src/mktemp.c

   1 /* Create a temporary file or directory, safely.
   2    Copyright (C) 2007-2023 Free Software Foundation, Inc.
   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 3 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, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Jim Meyering and Eric Blake.  */
  18
  19 #include <config.h>
  20 #include <sys/types.h>
  21 #include <getopt.h>
  22
  23 #include "system.h"
  24
  25 #include "close-stream.h"
  26 #include "filenamecat.h"
  27 #include "quote.h"
  28 #include "tempname.h"
  29
  30 /* The official name of this program (e.g., no 'g' prefix).  */
  31 #define PROGRAM_NAME "mktemp"
  32
  33 #define AUTHORS \
  34   proper_name ("Jim Meyering"), \
  35   proper_name ("Eric Blake")
  36
  37 static char const *default_template = "tmp.XXXXXXXXXX";
  38
  39 /* For long options that have no equivalent short option, use a
  40    non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
  41 enum
  42 {
  43   SUFFIX_OPTION = CHAR_MAX + 1,
  44 };
  45
  46 static struct option const longopts[] =
  47 {
  48   {"directory", no_argument, nullptr, 'd'},
  49   {"quiet", no_argument, nullptr, 'q'},
  50   {"dry-run", no_argument, nullptr, 'u'},
  51   {"suffix", required_argument, nullptr, SUFFIX_OPTION},
  52   {"tmpdir", optional_argument, nullptr, 'p'},
  53   {GETOPT_HELP_OPTION_DECL},
  54   {GETOPT_VERSION_OPTION_DECL},
  55   {nullptr, 0, nullptr, 0}
  56 };
  57
  58 void
  59 usage (int status)
  60 {
  61   if (status != EXIT_SUCCESS)
  62     emit_try_help ();
  63   else
  64     {
  65       printf (_("Usage: %s [OPTION]... [TEMPLATE]\n"), program_name);
  66       fputs (_("\
  67 Create a temporary file or directory, safely, and print its name.\n\
  68 TEMPLATE must contain at least 3 consecutive 'X's in last component.\n\
  69 If TEMPLATE is not specified, use tmp.XXXXXXXXXX, and --tmpdir is implied.\n\
  70 "), stdout);
  71       fputs (_("\
  72 Files are created u+rw, and directories u+rwx, minus umask restrictions.\n\
  73 "), stdout);
  74       fputs ("\n", stdout);
  75       fputs (_("\
  76   -d, --directory     create a directory, not a file\n\
  77   -u, --dry-run       do not create anything; merely print a name (unsafe)\n\
  78   -q, --quiet         suppress diagnostics about file/dir-creation failure\n\
  79 "), stdout);
  80       fputs (_("\
  81       --suffix=SUFF   append SUFF to TEMPLATE; SUFF must not contain a slash.\n\
  82                         This option is implied if TEMPLATE does not end in X\n\
  83 "), stdout);
  84       fputs (_("\
  85   -p DIR, --tmpdir[=DIR]  interpret TEMPLATE relative to DIR; if DIR is not\n\
  86                         specified, use $TMPDIR if set, else /tmp.  With\n\
  87                         this option, TEMPLATE must not be an absolute name;\n\
  88                         unlike with -t, TEMPLATE may contain slashes, but\n\
  89                         mktemp creates only the final component\n\
  90 "), stdout);
  91       fputs (_("\
  92   -t                  interpret TEMPLATE as a single file name component,\n\
  93                         relative to a directory: $TMPDIR, if set; else the\n\
  94                         directory specified via -p; else /tmp [deprecated]\n\
  95 "), stdout);
  96       fputs (HELP_OPTION_DESCRIPTION, stdout);
  97       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  98       emit_ancillary_info (PROGRAM_NAME);
  99     }
 100
 101   exit (status);
 102 }
 103
 104 static size_t
 105 count_consecutive_X_s (char const *s, size_t len)
 106 {
 107   size_t n = 0;
 108   for ( ; len && s[len - 1] == 'X'; len--)
 109     ++n;
 110   return n;
 111 }
 112
