string.c: Documentation update
[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 <regex.h>
26 #include <pwd.h>
27 #include <sys/utsname.h> /* uname() */
28 #include <string.h>
29
30 #include "error.h"
31
32 /**
33 * paraslash's version of realloc()
34 *
35 * \param p pointer to the memory block, may be NULL
36 * \param size desired new size
37 *
38 * A wrapper for realloc(3). It calls \p exit(\p EXIT_FAILURE) on errors,
39 * i.e. there is no need to check the return value in the caller.
40 *
41 * \return A pointer to the newly allocated memory, which is suitably aligned
42 * for any kind of variable and may be different from \p p.
43 *
44 * \sa realloc(3)
45 */
46 __must_check __malloc void *para_realloc(void *p, size_t size)
47 {
48 /*
49 * No need to check for NULL pointers: If p is NULL, the call
50 * to realloc is equivalent to malloc(size)
51 */
52 if (!(p = realloc(p, size))) {
53 PARA_EMERG_LOG("%s", "realloc failed, aborting\n");
54 exit(EXIT_FAILURE);
55 }
56 return p;
57 }
58
59 /**
60 * paraslash's version of malloc()
61 *
62 * \param size desired new size
63 *
64 * A wrapper for malloc(3) which exits on errors.
65 *
66 * \return A pointer to the allocated memory, which is suitably aligned for any
67 * kind of variable.
68 *
69 * \sa malloc(3)
70 */
71 __must_check __malloc void *para_malloc(size_t size)
72 {
73 void *p = malloc(size);
74
75 if (!p) {
76 PARA_EMERG_LOG("%s", "malloc failed, aborting\n");
77 exit(EXIT_FAILURE);
78 }
79 return p;
80 }
81
82 /**
83 * paraslash's version of calloc()
84 *
85 * \param size desired new size
86 *
87 * A wrapper for calloc(3) which exits on errors.
88 *
89 * A pointer to the allocated and zeroed-out memory, which is suitably aligned
90 * for any kind of variable.
91 *
92 * \sa calloc(3)
93 */
94 __must_check __malloc void *para_calloc(size_t size)
95 {
96 void *ret = para_malloc(size);
97
98 memset(ret, 0, size);
99 return ret;
100 }
101
102 /**
103 * paraslash's version of strdup()
104 *
105 * \param s string to be duplicated
106 *
107 * A wrapper for strdup(3). It calls exit(EXIT_FAILURE) on errors, i.e. there
108 * is no need to check the return value in the caller.
109 *
110 * \return A pointer to the duplicated string. If \p s was the NULL pointer,
111 * an pointer to an empty string is returned.
112 *
113 * \sa strdup(3)
114 */
115 __must_check __malloc char *para_strdup(const char *s)
116 {
117 char *ret;
118
119 if ((ret = strdup(s? s: "")))
120 return ret;
121 PARA_EMERG_LOG("%s", "strdup failed, aborting\n");
122 exit(EXIT_FAILURE);
123 }
124
125 /**
126 * allocate a sufficiently large string and print into it
127 *
128 * \param fmt usual format string
129 *
130 * Produce output according to \p fmt. No artificial bound on the length of the
131 * resulting string is imposed.
132 *
133 * \return This function either returns a pointer to a string that must be
134 * freed by the caller or aborts without returning.
135 *
136 * \sa printf(3)
137 */
138 __must_check __printf_1_2 __malloc char *make_message(const char *fmt, ...)
139 {
140 char *msg;
141
142 PARA_VSPRINTF(fmt, msg);
143 return msg;
144 }
145
146 /**
147 * paraslash's version of strcat()
148 *
149 * \param a string to be appended to
150 * \param b string to append
151 *
152 * Append \p b to \p a.
153 *
154 * \return If \p a is NULL, return a pointer to a copy of \p b, i.e.
155 * para_strcat(NULL, b) is equivalent to para_strdup(b). If \p b is NULL,
156 * return \p a without making a copy of \p a. Otherwise, construct the
157 * concatenation \p c, free \p a (but not \p b) and return \p c.
158 *
159 * \sa strcat(3)
160 */
161 __must_check __malloc char *para_strcat(char *a, const char *b)
162 {
163 char *tmp;
164
165 if (!a)
166 return para_strdup(b);
167 if (!b)
168 return a;
169 tmp = make_message("%s%s", a, b);
170 free(a);
171 return tmp;
172 }
173
174 /**
175 * paraslash's version of dirname()
176 *
177 * \param name pointer to the full path
178 *
179 * Compute the directory component of \p name
180 *
181 * \return If \p name is \รพ NULL or the empty string, return \p NULL.
