src/tee.c

   1 /* tee - read from standard input and write to standard output and files.
   2    Copyright (C) 1985-2023 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 /* Mike Parker, Richard M. Stallman, and David MacKenzie */
  18
  19 #include <config.h>
  20 #include <sys/types.h>
  21 #include <signal.h>
  22 #include <getopt.h>
  23
  24 #include "system.h"
  25 #include "argmatch.h"
  26 #include "fadvise.h"
  27 #include "iopoll.h"
  28 #include "stdio--.h"
  29 #include "xbinary-io.h"
  30 #include "iopoll.h"
  31
  32 /* The official name of this program (e.g., no 'g' prefix).  */
  33 #define PROGRAM_NAME "tee"
  34
  35 #define AUTHORS \
  36   proper_name ("Mike Parker"), \
  37   proper_name ("Richard M. Stallman"), \
  38   proper_name ("David MacKenzie")
  39
  40 static bool tee_files (int nfiles, char **files, bool);
  41
  42 /* If true, append to output files rather than truncating them. */
  43 static bool append;
  44
  45 /* If true, ignore interrupts. */
  46 static bool ignore_interrupts;
  47
  48 enum output_error
  49   {
  50     output_error_sigpipe,      /* traditional behavior, sigpipe enabled.  */
  51     output_error_warn,         /* warn on EPIPE, but continue.  */
  52     output_error_warn_nopipe,  /* ignore EPIPE, continue.  */
  53     output_error_exit,         /* exit on any output error.  */
  54     output_error_exit_nopipe   /* exit on any output error except EPIPE.  */
  55   };
  56
  57 static enum output_error output_error;
  58
  59 static struct option const long_options[] =
  60 {
  61   {"append", no_argument, nullptr, 'a'},
  62   {"ignore-interrupts", no_argument, nullptr, 'i'},
  63   {"output-error", optional_argument, nullptr, 'p'},
  64   {GETOPT_HELP_OPTION_DECL},
  65   {GETOPT_VERSION_OPTION_DECL},
  66   {nullptr, 0, nullptr, 0}
  67 };
  68
  69 static char const *const output_error_args[] =
  70 {
  71   "warn", "warn-nopipe", "exit", "exit-nopipe", nullptr
  72 };
  73 static enum output_error const output_error_types[] =
  74 {
  75   output_error_warn, output_error_warn_nopipe,
  76   output_error_exit, output_error_exit_nopipe
  77 };
  78 ARGMATCH_VERIFY (output_error_args, output_error_types);
  79
  80 void
  81 usage (int status)
  82 {
  83   if (status != EXIT_SUCCESS)
  84     emit_try_help ();
  85   else
  86     {
  87       printf (_("Usage: %s [OPTION]... [FILE]...\n"), program_name);
  88       fputs (_("\
  89 Copy standard input to each FILE, and also to standard output.\n\
  90 \n\
  91   -a, --append              append to the given FILEs, do not overwrite\n\
  92   -i, --ignore-interrupts   ignore interrupt signals\n\
  93 "), stdout);
  94       fputs (_("\
  95   -p                        operate in a more appropriate MODE with pipes.\n\
  96       --output-error[=MODE]   set behavior on write error.  See MODE below\n\
  97 "), stdout);
  98       fputs (HELP_OPTION_DESCRIPTION, stdout);
  99       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 100       fputs (_("\
 101 \n\
 102 MODE determines behavior with write errors on the outputs:\n\
 103   warn           diagnose errors writing to any output\n\
 104   warn-nopipe    diagnose errors writing to any output not a pipe\n\
 105   exit           exit on error writing to any output\n\
 106   exit-nopipe    exit on error writing to any output not a pipe\n\
 107 The default MODE for the -p option is 'warn-nopipe'.\n\
 108 With \"nopipe\" MODEs, exit immediately if all outputs become broken pipes.\n\
 109 The default operation when --output-error is not specified, is to\n\
 110 exit immediately on error writing to a pipe, and diagnose errors\n\
 111 writing to non pipe outputs.\n\
 112 "), stdout);
 113       emit_ancillary_info (PROGRAM_NAME);
 114     }
 115   exit (status);
 116 }
 117
 118 int
 119 main (int argc, char **argv)
 120 {
 121   initialize_main (&argc, &argv);
 122   set_program_name (argv[0]);
