apply_patch.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "bin_patch.h"

int main(int argc, char** argv) {
    if (argc < 3) {
        printf("usage: %s [patch] [old_file] [new_file]\n\n", argv[0]);
        printf("applies a patch to old_file and writes it to new_file.\n");
        printf("use generate_patch to make a compatible patch file.\n\n");
        return 1;
    }

    FILE *patch = fopen(argv[1], "rb");
    FILE *old   = fopen(argv[2], "rb");
    if (!patch || !old) {
        printf("opening patch or old file failed\n");
        return 2;
    }

    fseek(patch, 0L, SEEK_END);
    fseek(old,   0L, SEEK_END);
    uint32_t patch_len = ftell(patch);
    uint32_t old_len   = ftell(old);
    rewind(patch);
    rewind(old);

    u8_t *patch_buf = (u8_t *) malloc(patch_len);
    u8_t *old_buf   = (u8_t *) malloc(old_len);

    if (!patch_buf || !old_buf) {
        printf("patch or old buffer could not be allocated\n");
        fclose(patch);
        fclose(old);
        return 3;
    }

    fread(patch_buf, sizeof(u8_t), patch_len, patch);
    fread(old_buf,   sizeof(u8_t), old_len,   old);
    fclose(patch);
    fclose(old);

    index_t diff_leni = *((index_t *) patch_buf);
    len_t   diff_lenl = index_to_len(diff_leni);
    struct binary_patch bp = {
        .diff_len   = diff_leni,
        .diff_start = ((index_t *) patch_buf + 1),
        .diff_delta = ((index_t *) patch_buf + diff_lenl + 1),
        .heap       = (u8_t *) ((index_t *) patch_buf + diff_lenl * 2 + 1)
    };
    apply_patch(old_buf, &bp);

    FILE *new = fopen(argv[3], "wb");
    if (!new) {
        printf("new file could not be opened\n");
        free(patch_buf);
        free(old_buf);
        return 4;
    }
    fwrite(old_buf, sizeof(u8_t), old_len, new);
    fclose(new);

    free(patch_buf);
    free(old_buf);

    return 0;
}