sfeed.c

#include <sys/types.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <time.h>

#include "util.h"
#include "xml.h"

#define ISINCONTENT(ctx)  ((ctx).iscontent && !((ctx).iscontenttag))
#define ISCONTENTTAG(ctx) (!((ctx).iscontent) && (ctx).iscontenttag)
/* string and byte-length */
#define STRP(s)           s,sizeof(s)-1

enum FeedType {
	FeedTypeNone = 0,
	FeedTypeRSS  = 1,
	FeedTypeAtom = 2
};

enum ContentType {
	ContentTypeNone  = 0,
	ContentTypePlain = 1,
	ContentTypeHTML  = 2
};
static const char *contenttypes[] = { "", "plain", "html" };

/* String data / memory pool */
typedef struct string {
	char   *data;   /* data */
	size_t  len;    /* string length */
	size_t  bufsiz; /* allocated size */
} String;

/* NOTE: the order of these fields (content, date, author) indicate the
 *       priority to use them, from least important to high. */
enum TagId {
	TagUnknown = 0,
	/* RSS */
	RSSTagDcdate, RSSTagPubdate,
	RSSTagTitle,
	RSSTagMediaDescription, RSSTagDescription, RSSTagContentEncoded,
	RSSTagGuid,
	/* must be defined after GUID, because it can be a link (isPermaLink) */
	RSSTagLink,
	RSSTagEnclosure,
	RSSTagAuthor, RSSTagDccreator,
	/* Atom */
	AtomTagUpdated, AtomTagPublished,
	AtomTagTitle,
	AtomTagMediaDescription, AtomTagSummary, AtomTagContent,
	AtomTagId,
	AtomTagLink,
	AtomTagLinkAlternate,
	AtomTagLinkEnclosure,
	AtomTagAuthor,
	TagLast
};

typedef struct feedtag {
	char       *name; /* name of tag to match */
	size_t      len;  /* len of `name` */
	enum TagId  id;   /* unique ID */
} FeedTag;

typedef struct field {
	String     str;
	enum TagId tagid; /* tagid set previously, used for tag priority */
} FeedField;

enum {
	FeedFieldTime = 0, FeedFieldTitle, FeedFieldLink, FeedFieldContent,
	FeedFieldId, FeedFieldAuthor, FeedFieldEnclosure, FeedFieldLast
};

typedef struct feedcontext {
	String          *field;             /* current FeedItem field String */
	FeedField        fields[FeedFieldLast]; /* data for current item */
	enum TagId       tagid;             /* unique number for parsed tag */
	int              iscontent;         /* in content data */
	int              iscontenttag;      /* in content tag */
	enum ContentType contenttype;       /* content-type for item */
	enum FeedType    feedtype;
	int              attrcount; /* count item HTML element attributes */
} FeedContext;

static long long  datetounix(long long, int, int, int, int, int);
static enum TagId gettag(enum FeedType, const char *, size_t);
static long long  gettzoffset(const char *);
static int  isattr(const char *, size_t, const char *, size_t);
static int  istag(const char *, size_t, const char *, size_t);
static int  parsetime(const char *, time_t *);
static void printfields(void);
static void string_append(String *, const char *, size_t);
static void string_buffer_realloc(String *, size_t);
static void string_clear(String *);
static void string_print_encoded(String *);
static void string_print_timestamp(String *);
static void string_print_trimmed(String *);
static void string_print_uri(String *);
static void xmlattr(XMLParser *, const char *, size_t, const char *, size_t,
                    const char *, size_t);
static void xmlattrend(XMLParser *, const char *, size_t, const char *,
                       size_t);
static void xmlattrstart(XMLParser *, const char *, size_t, const char *,
                         size_t);
static void xmlcdata(XMLParser *, const char *, size_t);
static void xmldata(XMLParser *, const char *, size_t);
static void xmldataentity(XMLParser *, const char *, size_t);
static void xmltagend(XMLParser *, const char *, size_t, int);
static void xmltagstart(XMLParser *, const char *, size_t);
static void xmltagstartparsed(XMLParser *, const char *, size_t, int);

