2 * Copyright (C) 2006-2009 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. */
10 #include <sys/types.h>
14 #include <sys/select.h>
21 * Write a buffer to a file descriptor, re-write on short writes.
23 * \param fd The file descriptor.
24 * \param buf The buffer to be sent.
25 * \param len The length of \a buf.
27 * \return Standard. In any case, the number of bytes that have been written is
30 int write_all(int fd, const char *buf, size_t *len)
36 while (*len < total) {
37 int ret = write(fd, buf + *len, total - *len);
39 return -ERRNO_TO_PARA_ERROR(errno);
46 * Write a buffer to a non-blocking file descriptor.
48 * \param fd The file descriptor.
49 * \param buf the buffer to write.
50 * \param len the number of bytes of \a buf.
51 * \param max_bytes_per_write Do not write more than that many bytes at once.
53 * If \a max_bytes_per_write is non-zero, do not send more than that many bytes
56 * EAGAIN is not considered an error condition. For example CCID3 has a
57 * sending wait queue which fills up and is emptied asynchronously. The EAGAIN
58 * case means that there is currently no space in the wait queue, but this can
59 * change at any moment.
61 * \return Negative on errors, number of bytes written else.
63 int write_nonblock(int fd, const char *buf, size_t len,
64 size_t max_bytes_per_write)
69 while (written < len) {
70 size_t num = len - written;
72 if (max_bytes_per_write && max_bytes_per_write < num)
73 num = max_bytes_per_write;
74 ret = write(fd, buf + written, num);
75 if (ret < 0 && errno == EAGAIN)
78 return -ERRNO_TO_PARA_ERROR(errno);
85 * Simple wrapper for readv().
87 * \param fd The file descriptor to read from.
88 * \param iov Scatter/gather array used in readv().
89 * \param iovcnt Number of elements in \a iov.
91 * \return A negative error code on errors, the return value of the underlying
92 * call to readv() otherwise.
96 int para_readv(int fd, struct iovec *iov, int iovcnt)
98 int ret = readv(fd, iov, iovcnt);
101 return -ERRNO_TO_PARA_ERROR(errno);
106 * Check whether a file exists.
108 * \param fn The file name.
110 * \return Non-zero iff file exists.
112 int file_exists(const char *fn)
116 return !stat(fn, &statbuf);
120 * Paraslash's wrapper for select(2).
122 * It calls select(2) (with no exceptfds) and starts over if select() was
123 * interrupted by a signal.
125 * \param n The highest-numbered descriptor in any of the two sets, plus 1.
126 * \param readfds fds that should be checked for readability.
127 * \param writefds fds that should be checked for writablility.
128 * \param timeout_tv upper bound on the amount of time elapsed before select()
131 * \return The return value of the underlying select() call on success, the
132 * negative system error code on errors.
134 * All arguments are passed verbatim to select(2).
135 * \sa select(2) select_tut(2).
137 int para_select(int n, fd_set *readfds, fd_set *writefds,
138 struct timeval *timeout_tv)
142 ret = select(n, readfds, writefds, NULL, timeout_tv);
143 while (ret < 0 && errno == EINTR);
145 return -ERRNO_TO_PARA_ERROR(errno);
150 * Set a file descriptor to blocking mode.
152 * \param fd The file descriptor.
156 __must_check int mark_fd_blocking(int fd)
158 int flags = fcntl(fd, F_GETFL);
160 return -ERRNO_TO_PARA_ERROR(errno);
161 flags = fcntl(fd, F_SETFL, ((long)flags) & ~O_NONBLOCK);
163 return -ERRNO_TO_PARA_ERROR(errno);
168 * Set a file descriptor to non-blocking mode.
170 * \param fd The file descriptor.
174 __must_check int mark_fd_nonblocking(int fd)
176 int flags = fcntl(fd, F_GETFL);
178 return -ERRNO_TO_PARA_ERROR(errno);
179 flags = fcntl(fd, F_SETFL, ((long)flags) | O_NONBLOCK);
181 return -ERRNO_TO_PARA_ERROR(errno);
186 * Set a file descriptor in a fd_set.