 113 static int
 114 mkstemp_len (char *tmpl, size_t suff_len, size_t x_len, bool dry_run)
 115 {
 116   return gen_tempname_len (tmpl, suff_len, 0, dry_run ? GT_NOCREATE : GT_FILE,
 117                            x_len);
 118 }
 119
 120 static int
 121 mkdtemp_len (char *tmpl, size_t suff_len, size_t x_len, bool dry_run)
 122 {
 123   return gen_tempname_len (tmpl, suff_len, 0, dry_run ? GT_NOCREATE : GT_DIR,
 124                            x_len);
 125 }
 126
 127 /* True if we have already closed standard output.  */
 128 static bool stdout_closed;
 129
 130 /* Avoid closing stdout twice.  Since we conditionally call
 131    close_stream (stdout) in order to decide whether to clean up a
 132    temporary file, the exit hook needs to know whether to do all of
 133    close_stdout or just the stderr half.  */
 134 static void
 135 maybe_close_stdout (void)
 136 {
 137   if (!stdout_closed)
 138     close_stdout ();
 139   else if (close_stream (stderr) != 0)
 140     _exit (EXIT_FAILURE);
 141 }
 142
 143 int
 144 main (int argc, char **argv)
 145 {
 146   char const *dest_dir;
 147   char const *dest_dir_arg = nullptr;
 148   bool suppress_file_err = false;
 149   int c;
 150   unsigned int n_args;
 151   char *template;
 152   char *suffix = nullptr;
 153   bool use_dest_dir = false;
 154   bool deprecated_t_option = false;
 155   bool create_directory = false;
 156   bool dry_run = false;
 157   int status = EXIT_SUCCESS;
 158   size_t x_count;
 159   size_t suffix_len;
 160   char *dest_name;
 161
 162   initialize_main (&argc, &argv);
 163   set_program_name (argv[0]);
 164   setlocale (LC_ALL, "");
 165   bindtextdomain (PACKAGE, LOCALEDIR);
 166   textdomain (PACKAGE);
 167
 168   atexit (maybe_close_stdout);
 169
 170   while ((c = getopt_long (argc, argv, "dp:qtuV", longopts, nullptr)) != -1)
 171     {
 172       switch (c)
 173         {
 174         case 'd':
 175           create_directory = true;
 176           break;
 177         case 'p':
 178           dest_dir_arg = optarg;
 179           use_dest_dir = true;
 180           break;
 181         case 'q':
 182           suppress_file_err = true;
 183           break;
 184         case 't':
 185           use_dest_dir = true;
 186           deprecated_t_option = true;
 187           break;
 188         case 'u':
 189           dry_run = true;
 190           break;
 191
 192         case SUFFIX_OPTION:
 193           suffix = optarg;
 194           break;
 195
 196         case_GETOPT_HELP_CHAR;
 197
 198         case 'V': /* Undocumented alias, for compatibility with the original
 199                      mktemp program.  */
 200         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 201         default:
 202           usage (EXIT_FAILURE);
 203         }
 204     }
 205
 206   n_args = argc - optind;
 207   if (2 <= n_args)
 208     {
 209       error (0, 0, _("too many templates"));
 210       usage (EXIT_FAILURE);
 211     }
 212
 213   if (n_args == 0)
 214     {
 215       use_dest_dir = true;
 216       template = (char *) default_template;
 217     }
 218   else
 219     {
 220       template = argv[optind];
 221     }
 222
 223   if (suffix)
 224     {
 225       size_t len = strlen (template);
 226       if (!len || template[len - 1] != 'X')
 227         {
 228           error (EXIT_FAILURE, 0,
 229                  _("with --suffix, template %s must end in X"),
 230                  quote (template));
 231         }
 232       suffix_len = strlen (suffix);
 233       dest_name = xcharalloc (len + suffix_len + 1);
 234       memcpy (dest_name, template, len);
 235       memcpy (dest_name + len, suffix, suffix_len + 1);
 236       template = dest_name;