/* map tag name to TagId type */
/* RSS, must be alphabetical order */
static FeedTag rsstags[] = {
	{ STRP("author"),            RSSTagAuthor            },
	{ STRP("content:encoded"),   RSSTagContentEncoded    },
	{ STRP("dc:creator"),        RSSTagDccreator         },
	{ STRP("dc:date"),           RSSTagDcdate            },
	{ STRP("description"),       RSSTagDescription       },
	/* RSS: <enclosure url="" />, Atom has <link rel="enclosure" /> */
	{ STRP("enclosure"),         RSSTagEnclosure         },
	{ STRP("guid"),              RSSTagGuid              },
	{ STRP("link"),              RSSTagLink              },
	{ STRP("media:description"), RSSTagMediaDescription  },
	{ STRP("pubdate"),           RSSTagPubdate           },
	{ STRP("title"),             RSSTagTitle             }
};
/* Atom, must be alphabetical order */
static FeedTag atomtags[] = {
	/* <author><name></name></author> */
	{ STRP("author"),            AtomTagAuthor           },
	{ STRP("content"),           AtomTagContent          },
	{ STRP("id"),                AtomTagId               },
	/* Atom: <link href="" />, RSS has <link></link> */
	{ STRP("link"),              AtomTagLink             },
	{ STRP("media:description"), AtomTagMediaDescription },
	{ STRP("published"),         AtomTagPublished        },
	{ STRP("summary"),           AtomTagSummary          },
	{ STRP("title"),             AtomTagTitle            },
	{ STRP("updated"),           AtomTagUpdated          }
};

/* map TagId type to RSS/Atom field, all tags must be defined */
static int fieldmap[TagLast] = {
	[TagUnknown]              = -1,
	/* RSS */
	[RSSTagDcdate]            = FeedFieldTime,
	[RSSTagPubdate]           = FeedFieldTime,
	[RSSTagTitle]             = FeedFieldTitle,
	[RSSTagMediaDescription]  = FeedFieldContent,
	[RSSTagDescription]       = FeedFieldContent,
	[RSSTagContentEncoded]    = FeedFieldContent,
	[RSSTagGuid]              = FeedFieldId,
	[RSSTagLink]              = FeedFieldLink,
	[RSSTagEnclosure]         = FeedFieldEnclosure,
	[RSSTagAuthor]            = FeedFieldAuthor,
	[RSSTagDccreator]         = FeedFieldAuthor,
	/* Atom */
	[AtomTagUpdated]          = FeedFieldTime,
	[AtomTagPublished]        = FeedFieldTime,
	[AtomTagTitle]            = FeedFieldTitle,
	[AtomTagMediaDescription] = FeedFieldContent,
	[AtomTagSummary]          = FeedFieldContent,
	[AtomTagContent]          = FeedFieldContent,
	[AtomTagId]               = FeedFieldId,
	[AtomTagLink]             = -1,
	[AtomTagLinkAlternate]    = FeedFieldLink,
	[AtomTagLinkEnclosure]    = FeedFieldEnclosure,
	[AtomTagAuthor]           = FeedFieldAuthor
};

static const int FieldSeparator = '\t';
static const char *baseurl = "";

static FeedContext ctx;
static XMLParser parser; /* XML parser state */

static String atomlink;
static enum TagId atomlinktype;
static int rssidpermalink;

int
tagcmp(const void *v1, const void *v2)
{
	return strcasecmp(((FeedTag *)v1)->name, ((FeedTag *)v2)->name);
}

