icnspack.c

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#if defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define BigEndianToNative32(x) __builtin_bswap32(x)
#elif defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
#define BigEndianToNative32(x) (x)
#else
#include <arpa/inet.h>
#define BigEndianToNative32(x) ntohl(x)
#endif
 
#include <stdbool.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
 
static int read_file(const char *filename, uint8_t **buffer, size_t *size) {
  FILE *fh = fopen(filename, "rb");
  if (!fh) {
    fprintf(stderr, "Missing file %s!\n", filename);
    return -1;
  }
 
  if (fseek(fh, 0, SEEK_END)) {
    fprintf(stderr, "Failed to find end of %s!\n", filename);
    fclose(fh);
    return -1;
  }
 
  long pos = ftell(fh);
 
  if (pos <= 0) {
    fprintf(stderr, "Invalid file size (%ld) of %s!\n", pos, filename);
    fclose(fh);
    return -1;
  }
 
  if (fseek(fh, 0, SEEK_SET)) {
    fprintf(stderr, "Failed to rewind %s!\n", filename);
    fclose(fh);
    return -1;
  }
 
  *size = (size_t)pos;
  *buffer = (uint8_t *)malloc(*size);
 
  if (!*buffer) {
    fprintf(stderr, "Failed to allocate %zu bytes for %s!\n", *size, filename);
    fclose(fh);
    return -1;
  }
 
  if (fread(*buffer, *size, 1, fh) != 1) {
    fprintf(stderr, "Failed to read %zu bytes from %s!\n", *size, filename);
    fclose(fh);
    free(*buffer);
    return -1;
  }
 
  fclose(fh);
  return 0;
}
 
int main(int argc, char *argv[]) {
  if (argc != 4 ) {
    fprintf(stderr,
      "Usage:\n"
      " icnspack image.icns 1x.png 2x.png\n");
    return -1;
  }
 
  (void) remove(argv[1]);
  uint8_t *buffer1x;
  size_t size1x;
  int r1 = read_file(argv[2], &buffer1x, &size1x);
  uint8_t *buffer2x;
  size_t size2x;
  int r2 = read_file(argv[3], &buffer2x, &size2x);
 
  FILE *fh = NULL;
  if (r1 == 0 && r2 == 0) {
    fh = fopen (argv[1], "wb");
    if (fh != NULL) {
      uint32_t size = BigEndianToNative32(size1x + size2x + sizeof(uint32_t)*6);
      fwrite("icns", sizeof(uint32_t), 1, fh);
      fwrite(&size, sizeof(uint32_t), 1, fh);
 
      size = BigEndianToNative32(size1x + sizeof(uint32_t)*2);
      fwrite("ic07", sizeof(uint32_t), 1, fh);
      fwrite(&size, sizeof(uint32_t), 1, fh);
      fwrite(buffer1x, size1x, 1, fh);
 
      size = BigEndianToNative32(size2x + sizeof(uint32_t)*2);
      fwrite("ic13", sizeof(uint32_t), 1, fh);
      fwrite(&size, sizeof(uint32_t), 1, fh);
      fwrite(buffer2x, size2x, 1, fh);
 
      fclose(fh);
    }
  }
 
  if (r1 == 0) free(buffer1x);
  if (r2 == 0) free(buffer2x);
 
  return fh != NULL ? 0 : -1;
}