Get rid of E_OSL_STAT.
[osl.git] / fd.c
1 /*
2 * Copyright (C) 2006-2008 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file fd.c Helper functions for file descriptor handling. */
8
9 #include <sys/types.h>
10 #include <dirent.h>
11 #include <sys/mman.h>
12 #include <fcntl.h>
13 #include <sys/select.h>
14
15 #include "log.h"
16 #include "osl.h"
17 #include "error.h"
18 #include "fd.h"
19
20 /**
21 * Wrapper for the write system call.
22 *
23 * \param fd The file descriptor to write to.
24 * \param buf The buffer to write.
25 * \param size The length of \a buf in bytes.
26 *
27 * This function writes out the given buffer and retries if an interrupt
28 * occurred during the write.
29 *
30 * \return On success, the number of bytes written is returned, otherwise, a
31 * negative error code is returned.
32 *
33 * \sa write(2).
34 */
35 static ssize_t __write(int fd, const void *buf, size_t size)
36 {
37 ssize_t ret;
38
39 for (;;) {
40 ret = write(fd, buf, size);
41 if ((ret < 0) && (errno == EAGAIN || errno == EINTR))
42 continue;
43 return ret >= 0? ret : -ERRNO_TO_ERROR(errno);
44 }
45 }
46
47 /**
48 * Write a buffer to a file descriptor, re-write on short writes.
49 *
50 * \param fd The file descriptor.
51 * \param buf The buffer to be sent.
52 * \param len The length of \a buf.
53 *
54 * \return Standard. In any case, the number of bytes that have been written is
55 * stored in \a len.
56 */
57 int write_all(int fd, const char *buf, size_t *len)
58 {
59 size_t total = *len;
60
61 assert(total);
62 *len = 0;
63 while (*len < total) {
64 int ret = __write(fd, buf + *len, total - *len);
65 if (ret < 0)
66 return ret;
67 *len += ret;
68 }
69 return 1;
70 }
71
72 /**
73 * Wrapper for the open(2) system call.
74 *
75 * \param path The filename.
76 * \param flags The usual open(2) flags.
77 * \param mode Specifies the permissions to use.
78 *
79 * The mode parameter must be specified when O_CREAT is in the flags, and is
80 * ignored otherwise.
81 *
82 * \return The file descriptor on success, negative on errors.
83 *
84 * \sa open(2).
85 */
86 int osl_open(const char *path, int flags, mode_t mode)
87 {
88 int ret = open(path, flags, mode);
89
90 if (ret >= 0)
91 return ret;
92 return -ERRNO_TO_ERROR(errno);
93 }
94
95 /**
96 * Open a file, write the given buffer and close the file.
97 *
98 * \param filename Full path to the file to open.
99 * \param buf The buffer to write to the file.
100 * \param size The size of \a buf.
101 *
102 * \return Standard.
103 */
104 int write_file(const char *filename, const void *buf, size_t size)
105 {
106 int ret, fd;
107
108 ret = osl_open(filename, O_WRONLY | O_CREAT | O_EXCL, 0644);
109 if (ret < 0)
110 return ret;
111 fd = ret;
112 ret = write_all(fd, buf, &size);
113 if (ret < 0)
114 goto out;
115 ret = 1;
116 out:
117 close(fd);
118 return ret;
119 }
120
121 /**
122 * Wrapper for chdir(2).
123 *
124 * \param path The specified directory.
125 *
126 * \return Standard.
127 */
128 static int para_chdir(const char *path)
129 {
130 int ret = chdir(path);
131
132 if (ret >= 0)
133 return 1;
134 return -ERRNO_TO_ERROR(errno);
135 }
136
137 /**
138 * Save the cwd and open a given directory.
139 *
140 * \param dirname Path to the directory to open.
141 * \param dir Result pointer.
142 * \param cwd File descriptor of the current working directory.
143 *
144 * \return Standard.
145 *
146 * Opening the current directory (".") and calling fchdir() to return is
147 * usually faster and more reliable than saving cwd in some buffer and calling
148 * chdir() afterwards.
149 *
150 * If \a cwd is not \p NULL "." is opened and the resulting file descriptor is
151 * stored in \a cwd. If the function returns success, and \a cwd is not \p
152 * NULL, the caller must close this file descriptor (probably after calling
153 * fchdir(*cwd)).
154 *
155 * On errors, the function undos everything, so the caller needs neither close
156 * any files, nor change back to the original working directory.
157 *
158 * \sa getcwd(3).
159 *
160 */
161 int para_opendir(const char *dirname, DIR **dir, int *cwd)
162 {
163 int ret;
164
165 if (cwd) {
166 ret = osl_open(".", O_RDONLY, 0);
167 if (ret < 0)
168 return ret;
169 *cwd = ret;
170 }
171 ret = para_chdir(dirname);
172 if (ret < 0)
173 goto close_cwd;
174 *dir = opendir(".");
175 if (*dir)
176 return 1;
177 ret = -ERRNO_TO_ERROR(errno);
178 /* Ignore return value of fchdir() and close(). We're busted anyway. */
179 if (cwd)
180 fchdir(*cwd);
181 close_cwd:
182 if (cwd)
183 close(*cwd);
184 return ret;
185 }
186
187 /**
188 * A wrapper for fchdir().