/* Unique tagid for parsed tag name. */
static enum TagId
gettag(enum FeedType feedtype, const char *name, size_t namelen)
{
	FeedTag f, *r = NULL;

	f.name = (char *)name;

	switch (feedtype) {
	case FeedTypeRSS:
		r = bsearch(&f, rsstags, sizeof(rsstags) / sizeof(rsstags[0]),
		        sizeof(rsstags[0]), tagcmp);
		break;
	case FeedTypeAtom:
		r = bsearch(&f, atomtags, sizeof(atomtags) / sizeof(atomtags[0]),
		        sizeof(atomtags[0]), tagcmp);
		break;
	default:
		break;
	}

	return r ? r->id : TagUnknown;
}

static char *
ltrim(const char *s)
{
	for (; *s && isspace((unsigned char)*s); s++)
		;
	return (char *)s;
}

static char *
rtrim(const char *s)
{
	const char *e;

	for (e = s + strlen(s); e > s && isspace((unsigned char)*(e - 1)); e--)
		;
	return (char *)e;
}

/* Clear string only; don't free, prevents unnecessary reallocation. */
static void
string_clear(String *s)
{
	if (s->data)
		s->data[0] = '\0';
	s->len = 0;
}

static void
string_buffer_realloc(String *s, size_t newlen)
{
	size_t alloclen;

	for (alloclen = 64; alloclen <= newlen; alloclen *= 2)
		;
	if (!(s->data = realloc(s->data, alloclen)))
		err(1, "realloc");
	s->bufsiz = alloclen;
}

static void
string_append(String *s, const char *data, size_t len)
{
	if (!len)
		return;
	/* check if allocation is necesary, don't shrink buffer,
	 * should be more than bufsiz ofcourse. */
	if (s->len + len >= s->bufsiz)
		string_buffer_realloc(s, s->len + len + 1);
	memcpy(s->data + s->len, data, len);
	s->len += len;
	s->data[s->len] = '\0';
}

/* Print text, encode TABs, newlines and '\', remove other whitespace.
 * Remove leading and trailing whitespace. */
static void
string_print_encoded(String *s)
{
	const char *p, *e;

	if (!s->data || !s->len)
		return;

	p = ltrim(s->data);
	e = rtrim(p);

	for (; *p && p != e; p++) {
		switch (*p) {
		case '\n': fputs("\\n",  stdout); break;
		case '\\': fputs("\\\\", stdout); break;
		case '\t': fputs("\\t",  stdout); break;
		default:
			/* ignore control chars */
			if (!iscntrl((unsigned char)*p))
				putchar(*p);
			break;
		}
	}
}

/* Print text, replace TABs, carriage return and other whitespace with ' '.
 * Other control chars are removed. Remove leading and trailing whitespace. */
static void
string_print_trimmed(String *s)
{
	char *p, *e;

	if (!s->data || !s->len)
		return;

	p = ltrim(s->data);
	e = rtrim(p);

	for (; *p && p != e; p++) {
		if (isspace((unsigned char)*p))
			putchar(' '); /* any whitespace to space */
		else if (!iscntrl((unsigned char)*p))
			/* ignore other control chars */
			putchar(*p);
	}
}

/* always print absolute urls (using global baseurl) */
void
string_print_uri(String *s)
{
	char link[4096], *p, *e;
	int c;

	if (!s->data || !s->len)
		return;

	p = ltrim(s->data);
	e = rtrim(p);
	c = *e;
	*e = '\0';
	if (absuri(link, sizeof(link), p, baseurl) != -1)
		fputs(link, stdout);
	*e = c; /* restore */
}

/* print as UNIX timestamp, print nothing if the parsed time is invalid */
void
string_print_timestamp(String *s)
{
	time_t t;

	if (!s->data || !s->len)
		return;

	if (parsetime(s->data, &t) != -1)
		printf("%lld", (long long)t);
}

long long
datetounix(long long year, int mon, int day, int hour, int min, int sec)
{
	static const int secs_through_month[] = {
		0, 31 * 86400, 59 * 86400, 90 * 86400,
		120 * 86400, 151 * 86400, 181 * 86400, 212 * 86400,
		243 * 86400, 273 * 86400, 304 * 86400, 334 * 86400 };
	int is_leap = 0, cycles, centuries = 0, leaps = 0, rem;
	long long t;

