1/* vi: set sw=4 ts=4: */
2/*
3 *  Copyright 2003, Glenn McGrath
4 *
5 *  Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
6 *
7 *  Based on specification from
8 *  http://www.opengroup.org/onlinepubs/007904975/utilities/uuencode.html
9 *
10 *  Bugs: the spec doesn't mention anything about "`\n`\n" prior to the
11 *        "end" line
12 */
13
14
15#include "libbb.h"
16
17static void read_stduu(FILE *src_stream, FILE *dst_stream)
18{
19	char *line;
20
21	while ((line = xmalloc_fgetline(src_stream)) != NULL) {
22		int encoded_len, str_len;
23		char *line_ptr, *dst;
24
25		if (strcmp(line, "end") == 0) {
26			return; /* the only non-error exit */
27		}
28
29		line_ptr = line;
30		while (*line_ptr) {
31			*line_ptr = (*line_ptr - 0x20) & 0x3f;
32			line_ptr++;
33		}
34		str_len = line_ptr - line;
35
36		encoded_len = line[0] * 4 / 3;
37		/* Check that line is not too short. (we tolerate
38		 * overly _long_ line to accomodate possible extra '`').
39		 * Empty line case is also caught here. */
40		if (str_len <= encoded_len) {
41			break; /* go to bb_error_msg_and_die("short file"); */
42		}
43		if (encoded_len <= 0) {
44			/* Ignore the "`\n" line, why is it even in the encode file ? */
45			free(line);
46			continue;
47		}
48		if (encoded_len > 60) {
49			bb_error_msg_and_die("line too long");
50		}
51
52		dst = line;
53		line_ptr = line + 1;
54		do {
55			/* Merge four 6 bit chars to three 8 bit chars */
56			*dst++ = line_ptr[0] << 2 | line_ptr[1] >> 4;
57			encoded_len--;
58			if (encoded_len == 0) {
59				break;
60			}
61
62			*dst++ = line_ptr[1] << 4 | line_ptr[2] >> 2;
63			encoded_len--;
64			if (encoded_len == 0) {
65				break;
66			}
67
68			*dst++ = line_ptr[2] << 6 | line_ptr[3];
69			line_ptr += 4;
70			encoded_len -= 2;
71		} while (encoded_len > 0);
72		fwrite(line, 1, dst - line, dst_stream);
73		free(line);
74	}
75	bb_error_msg_and_die("short file");
76}
77
78static void read_base64(FILE *src_stream, FILE *dst_stream)
79{
80	int term_count = 1;
81
82	while (1) {
83		char translated[4];
84		int count = 0;
85
86		while (count < 4) {
87			char *table_ptr;
88			int ch;
89
90			/* Get next _valid_ character.
91			 * global vector bb_uuenc_tbl_base64[] contains this string:
92			 * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n"
93			 */
94			do {
95				ch = fgetc(src_stream);
96				if (ch == EOF) {
97					bb_error_msg_and_die("short file");
98				}
99				table_ptr = strchr(bb_uuenc_tbl_base64, ch);
100			} while (table_ptr == NULL);
101
102			/* Convert encoded character to decimal */
103			ch = table_ptr - bb_uuenc_tbl_base64;
104
105			if (*table_ptr == '=') {
106				if (term_count == 0) {
107					translated[count] = '\0';
108					break;
109				}
110				term_count++;
111			} else if (*table_ptr == '\n') {
112				/* Check for terminating line */
113				if (term_count == 5) {
114					return;
115				}
116				term_count = 1;
117				continue;
118			} else {
119				translated[count] = ch;
120				count++;
121				term_count = 0;
122			}
123		}
124
125		/* Merge 6 bit chars to 8 bit */
126		if (count > 1) {
127			fputc(translated[0] << 2 | translated[1] >> 4, dst_stream);
128		}
129		if (count > 2) {
130			fputc(translated[1] << 4 | translated[2] >> 2, dst_stream);
131		}
132		if (count > 3) {
133			fputc(translated[2] << 6 | translated[3], dst_stream);
134		}
135	}
136}
137
138int uudecode_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
139int uudecode_main(int argc UNUSED_PARAM, char **argv)
140{
141	FILE *src_stream;
142	char *outname = NULL;
143	char *line;
144
145	opt_complementary = "?1"; /* 1 argument max */
146	getopt32(argv, "o:", &outname);
147	argv += optind;
148
149	if (!*argv)
150		*--argv = (char*)"-";
151	src_stream = xfopen_stdin(*argv);
152
153	/* Search for the start of the encoding */
154	while ((line = xmalloc_fgetline(src_stream)) != NULL) {
155		void (*decode_fn_ptr)(FILE *src, FILE *dst);
156		char *line_ptr;
157		FILE *dst_stream;
158		int mode;
159
160		if (strncmp(line, "begin-base64 ", 13) == 0) {
161			line_ptr = line + 13;
162			decode_fn_ptr = read_base64;
163		} else if (strncmp(line, "begin ", 6) == 0) {
164			line_ptr = line + 6;
165			decode_fn_ptr = read_stduu;
166		} else {
167			free(line);
168			continue;
169		}
170
171		/* begin line found. decode and exit */
172		mode = bb_strtou(line_ptr, NULL, 8);
173		if (outname == NULL) {
174			outname = strchr(line_ptr, ' ');
175			if ((outname == NULL) || (*outname == '\0')) {
176				break;
177			}
178			outname++;
179		}
180		dst_stream = stdout;
181		if (NOT_LONE_DASH(outname)) {
182			dst_stream = xfopen_for_write(outname);
183			fchmod(fileno(dst_stream), mode & (S_IRWXU | S_IRWXG | S_IRWXO));
184		}
185		free(line);
186		decode_fn_ptr(src_stream, dst_stream);
187		/* fclose_if_not_stdin(src_stream); - redundant */
188		return EXIT_SUCCESS;
189	}
190	bb_error_msg_and_die("no 'begin' line");
191}
192
193/* Test script.
194Put this into an empty dir with busybox binary, an run.
195
196#!/bin/sh
197test -x busybox || { echo "No ./busybox?"; exit; }
198ln -sf busybox uudecode
199ln -sf busybox uuencode
200>A_null
201echo -n A >A
202echo -n AB >AB
203echo -n ABC >ABC
204echo -n ABCD >ABCD
205echo -n ABCDE >ABCDE
206echo -n ABCDEF >ABCDEF
207cat busybox >A_bbox
208for f in A*; do
209    echo uuencode $f
210    ./uuencode    $f <$f >u_$f
211    ./uuencode -m $f <$f >m_$f
212done
213mkdir unpk_u unpk_m 2>/dev/null
214for f in u_*; do
215    ./uudecode <$f -o unpk_u/${f:2}
216    diff -a ${f:2} unpk_u/${f:2} >/dev/null 2>&1
217    echo uudecode $f: $?
218done
219for f in m_*; do
220    ./uudecode <$f -o unpk_m/${f:2}
221    diff -a ${f:2} unpk_m/${f:2} >/dev/null 2>&1
222    echo uudecode $f: $?
223done
224*/
225