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+/* expand - convert tabs to spaces
+ Copyright (C) 1989, 1991 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 2, 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, write to the Free Software
+ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+/* By default, convert all tabs to spaces.
+ Preserves backspace characters in the output; they decrement the
+ column count for tab calculations.
+ The default action is equivalent to -8.
+
+ Options:
+ --tabs=tab1[,tab2[,...]]
+ -t tab1[,tab2[,...]]
+ -tab1[,tab2[,...]] If only one tab stop is given, set the tabs tab1
+ spaces apart instead of the default 8. Otherwise,
+ set the tabs at columns tab1, tab2, etc. (numbered from
+ 0); replace any tabs beyond the tabstops given with
+ single spaces.
+ --initial
+ -i Only convert initial tabs on each line to spaces.
+
+ David MacKenzie <djm@ai.mit.edu> */
+
+#define _GNU_SOURCE
+#include <ctype.h>
+#ifndef isblank
+#define isblank(c) ((c) == ' ' || (c) == '\t')
+#endif
+#include <stdio.h>
+#include <getopt.h>
+#include <sys/types.h>
+#include "system.h"
+
+#ifdef isascii
+#define ISDIGIT(c) (isascii ((c)) && isdigit ((c)))
+#else
+#define ISDIGIT(c) (isdigit ((c)))
+#endif
+
+/* The number of bytes added at a time to the amount of memory
+ allocated for the output line. */
+#define OUTPUT_BLOCK 256
+
+/* The number of bytes added at a time to the amount of memory
+ allocated for the list of tabstops. */
+#define TABLIST_BLOCK 256
+
+char *xmalloc ();
+char *xrealloc ();
+void error ();
+
+FILE *next_file ();
+void add_tabstop ();
+void expand ();
+void parse_tabstops ();
+void usage ();
+void validate_tabstops ();
+
+/* If nonzero, convert blanks even after nonblank characters have been
+ read on the line. */
+int convert_entire_line;
+
+/* If nonzero, the size of all tab stops. If zero, use `tab_list' instead. */
+int tab_size;
+
+/* Array of the explicit column numbers of the tab stops;
+ after `tab_list' is exhausted, each additional tab is replaced
+ by a space. The first column is column 0. */
+int *tab_list;
+
+/* The index of the first invalid element of `tab_list',
+ where the next element can be added. */
+int first_free_tab;
+
+/* Null-terminated array of input filenames. */
+char **file_list;
+
+/* Default for `file_list' if no files are given on the command line. */
+char *stdin_argv[] =
+{
+ "-", NULL
+};
+
+/* Nonzero if we have ever read standard input. */
+int have_read_stdin;
+
+/* Status to return to the system. */
+int exit_status;
+
+/* The name this program was run with. */
+char *program_name;
+
+struct option longopts[] =
+{
+ {"tabs", 1, NULL, 't'},
+ {"initial", 0, NULL, 'i'},
+ {NULL, 0, NULL, 0}
+};
+
+void
+main (argc, argv)
+ int argc;
+ char **argv;
+{
+ int tabval = -1; /* Value of tabstop being read, or -1. */
+ int c; /* Option character. */
+
+ have_read_stdin = 0;
+ exit_status = 0;
+ convert_entire_line = 1;
+ tab_list = NULL;
+ first_free_tab = 0;
+ program_name = argv[0];
+
+ while ((c = getopt_long (argc, argv, "it:,0123456789", longopts, (int *) 0))
+ != EOF)
+ {
+ switch (c)
+ {
+ case '?':
+ usage ();
+ case 'i':
+ convert_entire_line = 0;
+ break;
+ case 't':
+ parse_tabstops (optarg);
+ break;
+ case ',':
+ add_tabstop (tabval);
+ tabval = -1;
+ break;
+ default:
+ if (tabval == -1)
+ tabval = 0;
+ tabval = tabval * 10 + c - '0';
+ break;
+ }
+ }
+
+ add_tabstop (tabval);
+
+ validate_tabstops (tab_list, first_free_tab);
+
+ if (first_free_tab == 0)
+ tab_size = 8;
+ else if (first_free_tab == 1)
+ tab_size = tab_list[0];
+ else
+ tab_size = 0;
+
+ if (optind == argc)
+ file_list = stdin_argv;
+ else
+ file_list = &argv[optind];
+
+ expand ();
+
+ if (have_read_stdin && fclose (stdin) == EOF)
+ error (1, errno, "-");
+ if (ferror (stdout) || fclose (stdout) == EOF)
