[PATCH] os: don't malloc memory in LogVMessageVerb.

[Peter Hutterer]

LogVWrite is limited to a buffer size of 1024, so we don't loose anything here
by truncating. This way we can use LogVMessageVerb (and xf86Msg and friends)
during signal handlers with the normal message types.

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---

Currently, doing an xf86Msg() during a signal handler is a big no-no, it
deadlocks the system on malloc when the prefix is prepended. Only X_NONE
messages bypass this.
There isn't really a need to malloc though, we're limited to 1024 bytes anyway
in LogVWrite.

 os/log.c |   22 ++++++----------------
 1 files changed, 6 insertions(+), 16 deletions(-)

diff --git a/os/log.c b/os/log.c
index 3961b0b..8108890 100644
--- a/os/log.c
+++ b/os/log.c
@@ -316,7 +316,7 @@ void
 LogVMessageVerb(MessageType type, int verb, const char *format, va_list args)
 {
     const char *s  = X_UNKNOWN_STRING;
-    char *tmpBuf = NULL;
+    char tmpBuf[1024];
 
     /* Ignore verbosity for X_ERROR */
     if (logVerbosity >= verb || logFileVerbosity >= verb || type == X_ERROR) {
@@ -358,21 +358,11 @@ LogVMessageVerb(MessageType type, int verb, const char *format, va_list args)
 	    break;
 	}
 
-	/*
-	 * Prefix the format string with the message type.  We do it this way
-	 * so that LogVWrite() is only called once per message.
-	 */
-	if (s) {
-	    tmpBuf = malloc(strlen(format) + strlen(s) + 1 + 1);
-	    /* Silently return if malloc fails here. */
-	    if (!tmpBuf)
-		return;
-	    sprintf(tmpBuf, "%s ", s);
-	    strcat(tmpBuf, format);
-	    LogVWrite(verb, tmpBuf, args);
-	    free(tmpBuf);
-	} else
-	    LogVWrite(verb, format, args);
+        /* if s is not NULL we need a space before format */
+        snprintf(tmpBuf, sizeof(tmpBuf), "%s%s%s", s ? s : "",
+                                                   s ? " " : "",
+                                                   format);
+        LogVWrite(verb, tmpBuf, args);
     }
 }
 
-- 
1.6.2.2.447.g4afa7