[PATCH] Avoid use of uninitialized values in guid.c

[Chris Shoemaker]

  * Avoid use of uninitialized values in guid.c
    - prevent md5 seeding from using uninitialized stack contents
    - give used GUID recognizable memory signature
    - add a simple test case that helped testing for use of
        uninitialized values
    

Index: src/engine/guid.c
===================================================================
RCS file: /home/cvs/cvsroot/gnucash/src/engine/guid.c,v
retrieving revision 1.25.4.6
diff -u -r1.25.4.6 guid.c
--- src/engine/guid.c      31 May 2004 14:22:11 -0000      1.25.4.6
+++ src/engine/guid.c      10 Feb 2005 05:50:07 -0000
@@ -99,5 +99,5 @@
 const GUID *
 guid_null(void)
 {
-  static int null_inited = (0 == 1);
+  static int null_inited = 0;
   static GUID null_guid;

   if (!null_inited)
   {
     int i;
+    char *tmp = "NULLGUID.EMPTY.";

+    /* 16th space for '\O' */
     for (i = 0; i < 16; i++)
-      null_guid.data[i] = 0;
+      null_guid.data[i] = tmp[i];

-    null_inited = (0 == 0);
+    null_inited = 1;
   }

   return &null_guid;
@@ -186,2 +188,2 @@
   size_t file_bytes;
   FILE *fp;

+  memset(&stats, 0, sizeof(struct stat));
   if (stat(filename, &stats) != 0)
     return 0;

@@ -236,14 +239,15 @@
     if (de == NULL)
       break;
 
-    md5_process_bytes(de, sizeof(struct dirent), &guid_context);
-    total += sizeof(struct dirent);
+    md5_process_bytes(de->d_name, strlen(de->d_name), &guid_context);
+    total += strlen(de->d_name);
 
     result = snprintf(filename, sizeof(filename),
                       "%s/%s", dirname, de->d_name);
     if ((result < 0) || (result >= (int)sizeof(filename)))
       continue;
 
+    memset(&stats, 0, sizeof(struct stat));
     if (stat(filename, &stats) != 0)
       continue;
     md5_process_bytes(&stats, sizeof(stats), &guid_context);
@@ -298,7 +302,8 @@
 {
   size_t bytes = 0;
 
-  guid_memchunk_init();
+  /* Not needed: taken care of on first malloc.
+  /* guid_memchunk_init(); */
 
   md5_init_ctx(&guid_context);
 
@@ -387,7 +392,8 @@
   /* host info */
   {
     char string[1024];
-
+
+    memset((void *)string, 0, 1024);
     gethostname(string, sizeof(string));
     md5_process_bytes(string, sizeof(string), &guid_context);
     bytes += sizeof(string);
Index: src/engine/test/test-guid.c
===================================================================
RCS file: /home/cvs/cvsroot/gnucash/src/engine/test/test-guid.c,v
retrieving revision 1.2
diff -u -r1.2 test-guid.c
--- src/engine/test/test-guid.c	17 Oct 2003 04:25:46 -0000	1.2
+++ src/engine/test/test-guid.c	10 Feb 2005 02:10:41 -0000
@@ -16,8 +16,21 @@
 #include "qofid.h"
 #include "qofid-p.h"
 #include "qofsession.h"
+#include "guid.h"
 
+static void test1(void)
+{
+  GUID g;
+  GUID *gp;
+
+  g = guid_new_return();
+  gp = guid_malloc();
+  guid_new(gp);
 
+  do_test(guid_equal(guid_null(), guid_null()), "null guids equal");
+  do_test(!guid_equal(&g, gp), "two guids equal");
+  
+}
 
 static void
 run_test (void)
@@ -47,14 +60,16 @@
 	 ent->e_type = type;
 	 qof_collection_insert_entity (col, ent);
   }
+  qof_session_destroy(sess);
 }
 
 static void
 main_helper (void *closure, int argc, char **argv)
 {
-  g_log_set_always_fatal( G_LOG_LEVEL_CRITICAL | G_LOG_LEVEL_WARNING );
   do_test((NULL!=gnc_module_load("gnucash/engine", 0)), "couldn't load engine");
+  g_log_set_always_fatal( G_LOG_LEVEL_CRITICAL | G_LOG_LEVEL_WARNING );
 
+  test1();
   run_test ();
 
   print_test_results();
@@ -64,6 +79,7 @@
 int
 main (int argc, char **argv)
 {
-  scm_boot_guile(argc, argv, main_helper, NULL);
+  /* scm_boot_guile(argc, argv, main_helper, NULL); */
+  main_helper(NULL, argc, argv);
   return 0;
 }