OpenWrt – Rev 1

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/*
 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 */

#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdbool.h>
#include <sys/types.h>
#include <sys/stat.h>

static char *progname;
static unsigned int xtra_offset;
static unsigned char eof_mark[4] = {0xde, 0xad, 0xc0, 0xde};
static unsigned char jffs2_pad_be[] = "\x19\x85\x20\x04\x04\x00\x00\x00\xc4\x94\xdb\xf4";
static unsigned char jffs2_pad_le[] = "\x85\x19\x04\x20\x00\x00\x00\x04\xa8\xfb\xa0\xb4";
static unsigned char *pad = eof_mark;
static int pad_len = sizeof(eof_mark);
static bool pad_to_stdout = false;

#define ERR(fmt, ...) do { \
        fflush(0); \
        fprintf(stderr, "[%s] *** error: " fmt "\n", \
                        progname, ## __VA_ARGS__ ); \
} while (0)

#define ERRS(fmt, ...) do { \
        int save = errno; \
        fflush(0); \
        fprintf(stderr, "[%s] *** error: " fmt ", %s\n", \
                        progname, ## __VA_ARGS__, strerror(save)); \
} while (0)

#define BUF_SIZE        (64 * 1024)
#define ALIGN(_x,_y)    (((_x) + ((_y) - 1)) & ~((_y) - 1))

static int pad_image(char *name, uint32_t pad_mask)
{
        char *buf;
        int fd;
        int outfd;
        ssize_t in_len;
        ssize_t out_len;
        int ret = -1;

        buf = malloc(BUF_SIZE);
        if (!buf) {
                ERR("No memory for buffer");
                goto out;
        }

        fd = open(name, O_RDWR);
        if (fd < 0) {
                ERRS("Unable to open %s", name);
                goto free_buf;
        }

        in_len = lseek(fd, 0, SEEK_END);
        if (in_len < 0)
                goto close;

        if (!pad_to_stdout)
                outfd = fd;
        else
                outfd = STDOUT_FILENO;

        memset(buf, '\xff', BUF_SIZE);

        in_len += xtra_offset;

        out_len = in_len;
        while (pad_mask) {
                uint32_t mask;
                ssize_t t;
                int i;

                for (i = 10; i < 32; i++) {
                        mask = 1UL << i;
                        if (pad_mask & mask)
                                break;
                }

                in_len = ALIGN(in_len, mask);

                for (i = 10; i < 32; i++) {
                        mask = 1UL << i;
                        if ((in_len & (mask - 1)) == 0)
                                pad_mask &= ~mask;
                }

                fprintf(stderr, "padding image to %08x\n", (unsigned int) in_len - xtra_offset);

                while (out_len < in_len) {
                        ssize_t len;

                        len = in_len - out_len;
                        if (len > BUF_SIZE)
                                len = BUF_SIZE;

                        t = write(outfd, buf, len);
                        if (t != len) {
                                ERRS("Unable to write to %s", name);
                                goto close;
                        }

                        out_len += len;
                }

                /* write out the JFFS end-of-filesystem marker */
                t = write(outfd, pad, pad_len);
                if (t != pad_len) {
                        ERRS("Unable to write to %s", name);
                        goto close;
                }
                out_len += pad_len;
        }

        ret = 0;

close:
        close(fd);
free_buf:
        free(buf);
out:
        return ret;
}

static int usage(void)
{
        fprintf(stderr,
                "Usage: %s file [<options>] [pad0] [pad1] [padN]\n"
                "Options:\n"
                "  -x <offset>:          Add an extra offset for padding data\n"
                "  -J:                   Use a fake big-endian jffs2 padding element instead of EOF\n"
                "                        This is used to work around broken boot loaders that\n"
                "                        try to parse the entire firmware area as one big jffs2\n"
                "  -j:                   (like -J, but little-endian instead of big-endian)\n"
                "  -c:                   write padding to stdout\n"
                "\n",
                progname);
        return EXIT_FAILURE;
}

int main(int argc, char* argv[])
{
        char *image;
        uint32_t pad_mask;
        int ret = EXIT_FAILURE;
        int err;
        int ch, i;

        progname = basename(argv[0]);

        if (argc < 2)
                return usage();

        image = argv[1];
        argv++;
        argc--;

        pad_mask = 0;
        while ((ch = getopt(argc, argv, "x:Jjc")) != -1) {
                switch (ch) {
                case 'x':
                        xtra_offset = strtoul(optarg, NULL, 0);
                        fprintf(stderr, "assuming %u bytes offset\n",
                                xtra_offset);
                        break;
                case 'J':
                        pad = jffs2_pad_be;
                        pad_len = sizeof(jffs2_pad_be) - 1;
                        break;
                case 'j':
                        pad = jffs2_pad_le;
                        pad_len = sizeof(jffs2_pad_le) - 1;
                        break;
                case 'c':
                        pad_to_stdout = true;
                        break;
                default:
                        return usage();
                }
        }

        for (i = optind; i < argc; i++)
                pad_mask |= strtoul(argv[i], NULL, 0) * 1024;

        if (pad_mask == 0)
                pad_mask = (4 * 1024) | (8 * 1024) | (64 * 1024) |
                           (128 * 1024);

        err = pad_image(image, pad_mask);
        if (err)
                goto out;

        ret = EXIT_SUCCESS;

out:
        return ret;
}