Merge ../paraslash_meins/paraslash
[paraslash.git] / string.c
1 /*
2 * Copyright (C) 2004-2007 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 string.c memory allocation and string handling functions */
20
21 #include "para.h"
22 #include "string.h"
23
24 #include <sys/time.h> /* gettimeofday */
25 #include <pwd.h>
26 #include <sys/utsname.h> /* uname() */
27 #include <string.h>
28
29 #include "error.h"
30
31 /**
32 * paraslash's version of realloc()
33 *
34 * \param p pointer to the memory block, may be NULL
35 * \param size desired new size
36 *
37 * A wrapper for realloc(3). It calls \p exit(\p EXIT_FAILURE) on errors,
38 * i.e. there is no need to check the return value in the caller.
39 *
40 * \return A pointer to the newly allocated memory, which is suitably aligned
41 * for any kind of variable and may be different from \p p.
42 *
43 * \sa realloc(3)
44 */
45 __must_check __malloc void *para_realloc(void *p, size_t size)
46 {
47 /*
48 * No need to check for NULL pointers: If p is NULL, the call
49 * to realloc is equivalent to malloc(size)
50 */
51 if (!(p = realloc(p, size))) {
52 PARA_EMERG_LOG("%s", "realloc failed, aborting\n");
53 exit(EXIT_FAILURE);
54 }
55 return p;
56 }
57
58 /**
59 * paraslash's version of malloc()
60 *
61 * \param size desired new size
62 *
63 * A wrapper for malloc(3) which exits on errors.
64 *
65 * \return A pointer to the allocated memory, which is suitably aligned for any
66 * kind of variable.
67 *
68 * \sa malloc(3)
69 */
70 __must_check __malloc void *para_malloc(size_t size)
71 {
72 void *p = malloc(size);
73
74 if (!p) {
75 PARA_EMERG_LOG("%s", "malloc failed, aborting\n");
76 exit(EXIT_FAILURE);
77 }
78 return p;
79 }
80
81 /**
82 * paraslash's version of calloc()
83 *
84 * \param size desired new size
85 *
86 * A wrapper for calloc(3) which exits on errors.
87 *
88 * \return A pointer to the allocated and zeroed-out memory, which is suitably
89 * aligned for any kind of variable.
90 *
91 * \sa calloc(3)
92 */
93 __must_check __malloc void *para_calloc(size_t size)
94 {
95 void *ret = para_malloc(size);
96
97 memset(ret, 0, size);
98 return ret;
99 }
100
101 /**
102 * paraslash's version of strdup()
103 *
104 * \param s string to be duplicated
105 *
106 * A wrapper for strdup(3). It calls \p exit(EXIT_FAILURE) on errors, i.e.
107 * there is no need to check the return value in the caller.
108 *
109 * \return A pointer to the duplicated string. If \p s was the NULL pointer,
110 * an pointer to an empty string is returned.
111 *
112 * \sa strdup(3)
113 */
114 __must_check __malloc char *para_strdup(const char *s)
115 {
116 char *ret;
117
118 if ((ret = strdup(s? s: "")))
119 return ret;
120 PARA_EMERG_LOG("%s", "strdup failed, aborting\n");
121 exit(EXIT_FAILURE);
122 }
123
124 /**
125 * allocate a sufficiently large string and print into it
126 *
127 * \param fmt usual format string
128 *
129 * Produce output according to \p fmt. No artificial bound on the length of the
130 * resulting string is imposed.
131 *
132 * \return This function either returns a pointer to a string that must be
133 * freed by the caller or aborts without returning.
134 *
135 * \sa printf(3)
136 */
137 __must_check __printf_1_2 __malloc char *make_message(const char *fmt, ...)
138 {
139 char *msg;
140
141 PARA_VSPRINTF(fmt, msg);
142 return msg;
143 }
144
145 /**
146 * paraslash's version of strcat()
147 *
148 * \param a string to be appended to
149 * \param b string to append
150 *
151 * Append \p b to \p a.
152 *
153 * \return If \p a is NULL, return a pointer to a copy of \p b, i.e.
154 * para_strcat(NULL, b) is equivalent to para_strdup(b). If \p b is NULL,
155 * return \p a without making a copy of \p a. Otherwise, construct the
156 * concatenation \p c, free \p a (but not \p b) and return \p c.
157 *
158 * \sa strcat(3)
159 */
160 __must_check __malloc char *para_strcat(char *a, const char *b)
161 {
162 char *tmp;
163
164 if (!a)
165 return para_strdup(b);
166 if (!b)
167 return a;
168 tmp = make_message("%s%s", a, b);
169 free(a);
170 return tmp;
171 }
172
173 /**
174 * paraslash's version of dirname()
175 *
176 * \param name pointer to the full path
177 *
178 * Compute the directory component of \p name
179 *
180 * \return If \p name is \รพ NULL or the empty string, return \p NULL.
181 * Otherwise, Make a copy of \p name and return its directory component. Caller
182 * is responsible to free the result.
183 */
184 __must_check __malloc char *para_dirname(const char *name)
185 {
186 char *p, *ret;
187
188 if (!name || !*name)
189 return NULL;
190 ret = para_strdup(name);
191 p = strrchr(ret, '/');
192 if (!p)
193 *ret = '\0';
194 else
195 *p = '\0';
196 return ret;
197 }
198
199 /**
200 * paraslash's version of basename()
201 *
202 * \param name Pointer to the full path
203 *
204 * Compute the filename component of \p name
205 *
206 * \return If \p name is \p NULL or the empty string, return \p NULL,
207 * Otherwise, make a copy of \p name and return its filename component. Caller
208 * is responsible to free the result.
