULL;
        char *name;

        if (argc < 2) {
                errno = EINVAL;
                return -1;
        }

        if (env_init ())
                return -1;

        name = argv[1];

        /*
         * 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;
        }

        /*
         * Delete any existing definition
         */
        if (oldval) {
                /*
                 * Ethernet Address and serial# can be set only once
                 */
                if ((strcmp (name, "ethaddr") == 0) ||
                        (strcmp (name, "serial#") == 0)) {
                        fprintf (stderr, "Can't overwrite \"%s\"\n", name);
                        errno = EROFS;
                        return -1;
                }

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

        /* Delete only ? */
        if (argc < 3)
                goto WRITE_FLASH;

        /*
         * 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"  > CONFIG_ENV_SIZE - (env-environment)
         */
        len = strlen (name) + 2;
        /* add '=' for first arg, ' ' for all others */
        for (i = 2; i < argc; ++i) {
                len += strlen (argv[i]) + 1;
        }
        if (len > (&environment.data[ENV_SIZE] - env)) {
                fprintf (stderr,
                        "Error: environment overflow, \"%s\" deleted\n",
                        name);
                return -1;
        }
        while ((*env = *name++) != '\0')
                env++;
        for (i = 2; i < argc; ++i) {
                char *val = argv[i];

                *env = (i == 2) ? '=' : ' ';
                while ((*++env = *val++) != '\0');
        }

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

  WRITE_FLASH:

        /*
         * 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;
}

/*
 * 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", *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, uint8_t mtd_type)
{
        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 top_of_range;     /* end of the last block we may use */
        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;

        /*
         * Start of the first block to be read, relies on the fact, that
         * erase sector size is always a power of 2
         */
        blockstart = offset & ~(DEVESIZE (dev) - 1);

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

        if (mtd_type == 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);

                /*
                 * To calculate the top of the range, we have to use the
                 * global DEVOFFSET (dev), which can be different from offset
                 */
                top_of_range = (DEVOFFSET (dev) & ~(blocklen - 1)) +
                        ENVSECTORS (dev) * blocklen;

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

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

                if (blockstart + block_seek + readlen > top_of_range) {
                        /* 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 common/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\n",
                         rc, blockstart + block_seek);
#endif
                processed += readlen;
                readlen = min (blocklen, count - processed);
                block_seek = 0;
                blockstart += blocklen;
        }

        return processed;
}

/*
 * Write count bytes at offset, but stay within ENVSETCORS (dev) sectors of
 * DEVOFFSET (dev). Similar to the read case above, on NOR we erase and write
 * the whole data at once.
 */
static int flash_write_buf (int dev, int fd, void *buf, size_t count,
                            off_t offset, uint8_t mtd_type)
{
        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 - excludinig
                                   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 */
        off_t top_of_range;     /* end of the last block we may use */
        loff_t blockstart;      /* running start of the current block -
                                   MEMGETBADBLOCK needs 64 bits */
        int rc;

        blocklen = DEVESIZE (dev);

        /* Erase sector size is always a power of 2 */
        top_of_range = (DEVOFFSET (dev) & ~(blocklen - 1)) +
                ENVSECTORS (dev) * blocklen;

        erase_offset = offset & ~(blocklen - 1);

        /* Maximum area we may use */
        erase_len = top_of_range - erase_offset;

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

        /*
         * Data size we actually have to 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 - 1);

        /*
         * 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 %u bytes: %s\n",
                                 erase_len, strerror (errno));
                        return -1;
                }

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

                /* 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 (mtd_type == 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 */
        while (processed < write_total) {
                rc = flash_bad_block (fd, mtd_type, &blockstart);
                if (rc < 0)             /* block test failed */
                        return rc;

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

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

                erase.start = blockstart;
                ioctl (fd, MEMUNLOCK, &erase);

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

                ioctl (fd, MEMLOCK, &erase);

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

        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;

