8b9f1633d95be658c7a6ecc40f291a0e033943bd
[paraslash.git] / string.c
1 /*
2 * Copyright (C) 2004-2007 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file string.c memory allocation and string handling functions */
8
9 #include "para.h"
10 #include "string.h"
11
12 #include <sys/time.h> /* gettimeofday */
13 #include <pwd.h>
14 #include <sys/utsname.h> /* uname() */
15 #include <string.h>
16
17 #include "error.h"
18
19 /**
20 * paraslash's version of realloc()
21 *
22 * \param p pointer to the memory block, may be NULL
23 * \param size desired new size
24 *
25 * A wrapper for realloc(3). It calls \p exit(\p EXIT_FAILURE) on errors,
26 * i.e. there is no need to check the return value in the caller.
27 *
28 * \return A pointer to the newly allocated memory, which is suitably aligned
29 * for any kind of variable and may be different from \p p.
30 *
31 * \sa realloc(3)
32 */
33 __must_check __malloc void *para_realloc(void *p, size_t size)
34 {
35 /*
36 * No need to check for NULL pointers: If p is NULL, the call
37 * to realloc is equivalent to malloc(size)
38 */
39 assert(size);
40 if (!(p = realloc(p, size))) {
41 PARA_EMERG_LOG("realloc failed (size = %zu), aborting\n",
42 size);
43 exit(EXIT_FAILURE);
44 }
45 return p;
46 }
47
48 /**
49 * paraslash's version of malloc()
50 *
51 * \param size desired new size
52 *
53 * A wrapper for malloc(3) which exits on errors.
54 *
55 * \return A pointer to the allocated memory, which is suitably aligned for any
56 * kind of variable.
57 *
58 * \sa malloc(3)
59 */
60 __must_check __malloc void *para_malloc(size_t size)
61 {
62 assert(size);
63 void *p = malloc(size);
64
65 if (!p) {
66 PARA_EMERG_LOG("%s", "malloc failed, aborting\n");
67 exit(EXIT_FAILURE);
68 }
69 return p;
70 }
71
72 /**
73 * paraslash's version of calloc()
74 *
75 * \param size desired new size
76 *
77 * A wrapper for calloc(3) which exits on errors.
78 *
79 * \return A pointer to the allocated and zeroed-out memory, which is suitably
80 * aligned for any kind of variable.
81 *
82 * \sa calloc(3)
83 */
84 __must_check __malloc void *para_calloc(size_t size)
85 {
86 void *ret = para_malloc(size);
87
88 memset(ret, 0, size);
89 return ret;
90 }
91
92 /**
93 * paraslash's version of strdup()
94 *
95 * \param s string to be duplicated
96 *
97 * A wrapper for strdup(3). It calls \p exit(EXIT_FAILURE) on errors, i.e.
98 * there is no need to check the return value in the caller.
99 *
100 * \return A pointer to the duplicated string. If \p s was the NULL pointer,
101 * an pointer to an empty string is returned.
102 *
103 * \sa strdup(3)
104 */
105 __must_check __malloc char *para_strdup(const char *s)
106 {
107 char *ret;
108
109 if ((ret = strdup(s? s: "")))
110 return ret;
111 PARA_EMERG_LOG("%s", "strdup failed, aborting\n");
112 exit(EXIT_FAILURE);
113 }
114
115 /**
116 * allocate a sufficiently large string and print into it
117 *
118 * \param fmt usual format string
119 *
120 * Produce output according to \p fmt. No artificial bound on the length of the
121 * resulting string is imposed.
122 *
123 * \return This function either returns a pointer to a string that must be
124 * freed by the caller or aborts without returning.
125 *
126 * \sa printf(3)
127 */
128 __must_check __printf_1_2 __malloc char *make_message(const char *fmt, ...)
129 {
130 char *msg;
131
132 PARA_VSPRINTF(fmt, msg);
133 return msg;
134 }
135
136 /**
137 * paraslash's version of strcat()
138 *
139 * \param a string to be appended to
140 * \param b string to append
141 *
142 * Append \p b to \p a.
143 *
144 * \return If \p a is NULL, return a pointer to a copy of \p b, i.e.
145 * para_strcat(NULL, b) is equivalent to para_strdup(b). If \p b is NULL,
146 * return \p a without making a copy of \p a. Otherwise, construct the
147 * concatenation \p c, free \p a (but not \p b) and return \p c.
148 *
149 * \sa strcat(3)
150 */
151 __must_check __malloc char *para_strcat(char *a, const char *b)
152 {
153 char *tmp;
154
155 if (!a)
156 return para_strdup(b);
157 if (!b)
158 return a;
159 tmp = make_message("%s%s", a, b);
160 free(a);
161 return tmp;
162 }
163
164 /**
165 * paraslash's version of dirname()
166 *
167 * \param name pointer to the full path
168 *
169 * Compute the directory component of \p name
170 *
171 * \return If \p name is \รพ NULL or the empty string, return \p NULL.
172 * Otherwise, Make a copy of \p name and return its directory component. Caller
173 * is responsible to free the result.
174 */
175 __must_check __malloc char *para_dirname(const char *name)
176 {
177 char *p, *ret;
178
179 if (!name || !*name)
180 return NULL;
181 ret = para_strdup(name);
182 p = strrchr(ret, '/');
183 if (!p)
184 *ret = '\0';
185 else
186 *p = '\0';
187 return ret;
188 }
189
190 /**
191 * paraslash's version of basename()
192 *
193 * \param name Pointer to the full path
194 *
195 * Compute the filename component of \p name
196 *
197 * \return If \p name is \p NULL or the empty string, return \p NULL,
198 * Otherwise, make a copy of \p name and return its filename component. Caller
199 * is responsible to free the result.
