posix-hacks.c

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/*
    clsync - file tree sync utility based on inotify/kqueue/bsm/gio
 
    Copyright (C) 2013-2014 Dmitry Yu Okunev <dyokunev@ut.mephi.ru> 0x8E30679C
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifdef __FreeBSD__
 
#define _GNU_SOURCE
 
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
 
#define __POSIX_HACKS_C
 
int reserved_fd[FOPEN_MAX + 1] = { -1};
int reserved_fd_used;
 
 
static inline int reserve_fdpair ( int idx )
{
    int pipe_fds[2];
 
    if ( pipe2 ( pipe_fds, O_CLOEXEC | O_NONBLOCK ) )
        return errno;
 
    reserved_fd[ idx     ] = pipe_fds[0];
    reserved_fd[ idx + 1 ] = pipe_fds[1];
    return 0;
}
 
int posixhacks_init()
{
    int i;
    // Reserving file descriptors from start to bypass FOPEN_MAX limit on fopen()/fdopen()
    i = 0;
 
    while ( i < ( FOPEN_MAX + 1 ) / 2 ) {
        if ( reserve_fdpair ( i << 1 ) )
            return errno;
 
        i++;
    }
 
    reserved_fd_used = 0;
    return 0;
}
 
FILE *posixhacks_fopen ( const char *path, const char *mode )
{
    close ( reserved_fd[reserved_fd_used++] );
    return fopen ( path, mode );
}
 
int posixhacks_fclose ( FILE *fp )
{
    int rc;
    int pipe_fds[2];
    rc = fclose ( fp );
 
    // reserving the file descriptor
    if ( ! ( reserved_fd_used & 1 ) )
        close ( reserved_fd[reserved_fd_used++] );
 
    reserved_fd_used -= 2;
 
    if ( reserve_fdpair ( reserved_fd_used ) )
        return errno;
 
    return rc;
}
 
int posixhacks_deinit()
{
    int i;
    i = 0;
 
    while ( i < ( FOPEN_MAX + 1 ) / 2 ) {
        close ( reserved_fd[ ( i << 1 )     ] );
        close ( reserved_fd[ ( i << 1 ) + 1 ] );
        i++;
    }
 
    return 0;
}
 
#endif
 
extern int make_iso_compilers_happy; // anti-warning