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 "die.h"
  27 #include "error.h"
  28 #include "fadvise.h"
  29 #include "iopoll.h"
  30 #include "stdio--.h"
  31 #include "xbinary-io.h"
  32 #include "iopoll.h"
  33
  34 /* The official name of this program (e.g., no 'g' prefix).  */
  35 #define PROGRAM_NAME "tee"
  36
  37 #define AUTHORS \
  38   proper_name ("Mike Parker"), \
  39   proper_name ("Richard M. Stallman"), \
  40   proper_name ("David MacKenzie")
  41
  42 static bool tee_files (int nfiles, char **files, bool);
  43
  44 /* If true, append to output files rather than truncating them. */
  45 static bool append;
  46
  47 /* If true, ignore interrupts. */
  48 static bool ignore_interrupts;
  49
  50 enum output_error
  51   {
  52     output_error_sigpipe,      /* traditional behavior, sigpipe enabled.  */
  53     output_error_warn,         /* warn on EPIPE, but continue.  */
  54     output_error_warn_nopipe,  /* ignore EPIPE, continue.  */
  55     output_error_exit,         /* exit on any output error.  */
  56     output_error_exit_nopipe   /* exit on any output error except EPIPE.  */
  57   };
  58
  59 static enum output_error output_error;
  60
  61 static struct option const long_options[] =
  62 {
  63   {"append", no_argument, nullptr, 'a'},
  64   {"ignore-interrupts", no_argument, nullptr, 'i'},
  65   {"output-error", optional_argument, nullptr, 'p'},
  66   {GETOPT_HELP_OPTION_DECL},
  67   {GETOPT_VERSION_OPTION_DECL},
  68   {nullptr, 0, nullptr, 0}
  69 };
  70
  71 static char const *const output_error_args[] =
  72 {
  73   "warn", "warn-nopipe", "exit", "exit-nopipe", nullptr
  74 };
  75 static enum output_error const output_error_types[] =
  76 {
  77   output_error_warn, output_error_warn_nopipe,
  78   output_error_exit, output_error_exit_nopipe
  79 };
  80 ARGMATCH_VERIFY (output_error_args, output_error_types);
  81
  82 void
  83 usage (int status)
  84 {
  85   if (status != EXIT_SUCCESS)
  86     emit_try_help ();
  87   else
  88     {
  89       printf (_("Usage: %s [OPTION]... [FILE]...\n"), program_name);
  90       fputs (_("\
  91 Copy standard input to each FILE, and also to standard output.\n\
  92 \n\
  93   -a, --append              append to the given FILEs, do not overwrite\n\
  94   -i, --ignore-interrupts   ignore interrupt signals\n\
  95 "), stdout);
  96       fputs (_("\
  97   -p                        operate in a more appropriate MODE with pipes.\n\
  98       --output-error[=MODE]   set behavior on write error.  See MODE below\n\
  99 "), stdout);
 100       fputs (HELP_OPTION_DESCRIPTION, stdout);
 101       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 102       fputs (_("\
 103 \n\
 104 MODE determines behavior with write errors on the outputs:\n\
 105   warn           diagnose errors writing to any output\n\
 106   warn-nopipe    diagnose errors writing to any output not a pipe\n\
 107   exit           exit on error writing to any output\n\
 108   exit-nopipe    exit on error writing to any output not a pipe\n\
 109 The default MODE for the -p option is 'warn-nopipe'.\n\
 110 With \"nopipe\" MODEs, exit immediately if all outputs become broken pipes.\n\
 111 The default operation when --output-error is not specified, is to\n\
 112 exit immediately on error writing to a pipe, and diagnose errors\n\
 113 writing to non pipe outputs.\n\
 114 "), stdout);
 115       emit_ancillary_info (PROGRAM_NAME);
 116     }
 117   exit (status);
 118 }
 119
 120 int
 121 main (int argc, char **argv)
 122 {
 123   initialize_main (&argc, &argv);
 124   set_program_name (argv[0]);
 125   setlocale (LC_ALL, "");
 126   bindtextdomain (PACKAGE, LOCALEDIR);
 127   textdomain (PACKAGE);
 128
 129   atexit (close_stdout);
 130
 131   append = false;
