Refactor read_fields function

src/tiff/tiffread.c

@@ -35,6 +35,10 @@
 TiffHdr read_tiff_header(FILE *fp);
 TiffIFD read_ifd(FILE *fp, const TiffHdr *header, u32 offset, Arena *arena);
 TiffImage read_fields(FILE *fp, const TiffHdr *header, const TiffIFD *ifd);
+bool read_field(const TiffField *field, TiffImage *img,
+                u32 *image_type_identifier);
+bool validate_image_type(const TiffImage *img,
+                         const u32 *image_type_identifier);
 void read_from_file_with_offset(FILE *fp, void *dst, u64 count, u64 offset);
 
 Image *read_baseline_tiff(const char *file, Arena *arena) {
@@ -195,172 +199,13 @@ TiffImage read_fields(FILE *fp, const TiffHdr *header, const TiffIFD *ifd) {
       break;
     }
 
-    switch (field->tag) {
+    if (!read_field(field, &img_out, &image_type_identifier)) {
-    case TIFF_PUBLIC_TAG_IMAGE_WIDTH:
+      img_out = NULL_TIFF_IMAGE;
-      if (field->count > 1) {
+      goto READ_FIELDS_RETURN_IMAGE;
-        img_out = NULL_TIFF_IMAGE;
-        goto READ_FIELDS_RETURN_IMAGE;
-      }
-
-      img_out.image_width = field->value_offset;
-
-      break;
-    case TIFF_PUBLIC_TAG_IMAGE_LENGTH:
-      if (field->count > 1) {
-        img_out = NULL_TIFF_IMAGE;
-        goto READ_FIELDS_RETURN_IMAGE;
-      }
-
-      img_out.image_length = field->value_offset;
-
-      break;
-    case TIFF_PUBLIC_TAG_BITS_PER_SAMPLE:
-      image_type_identifier |= field->tag;
-
-      if (img_out.sample_count == INVALID_SAMPLE_COUNT) {
-        img_out.sample_count = field->count;
-      } else if (img_out.sample_count != field->count) {
-        img_out = NULL_TIFF_IMAGE;
-        goto READ_FIELDS_RETURN_IMAGE;
-      }
-
-      img_out.bits_per_sample = field->value_offset;
-
-      img_out.bits_per_sample_offset =
-          img_out.sample_count * field_types[field->type].byte_count > 4;
-
-      break;
-    case TIFF_PUBLIC_TAG_COMPRESSION:
-      if (field->count > 1 ||
-          field->value_offset != TIFF_COMPRESSION_UNCOMPRESSED) {
-        img_out = NULL_TIFF_IMAGE;
-        goto READ_FIELDS_RETURN_IMAGE;
-      }
-
-      img_out.compression = field->value_offset;
-
-      break;
-    case TIFF_PUBLIC_TAG_PHOTOMETRIC_INTERPRETATION:
-      if (field->count > 1) {
-        img_out = NULL_TIFF_IMAGE;
-        goto READ_FIELDS_RETURN_IMAGE;
-      }
-
-      img_out.photometric_interpretation = field->value_offset;
-
-      break;
-    case TIFF_PUBLIC_TAG_STRIP_OFFSETS:
-      img_out.strip_offsets = field->value_offset;
-
-      if (img_out.strip_count == INVALID_STRIP_COUNT) {
-        img_out.strip_count = field->count;
-      } else if (img_out.strip_count != field->count) {
-        img_out = NULL_TIFF_IMAGE;
-        goto READ_FIELDS_RETURN_IMAGE;
-      }
-
-      img_out.strip_offsets_offset =
-          img_out.strip_count * field_types[field->type].byte_count > 4;
-
-      break;
-    case TIFF_PUBLIC_TAG_SAMPLES_PER_PIXEL:
-      image_type_identifier |= field->tag;
-
-      if (field->count > 1) {
-        img_out = NULL_TIFF_IMAGE;
-        goto READ_FIELDS_RETURN_IMAGE;
-      }
-
-      img_out.sample_count = field->value_offset;
-
-      break;
-    case TIFF_PUBLIC_TAG_ROWS_PER_STRIP:
-      if (field->count > 1) {
-        img_out = NULL_TIFF_IMAGE;
-        goto READ_FIELDS_RETURN_IMAGE;
-      }
-
-      img_out.rows_per_strip = field->value_offset;
-
-      if (img_out.image_length > 0) {
-        img_out.strip_count =
-            floor((f64)(img_out.image_length + img_out.rows_per_strip - 1) /
-                  img_out.rows_per_strip);
-      } else {
-        img_out.strip_count = INVALID_STRIP_COUNT;
-      }
-
-      break;
-    case TIFF_PUBLIC_TAG_STRIP_BYTE_COUNTS:
-      img_out.strip_byte_counts = field->value_offset;
-
-      if (img_out.strip_count == INVALID_STRIP_COUNT) {
-        img_out.strip_count = field->count;
-      } else if (img_out.strip_count != field->count) {
-        img_out = NULL_TIFF_IMAGE;
-        goto READ_FIELDS_RETURN_IMAGE;
-      }
-
-      img_out.strip_byte_counts_offset =
-          img_out.strip_count * field_types[field->type].byte_count > 4;
-
-      break;
-    case TIFF_PUBLIC_TAG_COLOR_MAP:
-      image_type_identifier |= field->tag;
-      break;
-    case TIFF_PUBLIC_TAG_EXTRA_SAMPLES:
-      img_out.extra_samples_count = field->count;
-
-      img_out.extra_samples = field->value_offset;
-
-      img_out.extra_samples_offset =
-          img_out.extra_samples_count * field_types[field->type].byte_count > 4;
-
-      break;
-    case TIFF_PUBLIC_TAG_PLANAR_CONFIGURATION:
-      if (field->count > 1 ||
-          field->value_offset != TIFF_PLANAR_CONFIG_CHUNKY) {
-        img_out = NULL_TIFF_IMAGE;
-        goto READ_FIELDS_RETURN_IMAGE;
-      }
-
-      break;
     }
   }
 
