1  /* yes - output a string repeatedly until killed
       2     Copyright (C) 1991-2023 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  /* David MacKenzie <djm@gnu.ai.mit.edu> */
      18  
      19  #include <config.h>
      20  #include <stdio.h>
      21  #include <sys/types.h>
      22  
      23  #include "system.h"
      24  
      25  #include "full-write.h"
      26  #include "long-options.h"
      27  
      28  /* The official name of this program (e.g., no 'g' prefix).  */
      29  #define PROGRAM_NAME "yes"
      30  
      31  #define AUTHORS proper_name ("David MacKenzie")
      32  
      33  void
      34  usage (int status)
      35  {
      36    if (status != EXIT_SUCCESS)
      37      emit_try_help ();
      38    else
      39      {
      40        printf (_("\
      41  Usage: %s [STRING]...\n\
      42    or:  %s OPTION\n\
      43  "),
      44                program_name, program_name);
      45  
      46        fputs (_("\
      47  Repeatedly output a line with all specified STRING(s), or 'y'.\n\
      48  \n\
      49  "), stdout);
      50        fputs (HELP_OPTION_DESCRIPTION, stdout);
      51        fputs (VERSION_OPTION_DESCRIPTION, stdout);
      52        emit_ancillary_info (PROGRAM_NAME);
      53      }
      54    exit (status);
      55  }
      56  
      57  int
      58  main (int argc, char **argv)
      59  {
      60    initialize_main (&argc, &argv);
      61    set_program_name (argv[0]);
      62    setlocale (LC_ALL, "");
      63    bindtextdomain (PACKAGE, LOCALEDIR);
      64    textdomain (PACKAGE);
      65  
      66    atexit (close_stdout);
      67  
      68    parse_gnu_standard_options_only (argc, argv, PROGRAM_NAME, PACKAGE_NAME,
      69                                     Version, true, usage, AUTHORS,
      70                                     (char const *) nullptr);
      71  
      72    char **operands = argv + optind;
      73    char **operand_lim = argv + argc;
      74    if (optind == argc)
      75      *operand_lim++ = bad_cast ("y");
      76  
      77    /* Buffer data locally once, rather than having the
      78       large overhead of stdio buffering each item.  */
      79    size_t bufalloc = 0;
      80    bool reuse_operand_strings = true;
      81    char **operandp = operands;
      82    do
      83      {
      84        size_t operand_len = strlen (*operandp);
      85        bufalloc += operand_len + 1;
      86        if (operandp + 1 < operand_lim
      87            && *operandp + operand_len + 1 != operandp[1])
      88          reuse_operand_strings = false;
      89      }
      90    while (++operandp < operand_lim);
      91  
      92    /* Improve performance by using a buffer size greater than BUFSIZ / 2.  */
      93    if (bufalloc <= BUFSIZ / 2)
      94      {
      95        bufalloc = BUFSIZ;
      96        reuse_operand_strings = false;
      97      }
      98  
      99    /* Fill the buffer with one copy of the output.  If possible, reuse
     100       the operands strings; this wins when the buffer would be large.  */
     101    char *buf = reuse_operand_strings ? *operands : xmalloc (bufalloc);
     102    size_t bufused = 0;
     103    operandp = operands;
     104    do
     105      {
     106        size_t operand_len = strlen (*operandp);
     107        if (! reuse_operand_strings)
     108          memcpy (buf + bufused, *operandp, operand_len);
     109        bufused += operand_len;
     110        buf[bufused++] = ' ';
     111      }
     112    while (++operandp < operand_lim);
     113    buf[bufused - 1] = '\n';
     114  
     115    /* If a larger buffer was allocated, fill it by repeating the buffer
     116       contents.  */
     117    size_t copysize = bufused;
     118    for (size_t copies = bufalloc / copysize; --copies; )
     119      {
     120        memcpy (buf + bufused, buf, copysize);
     121        bufused += copysize;
     122      }
     123  
     124    /* Repeatedly output the buffer until there is a write error; then fail.  */
     125    while (full_write (STDOUT_FILENO, buf, bufused) == bufused)
     126      continue;
     127    error (0, errno, _("standard output"));
     128    main_exit (EXIT_FAILURE);
     129  }