From 0da101b7ba1b2e2ed1a905586a72b49a8d5049a0 Mon Sep 17 00:00:00 2001
From: Sergey Nikiforov <void234@gmail.com>
Date: Mon, 17 Oct 2022 16:12:31 -0300
Subject: [PATCH] Fix a crash while writing a long string to the log

Corresponding code is improved to not overrun a buffer.
Added an API to write long strings to the log without trimming them.
---
 common/logstuff.cpp | 42 +++++++++++++++++++++++++++++++++---------
 common/logstuff.h   |  3 +++
 2 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/common/logstuff.cpp b/common/logstuff.cpp
index e3aa6ca2b..71d02c3e1 100644
--- a/common/logstuff.cpp
+++ b/common/logstuff.cpp
@@ -493,12 +493,19 @@ static void InternalLogMail( const char *msgbuffer, unsigned int msglen, int /*f
 // a (va_list *) instead to avoid this problem
 void LogWithPointer( int loggingTo, const char *format, va_list *arglist )
 {
-  char msgbuffer[1024]; //min 1024!!, but also think of other OSs stack!!
+  int scrwidth = ASSUMED_SCREEN_WIDTH; /* assume this for consistency */
+  ConGetSize(&scrwidth,NULL); /* sets to 80 or does not touch if not supported */
+
+  char fixed_msgbuffer[1024]; //min 1024!!, but also think of other OSs stack!!
+  char *msgbuffer = &fixed_msgbuffer[0];
+
+  //the code below may insert some characters
+  unsigned extra_bytes = scrwidth > 4 ? scrwidth : 4;
+
   unsigned int msglen = 0, sel;
   char *buffptr, *obuffptr;
   int old_loggingTo = loggingTo;
 
-  msgbuffer[0]=0;
   loggingTo &= (logstatics.loggingTo|LOGTO_RAWMODE);
 
   if ( !format || !*format )
@@ -506,10 +513,21 @@ void LogWithPointer( int loggingTo, const char *format, va_list *arglist )
 
   if ( loggingTo != LOGTO_NONE )
   {
-    if ( arglist == NULL )
-      strcat( msgbuffer, format );
-    else
-      vsprintf( msgbuffer, format, *arglist );
+    if ( arglist == NULL ) {
+      const size_t len = strlen(format);
+      if (len >= sizeof(fixed_msgbuffer) - extra_bytes) {
+        msgbuffer = (char *)malloc(len + 1 + extra_bytes);
+        if (msgbuffer) {
+          memcpy(msgbuffer, format, len + 1);
+        } else {
+          msgbuffer = &fixed_msgbuffer[0];
+          memcpy(msgbuffer, format, sizeof(fixed_msgbuffer) - 1 - extra_bytes);
+          msgbuffer[sizeof(fixed_msgbuffer) - 1 - extra_bytes] = 0;
+        }
+      } else
+        memcpy(msgbuffer, format, len + 1);
+    } else
+      vsnprintf(msgbuffer, sizeof(fixed_msgbuffer) - extra_bytes, format, *arglist);
     msglen = strlen( msgbuffer );
 
     if ( msglen == 0 )
@@ -571,9 +589,6 @@ void LogWithPointer( int loggingTo, const char *format, va_list *arglist )
 
   if (( loggingTo & LOGTO_SCREEN ) != 0)
   {
-    int scrwidth = ASSUMED_SCREEN_WIDTH; /* assume this for consistancy */
-    ConGetSize(&scrwidth,NULL); /* gets set to 80 or untouched, if not supported */
-
     #ifdef ASSERT_WIDTH_80  //"show" where badly formatted lines are cropping up
     //if (logstatics.stdoutisatty)
     {
@@ -645,6 +660,10 @@ void LogWithPointer( int loggingTo, const char *format, va_list *arglist )
     }
   }
 
+  if (msgbuffer != &fixed_msgbuffer[0]) {
+    free(msgbuffer);
+  }
+
   return;
 }
 
@@ -716,6 +735,11 @@ void LogRaw( const char *format, ... )
   return;
 }
 
+void LogRawString( const char *str )
+{
+  LogWithPointer( LOGTO_RAWMODE | LOGAS_LOG, str, NULL);
+}
+
 void LogTo( int towhat, const char *format, ... )
 {
   va_list argptr;
diff --git a/common/logstuff.h b/common/logstuff.h
index 7c1deeb86..f42ecbbc9 100644
--- a/common/logstuff.h
+++ b/common/logstuff.h
@@ -50,6 +50,9 @@ extern void LogScreenRaw( const char *format, ... ) __CHKFMT_PRINTF;
 //Log to mail+file+screen. No adjustments.
 extern void LogRaw( const char *format, ... ) __CHKFMT_PRINTF;
 
+//Log to mail+file+screen. No adjustments. Supports very long strings but not formatting.
+extern void LogRawString( const char *str );
+
 //Log to LOGTO_* flags (RAW implies screen)
 extern void LogTo( int towhat, const char *format, ... ) __CHKFMT_LOGTO;