[src/trunk]: src/lib/librt Simplify previous by just doing an open() on the d...

[martin <martin%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/eccf9341872f
branches:  trunk
changeset: 339251:eccf9341872f
user:      martin <martin%NetBSD.org@localhost>
date:      Wed Jul 08 07:14:38 2015 +0000

description:
Simplify previous by just doing an open() on the directory and then using
the fstat* family to test for all relevant details.
Clean up buffer sizes and clarify a length check. Based on input from dholland.

diffstat:

 lib/librt/shm.c |  65 ++++++++++++++++++++++++--------------------------------
 1 files changed, 28 insertions(+), 37 deletions(-)

diffs (125 lines):

diff -r 8f6b719663c6 -r eccf9341872f lib/librt/shm.c
--- a/lib/librt/shm.c   Wed Jul 08 05:00:15 2015 +0000
+++ b/lib/librt/shm.c   Wed Jul 08 07:14:38 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: shm.c,v 1.2 2015/06/30 11:46:47 martin Exp $   */
+/*     $NetBSD: shm.c,v 1.3 2015/07/08 07:14:38 martin Exp $   */
 
 /*-
  * Copyright (c) 2013 The NetBSD Foundation, Inc.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: shm.c,v 1.2 2015/06/30 11:46:47 martin Exp $");
+__RCSID("$NetBSD: shm.c,v 1.3 2015/07/08 07:14:38 martin Exp $");
 
 #include <sys/mman.h>
 #include <sys/mount.h>
@@ -57,45 +57,36 @@
 
 #define        MOUNT_SHMFS             MOUNT_TMPFS
 
-static const char *            _shmfs_path = NULL;
-static char                    _shmfs_path_buf[PATH_MAX];
+static bool                    shm_ok = false;
 
 static bool
 _shm_check_fs(void)
 {
-       const char *shmfs = SHMFS_DIR_PATH;
+       int fd;
        struct statvfs sv;
        struct stat st;
-       char buf[PATH_MAX];
-       ssize_t cnt;
 
-       if ((cnt = readlink(shmfs, buf, sizeof(buf))) > 0) {
-               if ((size_t)cnt >= sizeof(buf))
-                       return false;
-               buf[cnt] = 0;
-               shmfs = buf;
-       }
-       if (statvfs1(shmfs, &sv, ST_NOWAIT) == -1) {
-               return false;
-       }
-       if (strncmp(sv.f_fstypename, MOUNT_SHMFS, sizeof(sv.f_fstypename))) {
+       fd = open(SHMFS_DIR_PATH, O_DIRECTORY|O_RDONLY);
+       if (fd == -1)
                return false;
-       }
+
+       if (fstatvfs1(fd, &sv, ST_NOWAIT) == -1)
+               goto out;
+
+       if (strncmp(sv.f_fstypename, MOUNT_SHMFS, sizeof(sv.f_fstypename)))
+               goto out;
 
-       if (lstat(shmfs, &st) == -1) {
-               return false;
-       }
-       if ((st.st_mode & SHMFS_DIR_MODE) != SHMFS_DIR_MODE) {
-               return false;
-       }
+       if (fstat(fd, &st) == -1)
+               goto out;
+
+       if ((st.st_mode & SHMFS_DIR_MODE) != SHMFS_DIR_MODE)
+               goto out;
 
-       if (shmfs == buf) {
-               strcpy(_shmfs_path_buf, buf);
-               _shmfs_path = _shmfs_path_buf;
-       } else {
-               _shmfs_path = shmfs;
-       }
-       return true;
+       shm_ok = true;
+
+out:
+       close(fd);
+       return shm_ok;
 }
 
 static bool
@@ -103,7 +94,7 @@
 {
        int ret;
 
-       if (__predict_false(!_shmfs_path) && !_shm_check_fs()) {
+       if (__predict_false(!shm_ok) && !_shm_check_fs()) {
                errno = ENOTSUP;
                return false;
        }
@@ -117,10 +108,10 @@
                return false;
        }
 
-       ret = snprintf(buf, len, "%s/%s%s",
-           _shmfs_path, SHMFS_OBJ_PREFIX, name);
+       ret = snprintf(buf, len, SHMFS_DIR_PATH "/" SHMFS_OBJ_PREFIX "%s",
+           name);
 
-       if ((size_t)ret >= PATH_MAX) {
+       if ((size_t)ret >= len) {
                errno = ENAMETOOLONG;
                return false;
        }
@@ -130,7 +121,7 @@
 int
 shm_open(const char *name, int oflag, mode_t mode)
 {
-       char path[PATH_MAX + 1];
+       char path[PATH_MAX];
 
        if (!_shm_get_path(path, sizeof(path), name)) {
                return -1;
@@ -141,7 +132,7 @@
 int
 shm_unlink(const char *name)
 {
-       char path[PATH_MAX + 1];
+       char path[PATH_MAX];
 
        if (!_shm_get_path(path, sizeof(path), name)) {
                return -1;