/* test whether fcntl locking works on this system */ #if defined(HAVE_UNISTD_H) #include <unistd.h> #endif #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #ifdef HAVE_FCNTL_H #include <fcntl.h> #endif #ifdef HAVE_SYS_FCNTL_H #include <sys/fcntl.h> #endif #include <errno.h> static int sys_waitpid(pid_t pid,int *status,int options) { #ifdef HAVE_WAITPID return waitpid(pid,status,options); #else /* USE_WAITPID */ return wait4(pid, status, options, NULL); #endif /* USE_WAITPID */ } #define DATA "conftest.fcntl" #ifndef SEEK_SET #define SEEK_SET 0 #endif /* lock a byte range in a open file */ int main(int argc, char *argv[]) { struct flock lock; int fd, ret, status=1; pid_t pid; if (!(pid=fork())) { sleep(2); fd = open(DATA, O_RDONLY); if (fd == -1) exit(1); lock.l_type = F_WRLCK; lock.l_whence = SEEK_SET; lock.l_start = 0; lock.l_len = 4; lock.l_pid = getpid(); lock.l_type = F_WRLCK; /* check if a lock applies */ ret = fcntl(fd,F_GETLK,&lock); if ((ret == -1) || (lock.l_type == F_UNLCK)) { exit(1); } else { exit(0); } } fd = open(DATA, O_RDWR|O_CREAT|O_TRUNC, 0600); 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); sys_waitpid(pid, &status, 0); 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) */ exit(status); }