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("realloc failed (size = %zu), aborting\n",
  53                         size);
  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  * \return A pointer to the allocated and zeroed-out memory, which is suitably
  90  * aligned 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 \p exit(EXIT_FAILURE) on errors, i.e.
 108  * there 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 \þ 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  * cut trailing newline
 228  *
 229  * \param buf the string to be chopped.
 230  *
 231  * Replace the last character in \p buf by zero if it is euqal to
 232  * the newline character.
 233  */
 234 void chop(char *buf)
 235 {
 236         int n = strlen(buf);
 237         if (!n)
 238                 return;
 239         if (buf[n - 1] == '\n')
 240                 buf[n - 1] = '\0';
 241 }
 242
 243 /**
 244  * get a random filename
 245  *
 246  * This is by no means a secure way to create temporary files in a hostile
 247  * direcory like \p /tmp. However, it is OK to use for temp files, fifos,
 248  * sockets that are created in ~/.paraslash. Result must be freed by the
 249  * caller.
 250  *
 251  * \return a pointer to a random filename.
 252  */
 253 __must_check __malloc char *para_tmpname(void)
 254 {
 255         struct timeval now;
 256         unsigned int seed;
 257
 258         gettimeofday(&now, NULL);
 259         seed = now.tv_usec;
 260         srand(seed);
 261         return make_message("%08i", rand());
 262 }
 263
 264 /**
 265  * create unique temporary file
 266  *
 267  * \param template the template to be passed to mkstemp()
 268  * \param mode the desired mode of the tempfile
 269  *
 270  * This wrapper for mkstemp additionally uses fchmod() to
 271  * set the given mode of the tempfile if mkstemp() returned success.
 272  *
 273  * \return The file descriptor of the temp file just created on success.
 274  * On errors, -E_MKSTEMP or -E_FCHMOD is returned.
 275  */
 276 __must_check int para_mkstemp(char *template, mode_t mode)
 277 {
 278         int tmp, fd = mkstemp(template);
 279
 280         if (fd < 0)
 281                 return -E_MKSTEMP;
 282         tmp = fchmod(fd, mode);
 283         if (tmp >= 0)
 284                 return fd;
 285         close(fd);
 286         unlink(template);
 287         return -E_FCHMOD;
 288 }
 289
 290 /**
 291  * get the logname of the current user
 292  *
 293  * \return A dynammically allocated string that must be freed by the caller. On
 294  * errors, the string "unknown user" is returned, i.e. this function never
 295  * returns NULL.
 296  *
 297  * \sa getpwuid(3)
 298  */
 299 __must_check __malloc char *para_logname(void)
 300 {
 301         struct passwd *pw = getpwuid(getuid());
 302         return para_strdup(pw? pw->pw_name : "unknown_user");
 303 }
 304
 305 /**
 306  * get the home directory of the current user
 307  *
 308  * \return A dynammically allocated string that must be freed by the caller. If
 309  * the home directory could not be found, this function returns "/tmp".
 310  */
 311 __must_check __malloc char *para_homedir(void)
 312 {
 313         struct passwd *pw = getpwuid(getuid());
 314         return para_strdup(pw? pw->pw_dir : "/tmp");
 315 }
 316
 317 /**
 318  * split string and return pointers to its parts.
 319  *
 320  * \param args the string to be split
 321  * \param argv_ptr  pointer to the list of substrings
 322  * \param delim delimiter
 323  *
 324  * This function modifies \a args by replacing each occurance of \a delim by
 325  * zero. A \p NULL-terminated array of pointers to char* is allocated dynamically
 326  * and these pointers are initialized to point to the broken-up substrings
 327  * within \a args. A pointer to this array is returned via \a argv_ptr. It's OK
 328  * to call this function with \a args \a == \p NULL.
 329  *
 330  * \return The number of substrings found in \a args.
 331  */
 332 __must_check unsigned split_args(char *args, char ***argv_ptr, const char *delim)
 333 {
 334         char *p = args;
 335         char **argv;
 336         size_t n = 0, i, j;
 337
 338         p = args + strspn(args, delim);
 339         for (;;) {
 340                 i = strcspn(p, delim);
 341                 if (!i)
 342                         break;
 343                 p += i;
 344                 n++;
 345                 p += strspn(p, delim);
 346         }
 347         *argv_ptr = para_malloc((n + 1) * sizeof(char *));
 348         argv = *argv_ptr;
 349         i = 0;
 350         p = args + strspn(args, delim);
 351         while (p) {
 352                 argv[i] = p;
 353                 j = strcspn(p, delim);
 354                 if (!j)
 355                         break;
 356                 p += strcspn(p, delim);
 357                 if (*p) {
 358                         *p = '\0';
 359                         p++;
 360                         p += strspn(p, delim);
 361                 }
 362                 i++;
 363         }
 364         argv[n] = NULL;
 365         return n;
 366 }
 367
 368 /**
 369  * ensure that file descriptors 0, 1, and 2 are valid
 370  *
 371  * Common approach that opens /dev/null until it gets a file descriptor greater
 372  * than two.
 373  *
 374  * \sa okir's Black Hats Manual.
 375  */
 376 void valid_fd_012(void)
 377 {
 378         while (1) {
 379         int     fd;
 380
 381                 fd = open("/dev/null", O_RDWR);
 382                 if (fd < 0)
 383                         exit(EXIT_FAILURE);
 384                 if (fd > 2) {
 385                         close(fd);
 386                         break;
 387                 }
 388         }
 389 }
 390
 391 /**
 392  * get the own hostname
 393  *
 394  * \return A dynammically allocated string containing the hostname.
 395  *
 396  * \sa uname(2)
 397  */
 398 __malloc char *para_hostname(void)
 399 {
 400         struct utsname u;
 401
 402         uname(&u);
 403         return para_strdup(u.nodename);
 404 }