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	md-printlinks.c (9757B)
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	1 /* process Markdown (based on smu code), but only output links */
	2 #include <sys/types.h>
	3
	4 #include <ctype.h>
	5 #include <errno.h>
	6 #include <stdarg.h>
	7 #include <stdio.h>
	8 #include <stdint.h>
	9 #include <stdlib.h>
	10 #include <string.h>
	11
	12 #ifdef __OpenBSD__
	13 #include <unistd.h>
	14 #else
	15 #define pledge(a,b) 0
	16 #endif
	17
	18 #define READ_BUF_SIZ 16384
	19 #define LEN(x) sizeof(x)/sizeof(x[0])
	20 #define ADDC(b,i) if (i % READ_BUF_SIZ == 0) { b = realloc(b, (i + READ…
	21
	22 typedef int (Parser)(const char , const char *, int);
	23 typedef struct {
	24 char *search;
	25 int process;
	26 char before, after;
	27 } Tag;
	28
	29 static int dolineprefix(const char begin, const char end, int newblock…
	30 static int dolink(const char begin, const char end, int newblock); …
	31 static int dolist(const char begin, const char end, int newblock); …
	32 static int doparagraph(const char begin, const char end, int newblock)…
	33 static int doshortlink(const char begin, const char end, int newblock)…
	34 static int dosurround(const char begin, const char end, int newblock);…
	35 static int dounderline(const char begin, const char end, int newblock)…
	36 static void ereallocz(void p, size_t size);
	37 static void hprint(const char begin, const char end); …
	38 static void process(const char begin, const char end, int newblock); …
	39
	40 /* list of parsers */
	41 static Parser parsers[] = {
	42 dounderline, dolineprefix, dolist, doparagraph, dosurround, doli…
	43 };
	44
	45 static Tag lineprefix[] = {
	46 { " ", 0, "<pre><code>", "</code></pre>" },
	47 { "\t", 0, "<pre><code>", "</code></pre>" …
	48 { "> ", 2, "<blockquote>", "</block…
	49 { "###### ", 1, "<h6>", "</h6>" },
	50 { "##### ", 1, "<h5>", "</h5>" },
	51 { "#### ", 1, "<h4>", "</h4>" },
	52 { "### ", 1, "<h3>", "</h3>" },
	53 { "## ", 1, "<h2>", "</h2>" },
	54 { "# ", 1, "<h1>", "</h1>" …
	55 { "- - -\n", 1, "<hr/>", ""},
	56 };
	57
	58 static Tag underline[] = {
	59 { "=", 1, "<h1>", "</h1>\n"…
	60 { "-", 1, "<h2>", "</h2>\n"…
	61 };
	62
	63 static Tag surround[] = {
	64 { "``", 0, "<code>", "</code>" },
	65 { "`", 0, "<code>", "</code>" },
	66 { "___", 1, "<b><i>", "</i></b>" },
	67 { "***", 1, "<b><i>", "</i></b>" },
	68 { "__", 1, "<b>", "</b>" },
	69 { "**", 1, "<b>", "</b>" },
	70 { "_", 1, "<i>", "</i>" },
	71 { "*", 1, "<i>", "</i>" },
	72 };
	73
	74 void
	75 eprint(const char *format, ...)
	76 {
	77 va_list ap;
	78
	79 va_start(ap, format);
	80 vfprintf(stderr, format, ap);
	81 va_end(ap);
	82 if (format[0] && format[strlen(format) - 1] == ':')
	83 fputs(strerror(errno), stderr);
	84 fputc('\n', stderr);
	85 exit(1);
	86 }
	87
	88 int
	89 dolineprefix(const char begin, const char end, int newblock)
	90 {
	91 unsigned int i, j, l;
	92 char *buffer;
	93 const char *p;
	94
	95 if (newblock)
	96 p = begin;
	97 else if (*begin == '\n')
	98 p = begin + 1;
	99 else
	100 return 0;
	101 for (i = 0; i < LEN(lineprefix); i++) {
	102 l = strlen(lineprefix[i].search);
	103 if (end - p < l)
	104 continue;
