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	uudecode.c - 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 f…
	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 *…
	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 terminate…
	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,-…
	75 -1,-1,-1,-1,-1,-1,-1,-1,-2,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,62,-1,-…
	76 52,53,54,55,56,57,58,59,60,61,-1,-1,-1, 0,-1,-1,-1, 0, 1, 2, 3, …
	77 7, 8, 9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,-1,-1,-…
	78 -1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,4…
	79 49,50,51,-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,-…
	81 -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,-…
	83 -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, …
	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 …
	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", …
	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 +…
	194 OUT_OF_RANGE(*p);
	195
	196 ch = DEC(p[0]) << 2 \| DEC(p[1]) …
	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]) …
	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 }