200 */
201 __must_check __malloc char *para_basename(const char *name)
202 {
203 char *p;
204
205 if (!name || !*name)
206 return NULL;
207 p = strrchr(name, '/');
208 if (!p)
209 return para_strdup(name);
210 p++;
211 if (!*p)
212 return NULL;
213 return para_strdup(p);
214 }
215
216 /**
217 * cut trailing newline
218 *
219 * \param buf the string to be chopped.
220 *
221 * Replace the last character in \p buf by zero if it is euqal to
222 * the newline character.
223 */
224 void chop(char *buf)
225 {
226 int n = strlen(buf);
227 if (!n)
228 return;
229 if (buf[n - 1] == '\n')
230 buf[n - 1] = '\0';
231 }
232
233 /**
234 * get a random filename
235 *
236 * This is by no means a secure way to create temporary files in a hostile
237 * direcory like \p /tmp. However, it is OK to use for temp files, fifos,
238 * sockets that are created in ~/.paraslash. Result must be freed by the
239 * caller.
240 *
241 * \return a pointer to a random filename.
242 */
243 __must_check __malloc char *para_tmpname(void)
244 {
245 struct timeval now;
246 unsigned int seed;
247
248 gettimeofday(&now, NULL);
249 seed = now.tv_usec;
250 srand(seed);
251 return make_message("%08i", rand());
252 }
253
254 /**
255 * create unique temporary file
256 *
257 * \param template the template to be passed to mkstemp()
258 * \param mode the desired mode of the tempfile
259 *
260 * This wrapper for mkstemp additionally uses fchmod() to
261 * set the given mode of the tempfile if mkstemp() returned success.
262 *
263 * \return The file descriptor of the temp file just created on success.
264 * On errors, -E_MKSTEMP or -E_FCHMOD is returned.
265 */
266 __must_check int para_mkstemp(char *template, mode_t mode)
267 {
268 int tmp, fd = mkstemp(template);
269
270 if (fd < 0)
271 return -E_MKSTEMP;
272 tmp = fchmod(fd, mode);
273 if (tmp >= 0)
274 return fd;
275 close(fd);
276 unlink(template);
277 return -E_FCHMOD;
278 }
279
280 /**
281 * get the logname of the current user
282 *
283 * \return A dynammically allocated string that must be freed by the caller. On
284 * errors, the string "unknown user" is returned, i.e. this function never
285 * returns NULL.
286 *
287 * \sa getpwuid(3)
288 */
289 __must_check __malloc char *para_logname(void)
290 {
291 struct passwd *pw = getpwuid(getuid());
292 return para_strdup(pw? pw->pw_name : "unknown_user");
293 }
294
295 /**
296 * get the home directory of the current user
297 *
298 * \return A dynammically allocated string that must be freed by the caller. If
299 * the home directory could not be found, this function returns "/tmp".
300 */
301 __must_check __malloc char *para_homedir(void)
302 {
303 struct passwd *pw = getpwuid(getuid());
304 return para_strdup(pw? pw->pw_dir : "/tmp");
305 }
306
307 /**
308 * split string and return pointers to its parts.
309 *
310 * \param args the string to be split
311 * \param argv_ptr pointer to the list of substrings
312 * \param delim delimiter
313 *
314 * This function modifies \a args by replacing each occurance of \a delim by
315 * zero. A \p NULL-terminated array of pointers to char* is allocated dynamically
316 * and these pointers are initialized to point to the broken-up substrings
317 * within \a args. A pointer to this array is returned via \a argv_ptr. It's OK
318 * to call this function with \a args \a == \p NULL.
319 *
320 * \return The number of substrings found in \a args.
321 */
322 __must_check unsigned split_args(char *args, char ***argv_ptr, const char *delim)
323 {
324 char *p = args;
325 char **argv;
326 size_t n = 0, i, j;
327
328 p = args + strspn(args, delim);
329 for (;;) {
330 i = strcspn(p, delim);
331 if (!i)
332 break;
333 p += i;
334 n++;
335 p += strspn(p, delim);
336 }
337 *argv_ptr = para_malloc((n + 1) * sizeof(char *));
338 argv = *argv_ptr;
339 i = 0;
340 p = args + strspn(args, delim);
341 while (p) {
342 argv[i] = p;
343 j = strcspn(p, delim);
344 if (!j)
345 break;
346 p += strcspn(p, delim);
347 if (*p) {
348 *p = '\0';
349 p++;
350 p += strspn(p, delim);
351 }
352 i++;
353 }
354 argv[n] = NULL;
355 return n;
356 }
357
358 /**
359 * ensure that file descriptors 0, 1, and 2 are valid
360 *
361 * Common approach that opens /dev/null until it gets a file descriptor greater
362 * than two.
363 *
364 * \sa okir's Black Hats Manual.
365 */
366 void valid_fd_012(void)
367 {
368 while (1) {
369 int fd;
370
371 fd = open("/dev/null", O_RDWR);
372 if (fd < 0)
373 exit(EXIT_FAILURE);
374 if (fd > 2) {
375 close(fd);
376 break;
377 }
378 }
379 }
380
381 /**
382 * get the own hostname
383 *
384 * \return A dynammically allocated string containing the hostname.
385 *
386 * \sa uname(2)
387 */
388 __malloc char *para_hostname(void)
389 {
390 struct utsname u;
391
392 uname(&u);
393 return para_strdup(u.nodename);
394 }