uudecode.c - sbase - suckless unix tools
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uudecode.c (7090B)
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1 /* See LICENSE file for copyright and license details. */
2 #include <sys/stat.h>
3
4 #include <errno.h>
5 #include <stdio.h>
6 #include <stdlib.h>
7 #include <string.h>
8
9 #include "util.h"
10
11 static int mflag = 0;
12 static int oflag = 0;
13
14 static FILE *
15 parsefile(const char *fname)
16 {
17 struct stat st;
18 int ret;
19
20 if (!strcmp(fname, "/dev/stdout") || !strcmp(fname, "-"))
21 return stdout;
22 ret = lstat(fname, &st);
23 /* if it is a new file, try to open it */
24 if (ret < 0 && errno == ENOENT)
25 goto tropen;
26 if (ret < 0) {
27 weprintf("lstat %s:", fname);
28 return NULL;
29 }
30 if (!S_ISREG(st.st_mode)) {
31 weprintf("for safety uudecode operates only on regular files and /dev/stdout\n");
32 return NULL;
33 }
34 tropen:
35 return fopen(fname, "w");
36 }
37
38 static void
39 parseheader(FILE *fp, const char *s, char **header, mode_t *mode, char **fname)
40 {
41 static char bufs[PATH_MAX + 18]; /* len header + mode + maxname */
42 char *p, *q;
43 size_t n;
44
45 if (!fgets(bufs, sizeof(bufs), fp))
46 if (ferror(fp))
47 eprintf("%s: read error:", s);
48 if (bufs[0] == '\0' || feof(fp))
49 eprintf("empty or nil header string\n");
50 if (!(p = strchr(bufs, '\n')))
51 eprintf("header string too long or non-newline terminated file\n");
52 p = bufs;
53 if (!(q = strchr(p, ' ')))
54 eprintf("malformed mode string in header, expected ' '\n");
55 *header = bufs;
56 *q++ = '\0';
57 p = q;
58 /* now header should be null terminated, q points to mode */
59 if (!(q = strchr(p, ' ')))
60 eprintf("malformed mode string in header, expected ' '\n");
61 *q++ = '\0';
62 /* now mode should be null terminated, q points to fname */
63 *mode = parsemode(p, *mode, 0);
64 n = strlen(q);
65 while (n > 0 && (q[n - 1] == '\n' || q[n - 1] == '\r'))
66 q[--n] = '\0';
67 if (n > 0)
68 *fname = q;
69 else
70 eprintf("header string does not contain output file\n");
71 }
72
73 static const char b64dt[] = {
74 -1,-1,-1,-1,-1,-1,-1,-1,-1,-2,-2,-2,-2,-2,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
75 -1,-1,-1,-1,-1,-1,-1,-1,-2,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,62,-1,-1,-1,63,
76 52,53,54,55,56,57,58,59,60,61,-1,-1,-1, 0,-1,-1,-1, 0, 1, 2, 3, 4, 5, 6,
77 7, 8, 9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,
78 -1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,
79 49,50,51,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
80 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
81 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
82 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
83 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
84 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
85 };
86
87 static void
88 uudecodeb64(FILE *fp, FILE *outfp)
89 {
90 char bufb[60], *pb;
91 char out[45], *po;
92 size_t n;
93 int b = 0, e, t = -1, l = 1;
94 unsigned char b24[3] = {0, 0, 0};
95
96 while ((n = fread(bufb, 1, sizeof(bufb), fp))) {
97 for (pb = bufb, po = out; pb < bufb + n; pb++) {
98 if (*pb == '\n') {
99 l++;
100 continue;
101 } else if (*pb == '=') {
102 switch (b) {
103 case 0:
104 /* expected '=' remaining
105 * including footer */
106 if (--t) {
107 fwrite(out, 1,
108 (po - out),
109 outfp);
110 return;
111 }
112 continue;
113 case 1:
114 eprintf("%d: unexpected \"=\""
115 "appeared\n", l);
116 case 2:
117 *po++ = b24[0];
118 b = 0;
119 t = 5; /* expect 5 '=' */
120 continue;
121 case 3:
122 *po++ = b24[0];
123 *po++ = b24[1];
124 b = 0;
125 t = 6; /* expect 6 '=' */
126 continue;
127 }
128 } else if ((e = b64dt[(int)*pb]) == -1)
129 eprintf("%d: invalid byte \"%c\"\n", l, *pb);
130 else if (e == -2) /* whitespace */