209 */
210 __must_check __malloc char *para_basename(const char *name)
211 {
212 char *p;
213
214 if (!name || !*name)
215 return NULL;
216 p = strrchr(name, '/');
217 if (!p)
218 return para_strdup(name);
219 p++;
220 if (!*p)
221 return NULL;
222 return para_strdup(p);
223 }
224
225 /**
226 * cut trailing newline
227 *
228 * \param buf the string to be chopped.
229 *
230 * Replace the last character in \p buf by zero if it is euqal to
231 * the newline character.
232 */
233 void chop(char *buf)
234 {
235 int n = strlen(buf);
236 if (!n)
237 return;
238 if (buf[n - 1] == '\n')
239 buf[n - 1] = '\0';
240 }
241
242 /**
243 * get a random filename
244 *
245 * This is by no means a secure way to create temporary files in a hostile
246 * direcory like \p /tmp. However, it is OK to use for temp files, fifos,
247 * sockets that are created in ~/.paraslash. Result must be freed by the
248 * caller.
249 *
250 * \return a pointer to a random filename.
251 */
252 __must_check __malloc char *para_tmpname(void)
253 {
254 struct timeval now;
255 gettimeofday(&now, NULL);
256 srand(now.tv_usec);
257 return make_message("%08i", rand());
258 }
259
260 /**
261 * create unique temporary file
262 *
263 * \param template the template to be passed to mkstemp()
264 * \param mode the desired mode of the tempfile
265 *
266 * This wrapper for mkstemp additionally uses fchmod() to
267 * set the given mode of the tempfile if mkstemp() returned success.
268 *
269 * \return The file descriptor of the temp file just created on success.
270 * On errors, -E_MKSTEMP or -E_FCHMOD is returned.
271 */
272 __must_check int para_mkstemp(char *template, mode_t mode)
273 {
274 int tmp, fd = mkstemp(template);
275
276 if (fd < 0)
277 return -E_MKSTEMP;
278 tmp = fchmod(fd, mode);
279 if (tmp >= 0)
280 return fd;
281 close(fd);
282 unlink(template);
283 return -E_FCHMOD;
284 }
285
286 /**
287 * get the logname of the current user
288 *
289 * \return A dynammically allocated string that must be freed by the caller. On
290 * errors, the string "unknown user" is returned, i.e. this function never
291 * returns NULL.
292 *
293 * \sa getpwuid(3)
294 */
295 __must_check __malloc char *para_logname(void)
296 {
297 struct passwd *pw = getpwuid(getuid());
298 return para_strdup(pw? pw->pw_name : "unknown_user");
299 }
300
301 /**
302 * get the home directory of the current user
303 *
304 * \return A dynammically allocated string that must be freed by the caller. If
305 * the home directory could not be found, this function returns "/tmp".
306 */
307 __must_check __malloc char *para_homedir(void)
308 {
309 struct passwd *pw = getpwuid(getuid());
310 return para_strdup(pw? pw->pw_dir : "/tmp");
311 }
312
313 /**
314 * split string and return pointers to its parts.
315 *
316 * \param args the string to be split
317 * \param argv_ptr pointer to the list of substrings
318 * \param delim delimiter
319 *
320 * This function modifies \p args by replacing each occurance of \p delim by
321 * zero. A NULL-terminated array of pointers to char* is allocated dynamically
322 * and these pointers are initialized to point to the broken-up substrings
323 * within \p args. A pointer to this array is returned via \p argv_ptr. It's OK
324 * to call this function with \p args \p == \p NULL.
325 *
326 * \return The number of substrings found in \p args.
327 */
328 __must_check unsigned split_args(char *args, char ***argv_ptr, const char *delim)
329 {
330 char *p = args;
331 char **argv;
332 size_t n = 0, i, j;
333
334 p = args + strspn(args, delim);
335 for (;;) {
336 i = strcspn(p, delim);
337 if (!i)
338 break;
339 p += i;
340 n++;
341 p += strspn(p, delim);
342 }
343 *argv_ptr = para_malloc((n + 1) * sizeof(char *));
344 argv = *argv_ptr;
345 i = 0;
346 p = args + strspn(args, delim);
347 while (p) {
348 argv[i] = p;
349 j = strcspn(p, delim);
350 if (!j)
351 break;
352 p += strcspn(p, delim);
353 if (*p) {
354 *p = '\0';
355 p++;
356 p += strspn(p, delim);
357 }
358 i++;
359 }
360 argv[n] = NULL;
361 return n;
362 }
363
364 /**
365 * ensure that file descriptors 0, 1, and 2 are valid
366 *
367 * Common approach that opens /dev/null until it gets a file descriptor greater
368 * than two.
369 *
370 * \sa okir's Black Hats Manual.
371 */
372 void valid_fd_012(void)
373 {
374 while (1) {
375 int fd;
376
377 fd = open("/dev/null", O_RDWR);
378 if (fd < 0)
379 exit(EXIT_FAILURE);
380 if (fd > 2) {
381 close(fd);
382 break;
383 }
384 }
385 }
386
387 /**
388 * get the own hostname
389 *
390 * \return A dynammically allocated string containing the hostname.
391 *
392 * \sa uname(2)
393 */
394 __malloc char *para_hostname(void)
395 {
396 struct utsname u;
397
398 uname(&u);
399 return para_strdup(u.nodename);
400 }