182 * Otherwise, Make a copy of \p name and return its directory component. Caller
183 * is responsible to free the result.
184 */
185 __must_check __malloc char *para_dirname(const char *name)
186 {
187 char *p, *ret;
188
189 if (!name || !*name)
190 return NULL;
191 ret = para_strdup(name);
192 p = strrchr(ret, '/');
193 if (!p)
194 *ret = '\0';
195 else
196 *p = '\0';
197 return ret;
198 }
199
200 /**
201 * paraslash's version of basename()
202 *
203 * \param name Pointer to the full path
204 *
205 * Compute the filename component of \p name
206 *
207 * \return If \p name is \p NULL or the empty string, return \p NULL,
208 * Otherwise, make a copy of \p name and return its filename component. Caller
209 * is responsible to free the result.
210 */
211 __must_check __malloc char *para_basename(const char *name)
212 {
213 char *p;
214
215 if (!name || !*name)
216 return NULL;
217 p = strrchr(name, '/');
218 if (!p)
219 return para_strdup(name);
220 p++;
221 if (!*p)
222 return NULL;
223 return para_strdup(p);
224 }
225
226 /**
227 * simple search and replace routine
228 *
229 * \param src source string
230 * \param macro_name the name of the macro
231 * \param replacement the replacement format string
232 *
233 * In \p src, replace each occurence of \p macro_name(arg) by the string
234 * determined by the \p replacement format string. \p replacement may (but
235 * needs not) contain a single string conversion specifier (%s) which gets
236 * replaced by \p arg.
237 *
238 * \return A string in which all matches in \p src are replaced, or \p NULL if
239 * an syntax error was encountered. Caller must free the result.
240 *
241 * \sa regcomp(3)
242 */
243 __must_check __malloc char *s_a_r(const char *src, const char* macro_name,
244 const char *replacement)
245 {
246 regex_t preg;
247 size_t nmatch = 1;
248 regmatch_t pmatch[1];
249 int eflags = 0;
250 char *dest = NULL;
251 const char *bufptr = src;
252
253 if (!macro_name || !replacement || !src)
254 return para_strdup(src);
255 regcomp(&preg, macro_name, 0);
256 while (regexec(&preg, bufptr, nmatch, pmatch, eflags)
257 != REG_NOMATCH) {
258 char *tmp, *arg, *o_bracket, *c_bracket;
259
260 o_bracket = strchr(bufptr + pmatch[0].rm_so, '(');
261 c_bracket = o_bracket? strchr(o_bracket, ')') : NULL;
262 if (!c_bracket)
263 goto out;
264 tmp = para_strdup(bufptr);
265 tmp[pmatch[0].rm_so] = '\0';
266 dest = para_strcat(dest, tmp);
267 free(tmp);
268
269 arg = para_strdup(o_bracket + 1);
270 arg[c_bracket - o_bracket - 1] = '\0';
271 tmp = make_message(replacement, arg);
272 free(arg);
273 dest = para_strcat(dest, tmp);
274 free(tmp);
275 bufptr = c_bracket;
276 bufptr++;
277 }
278 dest = para_strcat(dest, bufptr);
279 // PARA_DEBUG_LOG("%s: returning %s\n", __func__, dest);
280 out:
281 regfree(&preg);
282 return dest;
283 }
284
285 /**
286 * replace a string according to a list of macros
287 *
288 * \param macro_list the array containing a macro/replacement pairs.
289 * \param src the source string
290 *
291 * This function just calls s_a_r() for each element of \p macro_list.
292 *
293 * \return \p NULL if one of the underlying calls to \p s_a_r returned \p NULL.
294 * Otherwise the completely expanded version of \p src is returned.
295 */
296 __must_check __malloc char *s_a_r_list(struct para_macro *macro_list, char *src)
297 {
298 struct para_macro *mp = macro_list;
299 char *ret = NULL, *tmp = para_strdup(src);
300
301 while (mp->name) {
302 ret = s_a_r(tmp, mp->name, mp->replacement);
303 free(tmp);
304 if (!ret) /* syntax error */
305 return NULL;
306 tmp = ret;
307 mp++;
308 }
309 //PARA_DEBUG_LOG("%s: returning %s\n", __func__, dest);
310 return ret;
311 }
312
313 /**
314 * cut trailing newline
315 *
316 * \param buf the string to be chopped.
317 *
318 * Replace the last character in \p buf by zero if it is euqal to
319 * the newline character.