131 continue;
132 else if (t > 0) /* state is parsing pad/footer */
133 eprintf("%d: invalid byte \"%c\""
134 " after padding\n",
135 l, *pb);
136 switch (b) { /* decode next base64 chr based on state */
137 case 0: b24[0] |= e << 2; break;
138 case 1: b24[0] |= (e >> 4) & 0x3;
139 b24[1] |= (e & 0xf) << 4; break;
140 case 2: b24[1] |= (e >> 2) & 0xf;
141 b24[2] |= (e & 0x3) << 6; break;
142 case 3: b24[2] |= e; break;
143 }
144 if (++b == 4) { /* complete decoding an octet */
145 *po++ = b24[0];
146 *po++ = b24[1];
147 *po++ = b24[2];
148 b24[0] = b24[1] = b24[2] = 0;
149 b = 0;
150 }
151 }
152 fwrite(out, 1, (po - out), outfp);
153 }
154 eprintf("%d: invalid uudecode footer \"====\" not found\n", l);
155 }
156
157 static void
158 uudecode(FILE *fp, FILE *outfp)
159 {
160 char *bufb = NULL, *p;
161 size_t n = 0;
162 ssize_t len;
163 int ch, i;
164
165 #define DEC(c) (((c) - ' ') & 077) /* single character decode */
166 #define IS_DEC(c) ( (((c) - ' ') >= 0) && (((c) - ' ') <= 077 + 1) )
167 #define OUT_OF_RANGE(c) eprintf("character %c out of range: [%d-%d]\n", (c), 1 + ' ', 077 + ' ' + 1)
168
169 while ((len = getline(&bufb, &n, fp)) > 0) {
170 p = bufb;
171 /* trim newlines */
172 if (!len || bufb[len - 1] != '\n')
173 eprintf("no newline found, aborting\n");
174 bufb[len - 1] = '\0';
175
176 /* check for last line */
177 if ((i = DEC(*p)) <= 0)
178 break;
179 for (++p; i > 0; p += 4, i -= 3) {
180 if (i >= 3) {
181 if (!(IS_DEC(*p) && IS_DEC(*(p + 1)) &&
182 IS_DEC(*(p + 2)) && IS_DEC(*(p + 3))))
183 OUT_OF_RANGE(*p);
184
185 ch = DEC(p[0]) << 2 | DEC(p[1]) >> 4;
186 putc(ch, outfp);
187 ch = DEC(p[1]) << 4 | DEC(p[2]) >> 2;
188 putc(ch, outfp);
189 ch = DEC(p[2]) << 6 | DEC(p[3]);
190 putc(ch, outfp);
191 } else {
192 if (i >= 1) {
193 if (!(IS_DEC(*p) && IS_DEC(*(p + 1))))
194 OUT_OF_RANGE(*p);
195
196 ch = DEC(p[0]) << 2 | DEC(p[1]) >> 4;
197 putc(ch, outfp);
198 }
199 if (i >= 2) {
200 if (!(IS_DEC(*(p + 1)) &&
201 IS_DEC(*(p + 2))))
202 OUT_OF_RANGE(*p);
203
204 ch = DEC(p[1]) << 4 | DEC(p[2]) >> 2;
205 putc(ch, outfp);
206 }
207 }
208 }
209 if (ferror(fp))
210 eprintf("read error:");
211 }
212 /* check for end or fail */
213 if ((len = getline(&bufb, &n, fp)) < 0)
214 eprintf("getline:");
215 if (len < 3 || strncmp(bufb, "end", 3) || bufb[3] != '\n')
216 eprintf("invalid uudecode footer \"end\" not found\n");
217 free(bufb);
218 }
219
220 static void
221 usage(void)
222 {
223 eprintf("usage: %s [-m] [-o output] [file]\n", argv0);
224 }
225
226 int
227 main(int argc, char *argv[])
228 {
229 FILE *fp = NULL, *nfp = NULL;
230 mode_t mode = 0;
231 int ret = 0;
232 char *fname, *header, *ifname, *ofname = NULL;
233 void (*d) (FILE *, FILE *) = NULL;
234
235 ARGBEGIN {
236 case 'm':
237 mflag = 1; /* accepted but unused (autodetect file type) */
238 break;
239 case 'o':
240 oflag = 1;
241 ofname = EARGF(usage());
242 break;
243 default:
244 usage();
245 } ARGEND
246
247 if (argc > 1)
248 usage();
249
250 if (!argc || !strcmp(argv[0], "-")) {
251 fp = stdin;
252 ifname = "<stdin>";
253 } else {
254 if (!(fp = fopen(argv[0], "r")))
255 eprintf("fopen %s:", argv[0]);
256 ifname = argv[0];
257 }
258
259 parseheader(fp, ifname, &header, &mode, &fname);
260
261 if (!strncmp(header, "begin", sizeof("begin")))
262 d = uudecode;
263 else if (!strncmp(header, "begin-base64", sizeof("begin-base64")))
264 d = uudecodeb64;
265 else
266 eprintf("unknown header %s:", header);
267
268 if (oflag)
269 fname = ofname;
270 if (!(nfp = parsefile(fname)))
271 eprintf("fopen %s:", fname);
272
273 d(fp, nfp);
274
275 if (nfp != stdout && chmod(fname, mode) < 0)
276 eprintf("chmod %s:", fname);
277
278 ret |= fshut(fp, (fp == stdin) ? "<stdin>" : argv[0]);
279 ret |= fshut(nfp, (nfp == stdout) ? "<stdout>" : fname);
280
281 return ret;
282 }