+ error (1, 0, "write error");
+
+ exit (exit_status);
+}
+
+/* Add the comma or blank separated list of tabstops STOPS
+ to the list of tabstops. */
+
+void
+parse_tabstops (stops)
+ char *stops;
+{
+ int tabval = -1;
+
+ for (; *stops; stops++)
+ {
+ if (*stops == ',' || isblank (*stops))
+ {
+ add_tabstop (tabval);
+ tabval = -1;
+ }
+ else if (ISDIGIT (*stops))
+ {
+ if (tabval == -1)
+ tabval = 0;
+ tabval = tabval * 10 + *stops - '0';
+ }
+ else
+ error (1, 0, "tab size contains an invalid character");
+ }
+
+ add_tabstop (tabval);
+}
+
+/* Add tab stop TABVAL to the end of `tab_list', except
+ if TABVAL is -1, do nothing. */
+
+void
+add_tabstop (tabval)
+ int tabval;
+{
+ if (tabval == -1)
+ return;
+ if (first_free_tab % TABLIST_BLOCK == 0)
+ tab_list = (int *) xrealloc (tab_list, first_free_tab + TABLIST_BLOCK);
+ tab_list[first_free_tab++] = tabval;
+}
+
+/* Check that the list of tabstops TABS, with ENTRIES entries,
+ contains only nonzero, ascending values. */
+
+void
+validate_tabstops (tabs, entries)
+ int *tabs;
+ int entries;
+{
+ int prev_tab = 0;
+ int i;
+
+ for (i = 0; i < entries; i++)
+ {
+ if (tabs[i] == 0)
+ error (1, 0, "tab size cannot be 0");
+ if (tabs[i] <= prev_tab)
+ error (1, 0, "tab sizes must be ascending");
+ prev_tab = tabs[i];
+ }
+}
+
+/* Change tabs to spaces, writing to stdout.
+ Read each file in `file_list', in order. */
+
+void
+expand ()
+{
+ FILE *fp; /* Input stream. */
+ int c; /* Each input character. */
+ int tab_index = 0; /* Index in `tab_list' of next tabstop. */
+ int column = 0; /* Column on screen of the next char. */
+ int next_tab_column; /* Column the next tab stop is on. */
+ int convert = 1; /* If nonzero, perform translations. */
+
+ fp = next_file ((FILE *) NULL);
+ for (;;)
+ {
+ c = getc (fp);
+ if (c == EOF)
+ {
+ fp = next_file (fp);
+ if (fp == NULL)
+ break; /* No more files. */
+ else
+ continue;
+ }
+
+ if (c == '\n')
+ {
+ putchar (c);
+ tab_index = 0;
+ column = 0;
+ convert = 1;
+ }
+ else if (c == '\t' && convert)
+ {
+ if (tab_size == 0)
+ {
+ /* Do not let tab_index == first_free_tab;
+ stop when it is 1 less. */
+ while (tab_index < first_free_tab - 1
+ && column >= tab_list[tab_index])
+ tab_index++;
+ next_tab_column = tab_list[tab_index];
+ if (tab_index < first_free_tab - 1)
+ tab_index++;
+ if (column >= next_tab_column)
+ next_tab_column = column + 1; /* Ran out of tab stops. */
+ }
+ else
+ {
+ next_tab_column = column + tab_size - column % tab_size;
+ }
+ while (column < next_tab_column)
+ {
+ putchar (' ');
+ ++column;
+ }
+ }
+ else
+ {
+ if (convert)
+ {
+ if (c == '\b')
+ {
+ if (column > 0)
+ --column;
+ }
+ else
+ {
+ ++column;
+ if (convert_entire_line == 0)
+ convert = 0;
+ }
+ }
+ putchar (c);
+ }
+ }
+}
+
+/* Close the old stream pointer FP if it is non-NULL,
+ and return a new one opened to read the next input file.
+ Open a filename of `-' as the standard input.
+ Return NULL if there are no more input files. */
+
+FILE *
+next_file (fp)
+ FILE *fp;
+{
+ static char *prev_file;
+ char *file;
+
+ if (fp)
+ {
+ if (ferror (fp))
+ {
+ error (0, errno, "%s", prev_file);
+ exit_status = 1;
+ }
+ if (fp == stdin)
+ clearerr (fp); /* Also clear EOF. */
+ else if (fclose (fp) == EOF)
+ {
+ error (0, errno, "%s", prev_file);
+ exit_status = 1;
+ }
+ }
+
+ while ((file = *file_list++) != NULL)
+ {
+ if (file[0] == '-' && file[1] == '\0')
+ {
+ have_read_stdin = 1;
+ prev_file = file;
+ return stdin;
+ }
+ fp = fopen (file, "r");
+ if (fp)
+ {
+ prev_file = file;
+ return fp;
+ }
+ error (0, errno, "%s", file);
+ exit_status = 1;
+ }
+ return NULL;
+}
+
+void
+usage ()
+{
+ fprintf (stderr, "\
+Usage: %s [-tab1[,tab2[,...]]] [-t tab1[,tab2[,...]]] [-i]\n\
+ [--tabs=tab1[,tab2[,...]]] [--initial] [file...]\n",
+ program_name);
+ exit (1);
+}
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