From 777c360774832ac0a258af7b881e6a3842e9970e Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Sat, 6 Jul 2019 11:34:20 +0100
Subject: [PATCH] safer gifload delay array init

- remove assumptions about n_pages
- minor reformatting
---
 ChangeLog                   |  1 +
 libvips/foreign/gifload.c   | 32 ++++++++++++++++++++++++++------
 libvips/foreign/vips2webp.c |  7 +++++--
 3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index ad086f4e..27fb7bca 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,7 @@
 20/6/19 started 8.9.0
 - add vips_image_get/set_array_int()
 - disable webp alpha output if all frame fill the canvas and are solid
+- support arrays of delays for animated images [deftomat]
 
 24/5/19 started 8.8.1
 - improve realpath() use on older libc
diff --git a/libvips/foreign/gifload.c b/libvips/foreign/gifload.c
index 690f4a68..b72ec1f5 100644
--- a/libvips/foreign/gifload.c
+++ b/libvips/foreign/gifload.c
@@ -22,6 +22,8 @@
  * 	- init pages to 0 before load
  * 14/2/19
  * 	- rework as a sequential loader ... simpler, much lower mem use
+ * 6/7/19
+ * 	- support array of delays
  */
 
 /*
@@ -135,6 +137,7 @@ typedef struct _VipsForeignLoadGif {
 	/* Delays between frames (in milliseconds).
 	 */
 	int *delays;
+	int delays_length;
 
 	/* Number of times to loop the animation.
 	 */
@@ -519,10 +522,22 @@ vips_foreign_load_gif_scan_extension( VipsForeignLoadGif *gif )
 				gif->has_transparency = TRUE;
 			}
 
-			if( gif->n_pages % 64 == 0 )
-				gif->delays = (int *) g_realloc( gif->delays, (gif->n_pages + 64) * sizeof(int) );
+			if( gif->n_pages >= gif->delays_length ) {
+				int old = gif->delays_length;
+				int i;
 
-			gif->delays[gif->n_pages] = (extension[2] | (extension[3] << 8)) * 10;
+				gif->delays_length = 
+					gif->delays_length + gif->n_pages + 64;
+				gif->delays = (int *) g_realloc( gif->delays, 
+					gif->delays_length * sizeof( int ) );
+				for( i = old; i < gif->delays_length; i++ )
+					gif->delays[i] = 40;
+			}
+
+			/* giflib uses centiseconds, we use ms.
+			 */
+			gif->delays[gif->n_pages] = 
+				(extension[2] | (extension[3] << 8)) * 10;
 
 			while( extension != NULL )
 				if( vips_foreign_load_gif_ext_next( gif,
@@ -575,10 +590,14 @@ vips_foreign_load_gif_set_header( VipsForeignLoadGif *gif, VipsImage *image )
 	vips_image_set_int( image, "gif-loop", gif->loop );
 
 	if( gif->delays ) {
+		/* The deprecated gif-delay field is in centiseconds.
+		 */
 		vips_image_set_int( image,
-		 "gif-delay", VIPS_RINT( gif->delays[0] / 10.0 ) );
-		vips_image_set_array_int( image, "delay", gif->delays, gif->n_pages );
-	} else
+			"gif-delay", VIPS_RINT( gif->delays[0] / 10.0 ) );
+		vips_image_set_array_int( image, 
+			"delay", gif->delays, gif->n_pages );
+	} 
+	else
 		vips_image_set_int( image, "gif-delay", 4 );
 
 	if( gif->comment )
@@ -1122,6 +1141,7 @@ vips_foreign_load_gif_init( VipsForeignLoadGif *gif )
 	gif->n = 1;
 	gif->transparency = -1;
 	gif->delays = NULL;
+	gif->delays_length = 0;
 	gif->loop = 0;
 	gif->comment = NULL;
 	gif->dispose = 0;
diff --git a/libvips/foreign/vips2webp.c b/libvips/foreign/vips2webp.c
index b3e3ecc7..3e207457 100644
--- a/libvips/foreign/vips2webp.c
+++ b/libvips/foreign/vips2webp.c
@@ -306,10 +306,13 @@ get_array_int( VipsImage *image, const char *field, int* n )
 /* Returns a delay on a given index or the default delay.
  */
 static int 
-extract_delay( int index, int *delays, int delays_length, int default_delay )
+extract_delay( int index, const int *delays, int delays_length, 
+	int default_delay )
 {
-	if( delays == NULL || index > delays_length )
+	if( delays == NULL || 
+		index > delays_length )
 		return( default_delay );
+
 	return( delays[index] );
 }