Commit 993828d8 authored by Guillem Jover's avatar Guillem Jover

Add flopenat() function from FreeBSD

parent 30b4d507
......@@ -367,7 +367,7 @@ License: BSD-2-clause
Files:
src/flopen.c
Copyright:
Copyright © 2007 Dag-Erling Coïdan Smørgrav
Copyright © 2007-2009 Dag-Erling Coïdan Smørgrav
All rights reserved.
License: BSD-2-clause-verbatim
Redistribution and use in source and binary forms, with or without
......
......@@ -62,6 +62,7 @@ int humanize_number(char *buf, size_t len, int64_t bytes,
int expand_number(const char *_buf, uint64_t *_num);
int flopen(const char *_path, int _flags, ...);
int flopenat(int dirfd, const char *path, int flags, ...);
struct pidfh *pidfile_open(const char *path, mode_t mode, pid_t *pidptr);
int pidfile_write(struct pidfh *pfh);
......
......@@ -25,12 +25,13 @@
.\"
.\" $FreeBSD$
.\"
.Dd June 6, 2009
.Dd July 28, 2017
.Dt FLOPEN 3bsd
.Os
.Sh NAME
.Nm flopen
.Nd reliably open and lock a file
.Nm flopen ,
.Nm flopenat
.Nd "Reliably open and lock a file"
.Sh LIBRARY
.ds str-Lb-libbsd Utility functions from BSD systems (libbsd, \-lbsd)
.Lb libbsd
......@@ -44,6 +45,10 @@ for include usage.)
.Fn flopen "const char *path" "int flags"
.Ft int
.Fn flopen "const char *path" "int flags" "mode_t mode"
.Ft int
.Fn flopenat "int fd" "const char *path" "int flags"
.Ft int
.Fn flopenat "int fd" "const char *path" "int flags" "mode_t mode"
.Sh DESCRIPTION
The
.Fn flopen
......@@ -53,7 +58,7 @@ It is essentially equivalent with calling
with the same parameters followed by
.Fn flock
with an
.Va operation
.Fa operation
argument of
.Dv LOCK_EX ,
except that
......@@ -65,7 +70,7 @@ files, mailboxes and other kinds of files which are used for
synchronization between processes.
.Pp
If
.Va flags
.Fa flags
includes
.Dv O_NONBLOCK
and the file is already locked,
......@@ -78,11 +83,32 @@ to
As with
.Fn open ,
the additional
.Va mode
.Fa mode
argument is required if
.Va flags
.Fa flags
includes
.Dv O_CREAT .
.Pp
The
.Fn flopenat
function is equivalent to the
.Fn flopen
function except in the case where the
.Fa path
specifies a relative path.
In this case the file to be opened is determined relative to the directory
associated with the file descriptor
.Fa fd
instead of the current working directory.
If
.Fn flopenat
is passed the special value
.Dv AT_FDCWD
in the
.Fa fd
parameter, the current working directory is used
and the behavior is identical to a call to
.Fn flopen .
.Sh RETURN VALUES
If successful,
.Fn flopen
......@@ -102,4 +128,4 @@ and
The
.Nm
function and this manual page were written by
.An Dag-Erling Sm\(/orgrav Aq des@FreeBSD.org .
.An Dag-Erling Sm\(/orgrav Aq Mt des@FreeBSD.org .
/*-
* Copyright (c) 2007 Dag-Erling Coïdan Smørgrav
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2007-2009 Dag-Erling Coïdan Smørgrav
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
......@@ -30,13 +32,21 @@
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <unistd.h>
#include <libutil.h>
int
flopen(const char *path, int flags, ...)
/*
* 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;
......@@ -48,11 +58,7 @@ flopen(const char *path, int flags, ...)
mode = 0;
if (flags & O_CREAT) {
va_list ap;
va_start(ap, flags);
mode = (mode_t)va_arg(ap, int); /* mode_t promoted to int */
va_end(ap);
}
operation = LOCK_EX;
......@@ -63,7 +69,7 @@ flopen(const char *path, int flags, ...)
flags &= ~O_TRUNC;
for (;;) {
if ((fd = open(path, flags, mode)) == -1)
if ((fd = openat(dirfd, path, flags, mode)) == -1)
/* non-existent or no access */
return (-1);
if (flock(fd, operation) == -1) {
......@@ -73,7 +79,7 @@ flopen(const char *path, int flags, ...)
errno = serrno;
return (-1);
}
if (stat(path, &sb) == -1) {
if (fstatat(dirfd, path, &sb, 0) == -1) {
/* disappeared from under our feet */
(void)close(fd);
continue;
......@@ -98,6 +104,42 @@ flopen(const char *path, int flags, ...)
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);
}
}
int
flopen(const char *path, int flags, ...)
{
va_list ap;
int ret;
va_start(ap, flags);
ret = vflopenat(AT_FDCWD, path, flags, ap);
va_end(ap);
return (ret);
}
int
flopenat(int dirfd, const char *path, int flags, ...)
{
va_list ap;
int ret;
va_start(ap, flags);
ret = vflopenat(dirfd, path, flags, ap);
va_end(ap);
return (ret);
}
......@@ -139,3 +139,7 @@ LIBBSD_0.7 {
LIBBSD_0.8 {
explicit_bzero;
} LIBBSD_0.7;
LIBBSD_0.9 {
flopenat;
} LIBBSD_0.8;
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