GIF: Unify insufficient data error codes.

There is no difference in what the client needs to do.
If there are displayable frames, they can display them.
Otherwise more data is needed.

Internally only `GIF_INSUFFICIENT_DATA` is used now.

To remove the `GIF_INSUFFICIENT_FRAME_DATA` could make existing
client applications fail to compile, so it is left as an alias
to the same value.

At some point the API will be changed drastically, but for now
I want existing applications to still build.

3 files changed, 19 insertions, 43 deletions

diff --git a/include/libnsgif.h b/include/libnsgif.h
index 5bd26b4..309e2f0 100644
--- a/include/libnsgif.h
+++ b/include/libnsgif.h
@@ -23,9 +23,9 @@
 typedef enum {
 	GIF_WORKING = 1,
 	GIF_OK = 0,
-	GIF_INSUFFICIENT_FRAME_DATA = -1,
+	GIF_INSUFFICIENT_DATA = -1,
+	GIF_INSUFFICIENT_FRAME_DATA = GIF_INSUFFICIENT_DATA,
 	GIF_FRAME_DATA_ERROR = -2,
-	GIF_INSUFFICIENT_DATA = -3,
 	GIF_DATA_ERROR = -4,
 	GIF_INSUFFICIENT_MEMORY = -5,
 	GIF_FRAME_NO_DISPLAY = -6,
@@ -166,11 +166,9 @@ void gif_create(gif_animation *gif, gif_bitmap_callback_vt *bitmap_callbacks);
  *
  * \return Error return value.
  *         - GIF_FRAME_DATA_ERROR for GIF frame data error
- *         - GIF_INSUFFICIENT_FRAME_DATA for insufficient data to process
- *                                     any more frames
+ *         - GIF_INSUFFICIENT_DATA reached unexpected end of source data
  *         - GIF_INSUFFICIENT_MEMORY for memory error
  *         - GIF_DATA_ERROR for GIF error
- *         - GIF_INSUFFICIENT_DATA for insufficient data to do anything
  *         - GIF_OK for successful decoding
  *         - GIF_WORKING for successful decoding if more frames are expected
  */
@@ -181,9 +179,8 @@ gif_result gif_initialise(gif_animation *gif, size_t size, const uint8_t *data);
  *
  * \return Error return value.
  *         - GIF_FRAME_DATA_ERROR for GIF frame data error
- *         - GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame
  *         - GIF_DATA_ERROR for GIF error (invalid frame header)
- *         - GIF_INSUFFICIENT_DATA for insufficient data to do anything
+ *         - GIF_INSUFFICIENT_DATA reached unexpected end of source data
  *         - GIF_INSUFFICIENT_MEMORY for insufficient memory to process
  *         - GIF_OK for successful decoding
  */
diff --git a/src/libnsgif.c b/src/libnsgif.c
index f0fab44..457ce00 100644
--- a/src/libnsgif.c
+++ b/src/libnsgif.c
@@ -77,7 +77,7 @@ static gif_result gif_error_from_lzw(lzw_result l_res)
 		[LZW_OK]	= GIF_OK,
 		[LZW_OK_EOD]    = GIF_END_OF_FRAME,
 		[LZW_NO_MEM]    = GIF_INSUFFICIENT_MEMORY,
-		[LZW_NO_DATA]   = GIF_INSUFFICIENT_FRAME_DATA,
+		[LZW_NO_DATA]   = GIF_INSUFFICIENT_DATA,
 		[LZW_EOI_CODE]  = GIF_FRAME_DATA_ERROR,
 		[LZW_BAD_ICODE] = GIF_FRAME_DATA_ERROR,
 		[LZW_BAD_CODE]  = GIF_FRAME_DATA_ERROR,
@@ -560,7 +560,7 @@ static gif_result gif__update_bitmap(
  * \param[in] frame  The gif object we're decoding.
  * \param[in] data   The data to decode.
  * \param[in] len    Byte length of data.
- * \return GIF_INSUFFICIENT_FRAME_DATA if more data is needed,
+ * \return GIF_INSUFFICIENT_DATA if more data is needed,
  *         GIF_OK for success.
  */
 static gif_result gif__parse_extension_graphic_control(
@@ -581,7 +581,7 @@ static gif_result gif__parse_extension_graphic_control(
 	 *  +5  CHAR    Transparent Color Index
 	 */
 	if (len < 6) {
-		return GIF_INSUFFICIENT_FRAME_DATA;
+		return GIF_INSUFFICIENT_DATA;
 	}
 
 	frame->frame_delay = data[3] | (data[4] << 8);
@@ -616,7 +616,7 @@ static gif_result gif__parse_extension_graphic_control(
  * \param[in] gif   The gif object we're decoding.
  * \param[in] data  The data to decode.
  * \param[in] len   Byte length of data.
- * \return GIF_INSUFFICIENT_FRAME_DATA if more data is needed,
+ * \return GIF_INSUFFICIENT_DATA if more data is needed,
  *         GIF_OK for success.
  */
 static gif_result gif__parse_extension_application(
@@ -633,7 +633,7 @@ static gif_result gif__parse_extension_application(
 	 *  +13   1-256   Application Data (Data sub-blocks)
 	 */
 	if (len < 17) {
-		return GIF_INSUFFICIENT_FRAME_DATA;
+		return GIF_INSUFFICIENT_DATA;
 	}
 
 	if ((data[1] == 0x0b) &&
@@ -651,7 +651,7 @@ static gif_result gif__parse_extension_application(
  * \param[in] gif     The gif object we're decoding.
  * \param[in] frame   The frame to parse extensions for.
  * \param[in] decode  Whether to decode or skip over the extension.
- * \return GIF_INSUFFICIENT_FRAME_DATA if more data is needed,
+ * \return GIF_INSUFFICIENT_DATA if more data is needed,
  *         GIF_OK for success.
  */
 static gif_result gif__parse_frame_extensions(
@@ -673,7 +673,7 @@ static gif_result gif__parse_frame_extensions(
 		gif_bytes--;
 
 		if (gif_bytes == 0) {
-			return GIF_INSUFFICIENT_FRAME_DATA;
+			return GIF_INSUFFICIENT_DATA;
 		}
 
