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lxclock: use thread-safe *_OFD_* fcntl() locks

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If they aren't available fallback to BSD flock()s.

Closes #2245.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Christian Brauner 2018-03-30 06:54:40 +02:00
parent 16c92537a5
commit b19aabf5be
No known key found for this signature in database
GPG Key ID: 8EB056D53EECB12D
2 changed files with 32 additions and 16 deletions
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29
src/lxc/lxclock.c
View File

@ -55,7 +55,7 @@ static inline void dump_stacktrace(void)
strings = backtrace_symbols(array, size);
/* Using fprintf here as our logging module is not thread safe. */
fprintf(stderr, "\tObtained %zu stack frames.\n", size);
fprintf(stderr, "\tObtained %zu stack frames\n", size);
for (i = 0; i < size; i++)
fprintf(stderr, "\t\t%s\n", strings[i]);
@ -195,7 +195,7 @@ int lxclock(struct lxc_lock *l, int timeout)
case LXC_LOCK_ANON_SEM:
if (!timeout) {
ret = sem_wait(l->u.sem);
if (ret == -1)
if (ret < 0)
saved_errno = errno;
} else {
struct timespec ts;
@ -205,7 +205,7 @@ int lxclock(struct lxc_lock *l, int timeout)
}
ts.tv_sec += timeout;
ret = sem_timedwait(l->u.sem, &ts);
if (ret == -1)
if (ret < 0)
saved_errno = errno;
}
break;
@ -220,21 +220,22 @@ int lxclock(struct lxc_lock *l, int timeout)
goto out;
}
if (l->u.f.fd == -1) {
l->u.f.fd = open(l->u.f.fname, O_RDWR|O_CREAT,
S_IWUSR | S_IRUSR);
l->u.f.fd = open(l->u.f.fname, O_CREAT | O_RDWR | O_NOFOLLOW | O_CLOEXEC | O_NOCTTY, S_IWUSR | S_IRUSR);
if (l->u.f.fd == -1) {
ERROR("Error opening %s", l->u.f.fname);
saved_errno = errno;
goto out;
}
}
memset(&lk, 0, sizeof(struct flock));
lk.l_type = F_WRLCK;
lk.l_whence = SEEK_SET;
lk.l_start = 0;
lk.l_len = 0;
ret = fcntl(l->u.f.fd, F_SETLKW, &lk);
if (ret == -1)
ret = fcntl(l->u.f.fd, F_OFD_SETLKW, &lk);
if (ret < 0) {
if (errno == EINVAL)
ret = flock(l->u.f.fd, LOCK_EX);
saved_errno = errno;
}
break;
}
@ -259,13 +260,15 @@ int lxcunlock(struct lxc_lock *l)
break;
case LXC_LOCK_FLOCK:
if (l->u.f.fd != -1) {
memset(&lk, 0, sizeof(struct flock));
lk.l_type = F_UNLCK;
lk.l_whence = SEEK_SET;
lk.l_start = 0;
lk.l_len = 0;
ret = fcntl(l->u.f.fd, F_SETLK, &lk);
if (ret < 0)
ret = fcntl(l->u.f.fd, F_OFD_SETLK, &lk);
if (ret < 0) {
if (errno == EINVAL)
ret = flock(l->u.f.fd, LOCK_EX | LOCK_NB);
saved_errno = errno;
}
close(l->u.f.fd);
l->u.f.fd = -1;
} else

19
src/lxc/lxclock.h
View File

@ -23,12 +23,25 @@
#ifndef __LXC_LXCLOCK_H
#define __LXC_LXCLOCK_H
#include <fcntl.h> /* For O_* constants */
#include <sys/stat.h> /* For mode constants */
#include <sys/file.h>
#include <fcntl.h>
#include <semaphore.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <time.h>
#include <unistd.h>
#ifndef F_OFD_GETLK
#define F_OFD_GETLK 36
#endif
#ifndef F_OFD_SETLK
#define F_OFD_SETLK 37
#endif
#ifndef F_OFD_SETLKW
#define F_OFD_SETLKW 38
#endif
#define LXC_LOCK_ANON_SEM 1 /*!< Anonymous semaphore lock */
#define LXC_LOCK_FLOCK 2 /*!< flock(2) lock */