 123   setlocale (LC_ALL, "");
 124   bindtextdomain (PACKAGE, LOCALEDIR);
 125   textdomain (PACKAGE);
 126
 127   atexit (close_stdout);
 128
 129   append = false;
 130   ignore_interrupts = false;
 131
 132   int optc;
 133   while ((optc = getopt_long (argc, argv, "aip", long_options, nullptr)) != -1)
 134     {
 135       switch (optc)
 136         {
 137         case 'a':
 138           append = true;
 139           break;
 140
 141         case 'i':
 142           ignore_interrupts = true;
 143           break;
 144
 145         case 'p':
 146           if (optarg)
 147             output_error = XARGMATCH ("--output-error", optarg,
 148                                       output_error_args, output_error_types);
 149           else
 150             output_error = output_error_warn_nopipe;
 151           break;
 152
 153         case_GETOPT_HELP_CHAR;
 154
 155         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 156
 157         default:
 158           usage (EXIT_FAILURE);
 159         }
 160     }
 161
 162   if (ignore_interrupts)
 163     signal (SIGINT, SIG_IGN);
 164
 165   if (output_error != output_error_sigpipe)
 166     signal (SIGPIPE, SIG_IGN);
 167
 168   /* Whether to detect and close a broken pipe output.
 169      There is no need if the input is always ready for reading.  */
 170   bool pipe_check = ((output_error == output_error_warn_nopipe
 171                       || output_error == output_error_exit_nopipe)
 172                      && iopoll_input_ok (STDIN_FILENO));
 173
 174   /* Do *not* warn if tee is given no file arguments.
 175      POSIX requires that it work when given no arguments.  */
 176
 177   bool ok = tee_files (argc - optind, &argv[optind], pipe_check);
 178   if (close (STDIN_FILENO) != 0)
 179     error (EXIT_FAILURE, errno, "%s", _("standard input"));
 180
 181   return ok ? EXIT_SUCCESS : EXIT_FAILURE;
 182 }
 183
 184
 185 /* Return the index of the first non-null descriptor after idx,
 186    or -1 if all are null.  */
 187
 188 static int
 189 get_next_out (FILE **descriptors, int nfiles, int idx)
 190 {
 191   for (idx++; idx <= nfiles; idx++)
 192     if (descriptors[idx])
 193       return idx;
 194   return -1;  /* no outputs remaining */
 195 }
 196
 197 /* Remove descriptors[i] due to write failure or broken pipe.
 198    Return true if this indicates a reportable error.  */
 199
 200 static bool
 201 fail_output (FILE **descriptors, char **files, int i)
 202 {
 203   int w_errno = errno;
 204   bool fail = errno != EPIPE
 205               || output_error == output_error_exit
 206               || output_error == output_error_warn;
 207   if (descriptors[i] == stdout)
 208     clearerr (stdout); /* Avoid redundant close_stdout diagnostic.  */
 209   if (fail)
 210     {
 211       error (output_error == output_error_exit
 212              || output_error == output_error_exit_nopipe,
 213              w_errno, "%s", quotef (files[i]));
 214     }
 215   descriptors[i] = nullptr;
 216   return fail;
 217 }
 218
 219
 220 /* Copy the standard input into each of the NFILES files in FILES
 221    and into the standard output.  As a side effect, modify FILES[-1].
 222    Return true if successful.  */
 223
 224 static bool
 225 tee_files (int nfiles, char **files, bool pipe_check)
 226 {
 227   size_t n_outputs = 0;
 228   FILE **descriptors;
 229   bool *out_pollable IF_LINT ( = nullptr);
 230   char buffer[BUFSIZ];
 231   ssize_t bytes_read = 0;
 232   int i;
 233   int first_out = 0;  /* idx of first non-null output in descriptors */
 234   bool ok = true;
 235   char const *mode_string =
 236     (O_BINARY
 237      ? (append ? "ab" : "wb")
 238      : (append ? "a" : "w"));
 239
 240   xset_binary_mode (STDIN_FILENO, O_BINARY);
 241   xset_binary_mode (STDOUT_FILENO, O_BINARY);
 242   fadvise (stdin, FADVISE_SEQUENTIAL);
 243
 244   /* Set up FILES[0 .. NFILES] and DESCRIPTORS[0 .. NFILES].
