Extract function slurp_image from image loading

* src/image.c (slurp_image): New function...
(xbm_load, xpm_load, pbm_load, webp_load, svg_load): ...extracted from
here.

src/image.c

@@ -4355,6 +4355,27 @@ slurp_file (image_fd fd, ptrdiff_t *size)
   return buf;
 }
 
+/* Like slurp_file above, but with added error handling.  Value is
+   null if an error occurred.  Set SIZE to the size of the file.
+   IMAGE_TYPE describes the image type (e.g. "PNG").  */
+
+static char *
+slurp_image (Lisp_Object filename, ptrdiff_t *size, const char *image_type)
+{
+  image_fd fd;
+  Lisp_Object file = image_find_image_fd (filename, &fd);
+  if (!STRINGP (file))
+    {
+      image_not_found_error (filename);
+      return NULL;
+    }
+  char *result = slurp_file (fd, size);
+  if (result == NULL)
+    image_error ("Error loading %s image `%s'",
+		 make_unibyte_string (image_type, strlen (image_type)),
+		 file);
+  return result;
+}
 
 
 /***********************************************************************
@@ -5073,22 +5094,10 @@ xbm_load (struct frame *f, struct image *img)
   file_name = image_spec_value (img->spec, QCfile, NULL);
   if (STRINGP (file_name))
     {
-      image_fd fd;
-      Lisp_Object file = image_find_image_fd (file_name, &fd);
-      if (!STRINGP (file))
-	{
-	  image_not_found_error (file_name);
-	  return false;
-	}
-
       ptrdiff_t size;
-      char *contents = slurp_file (fd, &size);
+      char *contents = slurp_image (file_name, &size, "XBM");
       if (contents == NULL)
-	{
-	  image_error ("Error loading XBM image `%s'", file);
-	  return 0;
-	}
-
+	return false;
       success_p = xbm_load_image (f, img, contents, contents + size);
       xfree (contents);
     }
@@ -6369,21 +6378,10 @@ xpm_load (struct frame *f,
   file_name = image_spec_value (img->spec, QCfile, NULL);
   if (STRINGP (file_name))
     {
-      image_fd fd;
-      Lisp_Object file = image_find_image_fd (file_name, &fd);
-      if (!STRINGP (file))
-	{
-	  image_not_found_error (file_name);
-	  return false;
-	}
-
       ptrdiff_t size;
-      char *contents = slurp_file (fd, &size);
+      char *contents = slurp_image (file_name, &size, "XPM");
       if (contents == NULL)
-	{
-	  image_error ("Error loading XPM image `%s'", file);
-	  return 0;
-	}
+	return false;
 
       success_p = xpm_load_image (f, img, contents, contents + size);
       xfree (contents);
@@ -7398,21 +7396,10 @@ pbm_load (struct frame *f, struct image *img)
 
   if (STRINGP (specified_file))
     {
-      image_fd fd;
-      Lisp_Object file = image_find_image_fd (specified_file, &fd);
-      if (!STRINGP (file))
-	{
-	  image_not_found_error (specified_file);
-	  return false;
-	}
-
       ptrdiff_t size;
-      contents = slurp_file (fd, &size);
+      contents = slurp_image (specified_file, &size, "PBM");
       if (contents == NULL)
-	{
-	  image_error ("Error reading `%s'", file);
-	  return 0;
-	}
+	return false;
 
       p = contents;
       end = contents + size;
@@ -10302,20 +10289,9 @@ webp_load (struct frame *f, struct image *img)
 
   if (NILP (specified_data))
     {
-      image_fd fd;
-      file = image_find_image_fd (specified_file, &fd);
-      if (!STRINGP (file))
-	{
-	  image_not_found_error (specified_file);
-	  return false;
-	}
-
-      contents = (uint8_t *) slurp_file (fd, &size);
+      contents = (uint8_t *) slurp_image (specified_file, &size, "WebP");
       if (contents == NULL)
-	{
-	  image_error ("Error loading WebP image `%s'", file);
-	  return false;
-	}
+	return false;
     }
   else
     {
@@ -11708,22 +11684,11 @@ svg_load (struct frame *f, struct image *img)
   base_uri = image_spec_value (img->spec, QCbase_uri, NULL);
   if (STRINGP (file_name))
     {
-      image_fd fd;
-      Lisp_Object file = image_find_image_fd (file_name, &fd);
-      if (!STRINGP (file))
-	{
-	  image_not_found_error (file_name);
-	  return false;
-	}
-
-      /* Read the entire file into memory.  */
       ptrdiff_t size;
-      char *contents = slurp_file (fd, &size);
+      char *contents = slurp_image (file_name, &size, "SVG");
       if (contents == NULL)
-	{
-	  image_error ("Error loading SVG image `%s'", file);
-	  return 0;
-	}
+	return false;
+
       /* If the file was slurped into memory properly, parse it.  */
       if (!STRINGP (base_uri))
         base_uri = file;