Bug#1151438: imv FTBFS on big endian

[Pranav P]

Hi,

This failure does not show up in the upstream source code.
I have attached a diff which fixes the issue on big endian
machines. This function is taken directly from upstream
and handles the endianness differences using the functions
TIFFGetR, TIFFGetB, etc. as they using bitwise operations.

Thanks,
Pranav
diff --git a/src/backend_libtiff.c b/src/backend_libtiff.c
index 4a0f9cd..6d196b8 100644
--- a/src/backend_libtiff.c
+++ b/src/backend_libtiff.c
@@ -57,6 +57,22 @@ static void free_private(void *raw_private)
   free(private);
 }
 
+static uint8_t *convert_tiff_bitmap_to_rgba_inplace(
+    uint32_t *bitmap, size_t len)
+{
+  uint8_t *buf = (uint8_t *)bitmap;
+
+  for (size_t i = 0; i < len; i++) {
+    uint32_t tmp = bitmap[i];
+    buf[4 * i + 0] = TIFFGetR(tmp);
+    buf[4 * i + 1] = TIFFGetG(tmp);
+    buf[4 * i + 2] = TIFFGetB(tmp);
+    buf[4 * i + 3] = TIFFGetA(tmp);
+  }
+
+  return buf;
+}
+
 static void load_image(void *raw_private, struct imv_image **image, int *frametime)
 {
   *image = NULL;
@@ -81,7 +97,8 @@ static void load_image(void *raw_private, struct imv_image **image, int *frameti
   struct imv_bitmap *bmp = malloc(sizeof *bmp);
   bmp->width = private->width;
   bmp->height = private->height;
-  bmp->data = bitmap;
+  bmp->data = convert_tiff_bitmap_to_rgba_inplace(
+		  bitmap, imv_bitmap_size(bmp) / sizeof(uint32_t));
   *image = imv_image_create_from_bitmap(bmp);
 }
 
diff --git a/src/bitmap.c b/src/bitmap.c
index 9f84052..45483fb 100644
--- a/src/bitmap.c
+++ b/src/bitmap.c
@@ -1,7 +1,15 @@
 #include "bitmap.h"
 
+#include <assert.h>
+#include <stdint.h>
 #include <stdlib.h>
 
+size_t imv_bitmap_size(struct imv_bitmap* bmp)
+{
+  assert((size_t)bmp->width <= SIZE_MAX / bmp->height / BYTES_PER_CHANNEL);
+  return (size_t)bmp->width * bmp->height * BYTES_PER_CHANNEL;
+}
+
 void imv_bitmap_free(struct imv_bitmap *bmp)
 {
   free(bmp->data);
diff --git a/src/bitmap.h b/src/bitmap.h
index 87591d1..9d1dcca 100644
--- a/src/bitmap.h
+++ b/src/bitmap.h
@@ -1,12 +1,20 @@
 #ifndef IMV_BITMAP_H
 #define IMV_BITMAP_H
 
+#include <stdint.h>
+#include <stdlib.h>
+
+#define BYTES_PER_CHANNEL 4
+
 struct imv_bitmap {
   int width;
   int height;
   unsigned char *data;
 };
 
+/* Gets the size of the `data` buffer in bytes. */
+size_t imv_bitmap_size(struct imv_bitmap *bmp);
+
 /* Clean up a bitmap */
 void imv_bitmap_free(struct imv_bitmap *bmp);