189 *
190 * \param fd An open file descriptor.
191 *
192 * \return Standard.
193 */
194 int para_fchdir(int fd)
195 {
196 if (fchdir(fd) < 0)
197 return -ERRNO_TO_ERROR(errno);
198 return 1;
199 }
200
201 /**
202 * Open a file and map it into memory.
203 *
204 * \param path Name of the regular file to map.
205 * \param open_mode Either \p O_RDONLY or \p O_RDWR.
206 * \param map On success, the mapping is returned here.
207 * \param size size of the mapping.
208 * \param fd_ptr The file descriptor of the mapping.
209 *
210 * If \a fd_ptr is \p NULL, the file descriptor resulting from the underlying
211 * open call is closed after mmap(). Otherwise the file is kept open and the
212 * file descriptor is returned in \a fd_ptr.
213 *
214 * \return Standard.
215 *
216 * \sa osl_open(), mmap(2).
217 */
218 int mmap_full_file(const char *path, int open_mode, void **map,
219 size_t *size, int *fd_ptr)
220 {
221 int fd, ret, mmap_prot, mmap_flags;
222 struct stat file_status;
223
224 if (open_mode == O_RDONLY) {
225 mmap_prot = PROT_READ;
226 mmap_flags = MAP_PRIVATE;
227 } else {
228 mmap_prot = PROT_READ | PROT_WRITE;
229 mmap_flags = MAP_SHARED;
230 }
231 ret = osl_open(path, open_mode, 0);
232 if (ret < 0)
233 return ret;
234 fd = ret;
235 if (fstat(fd, &file_status) < 0) {
236 ret = -ERRNO_TO_ERROR(errno);
237 goto out;
238 }
239 *size = file_status.st_size;
240 ret = -E_OSL_EMPTY;
241 DEBUG_LOG("%s: size %zu\n", path, *size);
242 if (!*size)
243 goto out;
244 *map = mmap(NULL, *size, mmap_prot, mmap_flags, fd, 0);
245 if (*map == MAP_FAILED) {
246 *map = NULL;
247 ret = -E_OSL_MMAP;
248 goto out;
249 }
250 ret = 1;
251 out:
252 if (ret < 0 || !fd_ptr)
253 close(fd);
254 else
255 *fd_ptr = fd;
256 return ret;
257 }
258
259 /**
260 * A wrapper for munmap(2).
261 *
262 * \param start The start address of the memory mapping.
263 * \param length The size of the mapping.
264 *
265 * \return Positive on success, \p -E_MUNMAP on errors.
266 *
267 * \sa munmap(2), mmap_full_file().
268 */
269 int osl_munmap(void *start, size_t length)
270 {
271 int err;
272 if (munmap(start, length) >= 0)
273 return 1;
274 err = errno;
275 ERROR_LOG("munmap (%p/%zu) failed: %s\n", start, length,
276 strerror(err));
277 return -ERRNO_TO_ERROR(err);
278 }
279
280 /**
281 * Allocate a sufficiently large string and print into it.
282 *
283 * \param fmt A usual format string.
284 *
285 * Produce output according to \p fmt. No artificial bound on the length of the
286 * resulting string is imposed.
287 *
288 * \return This function either returns a pointer to a string that must be
289 * freed by the caller or \p NULL if memory allocation failed.
290 *
291 * \sa printf(3).
292 */
293 __must_check __printf_1_2 __malloc char *make_message(const char *fmt, ...)
294 {
295 int n;
296 size_t size = 100;
297 char *p = malloc(size);
298
299 if (!p)
300 return NULL;
301 while (1) {
302 char *q;
303 va_list ap;
304 /* Try to print in the allocated space. */
305 va_start(ap, fmt);
306 n = vsnprintf(p, size, fmt, ap);
307 va_end(ap);
308 /* If that worked, return the string. */
309 if (n > -1 && n < size)
310 break;
311 /* Else try again with more space. */
312 if (n > -1) /* glibc 2.1 */
313 size = n + 1; /* precisely what is needed */
314 else /* glibc 2.0 */
315 size *= 2; /* twice the old size */
316 q = realloc(p, size);
317 if (!q) {
318 free(p);
319 return NULL;
320 }
321 p = q;
322 }
323 return p;
324 }
325
326 /**
327 * A wrapper for truncate(2)
328 *
329 * \param path Name of the regular file to truncate
330 * \param size Number of bytes to \b shave \b off
331 *
332 * Truncate the regular file named by \a path by \a size bytes.
333 *
334 * \return Standard.
335 *
336 * \sa truncate(2)
337 */
338 int truncate_file(const char *path, off_t size)
339 {
340 int ret;
341 struct stat statbuf;
342
343 ret = osl_stat(path, &statbuf);
344 if (ret < 0)
345 goto out;
346 ret = -E_OSL_BAD_SIZE;
347 if (statbuf.st_size < size)
348 goto out;
349 ret = -E_OSL_TRUNC;
350 if (truncate(path, statbuf.st_size - size) < 0)
351 goto out;
352 ret = 1;
353 out:
354 return ret;
355 }
356