File Restructuring

common/image.c

@@ -0,0 +1,9 @@
+#include "image.h"
+#include <stdlib.h>
+
+void free_image(Image* img) {
+  if (img && img->data) {
+    free(img->data);
+    img->data = NULL;
+  }
+}

common/image.h

@@ -0,0 +1,10 @@
+#include <stdint.h>
+
+typedef struct {
+  int width;
+  int height;
+  int channels;
+  uint8_t* data;
+} image_t;
+
+void free_image(image_t* img);

common/utils.c

@@ -0,0 +1,7 @@
+#include "common.h"
+
+uint32_t char_to_uint32 (unsigned char* input) {
+  uint32_t val = (input[0] << 24) + (input[1] << 16) + (input[2] << 8) + input[3];
+
+  return val;
+}

common/utils.h

@@ -0,0 +1,3 @@
+#include <stdint.h>
+
+uint32_t char_to_uint32(unsigned char *input);

formats/img_png.c

@@ -0,0 +1,85 @@
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "img_png.h"
+#include "common.h"
+
+#define BUFSIZE 1024
+
+const unsigned char img_png_signature[] = {0x89, 'P', 'N', 'G', '\r', '\n', 0x1a, '\n'};
+
+
+int read_chunk(FILE *fp) {
+  struct img_png_chunk cur_chunk;
+
+  // Read chunk length
+  unsigned char len[4];
+  if(fread(len, sizeof(*len), 4, fp) < 4) {
+    fprintf(stderr, "Couldn\'t read chunk length.\n");
+    exit(EXIT_FAILURE);
+  }
+
+  cur_chunk.length = char_to_uint32(len);
+  printf("Chunk length: %lu\n", (unsigned long) cur_chunk.length);
+  
+  // Read chunk type
+  if(fread(cur_chunk.chunk_type, sizeof(*cur_chunk.chunk_type), 4, fp) < 4) {
+    fprintf(stderr, "Couldn\'t read chunk type.\n");
+    exit(EXIT_FAILURE);
+  }
+  printf("Chunk type: %.*s\n", 4, cur_chunk.chunk_type);
+
+  // Read chunk data
+  size_t chunk_size = cur_chunk.length / sizeof(unsigned char);
+  printf("Chunk size: %zu\n", chunk_size);
+  cur_chunk.chunk_data = malloc(chunk_size);
+
+  if(!cur_chunk.chunk_data) {
+    perror("Failed to allocate chunk data!");
+    exit(EXIT_FAILURE);
+  }
+
+  if(fread(cur_chunk.chunk_data, 1, cur_chunk.length, fp) != cur_chunk.length) {
+    if(feof(fp)) {
+      fprintf(stderr, "File ended prematurely.\n");
+      exit(EXIT_FAILURE);
+    }
+    fprintf(stderr, "Failed to read chunk data!\n");
+    exit(EXIT_FAILURE);
+  }
+
+  return feof(fp);
+}
+
+uint8_t* img_png_decode(FILE *fp) {
+  unsigned char magic[8];
+
+  // Check PNG Magic
+  if(fread(magic, sizeof(*magic), 8, fp) < 8) {
+    fprintf(stderr, "Couldn\'t read PNG magic.");
+    exit(EXIT_FAILURE);
+  }
+
+  if(memcmp(magic, img_png_signature, 8) != 0) {
+    fprintf(stderr, "Invalid PNG magic\n");
+    exit(EXIT_FAILURE);
+  }
+  
+  printf("PNG Magic: %#04x%02x%02x%02x%02x%02x%02x%02x\n", magic[0], magic[1], magic[2],
+         magic[3], magic[4], magic[5], magic[6], magic[7]);
+
+  struct img_png_chunk cur_chunk;  
+
+  // Read chunk   
+  
+  while (read_chunk(fp) == 0);
+  
+  if(!feof(fp)) {
+    perror("fread() failed!");
+    exit(EXIT_FAILURE);
+  }
+  
+
+  return NULL;
+}

formats/img_png.h

@@ -0,0 +1,12 @@
+#include <stdint.h>
+#include <stdio.h>
+
+
+struct img_png_chunk {
+  unsigned char* chunk_data;
+  uint32_t length;
+  uint32_t crc;
+  char chunk_type[4];
+};
+
+uint8_t* img_png_decode (FILE* fp);