-  if (image_type_identifier < TIFF_IMAGE_TYPE_BILEVEL ||
+  if (!validate_image_type(&img_out, &image_type_identifier)) {
-      image_type_identifier > TIFF_IMAGE_TYPE_RGB) {
-    img_out = NULL_TIFF_IMAGE;
-    goto READ_FIELDS_RETURN_IMAGE;
-  }
-
-  switch (image_type_identifier) {
-  case TIFF_IMAGE_TYPE_BILEVEL:
-  case TIFF_IMAGE_TYPE_GRAYSCALE:
-    if (img_out.photometric_interpretation >
-        TIFF_PHOTOMETRIC_INTERPRETATION_BLACK_IS_ZERO) {
-      img_out = NULL_TIFF_IMAGE;
-      goto READ_FIELDS_RETURN_IMAGE;
-    }
-
-    break;
-  case TIFF_IMAGE_TYPE_PALETTE:
-    if (img_out.photometric_interpretation !=
-        TIFF_PHOTOMETRIC_INTERPRETATION_RGB_PALETTE) {
-      img_out = NULL_TIFF_IMAGE;
-      goto READ_FIELDS_RETURN_IMAGE;
-    }
-
-    break;
-  case TIFF_IMAGE_TYPE_RGB:
-    if (img_out.photometric_interpretation !=
-        TIFF_PHOTOMETRIC_INTERPRETATION_RGB) {
-      img_out = NULL_TIFF_IMAGE;
-      goto READ_FIELDS_RETURN_IMAGE;
-    }
-
-    break;
-  default:
     img_out = NULL_TIFF_IMAGE;
     goto READ_FIELDS_RETURN_IMAGE;
   }
@@ -384,6 +229,169 @@ READ_FIELDS_RETURN_IMAGE:
   return img_out;
 }
 
