[gobject-introspection] scanner: Use PATH_MAX, not hardcoded 1024 for realpath()

[Colin Walters <walters src gnome org>]

commit ff2e8dd92d43e11705fcd2b493737bb58c4f2daa
Author: Colin Walters <walters verbum org>
Date:   Sat Nov 16 10:55:15 2013 -0500

    scanner: Use PATH_MAX, not hardcoded 1024 for realpath()
    
    Otherwise we can overflow the stack on longer pathnames.
    
    Tested-By: Mantas Mikulėnas <grawity gmail com>

 giscanner/scannerlexer.l |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)
---
diff --git a/giscanner/scannerlexer.l b/giscanner/scannerlexer.l
index f80a8d6..89a34b8 100644
--- a/giscanner/scannerlexer.l
+++ b/giscanner/scannerlexer.l
@@ -31,6 +31,9 @@
 %{
 #include <ctype.h>
 #include <stdio.h>
+#ifndef _WIN32
+#include <limits.h>
+#endif
 
 #include <glib.h>
 #include "sourcescanner.h"
@@ -317,11 +320,22 @@ check_identifier (GISourceScanner *scanner,
        return IDENTIFIER;
 }
 
+/* taken from glib/gfileutils.c */
+#if defined(MAXPATHLEN)
+#define G_PATH_LENGTH MAXPATHLEN
+#elif defined(PATH_MAX)
+#define G_PATH_LENGTH PATH_MAX
+#elif defined(_PC_PATH_MAX)
+#define G_PATH_LENGTH sysconf(_PC_PATH_MAX)
+#else
+#define G_PATH_LENGTH 2048
+#endif
+
 static inline char *
 _realpath (const char *path)
 {
 #ifndef _WIN32
-  char buffer[1025];
+  char buffer[G_PATH_LENGTH];
 
   return realpath (path, buffer) ? g_strdup (buffer) : NULL;
 #else