helpers: add helpers to automatically close fds

Add a inline helper function and a helper macro to be able to
automatically close file descriptors. Does nothing if the argument
is NULL or the pointed to integer is < 0.
This commit is contained in:
Christian Kellner 2019-04-30 13:47:47 +02:00
parent 6291c13cf4
commit 0c778200ae
3 changed files with 61 additions and 0 deletions

41
daemon/helpers.c Normal file
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@ -0,0 +1,41 @@
/*
Copyright (c) 2017-2019, Feral Interactive
Copyright (c) 2019, Red Hat
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
* 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.
* Neither the name of Feral Interactive nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
#define _GNU_SOURCE
#include "helpers.h"
/* Starting with C99 we can use "inline" without "static" and thus avoid
* having multiple (local) definitions of the same inline function. One
* consequence of that is that if the compiler decides to *not* inline
* a specific call to the function the linker will expect an definition.
*/
extern inline void cleanup_close(int *fd);

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@ -34,6 +34,7 @@ POSSIBILITY OF SUCH DAMAGE.
#include <stdio.h>
#include <string.h>
#include <sys/param.h>
#include <unistd.h>
/**
* Value clamping helper, works like MIN/MAX but constraints a value within the range.
@ -62,3 +63,21 @@ static inline const char *strtail(const char *haystack, const char *needle)
return pos;
return NULL;
}
/**
* Helper function for autoclosing file-descriptors. Does nothing if the argument
* is NULL or the referenced integer < 0.
*/
inline void cleanup_close(int *fd_ptr)
{
if (fd_ptr == NULL || *fd_ptr < 0)
return;
(void)close(*fd_ptr);
}
/**
* Helper macro for autoclosing file-descriptors: use by prefixing the variable,
* like "autoclose_fd int fd = -1;".
*/
#define autoclose_fd __attribute__((cleanup(cleanup_close)))

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@ -30,6 +30,7 @@ daemon_sources = [
'daemonize.c',
'dbus_messaging.c',
'daemon_config.c',
'helpers.c',
]
gamemoded_includes = libgamemode_includes