+bool read_field(const TiffField *field, TiffImage *img,
+                u32 *image_type_identifier) {
+  switch (field->tag) {
+  case TIFF_PUBLIC_TAG_IMAGE_WIDTH:
+    if (field->count > 1) {
+      return false;
+    }
+
+    img->image_width = field->value_offset;
+
+    break;
+  case TIFF_PUBLIC_TAG_IMAGE_LENGTH:
+    if (field->count > 1) {
+      return false;
+    }
+
+    img->image_length = field->value_offset;
+
+    break;
+  case TIFF_PUBLIC_TAG_BITS_PER_SAMPLE:
+    *image_type_identifier |= field->tag;
+
+    if (img->sample_count == INVALID_SAMPLE_COUNT) {
+      img->sample_count = field->count;
+    } else if (img->sample_count != field->count) {
+      return false;
+    }
+
+    img->bits_per_sample = field->value_offset;
+
+    img->bits_per_sample_offset =
+        img->sample_count * field_types[field->type].byte_count > 4;
+
+    break;
+  case TIFF_PUBLIC_TAG_COMPRESSION:
+    if (field->count > 1 ||
+        field->value_offset != TIFF_COMPRESSION_UNCOMPRESSED) {
+      return false;
+    }
+
+    img->compression = field->value_offset;
+
+    break;
+  case TIFF_PUBLIC_TAG_PHOTOMETRIC_INTERPRETATION:
+    if (field->count > 1) {
+      return false;
+    }
+
+    img->photometric_interpretation = field->value_offset;
+
+    break;
+  case TIFF_PUBLIC_TAG_STRIP_OFFSETS:
+    img->strip_offsets = field->value_offset;
+
+    if (img->strip_count == INVALID_STRIP_COUNT) {
+      img->strip_count = field->count;
+    } else if (img->strip_count != field->count) {
+      return false;
+    }
+
+    img->strip_offsets_offset =
+        img->strip_count * field_types[field->type].byte_count > 4;
+
+    break;
+  case TIFF_PUBLIC_TAG_SAMPLES_PER_PIXEL:
+    *image_type_identifier |= field->tag;
+
+    if (field->count > 1) {
+      return false;
+    }
+
+    img->sample_count = field->value_offset;
+
+    break;
+  case TIFF_PUBLIC_TAG_ROWS_PER_STRIP:
+    if (field->count > 1) {
+      return false;
+    }
+
+    img->rows_per_strip = field->value_offset;
+
+    if (img->image_length > 0) {
+      img->strip_count =
+          floor((f64)(img->image_length + img->rows_per_strip - 1) /
+                img->rows_per_strip);
+    } else {
+      img->strip_count = INVALID_STRIP_COUNT;
+    }
+
+    break;
+  case TIFF_PUBLIC_TAG_STRIP_BYTE_COUNTS:
+    img->strip_byte_counts = field->value_offset;
+
+    if (img->strip_count == INVALID_STRIP_COUNT) {
+      img->strip_count = field->count;
+    } else if (img->strip_count != field->count) {
+      return false;
+    }
+
+    img->strip_byte_counts_offset =
+        img->strip_count * field_types[field->type].byte_count > 4;
+
+    break;
+  case TIFF_PUBLIC_TAG_COLOR_MAP:
+    *image_type_identifier |= field->tag;
+    break;
+  case TIFF_PUBLIC_TAG_EXTRA_SAMPLES:
+    img->extra_samples_count = field->count;
+
+    img->extra_samples = field->value_offset;
+
+    img->extra_samples_offset =
+        img->extra_samples_count * field_types[field->type].byte_count > 4;
+
+    break;
+  case TIFF_PUBLIC_TAG_PLANAR_CONFIGURATION:
+    if (field->count > 1 || field->value_offset != TIFF_PLANAR_CONFIG_CHUNKY) {
+      return false;
+    }
+
+    break;
+  }
+
+  return true;
+}
+
+bool validate_image_type(const TiffImage *img,
+                         const u32 *image_type_identifier) {
+  if (*image_type_identifier < TIFF_IMAGE_TYPE_BILEVEL ||
+      *image_type_identifier > TIFF_IMAGE_TYPE_RGB) {
+    return false;
+  }
+
+  switch (*image_type_identifier) {
+  case TIFF_IMAGE_TYPE_BILEVEL:
+  case TIFF_IMAGE_TYPE_GRAYSCALE:
+    if (img->photometric_interpretation >
+        TIFF_PHOTOMETRIC_INTERPRETATION_BLACK_IS_ZERO) {
+      return false;
+    }
+
+    break;
+  case TIFF_IMAGE_TYPE_PALETTE:
+    if (img->photometric_interpretation !=
+        TIFF_PHOTOMETRIC_INTERPRETATION_RGB_PALETTE) {
+      return false;
+    }
+
+    break;
+  case TIFF_IMAGE_TYPE_RGB:
+    if (img->photometric_interpretation !=
+        TIFF_PHOTOMETRIC_INTERPRETATION_RGB) {
+      return false;
+    }
+
+    break;
+  default:
+    return false;
+  }
+
+  return true;
+}
+
 void read_from_file_with_offset(FILE *fp, void *dst, u64 count, u64 offset) {
   if (!fp || !dst) {
     return;