1 /* flock.c - manage advisory file locks 2 * 3 * Copyright 2015 The Android Open Source Project 4 5 USE_FLOCK(NEWTOY(flock, "<1>1nsux[-sux]", TOYFLAG_USR|TOYFLAG_BIN)) 6 7 config FLOCK 8 bool "flock" 9 default y 10 help 11 usage: flock [-sxun] fd 12 13 Manage advisory file locks. 14 15 -s Shared lock. 16 -x Exclusive lock (default). 17 -u Unlock. 18 -n Non-blocking: fail rather than wait for the lock. 19 */ 20 21 #define FOR_flock 22 #include "toys.h" 23 24 #include <sys/file.h> 25 flock_main(void)26void flock_main(void) 27 { 28 int fd = xstrtol(*toys.optargs, NULL, 10), op; 29 30 if (toys.optflags & FLAG_u) op = LOCK_UN; 31 else op = (toys.optflags & FLAG_s) ? LOCK_SH : LOCK_EX; 32 33 if (toys.optflags & FLAG_n) op |= LOCK_NB; 34 35 if (flock(fd, op)) { 36 if ((op & LOCK_NB) && errno == EAGAIN) toys.exitval = 1; 37 else perror_exit("flock"); 38 } 39 } 40