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
usage(int status)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
main(int argc,char ** argv)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 }
130