Security fix: mod_ffmpeg target used popen to run ffmpeg, change it to use pipe,...

git-svn-id: http://svn.voria.com/code@1181 1f10aa63-cdf2-0310-b900-c93c546f37ac

diff --git a/synfig-core/trunk/src/modules/mod_ffmpeg/trgt_ffmpeg.cpp b/synfig-core/trunk/src/modules/mod_ffmpeg/trgt_ffmpeg.cpp
index e41d1a5..251dc3a 100644 (file)
--- a/synfig-core/trunk/src/modules/mod_ffmpeg/trgt_ffmpeg.cpp
+++ b/synfig-core/trunk/src/modules/mod_ffmpeg/trgt_ffmpeg.cpp
@@ -124,11 +124,39 @@ ffmpeg_trgt::init()
        imagecount=desc.get_frame_start();
        if(desc.get_frame_end()-desc.get_frame_start()>0)
                multi_image=true;
-       string command;
 
-       command=strprintf("ffmpeg -f image2pipe -vcodec ppm -an -r %f -i pipe: -loop -hq -title \"%s\" -vcodec mpeg1video -y \"%s\"\n",desc.get_frame_rate(),get_canvas()->get_name().c_str(),filename.c_str());
-
-       file=popen(command.c_str(),POPEN_BINARY_WRITE_TYPE);
+       int p[2];
+  
+       if (pipe(p)) {
+               synfig::error(_("Unable to open pipe to ffmpeg"));
+               return false;
+       };
+  
+       pid_t pid = fork();
+  
+       if (pid == -1) {
+               synfig::error(_("Unable to open pipe to ffmpeg"));
+               return false;
+       }
+  
+       if (pid == 0){
+               // Child process
+               // Dup pipeout to stdin
+               if( dup2( p[0], STDIN_FILENO ) == -1 ){
+                       synfig::error(_("Unable to open pipe to ffmpeg"));
+                       return false;
+               }
+               execlp("ffmpeg", "ffmpeg", "-f", "image2pipe", "-vcodec", "ppm", "-an", "-r", strprintf("%f", desc.get_frame_rate()).c_str(), "-i", "pipe:", "-loop", "-hq", "-title", get_canvas()->get_name().c_str(), "-vcodec", "mpeg1video", "-y", filename.c_str(), (const char *)NULL);
+               // We should never reach here unless the exec failed
+               synfig::error(_("Unable to open pipe to ffmpeg"));
+               return false;
+       } else {
+               // Parent process
+               // Close pipein, not needed
+               close(p[0]);
+               // Save pipeout to file handle, will write to it later
+               file = fdopen(p[1], "wb");
+       }
 
        // etl::yield();