summaryrefslogtreecommitdiff
path: root/coreutils/uudecode.c
blob: 8b7de74ffac4010139c791fa6b61a0ba9428fbb0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
/* vi: set sw=4 ts=4: */
/*
 *  Copyright 2003, Glenn McGrath <bug1@iinet.net.au>
 *
 *  Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 *
 *  Based on specification from
 *  http://www.opengroup.org/onlinepubs/007904975/utilities/uuencode.html
 *
 *  Bugs: the spec doesn't mention anything about "`\n`\n" prior to the
 *        "end" line
 */


#include "busybox.h"

static int read_stduu(FILE *src_stream, FILE *dst_stream)
{
	char *line;

	while ((line = xmalloc_getline(src_stream)) != NULL) {
		int length;
		char *line_ptr = line;

		if (strcmp(line, "end") == 0) {
			return EXIT_SUCCESS;
		}
		length = ((*line_ptr - 0x20) & 0x3f)* 4 / 3;

		if (length <= 0) {
			/* Ignore the "`\n" line, why is it even in the encode file ? */
			continue;
		}
		if (length > 60) {
			bb_error_msg_and_die("line too long");
		}

		line_ptr++;
		/* Tolerate an overly long line to accomodate a possible exta '`' */
		if (strlen(line_ptr) < (size_t)length) {
			bb_error_msg_and_die("short file");
		}

		while (length > 0) {
			/* Merge four 6 bit chars to three 8 bit chars */
			fputc(((line_ptr[0] - 0x20) & 077) << 2 | ((line_ptr[1] - 0x20) & 077) >> 4, dst_stream);
			line_ptr++;
			length--;
			if (length == 0) {
				break;
			}

			fputc(((line_ptr[0] - 0x20) & 077) << 4 | ((line_ptr[1] - 0x20) & 077) >> 2, dst_stream);
			line_ptr++;
			length--;
			if (length == 0) {
				break;
			}

			fputc(((line_ptr[0] - 0x20) & 077) << 6 | ((line_ptr[1] - 0x20) & 077), dst_stream);
			line_ptr += 2;
			length -= 2;
		}
		free(line);
	}
	bb_error_msg_and_die("short file");
}

static int read_base64(FILE *src_stream, FILE *dst_stream)
{
	static const char base64_table[] =
		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n";
	char term_count = 0;

	while (1) {
		char translated[4];
		int count = 0;

		while (count < 4) {
			char *table_ptr;
			int ch;

			/* Get next _valid_ character */
			do {
				ch = fgetc(src_stream);
				if (ch == EOF) {
					bb_error_msg_and_die("short file");
				}
			} while ((table_ptr = strchr(base64_table, ch)) == NULL);

			/* Convert encoded charcter to decimal */
			ch = table_ptr - base64_table;

			if (*table_ptr == '=') {
				if (term_count == 0) {
					translated[count] = 0;
					break;
				}
				term_count++;
			}
			else if (*table_ptr == '\n') {
				/* Check for terminating line */
				if (term_count == 5) {
					return EXIT_SUCCESS;
				}
				term_count = 1;
				continue;
			} else {
				translated[count] = ch;
				count++;
				term_count = 0;
			}
		}

		/* Merge 6 bit chars to 8 bit */
	    fputc(translated[0] << 2 | translated[1] >> 4, dst_stream);
		if (count > 2) {
			fputc(translated[1] << 4 | translated[2] >> 2, dst_stream);
		}
		if (count > 3) {
			fputc(translated[2] << 6 | translated[3], dst_stream);
		}
	}
}

int uudecode_main(int argc, char **argv)
{
	FILE *src_stream;
	char *outname = NULL;
	char *line;

	getopt32(argc, argv, "o:", &outname);

	if (optind == argc) {
		src_stream = stdin;
	} else if (optind + 1 == argc) {
		src_stream = xfopen(argv[optind], "r");
	} else {
		bb_show_usage();
	}

	/* Search for the start of the encoding */
	while ((line = xmalloc_getline(src_stream)) != NULL) {
		int (*decode_fn_ptr)(FILE * src, FILE * dst);
		char *line_ptr;
		FILE *dst_stream;
		int mode;
		int ret;
		
		if (strncmp(line, "begin-base64 ", 13) == 0) {
			line_ptr = line + 13;
			decode_fn_ptr = read_base64;
		} else if (strncmp(line, "begin ", 6) == 0) {
			line_ptr = line + 6;
			decode_fn_ptr = read_stduu;
		} else {
			free(line);
			continue;
		}

		mode = strtoul(line_ptr, NULL, 8);
		if (outname == NULL) {
			outname = strchr(line_ptr, ' ');
			if ((outname == NULL) || (*outname == '\0')) {
				break;
			}
			outname++;
		}
		if (strcmp(outname, "-") == 0) {
			dst_stream = stdout;
		} else {
			dst_stream = xfopen(outname, "w");
			chmod(outname, mode & (S_IRWXU | S_IRWXG | S_IRWXO));
		}
		free(line);
		ret = decode_fn_ptr(src_stream, dst_stream);
		fclose_if_not_stdin(src_stream);
		return ret;
	}
	bb_error_msg_and_die("no 'begin' line");
}