1 files changed, 129 insertions, 0 deletions
diff --git a/src/yes.c b/src/yes.c
new file mode 100644
index 0000000..207b407
--- /dev/null
+++ b/src/yes.c
@@ -0,0 +1,129 @@
+/* yes - output a string repeatedly until killed
+   Copyright (C) 1991-2023 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* David MacKenzie <djm@gnu.ai.mit.edu> */
+
+#include <config.h>
+#include <stdio.h>
+#include <sys/types.h>
+
+#include "system.h"
+
+#include "full-write.h"
+#include "long-options.h"
+
+/* The official name of this program (e.g., no 'g' prefix).  */
+#define PROGRAM_NAME "yes"
+
+#define AUTHORS proper_name ("David MacKenzie")
+
+void
+usage (int status)
+{
+  if (status != EXIT_SUCCESS)
+    emit_try_help ();
+  else
+    {
+      printf (_("\
+Usage: %s [STRING]...\n\
+  or:  %s OPTION\n\
+"),
+              program_name, program_name);
+
+      fputs (_("\
+Repeatedly output a line with all specified STRING(s), or 'y'.\n\
+\n\
+"), stdout);
+      fputs (HELP_OPTION_DESCRIPTION, stdout);
+      fputs (VERSION_OPTION_DESCRIPTION, stdout);
+      emit_ancillary_info (PROGRAM_NAME);
+    }
+  exit (status);
+}
+
+int
+main (int argc, char **argv)
+{
+  initialize_main (&argc, &argv);
+  set_program_name (argv[0]);
+  setlocale (LC_ALL, "");
+  bindtextdomain (PACKAGE, LOCALEDIR);
+  textdomain (PACKAGE);
+
+  atexit (close_stdout);
+
+  parse_gnu_standard_options_only (argc, argv, PROGRAM_NAME, PACKAGE_NAME,
+                                   Version, true, usage, AUTHORS,
+                                   (char const *) nullptr);
+
+  char **operands = argv + optind;
+  char **operand_lim = argv + argc;
+  if (optind == argc)
+    *operand_lim++ = bad_cast ("y");
+
+  /* Buffer data locally once, rather than having the
+     large overhead of stdio buffering each item.  */
+  size_t bufalloc = 0;
+  bool reuse_operand_strings = true;
+  char **operandp = operands;
+  do
+    {
+      size_t operand_len = strlen (*operandp);
+      bufalloc += operand_len + 1;
+      if (operandp + 1 < operand_lim
+          && *operandp + operand_len + 1 != operandp[1])
+        reuse_operand_strings = false;
+    }
+  while (++operandp < operand_lim);
+
+  /* Improve performance by using a buffer size greater than BUFSIZ / 2.  */
+  if (bufalloc <= BUFSIZ / 2)
+    {
+      bufalloc = BUFSIZ;
+      reuse_operand_strings = false;
+    }
+
+  /* Fill the buffer with one copy of the output.  If possible, reuse
+     the operands strings; this wins when the buffer would be large.  */
+  char *buf = reuse_operand_strings ? *operands : xmalloc (bufalloc);
+  size_t bufused = 0;
+  operandp = operands;
+  do
+    {
+      size_t operand_len = strlen (*operandp);
+      if (! reuse_operand_strings)
+        memcpy (buf + bufused, *operandp, operand_len);
+      bufused += operand_len;
+      buf[bufused++] = ' ';
+    }
+  while (++operandp < operand_lim);
+  buf[bufused - 1] = '\n';
+
+  /* If a larger buffer was allocated, fill it by repeating the buffer
+     contents.  */
+  size_t copysize = bufused;
+  for (size_t copies = bufalloc / copysize; --copies; )
+    {
+      memcpy (buf + bufused, buf, copysize);
+      bufused += copysize;
+    }
+
+  /* Repeatedly output the buffer until there is a write error; then fail.  */
+  while (full_write (STDOUT_FILENO, buf, bufused) == bufused)
+    continue;
+  error (0, errno, _("standard output"));
+  main_exit (EXIT_FAILURE);
+}