	105 if (strncmp(lineprefix[i].search, p, l))
	106 continue;
	107 if (lineprefix[i].search[l-1] == '\n') {
	108 return l;
	109 }
	110 if (!(buffer = malloc(BUFSIZ)))
	111 eprint("malloc:");
	112 buffer[0] = '\0';
	113
	114 for (j = 0, p += l; p < end; p++, j++) {
	115 ADDC(buffer, j) = *p;
	116 if (*p == '\n' && p + l < end) {
	117 if (strncmp(lineprefix[i].search, p + 1,…
	118 break;
	119 p += l;
	120 }
	121 }
	122
	123 ADDC(buffer, j) = '\0';
	124 if (lineprefix[i].process)
	125 process(buffer, buffer + strlen(buffer), linepre…
	126 free(buffer);
	127 return -(p - begin);
	128 }
	129 return 0;
	130 }
	131
	132 int
	133 dolink(const char begin, const char end, int newblock)
	134 {
	135 int img, len, sep;
	136 const char desc, link, p, q, descend, linkend;
	137 const char title = NULL, titleend = NULL;
	138
	139 if (*begin == '[')
	140 img = 0;
	141 else if (strncmp(begin, "![", 2) == 0)
	142 img = 1;
	143 else
	144 return 0;
	145 p = desc = begin + 1 + img;
	146 if (!(p = strstr(desc, "](")) \|\| p > end)
	147 return 0;
	148 for (q = strstr(desc, "!["); q && q < end && q < p; q = strstr(q…
	149 if (!(p = strstr(p + 1, "](")) \|\| p > end)
	150 return 0;
	151 descend = p;
	152 link = p + 2;
	153 if (!(q = strchr(link, ')')) \|\| q > end)
	154 return 0;
	155 if ((p = strpbrk(link, "\"'")) && p < end && q > p) {
	156 sep = p[0]; /* separator: can be " or ' */
	157 title = p + 1;
	158 /* strip trailing whitespace */
	159 for (linkend = p; linkend > link && isspace(*(linkend - …
	160 ;
	161 if (!(p = strchr(title, sep)) \|\| q > end \|\| p > q)
	162 return 0;
	163 titleend = p;
	164 len = p + 2 - begin;
	165 }
	166 else {
	167 linkend = q;
	168 len = q + 1 - begin;
	169 }
	170 if (img) {
	171 fwrite(link, 1, linkend - link, stdout);
	172 fputs("\n", stdout);
	173 }
	174 else {
	175 fwrite(link, 1, linkend - link, stdout);
	176 fputs("\n", stdout);
	177
	178 process(desc, descend, 0);
	179 }
	180 return len;
	181 }
	182
	183 int
	184 dolist(const char begin, const char end, int newblock)
	185 {
	186 unsigned int i, j, indent, run, ul, isblock;
	187 const char p, q;
	188 char *buffer = NULL;
	189
	190 isblock = 0;
	191 if (newblock)
	192 p = begin;
	193 else if (*begin == '\n')
	194 p = begin + 1;
	195 else
	196 return 0;
	197 q = p;
	198 if (p == '-' \|\| p == '' \|\| p == '+')
	199 ul = 1;
	200 else {
	201 ul = 0;
	202 for (; p < end && p >= '0' && p <= '9'; p++)
	203 ;
	204 if (p >= end \|\| *p != '.')
	205 return 0;
	206 }
	207 p++;
	208 if (p >= end \|\| !(p == ' ' \|\| p == '\t'))
	209 return 0;
	210 for (p++; p != end && (p == ' ' \|\| p == '\t'); p++)
	211 ;
	212 indent = p - q;
	213 buffer = ereallocz(buffer, BUFSIZ);
	214 run = 1;
	215 for (; p < end && run; p++) {
	216 for (i = 0; p < end && run; p++, i++) {
	217 if (*p == '\n') {
	218 if (p + 1 == end)
	219 break;
	220 else if (p[1] == '\n') {
	221 p++;
	222 ADDC(buffer, i) = '\n';
	223 i++;
	224 run = 0;
	225 isblock++;
	226 }
	227 q = p + 1;
	228 j = 0;
	229 if (ul && (q == '-' \|\| q == '' \|\| q …
	230 j = 1;
	231 else if (!ul) {
	232 for (; q + j != end && q[j] >= '…
	233 ;
	234 if (q + j == end)
	235 break;
	236 if (j > 0 && q[j] == '.')
