[FFmpeg-devel] [PATCH]lavc/pnmdec: Do not fail by default for truncated pbm files

[Carl Eugen Hoyos]

Hi!

Some scanner - scannersoftware combination (HP_Officejet_Pro_X476dn_MFP 
- sane) truncates trailing zeros in pbm files and FreeImage (a library 
used in free and proprietary image software) reads such files.
Attached patch copies this behaviour and fixes ticket #5795.

Please comment, Carl Eugen
-------------- next part --------------
From af00c56b38b28e07bbba46031472da41300a8cf1 Mon Sep 17 00:00:00 2001
From: Carl Eugen Hoyos <cehoyos at ag.or.at>
Date: Sun, 4 Sep 2016 20:52:28 +0200
Subject: [PATCH] lavc/pnmdec: Do not abort by default for truncated pbm
 files.

Fixes ticket #5795.
---
 libavcodec/pnmdec.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/libavcodec/pnmdec.c b/libavcodec/pnmdec.c
index d4261a4..0b7a0f6 100644
--- a/libavcodec/pnmdec.c
+++ b/libavcodec/pnmdec.c
@@ -124,8 +124,12 @@ static int pnm_decode_frame(AVCodecContext *avctx, void *data,
     do_read:
         ptr      = p->data[0];
         linesize = p->linesize[0];
-        if (s->bytestream + n * avctx->height > s->bytestream_end)
-            return AVERROR_INVALIDDATA;
+        if (s->bytestream + n * avctx->height > s->bytestream_end) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "Invalid truncated file\n");
+            if (avctx->strict_std_compliance >= FF_COMPLIANCE_STRICT)
+                return AVERROR_INVALIDDATA;
+        }
         if(s->type < 4 || (is_mono && s->type==7)){
             for (i=0; i<avctx->height; i++) {
                 PutBitContext pb;
@@ -159,6 +163,8 @@ static int pnm_decode_frame(AVCodecContext *avctx, void *data,
             }
         }else{
         for (i = 0; i < avctx->height; i++) {
+            if (s->bytestream + n > s->bytestream_end)
+                continue;
             if (!upgrade)
                 samplecpy(ptr, s->bytestream, n, s->maxval);
             else if (upgrade == 1) {
-- 
1.7.10.4