 		/* Switch on extension label */
@@ -715,7 +715,7 @@ static gif_result gif__parse_frame_extensions(
 			 * the extension size itself
 			 */
 			if (gif_bytes < 2) {
-				return GIF_INSUFFICIENT_FRAME_DATA;
+				return GIF_INSUFFICIENT_DATA;
 			}
 			gif_data += 2 + gif_data[1];
 		}
@@ -725,7 +725,7 @@ static gif_result gif__parse_frame_extensions(
 		while (gif_data < gif_end && gif_data[0] != GIF_BLOCK_TERMINATOR) {
 			gif_data += gif_data[0] + 1;
 			if (gif_data >= gif_end) {
-				return GIF_INSUFFICIENT_FRAME_DATA;
+				return GIF_INSUFFICIENT_DATA;
 			}
 		}
 		gif_data++;
@@ -779,7 +779,7 @@ static gif_result gif__parse_image_descriptor(
 	assert(frame != NULL);
 
 	if (len < GIF_IMAGE_DESCRIPTOR_LEN) {
-		return GIF_INSUFFICIENT_FRAME_DATA;
+		return GIF_INSUFFICIENT_DATA;
 	}
 
 	if (decode) {
@@ -830,11 +830,7 @@ static gif_result gif__colour_table_extract(
 	size_t len = gif->gif_data + gif->buffer_size - data;
 
 	if (len < colour_table_entries * 3) {
-		if (colour_table == gif->local_colour_table) {
-			return GIF_INSUFFICIENT_FRAME_DATA;
-		} else {
-			return GIF_INSUFFICIENT_DATA;
-		}
+		return GIF_INSUFFICIENT_DATA;
 	}
 
 	if (decode) {
@@ -935,7 +931,7 @@ static gif_result gif__parse_image_data(
 			/* Fall through. */
 		case 1: if (data[0] == GIF_TRAILER) return GIF_OK;
 			/* Fall through. */
-		case 0: return GIF_INSUFFICIENT_FRAME_DATA;
+		case 0: return GIF_INSUFFICIENT_DATA;
 	}
 
 	minimum_code_size = data[0];
@@ -953,7 +949,7 @@ static gif_result gif__parse_image_data(
 		len--;
 
 		while (block_size != 1) {
-			if (len < 1) return GIF_INSUFFICIENT_FRAME_DATA;
+			if (len < 1) return GIF_INSUFFICIENT_DATA;
 			block_size = data[0] + 1;
 			/* Check if the frame data runs off the end of the file	*/
 			if (block_size > len) {
@@ -971,7 +967,7 @@ static gif_result gif__parse_image_data(
 
 		/* Check if we've finished */
 		if (len < 1) {
-			return GIF_INSUFFICIENT_FRAME_DATA;
+			return GIF_INSUFFICIENT_DATA;
 		} else {
 			if (data[0] == GIF_TRAILER) {
 				return GIF_OK;
@@ -1026,10 +1022,9 @@ static struct gif_frame *gif__get_frame(
  * \param[in] frame_idx The frame number to decode.
  * \param[in] decode    Whether to decode the graphical image data.
  * \return error code
- *         - GIF_INSUFFICIENT_DATA for insufficient data to do anything
+ *         - GIF_INSUFFICIENT_DATA reached unexpected end of source data.
  *         - GIF_FRAME_DATA_ERROR for GIF frame data error
  *         - GIF_INSUFFICIENT_MEMORY for insufficient memory to process
- *         - GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame
  *         - GIF_DATA_ERROR for GIF error (invalid frame header)
  *         - GIF_OK for successful decoding
  *         - GIF_WORKING for successful decoding if more frames are expected
@@ -1326,19 +1321,6 @@ gif_result gif_initialise(gif_animation *gif, size_t size, const uint8_t *data)
 	/* Repeatedly try to initialise frames */
 	while ((ret = gif__process_frame(gif, gif->frame_count, false)) == GIF_WORKING);
 
-	/* If there was a memory error tell the caller */
-	if ((ret == GIF_INSUFFICIENT_MEMORY) ||
-	    (ret == GIF_DATA_ERROR)) {
-		return ret;
-	}
-
-	/* If we didn't have some frames then a GIF_INSUFFICIENT_DATA becomes a
-	 * GIF_INSUFFICIENT_FRAME_DATA
-	 */
-	if (ret == GIF_INSUFFICIENT_DATA && gif->frame_count_partial > 0) {
-		return GIF_INSUFFICIENT_FRAME_DATA;
-	}
-
 	return ret;
 }
 
diff --git a/test/decode_gif.c b/test/decode_gif.c
index 64387ef..52d73b6 100644
--- a/test/decode_gif.c
+++ b/test/decode_gif.c
@@ -113,9 +113,6 @@ static void warning(const char *context, gif_result code)
         fprintf(stderr, "%s failed: ", context);
         switch (code)
         {
-        case GIF_INSUFFICIENT_FRAME_DATA:
-                fprintf(stderr, "GIF_INSUFFICIENT_FRAME_DATA");
-                break;
         case GIF_FRAME_DATA_ERROR:
                 fprintf(stderr, "GIF_FRAME_DATA_ERROR");
                 break;