 237       suffix = dest_name + len;
 238     }
 239   else
 240     {
 241       template = xstrdup (template);
 242       suffix = strrchr (template, 'X');
 243       if (!suffix)
 244         suffix = strchr (template, '\0');
 245       else
 246         suffix++;
 247       suffix_len = strlen (suffix);
 248     }
 249
 250   /* At this point, template is malloc'd, and suffix points into template.  */
 251   if (suffix_len && last_component (suffix) != suffix)
 252     {
 253       error (EXIT_FAILURE, 0,
 254              _("invalid suffix %s, contains directory separator"),
 255              quote (suffix));
 256     }
 257   x_count = count_consecutive_X_s (template, suffix - template);
 258   if (x_count < 3)
 259     error (EXIT_FAILURE, 0, _("too few X's in template %s"), quote (template));
 260
 261   if (use_dest_dir)
 262     {
 263       if (deprecated_t_option)
 264         {
 265           char *env = getenv ("TMPDIR");
 266           if (env && *env)
 267             dest_dir = env;
 268           else if (dest_dir_arg && *dest_dir_arg)
 269             dest_dir = dest_dir_arg;
 270           else
 271             dest_dir = "/tmp";
 272
 273           if (last_component (template) != template)
 274             error (EXIT_FAILURE, 0,
 275                    _("invalid template, %s, contains directory separator"),
 276                    quote (template));
 277         }
 278       else
 279         {
 280           if (dest_dir_arg && *dest_dir_arg)
 281             dest_dir = dest_dir_arg;
 282           else
 283             {
 284               char *env = getenv ("TMPDIR");
 285               dest_dir = (env && *env ? env : "/tmp");
 286             }
 287           if (IS_ABSOLUTE_FILE_NAME (template))
 288             error (EXIT_FAILURE, 0,
 289                    _("invalid template, %s; with --tmpdir,"
 290                      " it may not be absolute"),
 291                    quote (template));
 292         }
 293
 294       dest_name = file_name_concat (dest_dir, template, nullptr);
 295       free (template);
 296       template = dest_name;
 297       /* Note that suffix is now invalid.  */
 298     }
 299
 300   /* Make a copy to be used in case of diagnostic, since failing
 301      mkstemp may leave the buffer in an undefined state.  */
 302   dest_name = xstrdup (template);
 303
 304   if (create_directory)
 305     {
 306       int err = mkdtemp_len (dest_name, suffix_len, x_count, dry_run);
 307       if (err != 0)
 308         {
 309           if (!suppress_file_err)
 310             error (0, errno, _("failed to create directory via template %s"),
 311                    quote (template));
 312           status = EXIT_FAILURE;
 313         }
 314     }
 315   else
 316     {
 317       int fd = mkstemp_len (dest_name, suffix_len, x_count, dry_run);
 318       if (fd < 0 || (!dry_run && close (fd) != 0))
 319         {
 320           if (!suppress_file_err)
 321             error (0, errno, _("failed to create file via template %s"),
 322                    quote (template));
 323           status = EXIT_FAILURE;
 324         }
 325     }
 326
 327   if (status == EXIT_SUCCESS)
 328     {
 329       puts (dest_name);
 330       /* If we created a file, but then failed to output the file
 331          name, we should clean up the mess before failing.  */
 332       if (!dry_run && ((stdout_closed = true), close_stream (stdout) != 0))
 333         {
 334           int saved_errno = errno;
 335           remove (dest_name);
 336           if (!suppress_file_err)
 337             error (0, saved_errno, _("write error"));
 338           status = EXIT_FAILURE;
 339         }
 340     }
 341
 342   main_exit (status);
 343 }