MonetDB: Jan2014 - Avoid time-of-check time-of-use race by not u...

[Sjoerd Mullender]

Changeset: b7db1cf8709e for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=b7db1cf8709e
Modified Files:
        monetdb5/mal/mal_linker.c
Branch: Jan2014
Log Message:

Avoid time-of-check time-of-use race by not using stat to check.
There is no need to first use stat to check whether a file exists and
then using dlopen (or any other function that basically does the same
check again), and checking for the latter's result as well.  You might
as well skip stat.


diffs (68 lines):

diff --git a/monetdb5/mal/mal_linker.c b/monetdb5/mal/mal_linker.c
--- a/monetdb5/mal/mal_linker.c
+++ b/monetdb5/mal/mal_linker.c
@@ -78,9 +78,6 @@
 #ifdef HAVE_FCNTL_H
 #include <fcntl.h>
 #endif
-#ifdef HAVE_SYS_STAT_H
-#include <sys/stat.h>
-#endif
 #include <unistd.h>
 
 #if defined(_MSC_VER) && _MSC_VER >= 1400
@@ -237,7 +234,6 @@ loadLibrary(str filename, int flag)
 
        while (*mod_path) {
                char *p;
-               struct stat stbuf;
 
                if ((p = strchr(mod_path, PATH_SEP)) != NULL)
                        *p = '\0';
@@ -249,22 +245,19 @@ loadLibrary(str filename, int flag)
                snprintf(nme, MAXPATHLEN, "%s%c%s_%s%s",
                                mod_path, DIR_SEP, SO_PREFIX, s, SO_EXT);
 #endif
-               if (stat(nme, &stbuf) != 0 || !S_ISREG(stbuf.st_mode))
-                       *nme = '\0';
-               if (*nme == '\0' && strcmp(SO_EXT, ".so") != 0) {
+               handle = dlopen(nme, mode);
+               if (handle == NULL && strcmp(SO_EXT, ".so") != 0) {
                        /* try .so */
                        snprintf(nme, MAXPATHLEN, "%s%c%s_%s.so",
                                        mod_path, DIR_SEP, SO_PREFIX, s);
-                       if (stat(nme, &stbuf) != 0 || !S_ISREG(stbuf.st_mode))
-                               *nme = '\0';
+                       handle = dlopen(nme, mode);
                }
 #ifdef __APPLE__
-               if (*nme == '\0' && strcmp(SO_EXT, ".bundle") != 0) {
+               if (handle == NULL && strcmp(SO_EXT, ".bundle") != 0) {
                        /* try .bundle */
                        snprintf(nme, MAXPATHLEN, "%s%c%s_%s.bundle",
                                        mod_path, DIR_SEP, SO_PREFIX, s);
-                       if (stat(nme, &stbuf) != 0 || !S_ISREG(stbuf.st_mode))
-                               *nme = '\0';
+                       handle = dlopen(nme, mode);
                }
 #endif
 
@@ -272,17 +265,7 @@ loadLibrary(str filename, int flag)
                if (p != NULL)
                        *p = PATH_SEP;
 
-               if (*nme != '\0') {
-                       handle = dlopen(nme, mode);
-                       if (handle != NULL) {
-                               break;
-                       } else {
-                               throw(LOADER, "loadLibrary",
-                                               "failed to load library: %s", 
dlerror());
-                       }
-               }
-
-               if (p == NULL)
+               if (p == NULL || handle != NULL)
                        break;
                mod_path = p + 1;
        }
_______________________________________________
checkin-list mailing list
checkin-list@monetdb.org
https://www.monetdb.org/mailman/listinfo/checkin-list