	237 j++;
	238 else
	239 j = 0;
	240 }
	241 if (q + indent < end)
	242 for (; (q[j] == ' ' \|\| q[j] == '…
	243 ;
	244 if (j == indent) {
	245 ADDC(buffer, i) = '\n';
	246 i++;
	247 p += indent;
	248 run = 1;
	249 if (q == ' ' \|\| q == '\t')
	250 p++;
	251 else
	252 break;
	253 }
	254 }
	255 ADDC(buffer, i) = *p;
	256 }
	257 ADDC(buffer, i) = '\0';
	258 process(buffer, buffer + i, isblock > 1 \|\| (isblock == 1…
	259 }
	260 free(buffer);
	261 p--;
	262 while (*(--p) == '\n')
	263 ;
	264 return -(p - begin + 1);
	265 }
	266
	267 int
	268 doparagraph(const char begin, const char end, int newblock)
	269 {
	270 const char *p;
	271
	272 if (!newblock)
	273 return 0;
	274 p = strstr(begin, "\n\n");
	275 if (!p \|\| p > end)
	276 p = end;
	277 if (p == begin)
	278 return 0;
	279 process(begin, p, 0);
	280 return -(p - begin);
	281 }
	282
	283 int
	284 doshortlink(const char begin, const char end, int newblock)
	285 {
	286 const char *p;
	287 int ismail = 0;
	288
	289 if (*begin != '<')
	290 return 0;
	291 for (p = begin + 1; p != end; p++) {
	292 switch (*p) {
	293 case ' ':
	294 case '\t':
	295 case '\n':
	296 return 0;
	297 case '#':
	298 case ':':
	299 ismail = -1;
	300 break;
	301 case '@':
	302 if (ismail == 0)
	303 ismail = 1;
	304 break;
	305 case '>':
	306 if (ismail == 0)
	307 return 0;
	308 if (ismail != 1) {
	309 fwrite(begin + 1, 1, p - begin - 1, stdo…
	310 fputs("\n", stdout);
	311 }
	312 return p - begin + 1;
	313 }
	314 }
	315 return 0;
	316 }
	317
	318 int
	319 dosurround(const char begin, const char end, int newblock)
	320 {
	321 unsigned int i, l;
	322 const char p, start, *stop;
	323
	324 for (i = 0; i < LEN(surround); i++) {
	325 l = strlen(surround[i].search);
	326 if (end - begin < 2*l \|\| strncmp(begin, surround[i].sear…
	327 continue;
	328 start = begin + l;
	329 p = start - 1;
	330 do {
	331 stop = p;
	332 p = strstr(p + 1, surround[i].search);
	333 } while (p && p[-1] == '\\');
	334 if (p && p[-1] != '\\')
	335 stop = p;
	336 if (!stop \|\| stop < start \|\| stop >= end)
	337 continue;
	338 if (surround[i].process)
	339 process(start, stop, 0);
	340 else
	341 hprint(start, stop);
	342 return stop - begin + l;
	343 }
	344 return 0;
	345 }
	346
	347 int
	348 dounderline(const char begin, const char end, int newblock)
	349 {
	350 unsigned int i, j, l;
	351 const char *p;
	352
	353 if (!newblock)
	354 return 0;
	355 p = begin;
	356 for (l = 0; p + l != end && p[l] != '\n'; l++)
	357 ;
	358 p += l + 1;
	359 if (l == 0)
	360 return 0;
	361 for (i = 0; i < LEN(underline); i++) {
	362 for (j = 0; p + j != end && p[j] != '\n' && p[j] == unde…
	363 ;
	364 if (j >= l) {
	365 if (underline[i].process)
	366 process(begin, begin + l, 0);
	367 else
	368 hprint(begin, begin + l);
	369 return -(j + p - begin);
	370 }
	371 }
	372 return 0;
	373 }
	374
	375 void *
	376 ereallocz(void *p, size_t size)
	377 {
	378 if (!(p = realloc(p, size)))
	379 eprint("realloc: could not allocate %u bytes:", size);
	380 return p;
	381 }
	382
	383 void
	384 hprint(const char begin, const char end)
	385 {
	386 }
	387
	388 void
	389 process(const char begin, const char end, int newblock)
	390 {
	391 const char p, q;
	392 int affected;
	393 unsigned int i;
	394
	395 for (p = begin; p < end;) {
	396 if (newblock)
	397 while (*p == '\n')
	398 if (++p == end)
	399 return;
	400 affected = 0;
	401 for (i = 0; i < LEN(parsers) && !affected; i++)
	402 affected = parsers[i](p, end, newblock);
	403 p += abs(affected);
	404 if (!affected) {
	405 p++;
	406 }
	407 for (q = p; q != end && *q == '\n'; q++)
	408 ;
	409 if (q == end)
	410 return;
	411 else if (p[0] == '\n' && p + 1 != end && p[1] == '\n')
	412 newblock = 1;
	413 else
	414 newblock = (affected < 0);
	415 }
	416 }
	417
	418 int
	419 main(int argc, char **argv)
	420 {
	421 char *buffer;
	422 int s;
	423 size_t len, bsize;
	424
	425 if (pledge("stdio", NULL) < 0)
	426 eprint("pledge:");
	427
	428 bsize = 2 * READ_BUF_SIZ;
	429 buffer = ereallocz(NULL, bsize);
	430 len = 0;
	431 while ((s = fread(buffer + len, 1, READ_BUF_SIZ, stdin))) {
	432 len += s;
	433 if (READ_BUF_SIZ + len + 1 > bsize) {
	434 bsize += READ_BUF_SIZ;
	435 if (!(buffer = realloc(buffer, bsize)))
	436 eprint("realloc:");
	437 }
	438 }
	439 buffer[len] = '\0';
	440 process(buffer, buffer + len, 1);
	441 free(buffer);
	442
	443 return 0;
	444 }