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Index: lib/libutil/flopen.3
===================================================================
--- lib/libutil/flopen.3
+++ lib/libutil/flopen.3
@@ -25,7 +25,7 @@
.\"
.\" $FreeBSD$
.\"
-.Dd July 28, 2017
+.Dd March 19, 2021
.Dt FLOPEN 3
.Os
.Sh NAME
@@ -49,21 +49,12 @@
The
.Fn flopen
function opens or creates a file and acquires an exclusive lock on it.
-It is essentially equivalent with calling
+It is equivalent to
.Fn open
-with the same parameters followed by
-.Fn flock
-with an
-.Fa operation
+with the
+.Fa flags
argument of
-.Dv LOCK_EX ,
-except that
-.Fn flopen
-will attempt to detect and handle races that may occur between opening
-/ creating the file and locking it.
-Thus, it is well suited for opening lock files, PID files, spool
-files, mailboxes and other kinds of files which are used for
-synchronization between processes.
+.Dv O_EXLOCK .
.Pp
If
.Fa flags
Index: lib/libutil/flopen.c
===================================================================
--- lib/libutil/flopen.c
+++ lib/libutil/flopen.c
@@ -39,87 +39,19 @@
#include <libutil.h>
-/*
- * Reliably open and lock a file.
- *
- * Please do not modify this code without first reading the revision history
- * and discussing your changes with <des@freebsd.org>. Don't be fooled by the
- * code's apparent simplicity; there would be no need for this function if it
- * was easy to get right.
- */
static int
vflopenat(int dirfd, const char *path, int flags, va_list ap)
{
- int fd, operation, serrno, trunc;
- struct stat sb, fsb;
mode_t mode;
-#ifdef O_EXLOCK
- flags &= ~O_EXLOCK;
-#endif
-
mode = 0;
if (flags & O_CREAT) {
mode = (mode_t)va_arg(ap, int); /* mode_t promoted to int */
}
- operation = LOCK_EX;
- if (flags & O_NONBLOCK)
- operation |= LOCK_NB;
-
- trunc = (flags & O_TRUNC);
- flags &= ~O_TRUNC;
-
- for (;;) {
- if ((fd = openat(dirfd, path, flags, mode)) == -1)
- /* non-existent or no access */
- return (-1);
- if (flock(fd, operation) == -1) {
- /* unsupported or interrupted */
- serrno = errno;
- (void)close(fd);
- errno = serrno;
- return (-1);
- }
- if (fstatat(dirfd, path, &sb, 0) == -1) {
- /* disappeared from under our feet */
- (void)close(fd);
- continue;
- }
- if (fstat(fd, &fsb) == -1) {
- /* can't happen [tm] */
- serrno = errno;
- (void)close(fd);
- errno = serrno;
- return (-1);
- }
- if (sb.st_dev != fsb.st_dev ||
- sb.st_ino != fsb.st_ino) {
- /* changed under our feet */
- (void)close(fd);
- continue;
- }
- if (trunc && ftruncate(fd, 0) != 0) {
- /* can't happen [tm] */
- serrno = errno;
- (void)close(fd);
- errno = serrno;
- return (-1);
- }
- /*
- * The following change is provided as a specific example to
- * avoid.
- */
-#if 0
- if (fcntl(fd, F_SETFD, FD_CLOEXEC) != 0) {
- serrno = errno;
- (void)close(fd);
- errno = serrno;
- return (-1);
- }
-#endif
- return (fd);
- }
+ flags &= ~O_SHLOCK;
+ flags |= O_EXLOCK;
+ return (openat(dirfd, path, flags, mode));
}
int

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