	if (year - 2ULL <= 136) {
		leaps = (year - 68) >> 2;
		if (!((year - 68) & 3)) {
			leaps--;
			is_leap = 1;
		} else {
			is_leap = 0;
		}
		t = 31536000 * (year - 70) + 86400 * leaps;
	} else {
		cycles = (year - 100) / 400;
		rem = (year - 100) % 400;
		if (rem < 0) {
			cycles--;
			rem += 400;
		}
		if (!rem) {
			is_leap = 1;
		} else {
			if (rem >= 300)
				centuries = 3, rem -= 300;
			else if (rem >= 200)
				centuries = 2, rem -= 200;
			else if (rem >= 100)
				centuries = 1, rem -= 100;
			if (rem) {
				leaps = rem / 4U;
				rem %= 4U;
				is_leap = !rem;
			}
		}
		leaps += 97 * cycles + 24 * centuries - is_leap;
		t = (year - 100) * 31536000LL + leaps * 86400LL + 946684800 + 86400;
	}
	t += secs_through_month[mon];
	if (is_leap && mon >= 2)
		t += 86400;
	t += 86400LL * (day - 1);
	t += 3600LL * hour;
	t += 60LL * min;
	t += sec;

	return t;
}

/* Get timezone from string, return time offset in seconds from UTC.
 * NOTE: only parses timezones in RFC-822, many other timezone names are
 * ambiguous anyway.
 * ANSI and military zones are defined wrong in RFC822 and are unsupported,
 * see note on RFC2822 4.3 page 32. */
static long long
gettzoffset(const char *s)
{
	static struct {
		char *name;
		const int offhour;
	} tzones[] = {
		{ "CDT", -5 * 3600 },
		{ "CST", -6 * 3600 },
		{ "EDT", -4 * 3600 },
		{ "EST", -5 * 3600 },
		{ "MDT", -6 * 3600 },
		{ "MST", -7 * 3600 },
		{ "PDT", -7 * 3600 },
		{ "PST", -8 * 3600 },
	};
	const char *p;
	int tzhour = 0, tzmin = 0;
	size_t i;

	for (; *s && isspace((unsigned char)*s); s++)
		;
	switch (*s) {
	case '-': /* offset */
	case '+':
		for (i = 0, p = s + 1; i < 2 && *p && isdigit((unsigned char)*p); i++, p++)
			tzhour = (tzhour * 10) + (*p - '0');
		if (*p == ':')
			p++;
		for (i = 0; i < 2 && *p && isdigit((unsigned char)*p); i++, p++)
			tzmin = (tzmin * 10) + (*p - '0');
		return ((tzhour * 3600) + (tzmin * 60)) * (s[0] == '-' ? -1 : 1);
	default: /* timezone name */
		for (i = 0; *s && isalpha((unsigned char)s[i]); i++)
			;
		if (i != 3)
			return 0;
		/* compare tz and adjust offset relative to UTC */
		for (i = 0; i < sizeof(tzones) / sizeof(*tzones); i++) {
			if (!memcmp(s, tzones[i].name, 3))
				return tzones[i].offhour;
		}
	}
	return 0;
}

static int
parsetime(const char *s, time_t *tp)
{
	static struct {
		char *name;
		int len;
	} mons[] = {
		{ STRP("January"),   },
		{ STRP("February"),  },
		{ STRP("March"),     },
		{ STRP("April"),     },
		{ STRP("May"),       },
		{ STRP("June"),      },
		{ STRP("July"),      },
		{ STRP("August"),    },
		{ STRP("September"), },
		{ STRP("October"),   },
		{ STRP("November"),  },
		{ STRP("December"),  },
	};
	int va[6] = { 0 }, i, j, v, vi;
	size_t m;

	for (; *s && isspace((unsigned char)*s); s++)
		;
	if (!isdigit((unsigned char)*s) && !isalpha((unsigned char)*s))
		return -1;