188 * \param fd The file descriptor to be set.
189 * \param fds The file descriptor set.
190 * \param max_fileno Highest-numbered file descriptor.
192 * This wrapper for FD_SET() passes its first two arguments to \p FD_SET. Upon
193 * return, \a max_fileno contains the maximum of the old_value and \a fd.
197 void para_fd_set(int fd, fd_set *fds, int *max_fileno)
199 assert(fd >= 0 && fd < FD_SETSIZE);
202 int flags = fcntl(fd, F_GETFL);
203 if (!(flags & O_NONBLOCK)) {
204 PARA_EMERG_LOG("fd %d is a blocking file descriptor\n", fd);
210 *max_fileno = PARA_MAX(*max_fileno, fd);
214 * Paraslash's wrapper for fgets(3).
216 * \param line Pointer to the buffer to store the line.
217 * \param size The size of the buffer given by \a line.
218 * \param f The stream to read from.
220 * \return Unlike the standard fgets() function, an integer value
221 * is returned. On success, this function returns 1. On errors, -E_FGETS
222 * is returned. A zero return value indicates an end of file condition.
224 __must_check int para_fgets(char *line, int size, FILE *f)
227 if (fgets(line, size, f))
233 if (errno != EINTR) {
234 PARA_ERROR_LOG("%s\n", strerror(errno));
242 * Paraslash's wrapper for mmap.
244 * \param length Number of bytes to mmap.
245 * \param prot Either PROT_NONE or the bitwise OR of one or more of
246 * PROT_EXEC PROT_READ PROT_WRITE.
247 * \param flags Exactly one of MAP_SHARED and MAP_PRIVATE.
248 * \param fd The file to mmap from.
249 * \param offset Mmap start.
250 * \param map Result pointer.
256 int para_mmap(size_t length, int prot, int flags, int fd, off_t offset,
264 *m = mmap(NULL, length, prot, flags, fd, offset);
265 if (*m != MAP_FAILED)
269 return -ERRNO_TO_PARA_ERROR(errno);
273 * Wrapper for the open(2) system call.
275 * \param path The filename.
276 * \param flags The usual open(2) flags.
277 * \param mode Specifies the permissions to use.
279 * The mode parameter must be specified when O_CREAT is in the flags, and is
282 * \return The file descriptor on success, negative on errors.
286 int para_open(const char *path, int flags, mode_t mode)
288 int ret = open(path, flags, mode);
292 return -ERRNO_TO_PARA_ERROR(errno);
296 * Wrapper for chdir(2).
298 * \param path The specified directory.
302 int para_chdir(const char *path)
304 int ret = chdir(path);
308 return -ERRNO_TO_PARA_ERROR(errno);
312 * Save the cwd and open a given directory.
314 * \param dirname Path to the directory to open.
315 * \param dir Result pointer.
316 * \param cwd File descriptor of the current working directory.
320 * Opening the current directory (".") and calling fchdir() to return is
321 * usually faster and more reliable than saving cwd in some buffer and calling
322 * chdir() afterwards.
324 * If \a cwd is not \p NULL "." is opened and the resulting file descriptor is
325 * stored in \a cwd. If the function returns success, and \a cwd is not \p
326 * NULL, the caller must close this file descriptor (probably after calling
329 * On errors, the function undos everything, so the caller needs neither close
330 * any files, nor change back to the original working directory.
335 int para_opendir(const char *dirname, DIR **dir, int *cwd)
340 ret = para_open(".", O_RDONLY, 0);
345 ret = para_chdir(dirname);
351 ret = -ERRNO_TO_PARA_ERROR(errno);
352 /* Ignore return value of fchdir() and close(). We're busted anyway. */
354 int __a_unused ret2 = fchdir(*cwd); /* STFU, gcc */
363 * A wrapper for fchdir().
365 * \param fd An open file descriptor.
