OpenWrt – Rev 1

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/* J J Larworthy 27 September 2006 */

/* file to read the boot sector of a dis and the loaded image and report
 * if the boot rom would accept the data as intact and suitable for use
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/errno.h>

#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

extern uint32_t crc32(uint32_t, const unsigned char *, unsigned int);

#define NUMBER_VECTORS   12
struct {
        unsigned int start_vector[NUMBER_VECTORS];
        char code[4];
        unsigned int header_length;
        unsigned int reserved[3];
        unsigned int length;
        unsigned int img_CRC;
        unsigned int CRC;
} img_header;

void print_usage(void)
{
        printf("update_header file.bin\n");
}

void print_header(void)
{
        int i;

        printf("vectors in header\n");
        for (i = 0; i < NUMBER_VECTORS; i++) {
                printf("%d:0x%08x\n", i, img_header.start_vector[i]);
        }
        printf("length:%8x\nimg_CRC:0x%08x\nHeader CRC:0x%08x\n",
                img_header.length, img_header.img_CRC, img_header.CRC);
}

int main(int argc, char **argv)
{
        int in_file;
        int status;
        int unsigned crc;
        int file_length;
        int len;

        struct stat file_stat;

        void *executable;

        in_file = open(argv[1], O_RDWR);

        if (in_file < 0) {
                printf("failed to open file:%s\n", argv[optind]);
                return -ENOENT;
        }

        status = fstat(in_file, &file_stat);

        /* read header and obtain size of image */
        status = read(in_file, &img_header, sizeof(img_header));

        file_length = file_stat.st_size - sizeof(img_header);

        if (img_header.length != file_length) {
                printf("size in header:%d, size of file: %d\n",
                        img_header.length, file_length);
        }
        img_header.length = file_length;

        /* read working image and CRC */
        executable = malloc(file_length);

        status = read(in_file, executable, file_length);

        if (status != file_length) {
                printf("Failed to load image\n");
                return -ENOENT;
        }

        /* verify image CRC */
        crc = crc32(0, (const unsigned char *) executable, img_header.length);

        if (crc != img_header.img_CRC) {
                printf("New Image CRC:0x%08x, hdr:0x%08x\n", crc,
                        img_header.img_CRC);
                img_header.img_CRC = crc;
        }
        memcpy(img_header.code, "BOOT", 4);
        img_header.header_length = sizeof(img_header);

        /* check header CRC */
        crc = crc32(0, (const unsigned char *) &img_header,
                        sizeof(img_header) - sizeof(unsigned int));
        if (crc != img_header.CRC) {
                printf("New header CRC - crc:0x%08x hdr:0x%08x\n", crc,
                        img_header.CRC);
                img_header.CRC = crc;
        }

        /* re-write the file */
        status = lseek(in_file, 0, SEEK_SET);
        if (status != 0) {
                printf("failed to rewind\n");
                return 1;
        }
        len = write(in_file, &img_header, sizeof(img_header));
        assert(len == sizeof(img_header));
        len = write(in_file, executable, file_length);
        assert(len == file_length);
        close(in_file);

        return 0;
}