diff options
author | Guillem Jover <guillem@hadrons.org> | 2010-01-09 23:49:32 +0100 |
---|---|---|
committer | Guillem Jover <guillem@hadrons.org> | 2010-01-10 13:36:38 +0100 |
commit | 98a2479f0ba02a0c54ff360aa5745ff5a6939b2e (patch) | |
tree | 3b0476711febb247822421d586d02f57af66176c | |
parent | 57cc5326cf75826c5d3b415673e2574384d12850 (diff) |
Add flopen function
Taken from FreeBSD.
-rw-r--r-- | Makefile | 2 | ||||
-rw-r--r-- | Versions | 2 | ||||
-rw-r--r-- | include/libutil.h | 2 | ||||
-rw-r--r-- | src/flopen.3 | 102 | ||||
-rw-r--r-- | src/flopen.c | 105 |
5 files changed, 213 insertions, 0 deletions
@@ -25,6 +25,7 @@ LIB_SRCS := \ bsd_getopt.c \ err.c \ fgetln.c \ + flopen.c \ heapsort.c \ humanize_number.c \ dehumanize_number.c \ @@ -76,6 +77,7 @@ LIB_MANS := \ strlcpy.3 \ strlcat.3 \ fgetln.3 \ + flopen.3 \ readpassphrase.3 \ humanize_number.3 \ fmtcheck.3 \ @@ -51,5 +51,7 @@ LIBBSD_0.2 { dehumanize_number; readpassphrase; + + flopen; } LIBBSD_0.1; diff --git a/include/libutil.h b/include/libutil.h index 5f72f8c..298bbc3 100644 --- a/include/libutil.h +++ b/include/libutil.h @@ -46,6 +46,8 @@ __BEGIN_DECLS int humanize_number(char *buf, size_t len, int64_t bytes, const char *suffix, int scale, int flags); + +int flopen(const char *_path, int _flags, ...); __END_DECLS /* humanize_number(3) */ diff --git a/src/flopen.3 b/src/flopen.3 new file mode 100644 index 0000000..4c53d46 --- /dev/null +++ b/src/flopen.3 @@ -0,0 +1,102 @@ +.\"- +.\" 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. +.\" 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. +.\" +.\" $FreeBSD$ +.\" +.Dd June 6, 2009 +.Dt FLOPEN 3 +.Os +.Sh NAME +.Nm flopen +.Nd "Reliably open and lock a file" +.Sh LIBRARY +.ds str-Lb-libbsd Utility functions from BSD systems (libbsd, \-lbsd) +.Lb libbsd +.Sh SYNOPSIS +.In sys/fcntl.h +.In libutil.h +.Ft int +.Fn flopen "const char *path" "int flags" +.Ft int +.Fn flopen "const char *path" "int flags" "mode_t mode" +.Sh DESCRIPTION +The +.Fn flopen +function opens or creates a file and acquires an exclusive lock on it. +It is essentially equivalent with calling +.Fn open +with the same parameters followed by +.Fn flock +with an +.Va operation +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. +.Pp +If +.Va flags +includes +.Dv O_NONBLOCK +and the file is already locked, +.Fn flopen +will fail and set +.Va errno +to +.Dv EWOULDBLOCK . +.Pp +As with +.Fn open , +the additional +.Va mode +argument is required if +.Va flags +includes +.Dv O_CREAT . +.Sh RETURN VALUES +If successful, +.Fn flopen +returns a valid file descriptor. +Otherwise, it returns -1, and sets +.Va errno +as described in +.Xr flock 2 +and +.Xr open 2 . +.Sh SEE ALSO +.Xr errno 2 , +.Xr flock 2 , +.Xr open 2 +.Sh AUTHORS +.An -nosplit +The +.Nm +function and this manual page were written by +.An Dag-Erling Sm\(/orgrav Aq des@FreeBSD.org . diff --git a/src/flopen.c b/src/flopen.c new file mode 100644 index 0000000..754c9c0 --- /dev/null +++ b/src/flopen.c @@ -0,0 +1,105 @@ +/*- + * 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. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/file.h> +#include <sys/stat.h> + +#include <errno.h> +#include <stdarg.h> +#include <unistd.h> + +#include <libutil.h> + +int +flopen(const char *path, int flags, ...) +{ + 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) { + 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; + if (flags & O_NONBLOCK) + operation |= LOCK_NB; + + trunc = (flags & O_TRUNC); + flags &= ~O_TRUNC; + + for (;;) { + if ((fd = open(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 (stat(path, &sb) == -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); + } + return (fd); + } +} |