320 */
321 void chop(char *buf)
322 {
323 int n = strlen(buf);
324 if (!n)
325 return;
326 if (buf[n - 1] == '\n')
327 buf[n - 1] = '\0';
328 }
329
330 /**
331 * get a random filename
332 *
333 * This is by no means a secure way to create temporary files in a hostile
334 * direcory like \p /tmp. However, it is OK to use for temp files, fifos,
335 * sockets that are created in ~/.paraslash. Result must be freed by the
336 * caller.
337 *
338 * \return a pointer to a random filename.
339 */
340 __must_check __malloc char *para_tmpname(void)
341 {
342 struct timeval now;
343 gettimeofday(&now, NULL);
344 srand(now.tv_usec);
345 return make_message("%08i", rand());
346 }
347
348 /**
349 * create unique temporary file
350 *
351 * \param template the template to be passed to mkstemp()
352 * \param mode the desired mode of the tempfile
353 *
354 * This wrapper for mkstemp additionally uses fchmod() to
355 * set the given mode of the tempfile if mkstemp() returned success.
356 *
357 * \return The file descriptor of the temp file just created on success.
358 * On errors, -E_MKSTEMP or -E_FCHMOD is returned.
359 */
360 __must_check int para_mkstemp(char *template, mode_t mode)
361 {
362 int tmp, fd = mkstemp(template);
363
364 if (fd < 0)
365 return -E_MKSTEMP;
366 tmp = fchmod(fd, mode);
367 if (tmp >= 0)
368 return fd;
369 close(fd);
370 unlink(template);
371 return -E_FCHMOD;
372 }
373
374 /**
375 * get the logname of the current user
376 *
377 * \return A dynammically allocated string that must be freed by the caller. On
378 * errors, the string "unknown user" is returned, i.e. this function never
379 * returns NULL.
380 *
381 * \sa getpwuid(3)
382 */
383 __must_check __malloc char *para_logname(void)
384 {
385 struct passwd *pw = getpwuid(getuid());
386 return para_strdup(pw? pw->pw_name : "unknown_user");
387 }
388
389 /**
390 * get the home directory of the current user
391 *
392 * \return A dynammically allocated string that must be freed by the caller. If
393 * the home directory could not be found, this function returns "/tmp".
394 */
395 __must_check __malloc char *para_homedir(void)
396 {
397 struct passwd *pw = getpwuid(getuid());
398 return para_strdup(pw? pw->pw_dir : "/tmp");
399 }
400
401 /**
402 * split string and return pointers to its parts.
403 *
404 * \param args the string to be split
405 * \param argv_ptr pointer to the list of substrings
406 * \param delim delimiter
407 *
408 * This function modifies \p args by replacing each occurance of \p delim by
409 * zero. A NULL-terminated array of pointers to char* is allocated dynamically
410 * and these pointers are initialized to point to the broken-up substrings
411 * within \p args. A pointer to this array is returned via \p argv_ptr. It's OK
412 * to call this function with \p args \p == \p NULL.
413 *
414 * \return The number of substrings found in \p args.
415 */
416 __must_check unsigned split_args(char *args, char ***argv_ptr, const char *delim)
417 {
418 char *p = args;
419 char **argv;
420 size_t n = 0, i, j;
421
422 p = args + strspn(args, delim);
423 for (;;) {
424 i = strcspn(p, delim);
425 if (!i)
426 break;
427 p += i;
428 n++;
429 p += strspn(p, delim);
430 }
431 *argv_ptr = para_malloc((n + 1) * sizeof(char *));
432 argv = *argv_ptr;
433 i = 0;
434 p = args + strspn(args, delim);
435 while (p) {
436 argv[i] = p;
437 j = strcspn(p, delim);
438 if (!j)
439 break;
440 p += strcspn(p, delim);
441 if (*p) {
442 *p = '\0';
443 p++;
444 p += strspn(p, delim);
445 }
446 i++;
447 }
448 argv[n] = NULL;
449 return n;
450 }
451
452 /**
453 * ensure that file descriptors 0, 1, and 2 are valid
454 *
455 * Common approach that opens /dev/null until it gets a file descriptor greater
456 * than two.
457 *
458 * \sa okir's Black Hats Manual.
459 */
460 void valid_fd_012(void)
461 {
462 while (1) {
463 int fd;
464
465 fd = open("/dev/null", O_RDWR);
466 if (fd < 0)
467 exit(EXIT_FAILURE);
468 if (fd > 2) {
469 close(fd);
470 break;
471 }
472 }
473 }
474
475 /**
476 * get the own hostname
477 *
478 * \return A dynammically allocated string containing the hostname.
479 *
480 * \sa uname(2)
481 */
482 __malloc char *para_hostname(void)
483 {
484 struct utsname u;
485
486 uname(&u);
487 return para_strdup(u.nodename);
488 }