        /* 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;
        }
        rc = write (fd, &obsolete_flag, sizeof (obsolete_flag));
        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
        printf ("Writing new environment at 0x%lx on %s\n",
                DEVOFFSET (dev_target), DEVNAME (dev_target));
#endif
        rc = flash_write_buf (dev_target, fd_target, environment.image,
                              CONFIG_ENV_SIZE, DEVOFFSET (dev_target),
                              DEVTYPE(dev_target));
        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
                printf ("Setting obsolete flag in environment at 0x%lx 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)
{
        struct mtd_info_user mtdinfo;
        int rc;

        rc = ioctl (fd, MEMGETINFO, &mtdinfo);
        if (rc < 0) {
                perror ("Cannot get MTD information");
                return -1;
        }

        if (mtdinfo.type != MTD_NORFLASH && mtdinfo.type != MTD_NANDFLASH) {
                fprintf (stderr, "Unsupported flash type %u\n", mtdinfo.type);
                return -1;
        }

        DEVTYPE(dev_current) = mtdinfo.type;

        rc = flash_read_buf (dev_current, fd, environment.image, CONFIG_ENV_SIZE,
                             DEVOFFSET (dev_current), mtdinfo.type);

        return (rc != CONFIG_ENV_SIZE) ? -1 : 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 (HaveRedundEnv) {
                        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;
}

/*
 * 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)
{

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

/*
 * Prevent confusion if running from erased flash memory
 */
static int env_init (void)
{
        int crc0, crc0_ok;
        char flag0;
        void *addr0;

        int crc1, crc1_ok;
        char flag1;
        void *addr1;

        struct env_image_single *single;
        struct env_image_redundant *redundant;

        if (parse_config ())            /* should fill envdevices */
                return -1;

        addr0 = calloc (1, CONFIG_ENV_SIZE);
        if (addr0 == NULL) {
                fprintf (stderr,
                        "Not enough memory for environment (%ld bytes)\n",
                        CONFIG_ENV_SIZE);
                return -1;
        }

        /* 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))
                return -1;

        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, CONFIG_ENV_SIZE);
                if (addr1 == NULL) {
                        fprintf (stderr,
                                "Not enough memory for environment (%ld bytes)\n",
                                CONFIG_ENV_SIZE);
                        return -1;
                }
                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))
                        return -1;

                /* 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 {
                        fprintf (stderr, "Incompatible flash types!\n");
                        return -1;
                }

                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) ||
                                    flag1 > flag0)
                                        dev_current = 1;
                                else if ((flag1 == 255 && flag0 == 0) ||
                                         flag0 > flag1)
                                        dev_current = 0;
                                else /* flags are equal - almost impossible */
                                        dev_current = 0;
                                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);
                }
        }
        return 0;
}


static int parse_config ()
{
        struct stat st;

#if defined(CONFIG_FILE)
        /* Fills in DEVNAME(), ENVSIZE(), DEVESIZE(). Or don't. */
        if (get_config (CONFIG_FILE)) {
                fprintf (stderr,
                        "Cannot parse config file: %s\n", strerror (errno));
                return -1;
        }
#else
        strcpy (DEVNAME (0), DEVICE1_NAME);
        DEVOFFSET (0) = DEVICE1_OFFSET;
        ENVSIZE (0) = ENV1_SIZE;
        DEVESIZE (0) = DEVICE1_ESIZE;
        ENVSECTORS (0) = DEVICE1_ENVSECTORS;
#ifdef HAVE_REDUND
        strcpy (DEVNAME (1), DEVICE2_NAME);
        DEVOFFSET (1) = DEVICE2_OFFSET;
        ENVSIZE (1) = ENV2_SIZE;
        DEVESIZE (1) = DEVICE2_ESIZE;
        ENVSECTORS (1) = DEVICE2_ENVSECTORS;
        HaveRedundEnv = 1;
#endif
#endif
        if (stat (DEVNAME (0), &st)) {
                fprintf (stderr,
                        "Cannot access MTD device %s: %s\n",
                        DEVNAME (0), strerror (errno));
                return -1;
        }

        if (HaveRedundEnv && stat (DEVNAME (1), &st)) {
                fprintf (stderr,
                        "Cannot access MTD device %s: %s\n",
                        DEVNAME (1), strerror (errno));
                return -1;
        }
        return 0;
}

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

        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, "%s %lx %lx %lx %lx",
                             DEVNAME (i),
                             &DEVOFFSET (i),
                             &ENVSIZE (i),
                             &DEVESIZE (i),
                             &ENVSECTORS (i));

                if (rc < 4)
                        continue;

                if (rc < 5)
                        /* Default - 1 sector */
                        ENVSECTORS (i) = 1;

                i++;
        }
        fclose (fp);

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