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author | Dag-Erling Smørgrav <des@FreeBSD.org> | 2007-05-10 14:43:31 +0000 |
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committer | Dag-Erling Smørgrav <des@FreeBSD.org> | 2007-05-10 14:43:31 +0000 |
commit | 82c0a122ffb4ff24e53e2a3ef557704add29659c (patch) | |
tree | 19dfb1de00337a8c2da1d8972a332cbc57b4c5f1 /libutil | |
parent | c18c6a8c9f11aa3722d3903630c5159d3e4bcd87 (diff) | |
download | pw-darwin-82c0a122ffb4ff24e53e2a3ef557704add29659c.tar.gz pw-darwin-82c0a122ffb4ff24e53e2a3ef557704add29659c.tar.zst pw-darwin-82c0a122ffb4ff24e53e2a3ef557704add29659c.zip |
I'm tired of seeing this done incorrectly and non-portably, so add a
flopen(3) function which reliably opens and locks a file.
MFC after: 3 weeks
Diffstat (limited to 'libutil')
-rw-r--r-- | libutil/flopen.c | 91 | ||||
-rw-r--r-- | libutil/libutil.h | 1 |
2 files changed, 92 insertions, 0 deletions
diff --git a/libutil/flopen.c b/libutil/flopen.c new file mode 100644 index 0000000..66d4e47 --- /dev/null +++ b/libutil/flopen.c @@ -0,0 +1,91 @@ +/*- + * Copyright (c) 2007 Dag-Erling Coïdan Smørgrav + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer + * in this position and unchanged. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $Id$ + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/stat.h> + +#include <errno.h> +#include <fcntl.h> +#include <stdarg.h> + +int +flopen(const char *path, int flags, ...) +{ + struct stat sb, fsb; + mode_t mode; + int fd, serrno; + +#ifdef O_EXLOCK + flags &= ~O_EXLOCK; +#endif + + if (flags & O_CREAT) { + va_list ap; + + va_start(ap, flags); + mode = va_arg(ap, int); /* mode_t promoted to int */ + va_end(ap); + } else { + mode = 0; + } + + for (;;) { + if ((fd = open(path, flags, mode)) == -1) + /* non-existent or no access */ + return (-1); + if (flock(fd, LOCK_EX) == -1) { + /* unsupported or interrupted */ + serrno = errno; + close(fd); + errno = serrno; + return (-1); + } + if (stat(path, &sb) == -1) { + /* disappeared from under our feet */ + close(fd); + continue; + } + if (fstat(fd, &fsb) == -1) { + /* can't happen [tm] */ + serrno = errno; + close(fd); + errno = serrno; + return (-1); + } + if (sb.st_dev != fsb.st_dev || + sb.st_ino != fsb.st_ino) { + /* changed under our feet */ + close(fd); + continue; + } + return (fd); + } +} diff --git a/libutil/libutil.h b/libutil/libutil.h index aefff0c..4a89856 100644 --- a/libutil/libutil.h +++ b/libutil/libutil.h @@ -70,6 +70,7 @@ void clean_environment(const char * const *_white, const char * const *_more_white); int extattr_namespace_to_string(int _attrnamespace, char **_string); int extattr_string_to_namespace(const char *_string, int *_attrnamespace); +int flopen(const char *_path, int _flags, mode_t _mode); void login(struct utmp *_ut); int login_tty(int _fd); int logout(const char *_line); |