 132   ignore_interrupts = false;
 133
 134   int optc;
 135   while ((optc = getopt_long (argc, argv, "aip", long_options, nullptr)) != -1)
 136     {
 137       switch (optc)
 138         {
 139         case 'a':
 140           append = true;
 141           break;
 142
 143         case 'i':
 144           ignore_interrupts = true;
 145           break;
 146
 147         case 'p':
 148           if (optarg)
 149             output_error = XARGMATCH ("--output-error", optarg,
 150                                       output_error_args, output_error_types);
 151           else
 152             output_error = output_error_warn_nopipe;
 153           break;
 154
 155         case_GETOPT_HELP_CHAR;
 156
 157         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 158
 159         default:
 160           usage (EXIT_FAILURE);
 161         }
 162     }
 163
 164   if (ignore_interrupts)
 165     signal (SIGINT, SIG_IGN);
 166
 167   if (output_error != output_error_sigpipe)
 168     signal (SIGPIPE, SIG_IGN);
 169
 170   /* Whether to detect and close a broken pipe output.
 171      There is no need if the input is always ready for reading.  */
 172   bool pipe_check = ((output_error == output_error_warn_nopipe
 173                       || output_error == output_error_exit_nopipe)
 174                      && iopoll_input_ok (STDIN_FILENO));
 175
 176   /* Do *not* warn if tee is given no file arguments.
 177      POSIX requires that it work when given no arguments.  */
 178
 179   bool ok = tee_files (argc - optind, &argv[optind], pipe_check);
 180   if (close (STDIN_FILENO) != 0)
 181     die (EXIT_FAILURE, errno, "%s", _("standard input"));
 182
 183   return ok ? EXIT_SUCCESS : EXIT_FAILURE;
 184 }
 185
 186
 187 /* Return the index of the first non-null descriptor after idx,
 188    or -1 if all are null.  */
 189
 190 static int
 191 get_next_out (FILE **descriptors, int nfiles, int idx)
 192 {
 193   for (idx++; idx <= nfiles; idx++)
 194     if (descriptors[idx])
 195       return idx;
 196   return -1;  /* no outputs remaining */
 197 }
 198
 199 /* Remove descriptors[i] due to write failure or broken pipe.
 200    Return true if this indicates a reportable error.  */
 201
 202 static bool
 203 fail_output (FILE **descriptors, char **files, int i)
 204 {
 205   int w_errno = errno;
 206   bool fail = errno != EPIPE
 207               || output_error == output_error_exit
 208               || output_error == output_error_warn;
 209   if (descriptors[i] == stdout)
 210     clearerr (stdout); /* Avoid redundant close_stdout diagnostic.  */
 211   if (fail)
 212     {
 213       error (output_error == output_error_exit
 214              || output_error == output_error_exit_nopipe,
 215              w_errno, "%s", quotef (files[i]));
 216     }
 217   descriptors[i] = nullptr;
 218   return fail;
 219 }
 220
 221
 222 /* Copy the standard input into each of the NFILES files in FILES
 223    and into the standard output.  As a side effect, modify FILES[-1].
 224    Return true if successful.  */
 225
 226 static bool
 227 tee_files (int nfiles, char **files, bool pipe_check)
 228 {
 229   size_t n_outputs = 0;
 230   FILE **descriptors;
 231   bool *out_pollable IF_LINT ( = nullptr);
 232   char buffer[BUFSIZ];
 233   ssize_t bytes_read = 0;
 234   int i;
 235   int first_out = 0;  /* idx of first non-null output in descriptors */
 236   bool ok = true;
 237   char const *mode_string =
 238     (O_BINARY
 239      ? (append ? "ab" : "wb")
 240      : (append ? "a" : "w"));
 241
 242   xset_binary_mode (STDIN_FILENO, O_BINARY);
 243   xset_binary_mode (STDOUT_FILENO, O_BINARY);
 244   fadvise (stdin, FADVISE_SEQUENTIAL);
 245
 246   /* Set up FILES[0 .. NFILES] and DESCRIPTORS[0 .. NFILES].
