30483006be2e4df5e3c2c3cd02650430eb949dbb
2 * Copyright (C) 2006-2007 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file fd.c Helper functions for file descriptor handling. */
13 #include <sys/select.h>
19 * Check whether a file exists.
21 * \param fn The file name.
23 * \return Non-zero iff file exists.
25 int file_exists(const char *fn
)
29 return !stat(fn
, &statbuf
);
33 * Paraslash's wrapper for select(2).
35 * It calls select(2) (with no exceptfds) and starts over if select() was
36 * interrupted by a signal.
38 * \param n The highest-numbered descriptor in any of the two sets, plus 1.
39 * \param readfds fds that should be checked for readability.
40 * \param writefds fds that should be checked for writablility.
41 * \param timeout_tv upper bound on the amount of time elapsed before select()
44 * \return The return value of the underlying select() call on success, the
45 * negative system error code on errors.
47 * All arguments are passed verbatim to select(2).
48 * \sa select(2) select_tut(2).
50 int para_select(int n
, fd_set
*readfds
, fd_set
*writefds
,
51 struct timeval
*timeout_tv
)
55 ret
= select(n
, readfds
, writefds
, NULL
, timeout_tv
);
57 } while (ret
< 0 && err
== EINTR
);
59 return -ERRNO_TO_PARA_ERROR(errno
);
64 * Set a file descriptor to non-blocking mode.
66 * \param fd The file descriptor.
70 int mark_fd_nonblock(int fd
)
72 int flags
= fcntl(fd
, F_GETFL
);
74 return -ERRNO_TO_PARA_ERROR(errno
);
75 flags
= fcntl(fd
, F_SETFL
, ((long)flags
) | O_NONBLOCK
);
77 return -ERRNO_TO_PARA_ERROR(errno
);
82 * Set a file descriptor in a fd_set.
84 * \param fd The file descriptor to be set.
85 * \param fds The file descriptor set.
86 * \param max_fileno Highest-numbered file descriptor.
88 * This wrapper for FD_SET() passes its first two arguments to \p FD_SET. Upon
89 * return, \a max_fileno contains the maximum of the old_value and \a fd.
93 void para_fd_set(int fd
, fd_set
*fds
, int *max_fileno
)
96 if (fd
< 0 || fd
>= FD_SETSIZE
) {
97 PARA_EMERG_LOG("fatal: tried to add invalid fd %d\n", fd
);
102 int flags
= fcntl(fd
, F_GETFL
);
103 if (!(flags
& O_NONBLOCK
)) {
104 PARA_EMERG_LOG("fd %d is a blocking file descriptor\n", fd
);
110 *max_fileno
= PARA_MAX(*max_fileno
, fd
);
114 * Paraslash's wrapper for fgets(3).
116 * \param line Pointer to the buffer to store the line.
117 * \param size The size of the buffer given by \a line.
118 * \param f The stream to read from.
120 * \return Unlike the standard fgets() function, an integer value
121 * is returned. On success, this function returns 1. On errors, -E_FGETS
122 * is returned. A zero return value indicates an end of file condition.
124 __must_check
int para_fgets(char *line
, int size
, FILE *f
)
127 if (fgets(line
, size
, f
))
133 if (errno
!= EINTR
) {
134 PARA_ERROR_LOG("%s\n", strerror(errno
));
142 * Paraslash's wrapper for mmap.
144 * \param length Number of bytes to mmap.
145 * \param prot Either PROT_NONE or the bitwise OR of one or more of
146 * PROT_EXEC PROT_READ PROT_WRITE.
147 * \param flags Exactly one of MAP_SHARED and MAP_PRIVATE.
148 * \param fd The file to mmap from.
149 * \param offset Mmap start.
151 * \return This function either returns a valid pointer to the mapped area
152 * or calls exit() on errors.
154 void *para_mmap(size_t length
, int prot
, int flags
, int fd
, off_t offset
)
156 void *ret
= mmap(NULL
, length
, prot
, flags
, fd
, offset
);
157 if (ret
!= MAP_FAILED
)
159 PARA_EMERG_LOG("mmap failed: %s\n", strerror(errno
));
160 PARA_EMERG_LOG("length: %zu, flags: %d, fd: %d, offset: %zu\n",
161 length
, flags
, fd
, (size_t)offset
);
166 * Wrapper for the open(2) system call.
168 * \param path The filename.
169 * \param flags The usual open(2) flags.
170 * \param mode Specifies the permissions to use.
172 * The mode parameter must be specified when O_CREAT is in the flags, and is
175 * \return The file descriptor on success, negative on errors.
179 int para_open(const char *path
, int flags
, mode_t mode
)
181 int ret
= open(path
, flags
, mode
);
185 return -ERRNO_TO_PARA_ERROR(errno
);
189 * Wrapper for chdir(2).
191 * \param path The specified directory.
195 int para_chdir(const char *path
)
197 int ret
= chdir(path
);
201 return -ERRNO_TO_PARA_ERROR(errno
);
205 * Save the cwd and open a given directory.
207 * \param dirname Path to the directory to open.
208 * \param dir Result pointer.
209 * \param cwd File descriptor of the current working directory.
213 * Opening the current directory (".") and calling fchdir() to return is
214 * usually faster and more reliable than saving cwd in some buffer and calling
215 * chdir() afterwards.
217 * If \a cwd is not \p NULL "." is opened and the resulting file descriptor is
218 * stored in \a cwd. If the function returns success, and \a cwd is not \p
219 * NULL, the caller must close this file descriptor (probably after calling
222 * On errors, the function undos everything, so the caller needs neither close
223 * any files, nor change back to the original working directory.
228 int para_opendir(const char *dirname
, DIR **dir
, int *cwd
)
233 ret
= para_open(".", O_RDONLY
, 0);
238 ret
= para_chdir(dirname
);
244 ret
= -ERRNO_TO_PARA_ERROR(errno
);
245 /* Ignore return value of fchdir() and close(). We're busted anyway. */
255 * A wrapper for fchdir().
257 * \param fd An open file descriptor.
261 int para_fchdir(int fd
)
264 return -ERRNO_TO_PARA_ERROR(errno
);
269 * A wrapper for mkdir(2).
271 * \param path Name of the directory to create.
272 * \param mode The permissions to use.
276 int para_mkdir(const char *path
, mode_t mode
)
278 if (!mkdir(path
, mode
))
280 return -ERRNO_TO_PARA_ERROR(errno
);