Fix some typos in CREDITS
[paraslash.git] / fd.c
1 /*
2 * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
17 */
18
19 /** \file fd.c helper functions for file descriptor handling */
20
21 #include "para.h"
22
23 #include <fcntl.h>
24 #include <sys/select.h>
25
26 #include "error.h"
27 /**
28 * check whether a file exists
29 *
30 * \param fn the file name
31 *
32 * \return Non-zero iff file exists.
33 */
34 int file_exists(const char *fn)
35 {
36 struct stat statbuf;
37
38 return !stat(fn, &statbuf);
39 }
40
41 /**
42 * paraslash's wrapper for select(2)
43 *
44 * It calls select(2) (with no exceptfds) and starts over if select() was
45 * interrupted by a signal.
46 *
47 * \param n the highest-numbered descriptor in any of the two sets, plus 1
48 * \param readfds fds that should be checked for readability
49 * \param writefds fds that should be checked for writablility
50 * \param timeout upper bound on the amount of time elapsed before select()
51 * returns
52 *
53 * \return The return value of the underlying select() call.
54 *
55 * All arguments are passed verbatim to select(2).
56 * \sa select(2) select_tut(2)
57 */
58 int para_select(int n, fd_set *readfds, fd_set *writefds,
59 struct timeval *timeout)
60 {
61 int ret, err;
62 do {
63 ret = select(n, readfds, writefds, NULL, timeout);
64 err = errno;
65 } while (ret < 0 && err == EINTR);
66 if (ret < 0)
67 PARA_CRIT_LOG("select error (%s)\n", strerror(err));
68 return ret;
69 }
70
71 /**
72 * set a file descriptor to non-blocking mode
73 *
74 * \param fd The file descriptor
75 *
76 * \returns 1 on success, -E_F_GETFL, -E_F_SETFL, on errors.
77 */
78 int mark_fd_nonblock(int fd)
79 {
80 int flags = fcntl(fd, F_GETFL);
81 if (flags < 0)
82 return -E_F_GETFL;
83 if (fcntl(fd, F_SETFL, ((long)flags) | O_NONBLOCK) < 0)
84 return -E_F_SETFL;
85 return 1;
86 }
87
88 /**
89 * set a file descriptor in a fd_set
90 *
91 * \param fd the file descriptor to be set
92 * \param fds the file descriptor set
93 * \param max_fileno highest-numbered file descriptor
94 *
95 * This wrapper for FD_SET() passes its first two arguments to \p FD_SET. Upon
96 * return, \a max_fileno contains the maximum of the old_value and \a fd.
97 */
98 void para_fd_set(int fd, fd_set *fds, int *max_fileno)
99 {
100 FD_SET(fd, fds);
101 *max_fileno = PARA_MAX(*max_fileno, fd);
102 }