From: Todd C. Miller <Todd.Miller@courtesan.com>
Date: Sat, 9 Jun 2007 11:26:43 +0000 (+0000)
Subject: Use /proc/self/fd instead of /proc/$$/fd
X-Git-Tag: SUDO_1_7_0~565
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=8ae409b8f230eccada72cfe7a28876f283e99423;p=sudo

Use /proc/self/fd instead of /proc/$$/fd

Move old-style fd closing into closefrom_fallback() and call
that if /proc/self/fd doesn't exist or the F_CLOSEM fcntl() fails
---

diff --git a/closefrom.c b/closefrom.c
index 03ee1b2c6..a6118b83b 100644
--- a/closefrom.c
+++ b/closefrom.c
@@ -51,31 +51,64 @@
 __unused static const char rcsid[] = "$Sudo$";
 #endif /* lint */
 
+#ifndef HAVE_FCNTL_CLOSEM
+# ifndef HAVE_DIRFD
+#   define closefrom_fallback	closefrom
+# endif
+#endif
+
 /*
  * Close all file descriptors greater than or equal to lowfd.
+ * This is the expensive (ballback) method.
+ */
+void
+closefrom_fallback(lowfd)
+    int lowfd;
+{
+    long fd, maxfd;
+
+    /*
+     * Fall back on sysconf() or getdtablesize().  We avoid checking
+     * resource limits since it is possible to open a file descriptor
+     * and then drop the rlimit such that it is below the open fd.
+     */
+#ifdef HAVE_SYSCONF
+    maxfd = sysconf(_SC_OPEN_MAX);
+#else
+    maxfd = getdtablesize();
+#endif /* HAVE_SYSCONF */
+    if (maxfd < 0)
+	maxfd = OPEN_MAX;
+
+    for (fd = lowfd; fd < maxfd; fd++)
+	(void) close((int) fd);
+}
+
+/*
+ * Close all file descriptors greater than or equal to lowfd.
+ * We try the fast way first, falling back on the slow method.
  */
 #ifdef HAVE_FCNTL_CLOSEM
 void
 closefrom(lowfd)
     int lowfd;
 {
-    (void) fcntl(lowfd, F_CLOSEM, 0);
+    if (fcntl(lowfd, F_CLOSEM, 0) == -1)
+	closefrom_fallback(lowfd);
 }
 #else
+# ifdef HAVE_DIRFD
 void
 closefrom(lowfd)
     int lowfd;
 {
-    long fd, maxfd;
-#ifdef HAVE_DIRFD
-    char fdpath[PATH_MAX], *endp;
     struct dirent *dent;
     DIR *dirp;
-    int len;
+    char *endp;
+    long fd;
 
-    /* Check for a /proc/$$/fd directory. */
-    len = snprintf(fdpath, sizeof(fdpath), "/proc/%ld/fd", (long)getpid());
-    if (len > 0 && (size_t)len <= sizeof(fdpath) && (dirp = opendir(fdpath))) {
+    /* Use /proc/self/fd directory if it exists. */
+    if ((dirp = opendir("/proc/self/fd")) != NULL) {
 	while ((dent = readdir(dirp)) != NULL) {
 	    fd = strtol(dent->d_name, &endp, 10);
 	    if (dent->d_name != endp && *endp == '\0' &&
@@ -84,23 +117,7 @@ closefrom(lowfd)
 	}
 	(void) closedir(dirp);
     } else
-#endif
-    {
-	/*
-	 * Fall back on sysconf() or getdtablesize().  We avoid checking
-	 * resource limits since it is possible to open a file descriptor
-	 * and then drop the rlimit such that it is below the open fd.
-	 */
-#ifdef HAVE_SYSCONF
-	maxfd = sysconf(_SC_OPEN_MAX);
-#else
-	maxfd = getdtablesize();
-#endif /* HAVE_SYSCONF */
-	if (maxfd < 0)
-	    maxfd = OPEN_MAX;
-
-	for (fd = lowfd; fd < maxfd; fd++)
-	    (void) close((int) fd);
-    }
+	closefrom_fallback(lowfd);
 }
-#endif /* !HAVE_FCNTL_CLOSEM */
+#endif /* HAVE_DIRFD */
+#endif /* HAVE_FCNTL_CLOSEM */