glenn made more edits to this file

Docs/Changelog_sm-ssc.txt

@@ -19,6 +19,10 @@ sm-ssc v1.0 Release Candidate 2 | 201007xx
 sm4svn commits:
  * r28367: fix resampler noise [Glenn Maynard]
  * r28368: fix get_readable_ranges error handling [Glenn Maynard]
+ * r28369: don't use fprintf from the crash handler [Glenn Maynard]
+ * r28370: work around not all recursive crashes being caught [Glenn Maynard]
+ * r28371: use /proc weirdness to make the crash handler work even after
+   the binary has been deleted or replaced [Glenn Maynard]
 
 sm-ssc:
 * [ScreenDebugOverlay] add new metrics: LineStartY, LineSpacing,

src/archutils/Unix/CrashHandler.cpp

@@ -48,22 +48,10 @@ static void safe_print( int fd, ... )
 #if defined(LINUX)
 static void GetExecutableName( char *buf, int bufsize )
 {
-	/* readlink(/proc/pid/exe).  This is more reliable than argv[0]. */
+	/* Reading /proc/self/exe always gives the running binary, even if it no
-	char proc_fn[1024] = "/proc/";
+	 * longer exists. */
-	strcat( proc_fn, itoa( getpid() ) );
+	strncpy( buf, "/proc/self/exe", bufsize );
-	strcat( proc_fn, "/exe" );
+	buf[bufsize-1] = 0;
-
-	int got = readlink( proc_fn, buf, bufsize-1 );
-	if( got == -1 )
-	{
-		safe_print( fileno(stderr), "Crash handler readlink ", proc_fn, " failed: ", strerror(errno), "\n", NULL );
-
-		strncpy( buf, g_pCrashHandlerArgv0, bufsize );
-		buf[bufsize-1] = 0;
-	}
-
-
-	buf[got] = 0;
 }
 #else
 static void GetExecutableName( char *buf, int bufsize )
@@ -385,19 +373,22 @@ void CrashHandler::ForceDeadlock( RString reason, uint64_t iID )
 	_exit( 1 );
 }
 
-
-
 void CrashHandler::CrashSignalHandler( int signal, siginfo_t *si, const ucontext_t *uc )
 {
-	static bool bInCrashSignalHandler = false;
+	static volatile bool bInCrashSignalHandler = false;
 	if( bInCrashSignalHandler )
 	{
-		fprintf(stderr, "Fatal: crash from within the crash signal handler\n");
+		safe_print( 2, "Fatal: crash from within the crash signal handler\n", NULL );
 		_exit(1);
 	}
 
 	bInCrashSignalHandler = true;
 
+	/* Work around a gcc bug: it reorders the above assignment past other work down
+	 * here, even if we declare it volatile.  This makes us not catch recursive
+	 * crashes. */
+	asm volatile("nop");
+
 	CrashData crash;
 	memset( &crash, 0, sizeof(crash) );