bugfix(minor): handling of extremely large strings in dbgprintf() fixed

Previously, it could lead to garbagge output and, in extreme cases, also
to segfaults. Note: this was a problem only when debug output was
actually enabled, so it caused no problem in production use.

2 files changed, 13 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 7fe59dd9..4a57639e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -20,6 +20,10 @@ Version 4.6.2  [v4-stable] (rgerhards), 2010-03-??
   in proper retries.
 - bugfix: $omfileFlushOnTXEnd was turned on when set to off and vice
   versa due to an invalid check
+- bugfix(minor): handling of extremely large strings in dbgprintf() fixed
+  Previously, it could lead to garbagge output and, in extreme cases, also
+  to segfaults. Note: this was a problem only when debug output was 
+  actually enabled, so it caused no problem in production use.
 ---------------------------------------------------------------------------
 Version 4.6.1  [v4-stable] (rgerhards), 2010-03-04
 - re-enabled old pipe output (using new module ompipe, built-in) after
diff --git a/runtime/debug.c b/runtime/debug.c
index 4504aaad..bc581a5d 100644
--- a/runtime/debug.c
+++ b/runtime/debug.c
@@ -961,6 +961,15 @@ dbgprintf(char *fmt, ...)
 	va_start(ap, fmt);
 	lenWriteBuf = vsnprintf(pszWriteBuf, sizeof(pszWriteBuf), fmt, ap);
 	va_end(ap);
+	if(lenWriteBuf >= sizeof(pszWriteBuf)) {
+		/* prevent buffer overrruns and garbagge display */
+		pszWriteBuf[sizeof(pszWriteBuf) - 5] = '.';
+		pszWriteBuf[sizeof(pszWriteBuf) - 4] = '.';
+		pszWriteBuf[sizeof(pszWriteBuf) - 3] = '.';
+		pszWriteBuf[sizeof(pszWriteBuf) - 2] = '\n';
+		pszWriteBuf[sizeof(pszWriteBuf) - 1] = '\0';
+		lenWriteBuf = sizeof(pszWriteBuf);
+	}
 	dbgprint(NULL, pszWriteBuf, lenWriteBuf);
 }