From 1fd3b478e1921402aa855bd9c6e3dd2367a8909d Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Sat, 14 Dec 2019 05:13:44 +0000
Subject: [PATCH] always check memory area length

vips_image_new_from_memory() allowed you to use length == 0 to mean
"don't check memory length". This was part of some very old vips7
compatibility.

The ppm loader could pass length == 0 if header size was equal to file
size, bypassing the length check.
---
 libvips/foreign/ppmload.c | 6 ++++--
 libvips/iofuncs/image.c   | 6 +-----
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/libvips/foreign/ppmload.c b/libvips/foreign/ppmload.c
index f22554a9..33ed119e 100644
--- a/libvips/foreign/ppmload.c
+++ b/libvips/foreign/ppmload.c
@@ -65,8 +65,8 @@
  */
 
 /*
-#define DEBUG
  */
+#define DEBUG
 
 #ifdef HAVE_CONFIG_H
 #include <config.h>
@@ -426,6 +426,7 @@ vips_foreign_load_ppm_generate_binary( VipsRegion *or,
 {
         VipsRect *r = &or->valid;
 	VipsForeignLoadPpm *ppm = (VipsForeignLoadPpm *) a;
+	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( ppm );
 	VipsImage *image = or->im;
 	size_t sizeof_line = VIPS_IMAGE_SIZEOF_LINE( image );
 
@@ -438,7 +439,8 @@ vips_foreign_load_ppm_generate_binary( VipsRegion *or,
 
 		bytes_read = vips_streami_read( ppm->streami, q, sizeof_line );
 		if( bytes_read != sizeof_line ) {
-			vips_error( "ppmload", "%s", _( "file truncated" ) );
+			vips_error( class->nickname, 
+				"%s", _( "file truncated" ) );
 			return( -1 );
 		}
 	}
diff --git a/libvips/iofuncs/image.c b/libvips/iofuncs/image.c
index 36a480de..3d41f19d 100644
--- a/libvips/iofuncs/image.c
+++ b/libvips/iofuncs/image.c
@@ -2072,11 +2072,7 @@ vips_image_new_from_memory( const void *data, size_t size,
 		return( NULL );
 	}
 
-	/* Allow len == 0, meaning don't check. Used for im_image()
-	 * compatibility.
-	 */
-	if( size > 0 && 
-		size < VIPS_IMAGE_SIZEOF_IMAGE( image ) ) {
+	if( size < VIPS_IMAGE_SIZEOF_IMAGE( image ) ) {
 		vips_error( "VipsImage",
 			_( "memory area too small --- "
 				"should be %" G_GINT64_FORMAT " bytes, "