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authorRich Felker <dalias@aerifal.cx>2012-09-30 17:53:54 -0400
committerRich Felker <dalias@aerifal.cx>2012-09-30 17:53:54 -0400
commit6e2372a86c7e862ed931910f8a5f4b908639d689 (patch)
tree57892b1e0d718fbb9ab86767915bca095cc5e307
parent2e3648b85db1c71bfc684233f7a521b0d4bbeb20 (diff)
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clean up, bugfixes, and general improvement for shm_open/shm_unlink
1. don't make non-cloexec file descriptors 2. cancellation safety (cleanup handlers were missing, now unneeded) 3. share name validation/mapping code between open/unlink functions 4. avoid wasteful/slow syscalls
-rw-r--r--src/mman/shm_open.c37
-rw-r--r--src/mman/shm_unlink.c21
2 files changed, 28 insertions, 30 deletions
diff --git a/src/mman/shm_open.c b/src/mman/shm_open.c
index d368622d..a9be899b 100644
--- a/src/mman/shm_open.c
+++ b/src/mman/shm_open.c
@@ -3,19 +3,38 @@
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
+#include <limits.h>
-int shm_open(const char *name, int flag, mode_t mode)
-{
- int fd, dir;
+char *__strchrnul(const char *, int);
+static const char *mapname(const char *name, char *buf)
+{
+ char *p;
while (*name == '/') name++;
- if (strchr(name, '/')) {
+ if (*(p = __strchrnul(name, '/')) || p==name ||
+ (p-name <= 2 && name[0]=='.' && p[-1]=='.')) {
errno = EINVAL;
- return -1;
+ return 0;
}
+ if (p-name > NAME_MAX) {
+ errno = ENAMETOOLONG;
+ return 0;
+ }
+ memcpy(buf, "/dev/shm/", 9);
+ memcpy(buf+9, name, p-name+1);
+ return buf;
+}
- if ((dir = open("/dev/shm", O_DIRECTORY|O_RDONLY)) < 0) return -1;
- fd = openat(dir, name, flag|O_NOFOLLOW|O_CLOEXEC|O_NONBLOCK, mode);
- close(dir);
- return fd;
+int shm_open(const char *name, int flag, mode_t mode)
+{
+ char buf[NAME_MAX+10];
+ if (!(name = mapname(name, buf))) return -1;
+ return open(name, flag|O_NOFOLLOW|O_CLOEXEC|O_NONBLOCK, mode);
+}
+
+int shm_unlink(const char *name)
+{
+ char buf[NAME_MAX+10];
+ if (!(name = mapname(name, buf))) return -1;
+ return unlink(name);
}
diff --git a/src/mman/shm_unlink.c b/src/mman/shm_unlink.c
deleted file mode 100644
index 46e60b3b..00000000
--- a/src/mman/shm_unlink.c
+++ /dev/null
@@ -1,21 +0,0 @@
-#include <sys/mman.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <string.h>
-
-int shm_unlink(const char *name)
-{
- int dir, ret;
-
- while (*name == '/') name++;
- if (strchr(name, '/')) {
- errno = EINVAL;
- return -1;
- }
-
- if ((dir = open("/dev/shm", O_DIRECTORY|O_RDONLY)) < 0) return -1;
- ret = unlinkat(dir, name, 0);
- close(dir);
- return ret;
-}