fd.c: Make __write() static.
[adu.git] / fd.c
1 /*
2 * Copyright (C) 2006-2008 Andre Noll <maan@tuebingen.mpg.de>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file fd.c \brief Helper functions for file descriptor handling. */
8
9 #include <sys/types.h>
10 #include <dirent.h>
11 #include <sys/mman.h>
12 #include <string.h>
13
14 #include "adu.h"
15 #include "error.h"
16 #include "string.h"
17 #include "fd.h"
18
19 /**
20 * Wrapper for the write system call.
21 *
22 * \param fd The file descriptor to write to.
23 * \param buf The buffer to write.
24 * \param size The length of \a buf in bytes.
25 *
26 * This function writes out the given buffer and retries if an interrupt
27 * occurred during the write.
28 *
29 * \return Standard.
30 *
31 * \sa write(2).
32 */
33 static ssize_t __write(int fd, const void *buf, size_t size)
34 {
35 ssize_t ret;
36
37 for (;;) {
38 ret = write(fd, buf, size);
39 if ((ret < 0) && (errno == EAGAIN || errno == EINTR))
40 continue;
41 return ret >= 0? ret : -ERRNO_TO_ERROR(errno);
42 }
43 }
44
45 /**
46 * Write the whole buffer to a file descriptor.
47 *
48 * \param fd The file descriptor to write to.
49 * \param buf The buffer to write.
50 * \param size The length of \a buf in bytes.
51 *
52 * This function writes the given buffer and continues on short writes and
53 * when interrupted by a signal.
54 *
55 * \return Standard.
56 */
57 static ssize_t write_all(int fd, const void *buf, size_t size)
58 {
59 // DEBUG_LOG("writing %zu bytes\n", size);
60 const char *b = buf;
61 while (size) {
62 ssize_t ret = __write(fd, b, size);
63 // DEBUG_LOG("ret: %zd\n", ret);
64 if (ret < 0)
65 return ret;
66 b += ret;
67 size -= 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 static int __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 adu_write_file(const char *filename, const void *buf, size_t size)
105 {
106 int ret, fd;
107
108 ret = __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 __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 adu_opendir(const char *dirname, DIR **dir, int *cwd)
162 {
163 int ret;
164
165 if (cwd) {
166 ret = __open(".", O_RDONLY, 0);
167 if (ret < 0)
168 return ret;
169 *cwd = ret;
170 }
171 ret = __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 adu_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 read-only and map it into memory.
203 *
204 * \param path Name of the regular file to map.
205 * \param map On success, the mapping is returned here.
206 * \param size Result parameter: size of the mapping in bytes.
207 *
208 * The file will be mapped privately with memory protection PROT_READ. The file
209 * descriptor resulting from the underlying open call is closed after mmap().
210 *
211 * \return Standard.
212 *
213 * \sa mmap(2).
214 */
215 int mmap_file_ro(const char *path, void **map, size_t *size)
216 {
217 int fd, ret;
218 struct stat file_status;
219
220 ret = __open(path, O_RDONLY, 0);
221 if (ret < 0)
222 return ret;
223 fd = ret;
224 if (fstat(fd, &file_status) < 0) {
225 ret = -ERRNO_TO_ERROR(errno);
226 goto out;
227 }
228 *size = file_status.st_size;
229 ret = -E_EMPTY;
230 DEBUG_LOG("%s: size %zu\n", path, *size);
231 if (!*size)
232 goto out;
233 *map = mmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
234 if (*map == MAP_FAILED) {
235 *map = NULL;
236 ret = -E_MMAP;
237 goto out;
238 }
239 ret = 1;
240 out:
241 close(fd);
242 return ret;
243 }
244
245 /**
246 * A wrapper for munmap(2).
247 *
248 * \param start The start address of the memory mapping.
249 * \param length The size of the mapping.
250 *
251 * \return Positive on success, \p -E_MUNMAP on errors.
252 *
253 * \sa munmap(2), mmap_full_file().
254 */
255 int adu_munmap(void *start, size_t length)
256 {
257 int err;
258 if (munmap(start, length) >= 0)
259 return 1;
260 err = errno;
261 ERROR_LOG("munmap (%p/%zu) failed: %s\n", start, length,
262 strerror(err));
263 return -ERRNO_TO_ERROR(err);
264 }
265
266 __must_check __malloc static char *adu_dirname(const char *name)
267 {
268 char *p, *ret;
269
270 if (!name || !*name)
271 return NULL;
272 ret = adu_strdup(name);
273 p = strrchr(ret, '/');
274 if (!p)
275 *ret = '\0';
276 else
277 *p = '\0';
278 return ret;
279 }
280
281 /**
282 * Recursive mkdir
283 *
284 * \param p Full path that should be created.
285 *
286 * \param mode Use this mode when creating directories.
287 *
288 * \return 0 if successful, -E_MKDIR on errors.
289 */
290 int mkpath(const char *p, mode_t mode)
291 {
292 char *parent, *path;
293 int ret = -E_MKDIR;
294
295 DEBUG_LOG("%s\n", p);
296 if (strcmp(p, ".") == 0 || strcmp(p, "/") == 0 || strcmp(p, "") == 0) {
297 DEBUG_LOG("reached beginning of path\n");
298 return 0;
299 }
300 path = adu_strdup(p);
301 parent = adu_dirname(p);
302 if (!parent)
303 goto out;
304 ret = mkpath(parent, mode);
305 if (ret < 0)
306 goto out;
307 INFO_LOG("making dir %s\n", path);
308 ret = 0;
309 if ((mkdir(path, mode) == -1) && (errno != EEXIST))
310 ret = -E_MKDIR;
311 out:
312 free(parent);
313 free(path);
314 return ret;
315 }