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Add flopenat() function from FreeBSD

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This commit is contained in:
Guillem Jover
2018-05-21 01:11:46 +02:00
parent 30b4d50754
commit 993828d84e
5 changed files with 92 additions and 19 deletions
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62
src/flopen.c
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@@ -1,5 +1,7 @@
/*-
* 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);
}