+/*
+
+@deftypefn Extension int writeargv (char * const *@var{argv}, FILE *@var{file})
+
+Write each member of ARGV, handling all necessary quoting, to the file
+named by FILE, separated by whitespace. Return 0 on success, non-zero
+if an error occurred while writing to FILE.
+
+@end deftypefn
+
+*/
+
+int
+writeargv (char * const *argv, FILE *f)
+{
+ int status = 0;
+
+ if (f == NULL)
+ return 1;
+
+ while (*argv != NULL)
+ {
+ const char *arg = *argv;
+
+ while (*arg != EOS)
+ {
+ char c = *arg;
+
+ if (ISSPACE(c) || c == '\\' || c == '\'' || c == '"')
+ if (EOF == fputc ('\\', f))
+ {
+ status = 1;
+ goto done;
+ }
+
+ if (EOF == fputc (c, f))
+ {
+ status = 1;
+ goto done;
+ }
+ arg++;
+ }
+
+ /* Write out a pair of quotes for an empty argument. */
+ if (arg == *argv)
+ if (EOF == fputs ("\"\"", f))
+ {
+ status = 1;
+ goto done;
+ }
+
+ if (EOF == fputc ('\n', f))
+ {
+ status = 1;
+ goto done;
+ }
+ argv++;
+ }
+
+ done:
+ return status;
+}
+
+/*
+
+@deftypefn Extension void expandargv (int *@var{argcp}, char ***@var{argvp})
+
+The @var{argcp} and @code{argvp} arguments are pointers to the usual
+@code{argc} and @code{argv} arguments to @code{main}. This function
+looks for arguments that begin with the character @samp{@@}. Any such
+arguments are interpreted as ``response files''. The contents of the
+response file are interpreted as additional command line options. In
+particular, the file is separated into whitespace-separated strings;
+each such string is taken as a command-line option. The new options
+are inserted in place of the option naming the response file, and
+@code{*argcp} and @code{*argvp} will be updated. If the value of
+@code{*argvp} is modified by this function, then the new value has
+been dynamically allocated and can be deallocated by the caller with
+@code{freeargv}. However, most callers will simply call
+@code{expandargv} near the beginning of @code{main} and allow the
+operating system to free the memory when the program exits.
+
+@end deftypefn
+
+*/
+
+void
+expandargv (int *argcp, char ***argvp)
+{
+ /* The argument we are currently processing. */
+ int i = 0;
+ /* To check if ***argvp has been dynamically allocated. */
+ char ** const original_argv = *argvp;
+ /* Limit the number of response files that we parse in order
+ to prevent infinite recursion. */
+ unsigned int iteration_limit = 2000;
+ /* Loop over the arguments, handling response files. We always skip
+ ARGVP[0], as that is the name of the program being run. */
+ while (++i < *argcp)
+ {
+ /* The name of the response file. */
+ const char *filename;
+ /* The response file. */
+ FILE *f;
+ /* An upper bound on the number of characters in the response
+ file. */
+ long pos;
+ /* The number of characters in the response file, when actually
+ read. */
+ size_t len;
+ /* A dynamically allocated buffer used to hold options read from a
+ response file. */
+ char *buffer;
+ /* Dynamically allocated storage for the options read from the
+ response file. */
+ char **file_argv;
+ /* The number of options read from the response file, if any. */
+ size_t file_argc;
+#ifdef S_ISDIR
+ struct stat sb;
+#endif
+ /* We are only interested in options of the form "@file". */
+ filename = (*argvp)[i];
+ if (filename[0] != '@')
+ continue;
+ /* If we have iterated too many times then stop. */
+ if (-- iteration_limit == 0)
+ {
+ fprintf (stderr, "%s: error: too many @-files encountered\n", (*argvp)[0]);
+ xexit (1);
+ }
+#ifdef S_ISDIR
+ if (stat (filename+1, &sb) < 0)
+ continue;
+ if (S_ISDIR(sb.st_mode))
+ {
+ fprintf (stderr, "%s: error: @-file refers to a directory\n", (*argvp)[0]);
+ xexit (1);
+ }
+#endif
+ /* Read the contents of the file. */
+ f = fopen (++filename, "r");
+ if (!f)
+ continue;
+ if (fseek (f, 0L, SEEK_END) == -1)
+ goto error;
+ pos = ftell (f);
+ if (pos == -1)
+ goto error;
+ if (fseek (f, 0L, SEEK_SET) == -1)
+ goto error;
+ buffer = (char *) xmalloc (pos * sizeof (char) + 1);
+ len = fread (buffer, sizeof (char), pos, f);
+ if (len != (size_t) pos
+ /* On Windows, fread may return a value smaller than POS,
+ due to CR/LF->CR translation when reading text files.
+ That does not in-and-of itself indicate failure. */
+ && ferror (f))
+ goto error;
+ /* Add a NUL terminator. */
+ buffer[len] = '\0';
+ /* If the file is empty or contains only whitespace, buildargv would
+ return a single empty argument. In this context we want no arguments,
+ instead. */
+ if (only_whitespace (buffer))
+ {
+ file_argv = (char **) xmalloc (sizeof (char *));
+ file_argv[0] = NULL;
+ }
+ else
+ /* Parse the string. */
+ file_argv = buildargv (buffer);
+ /* If *ARGVP is not already dynamically allocated, copy it. */
+ if (*argvp == original_argv)
+ *argvp = dupargv (*argvp);
+ /* Count the number of arguments. */
+ file_argc = 0;
+ while (file_argv[file_argc])
+ ++file_argc;
+ /* Free the original option's memory. */
+ free ((*argvp)[i]);
+ /* Now, insert FILE_ARGV into ARGV. The "+1" below handles the
+ NULL terminator at the end of ARGV. */
+ *argvp = ((char **)
+ xrealloc (*argvp,
+ (*argcp + file_argc + 1) * sizeof (char *)));
+ memmove (*argvp + i + file_argc, *argvp + i + 1,
+ (*argcp - i) * sizeof (char *));
+ memcpy (*argvp + i, file_argv, file_argc * sizeof (char *));
+ /* The original option has been replaced by all the new
+ options. */
+ *argcp += file_argc - 1;
+ /* Free up memory allocated to process the response file. We do
+ not use freeargv because the individual options in FILE_ARGV
+ are now in the main ARGV. */
+ free (file_argv);
+ free (buffer);
+ /* Rescan all of the arguments just read to support response
+ files that include other response files. */
+ --i;
+ error:
+ /* We're all done with the file now. */
+ fclose (f);
+ }
+}
+
+/*
+
+@deftypefn Extension int countargv (char * const *@var{argv})
+
+Return the number of elements in @var{argv}.
+Returns zero if @var{argv} is NULL.
+
+@end deftypefn
+
+*/
+
+int
+countargv (char * const *argv)
+{
+ int argc;
+
+ if (argv == NULL)
+ return 0;
+ for (argc = 0; argv[argc] != NULL; argc++)
+ continue;
+ return argc;
+}
+