369 int para_fchdir(int fd)
372 return -ERRNO_TO_PARA_ERROR(errno);
377 * A wrapper for mkdir(2).
379 * \param path Name of the directory to create.
380 * \param mode The permissions to use.
384 int para_mkdir(const char *path, mode_t mode)
386 if (!mkdir(path, mode))
388 return -ERRNO_TO_PARA_ERROR(errno);
392 * Open a file and map it into memory.
394 * \param path Name of the regular file to map.
395 * \param open_mode Either \p O_RDONLY or \p O_RDWR.
396 * \param map On success, the mapping is returned here.
397 * \param size size of the mapping.
398 * \param fd_ptr The file descriptor of the mapping.
400 * If \a fd_ptr is \p NULL, the file descriptor resulting from the underlying
401 * open call is closed after mmap(). Otherwise the file is kept open and the
402 * file descriptor is returned in \a fd_ptr.
406 * \sa para_open(), mmap(2).
408 int mmap_full_file(const char *path, int open_mode, void **map,
409 size_t *size, int *fd_ptr)
411 int fd, ret, mmap_prot, mmap_flags;
412 struct stat file_status;
414 if (open_mode == O_RDONLY) {
415 mmap_prot = PROT_READ;
416 mmap_flags = MAP_PRIVATE;
418 mmap_prot = PROT_READ | PROT_WRITE;
419 mmap_flags = MAP_SHARED;
421 ret = para_open(path, open_mode, 0);
425 if (fstat(fd, &file_status) < 0) {
426 ret = -ERRNO_TO_PARA_ERROR(errno);
429 *size = file_status.st_size;
430 ret = para_mmap(*size, mmap_prot, mmap_flags, fd, 0, map);
432 if (ret < 0 || !fd_ptr)
440 * A wrapper for munmap(2).
442 * \param start The start address of the memory mapping.
443 * \param length The size of the mapping.
447 * \sa munmap(2), mmap_full_file().
449 int para_munmap(void *start, size_t length)
452 if (munmap(start, length) >= 0)
455 PARA_ERROR_LOG("munmap (%p/%zu) failed: %s\n", start, length,
457 return -ERRNO_TO_PARA_ERROR(err);
461 * Check a file descriptor for writability.
463 * \param fd The file descriptor.
465 * \return positive if fd is ready for writing, zero if it isn't, negative if
478 return para_select(fd + 1, NULL, &wfds, &tv);
482 * Ensure that file descriptors 0, 1, and 2 are valid.
484 * Common approach that opens /dev/null until it gets a file descriptor greater
487 * \sa okir's Black Hats Manual.
489 void valid_fd_012(void)
492 int fd = open("/dev/null", O_RDWR);
503 * Traverse the given directory recursively.
505 * \param dirname The directory to traverse.
506 * \param func The function to call for each entry.
507 * \param private_data Pointer to an arbitrary data structure.
509 * For each regular file under \a dirname, the supplied function \a func is
510 * called. The full path of the regular file and the \a private_data pointer
511 * are passed to \a func. Directories for which the calling process has no
512 * permissions to change to are silently ignored.
516 int for_each_file_in_dir(const char *dirname,
517 int (*func)(const char *, void *), void *private_data)
520 struct dirent *entry;
521 int cwd_fd, ret2, ret = para_opendir(dirname, &dir, &cwd_fd);
524 return ret == -ERRNO_TO_PARA_ERROR(EACCES)? 1 : ret;
525 /* scan cwd recursively */
526 while ((entry = readdir(dir))) {
531 if (!strcmp(entry->d_name, "."))
533 if (!strcmp(entry->d_name, ".."))
535 if (lstat(entry->d_name, &s) == -1)
538 if (!S_ISREG(m) && !S_ISDIR(m))
540 tmp = make_message("%s/%s", dirname, entry->d_name);
542 ret = func(tmp, private_data);
549 ret = for_each_file_in_dir(tmp, func, private_data);
557 ret2 = para_fchdir(cwd_fd);
558 if (ret2 < 0 && ret >= 0)