sbase

suckless unix tools
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uudecode.c (7090B)


      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 }