 245      In both arrays, entry 0 corresponds to standard output.  */
 246
 247   descriptors = xnmalloc (nfiles + 1, sizeof *descriptors);
 248   if (pipe_check)
 249     out_pollable = xnmalloc (nfiles + 1, sizeof *out_pollable);
 250   files--;
 251   descriptors[0] = stdout;
 252   if (pipe_check)
 253     out_pollable[0] = iopoll_output_ok (fileno (descriptors[0]));
 254   files[0] = bad_cast (_("standard output"));
 255   setvbuf (stdout, nullptr, _IONBF, 0);
 256   n_outputs++;
 257
 258   for (i = 1; i <= nfiles; i++)
 259     {
 260       /* Do not treat "-" specially - as mandated by POSIX.  */
 261        descriptors[i] = fopen (files[i], mode_string);
 262       if (descriptors[i] == nullptr)
 263         {
 264           if (pipe_check)
 265             out_pollable[i] = false;
 266           error (output_error == output_error_exit
 267                  || output_error == output_error_exit_nopipe,
 268                  errno, "%s", quotef (files[i]));
 269           ok = false;
 270         }
 271       else
 272         {
 273           if (pipe_check)
 274             out_pollable[i] = iopoll_output_ok (fileno (descriptors[i]));
 275           setvbuf (descriptors[i], nullptr, _IONBF, 0);
 276           n_outputs++;
 277         }
 278     }
 279
 280   while (n_outputs)
 281     {
 282       if (pipe_check && out_pollable[first_out])
 283         {
 284           /* Monitor for input, or errors on first valid output.  */
 285           int err = iopoll (STDIN_FILENO, fileno (descriptors[first_out]),
 286                             true);
 287
 288           /* Close the output if it became a broken pipe.  */
 289           if (err == IOPOLL_BROKEN_OUTPUT)
 290             {
 291               errno = EPIPE;  /* behave like write produced EPIPE */
 292               if (fail_output (descriptors, files, first_out))
 293                 ok = false;
 294               n_outputs--;
 295               first_out = get_next_out (descriptors, nfiles, first_out);
 296               continue;
 297             }
 298           else if (err == IOPOLL_ERROR)
 299             {
 300               error (0, errno, _("iopoll error"));
 301               ok = false;
 302             }
 303         }
 304
 305       bytes_read = read (STDIN_FILENO, buffer, sizeof buffer);
 306       if (bytes_read < 0 && errno == EINTR)
 307         continue;
 308       if (bytes_read <= 0)
 309         break;
 310
 311       /* Write to all NFILES + 1 descriptors.
 312          Standard output is the first one.  */
 313       for (i = 0; i <= nfiles; i++)
 314         if (descriptors[i]
 315             && ! fwrite_wait (buffer, bytes_read, descriptors[i]))
 316           {
 317             if (fail_output (descriptors, files, i))
 318               ok = false;
 319             n_outputs--;
 320             if (i == first_out)
 321               first_out = get_next_out (descriptors, nfiles, first_out);
 322           }
 323     }
 324
 325   if (bytes_read == -1)
 326     {
 327       error (0, errno, _("read error"));
 328       ok = false;
 329     }
 330
 331   /* Close the files, but not standard output.  */
 332   for (i = 1; i <= nfiles; i++)
 333     if (descriptors[i] && ! fclose_wait (descriptors[i]))
 334       {
 335         error (0, errno, "%s", quotef (files[i]));
 336         ok = false;
 337       }
 338
 339   free (descriptors);
 340   if (pipe_check)
 341     free (out_pollable);
 342
 343   return ok;
 344 }