 247      In both arrays, entry 0 corresponds to standard output.  */
 248
 249   descriptors = xnmalloc (nfiles + 1, sizeof *descriptors);
 250   if (pipe_check)
 251     out_pollable = xnmalloc (nfiles + 1, sizeof *out_pollable);
 252   files--;
 253   descriptors[0] = stdout;
 254   if (pipe_check)
 255     out_pollable[0] = iopoll_output_ok (fileno (descriptors[0]));
 256   files[0] = bad_cast (_("standard output"));
 257   setvbuf (stdout, nullptr, _IONBF, 0);
 258   n_outputs++;
 259
 260   for (i = 1; i <= nfiles; i++)
 261     {
 262       /* Do not treat "-" specially - as mandated by POSIX.  */
 263        descriptors[i] = fopen (files[i], mode_string);
 264       if (descriptors[i] == nullptr)
 265         {
 266           if (pipe_check)
 267             out_pollable[i] = false;
 268           error (output_error == output_error_exit
 269                  || output_error == output_error_exit_nopipe,
 270                  errno, "%s", quotef (files[i]));
 271           ok = false;
 272         }
 273       else
 274         {
 275           if (pipe_check)
 276             out_pollable[i] = iopoll_output_ok (fileno (descriptors[i]));
 277           setvbuf (descriptors[i], nullptr, _IONBF, 0);
 278           n_outputs++;
 279         }
 280     }
 281
 282   while (n_outputs)
 283     {
 284       if (pipe_check && out_pollable[first_out])
 285         {
 286           /* Monitor for input, or errors on first valid output.  */
 287           int err = iopoll (STDIN_FILENO, fileno (descriptors[first_out]),
 288                             true);
 289
 290           /* Close the output if it became a broken pipe.  */
 291           if (err == IOPOLL_BROKEN_OUTPUT)
 292             {
 293               errno = EPIPE;  /* behave like write produced EPIPE */
 294               if (fail_output (descriptors, files, first_out))
 295                 ok = false;
 296               n_outputs--;
 297               first_out = get_next_out (descriptors, nfiles, first_out);
 298               continue;
 299             }
 300           else if (err == IOPOLL_ERROR)
 301             {
 302               error (0, errno, _("iopoll error"));
 303               ok = false;
 304             }
 305         }
 306
 307       bytes_read = read (STDIN_FILENO, buffer, sizeof buffer);
 308       if (bytes_read < 0 && errno == EINTR)
 309         continue;
 310       if (bytes_read <= 0)
 311         break;
 312
 313       /* Write to all NFILES + 1 descriptors.
 314          Standard output is the first one.  */
 315       for (i = 0; i <= nfiles; i++)
 316         if (descriptors[i]
 317             && ! fwrite_wait (buffer, bytes_read, descriptors[i]))
 318           {
 319             if (fail_output (descriptors, files, i))
 320               ok = false;
 321             n_outputs--;
 322             if (i == first_out)
 323               first_out = get_next_out (descriptors, nfiles, first_out);
 324           }
 325     }
 326
 327   if (bytes_read == -1)
 328     {
 329       error (0, errno, _("read error"));
 330       ok = false;
 331     }
 332
 333   /* Close the files, but not standard output.  */
 334   for (i = 1; i <= nfiles; i++)
 335     if (descriptors[i] && ! fclose_wait (descriptors[i]))
 336       {
 337         error (0, errno, "%s", quotef (files[i]));
 338         ok = false;
 339       }
 340
 341   free (descriptors);
 342   if (pipe_check)
 343     free (out_pollable);
 344
 345   return ok;
 346 }