/* test whether fcntl locking works between threads on this Linux system */ #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <fcntl.h> #include <sys/fcntl.h> #include <sys/wait.h> #include <errno.h> #include <pthread.h> static int sys_waitpid(pid_t pid,int *status,int options) { return waitpid(pid,status,options); } #define DATA "conftest.fcntl" #define SEEK_SET 0 static void *test_thread(void *thread_parm) { int *status = thread_parm; int fd, ret; struct flock lock; sleep(2); fd = open(DATA, O_RDWR); if (fd == -1) { fprintf(stderr,"ERROR: failed to open %s (errno=%d)\n", DATA, (int)errno); pthread_exit(thread_parm); } lock.l_type = F_WRLCK; lock.l_whence = SEEK_SET; lock.l_start = 0; lock.l_len = 4; lock.l_pid = 0; /* check if a lock applies */ ret = fcntl(fd,F_SETLK,&lock); if ((ret != -1)) { fprintf(stderr,"ERROR: lock test failed (ret=%d errno=%d)\n", ret, (int)errno); } else { *status = 0; /* SUCCESS! */ } pthread_exit(thread_parm); } /* lock a byte range in a open file */ int main(int argc, char *argv[]) { struct flock lock; int fd, ret, status=1, rc; pid_t pid; char *testdir = NULL; pthread_t thread_id; pthread_attr_t thread_attr; testdir = getenv("TESTDIR"); if (testdir) chdir(testdir); alarm(10); pthread_attr_init(&thread_attr); pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED); rc = pthread_create(&thread_id, &thread_attr, &test_thread, &status); pthread_attr_destroy(&thread_attr); if (rc == 0) { fprintf(stderr,"created thread_id=%lu\n", (unsigned long int)thread_id); } else { fprintf(stderr,"ERROR: thread create failed, rc=%d\n", rc); } unlink(DATA); fd = open(DATA, O_RDWR|O_CREAT|O_RDWR, 0600); if (fd == -1) { fprintf(stderr,"ERROR: failed to open %s (errno=%d)\n", DATA, (int)errno); exit(1); } lock.l_type = F_WRLCK; lock.l_whence = SEEK_SET; lock.l_start = 0; lock.l_len = 4; lock.l_pid = getpid(); /* set a 4 byte write lock */ fcntl(fd,F_SETLK,&lock); sleep(4); /* allow thread to try getting lock */ unlink(DATA); #if defined(WIFEXITED) && defined(WEXITSTATUS) if(WIFEXITED(status)) { status = WEXITSTATUS(status); } else { status = 1; } #else /* defined(WIFEXITED) && defined(WEXITSTATUS) */ status = (status == 0) ? 0 : 1; #endif /* defined(WIFEXITED) && defined(WEXITSTATUS) */ if (status) { fprintf(stderr,"ERROR: lock test failed with status=%d\n", status); } exit(status); }