path: root/coreutils/fold.c (plain)
blob: 01f9bce74e8c061a3c1e5fa4e776d84ac4b7a8c8

1	/* vi: set sw=4 ts=4: */
2	/* fold -- wrap each input line to fit in specified width.
3
4	Written by David MacKenzie, djm@gnu.ai.mit.edu.
5	Copyright (C) 91, 1995-2002 Free Software Foundation, Inc.
6
7	Modified for busybox based on coreutils v 5.0
8	Copyright (C) 2003 Glenn McGrath
9
10	Licensed under GPLv2 or later, see file LICENSE in this source tree.
11	*/
12	//config:config FOLD
13	//config: bool "fold"
14	//config: default y
15	//config: help
16	//config: Wrap text to fit a specific width.
17
18	//applet:IF_FOLD(APPLET_NOEXEC(fold, fold, BB_DIR_USR_BIN, BB_SUID_DROP, fold))
19
20	//kbuild:lib-$(CONFIG_FOLD) += fold.o
21
22	//usage:#define fold_trivial_usage
23	//usage: "[-bs] [-w WIDTH] [FILE]..."
24	//usage:#define fold_full_usage "\n\n"
25	//usage: "Wrap input lines in each FILE (or stdin), writing to stdout\n"
26	//usage: "\n -b Count bytes rather than columns"
27	//usage: "\n -s Break at spaces"
28	//usage: "\n -w Use WIDTH columns instead of 80"
29
30	#include "libbb.h"
31	#include "unicode.h"
32
33	/* This is a NOEXEC applet. Be very careful! */
34
35	/* Must match getopt32 call */
36	#define FLAG_COUNT_BYTES 1
37	#define FLAG_BREAK_SPACES 2
38	#define FLAG_WIDTH 4
39
40	/* Assuming the current column is COLUMN, return the column that
41	printing C will move the cursor to.
42	The first column is 0. */
43	static int adjust_column(unsigned column, char c)
44	{
45	if (option_mask32 & FLAG_COUNT_BYTES)
46	return ++column;
47
48	if (c == '\t')
49	return column + 8 - column % 8;
50
51	if (c == '\b') {
52	if ((int)--column < 0)
53	column = 0;
54	}
55	else if (c == '\r')
56	column = 0;
57	else { /* just a printable char */
58	if (unicode_status != UNICODE_ON /* every byte is a new char */
59	|| (c & 0xc0) != 0x80 /* it isn't a 2nd+ byte of a Unicode char */
60	) {
61	column++;
62	}
63	}
64	return column;
65	}
66
67	/* Note that this function can write NULs, unlike fputs etc. */
68	static void write2stdout(const void *buf, unsigned size)
69	{
70	fwrite(buf, 1, size, stdout);
71	}
72
73	int fold_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
74	int fold_main(int argc UNUSED_PARAM, char **argv)
75	{
76	char *line_out = NULL;
77	const char *w_opt = "80";
78	unsigned width;
79	smallint exitcode = EXIT_SUCCESS;
80
81	init_unicode();
82
83	if (ENABLE_INCLUDE_SUSv2) {
84	/* Turn any numeric options into -w options. */
85	int i;
86	for (i = 1; argv[i]; i++) {
87	const char *a = argv[i];
88	if (*a == '-') {
89	a++;
90	if (*a == '-' && !a[1]) /* "--" */
91	break;
92	if (isdigit(*a))
93	argv[i] = xasprintf("-w%s", a);
94	}
95	}
96	}
97
98	getopt32(argv, "bsw:", &w_opt);
99	width = xatou_range(w_opt, 1, 10000);
100
101	argv += optind;
102	if (!*argv)
103	*--argv = (char*)"-";
104
105	do {
106	FILE *istream = fopen_or_warn_stdin(*argv);
107	int c;
108	unsigned column = 0; /* Screen column where next char will go */
109	unsigned offset_out = 0; /* Index in 'line_out' for next char */
110
111	if (istream == NULL) {
112	exitcode = EXIT_FAILURE;
113	continue;
114	}
115
116	while ((c = getc(istream)) != EOF) {
117	/* We grow line_out in chunks of 0x1000 bytes */
118	if ((offset_out & 0xfff) == 0) {
119	line_out = xrealloc(line_out, offset_out + 0x1000);
120	}
121	rescan:
122	line_out[offset_out] = c;
123	if (c == '\n') {
124	write2stdout(line_out, offset_out + 1);
125	column = offset_out = 0;
126	continue;
127	}
128	column = adjust_column(column, c);
129	if (column <= width || offset_out == 0) {
130	/* offset_out == 0 case happens
131	* with small width (say, 1) and tabs.
132	* The very first tab already goes to column 8,
133	* but we must not wrap it */
134	offset_out++;
135	continue;
136	}
137
138	/* This character would make the line too long.
139	* Print the line plus a newline, and make this character
140	* start the next line */
141	if (option_mask32 & FLAG_BREAK_SPACES) {
142	unsigned i;
143	unsigned logical_end;
144
145	/* Look for the last blank. */
146	for (logical_end = offset_out - 1; (int)logical_end >= 0; logical_end--) {
147	if (!isblank(line_out[logical_end]))
148	continue;
149
150	/* Found a space or tab.
151	* Output up to and including it, and start a new line */
152	logical_end++;
153	/*line_out[logical_end] = '\n'; - NO! this nukes one buffered character */
154	write2stdout(line_out, logical_end);
155	putchar('\n');
156	/* Move the remainder to the beginning of the next line.
157	* The areas being copied here might overlap. */
158	memmove(line_out, line_out + logical_end, offset_out - logical_end);
159	offset_out -= logical_end;
160	for (column = i = 0; i < offset_out; i++) {
161	column = adjust_column(column, line_out[i]);
162	}
163	goto rescan;
164	}
165	/* No blank found, wrap will split the overlong word */
166	}
167	/* Output what we accumulated up to now, and start a new line */
168	line_out[offset_out] = '\n';
169	write2stdout(line_out, offset_out + 1);
170	column = offset_out = 0;
171	goto rescan;
172	} /* while (not EOF) */
173
174	if (offset_out) {
175	write2stdout(line_out, offset_out);
176	}
177
178	if (fclose_if_not_stdin(istream)) {
179	bb_simple_perror_msg(*argv);
180	exitcode = EXIT_FAILURE;
181	}
182	} while (*++argv);
183
184	fflush_stdout_and_exit(exitcode);
185	}
186