disallow strcat

Originally committed as revision 3826 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/common.h

@@ -500,6 +500,7 @@ tend= rdtsc();\
 #define rand rand_is_forbidden_due_to_state_trashing
 #define srand srand_is_forbidden_due_to_state_trashing
 #define sprintf sprintf_is_forbidden_due_to_security_issues_use_snprintf
+#define strcat strcat_is_forbidden_due_to_security_issues_use_pstrcat
 #if !(defined(LIBAVFORMAT_BUILD) || defined(_FRAMEHOOK_H))
 #define printf please_use_av_log
 #define fprintf please_use_av_log

vhook/ppm.c

@@ -55,14 +55,15 @@ rwpipe *rwpipe_open( int argc, char *argv[] )
 
         if ( this->pid == 0 )
         {
-            char *command = av_mallocz( 10240 );
+#define COMMAND_SIZE 10240
+            char *command = av_mallocz( COMMAND_SIZE );
             int i;
 
             strcpy( command, "" );
             for ( i = 0; i < argc; i ++ )
             {
-                strcat( command, argv[ i ] );
-                strcat( command, " " );
+                pstrcat( command, COMMAND_SIZE, argv[ i ] );
+                pstrcat( command, COMMAND_SIZE, " " );
             }
 
             dup2( output[ 0 ], STDIN_FILENO );