	if (strspn(s, "0123456789") == 4) {
		/* format "%Y-%m-%d %H:%M:%S" or "%Y-%m-%dT%H:%M:%S" */
		vi = 0;
	} else {
		/* format: "[%a, ]%d %b %Y %H:%M:%S" */
		/* parse "[%a, ]%d %b %Y " part, then use time parsing as above */
		for (; *s && isalpha((unsigned char)*s); s++)
			;
		for (; *s && isspace((unsigned char)*s); s++)
			;
		if (*s == ',')
			s++;
		for (; *s && isspace((unsigned char)*s); s++)
			;
		for (v = 0, i = 0; *s && i < 4 && isdigit((unsigned char)*s); s++, i++)
			v = (v * 10) + (*s - '0');
		va[2] = v; /* day */
		for (; *s && isspace((unsigned char)*s); s++)
			;
		/* end of word month */
		for (j = 0; *s && isalpha((unsigned char)s[j]); j++)
			;
		/* check month name */
		if (j < 3 || j > 9)
			return -1; /* month cannot match */
		for (m = 0; m < sizeof(mons) / sizeof(*mons); m++) {
			/* abbreviation (3 length) or long name */
			if ((j == 3 || j == mons[m].len) &&
			    !strncasecmp(mons[m].name, s, j)) {
				va[1] = m + 1;
				s += j;
				break;
			}
		}
		if (m >= 12)
			return -1; /* no month found */
		for (; *s && isspace((unsigned char)*s); s++)
			;
		for (v = 0, i = 0; *s && i < 4 && isdigit((unsigned char)*s); s++, i++)
			v = (v * 10) + (*s - '0');
		va[0] = v; /* year */
		for (; *s && isspace((unsigned char)*s); s++)
			;
		/* parse only regular time part, see below */
		vi = 3;
	}

	/* parse time part */
	for (; *s && vi < 6; vi++) {
		for (i = 0, v = 0; *s && i < 4 && isdigit((unsigned char)*s); s++, i++)
			v = (v * 10) + (*s - '0');
		va[vi] = v;
		if ((vi < 2 && *s == '-') ||
		    (vi == 2 && (*s == 'T' || isspace((unsigned char)*s))) ||
		    (vi > 2 && *s == ':'))
			s++;
	}

	/* skip milliseconds in for example: "%Y-%m-%dT%H:%M:%S.000Z" */
	if (*s == '.') {
		for (s++; *s && isdigit((unsigned char)*s); s++)
			;
	}

	/* invalid range */
	if (va[0] < 0 || va[0] > 9999 ||
	    va[1] < 1 || va[1] > 12 ||
	    va[2] < 1 || va[2] > 31 ||
	    va[3] < 0 || va[3] > 23 ||
	    va[4] < 0 || va[4] > 59 ||
	    va[5] < 0 || va[5] > 59)
		return -1;

	if (tp)
		*tp = datetounix(va[0] - 1900, va[1] - 1, va[2], va[3], va[4], va[5]) -
		      gettzoffset(s);
	return 0;
}

static void
printfields(void)
{
	string_print_timestamp(&ctx.fields[FeedFieldTime].str);
	putchar(FieldSeparator);
	string_print_trimmed(&ctx.fields[FeedFieldTitle].str);
	putchar(FieldSeparator);
	string_print_uri(&ctx.fields[FeedFieldLink].str);
	putchar(FieldSeparator);
	string_print_encoded(&ctx.fields[FeedFieldContent].str);
	putchar(FieldSeparator);
	fputs(contenttypes[ctx.contenttype], stdout);
	putchar(FieldSeparator);
	string_print_trimmed(&ctx.fields[FeedFieldId].str);
	putchar(FieldSeparator);
	string_print_trimmed(&ctx.fields[FeedFieldAuthor].str);
	putchar(FieldSeparator);
	string_print_uri(&ctx.fields[FeedFieldEnclosure].str);
	putchar('\n');
}

static int
istag(const char *name, size_t len, const char *name2, size_t len2)
{
	return (len == len2 && !strcasecmp(name, name2));
}

static int
isattr(const char *name, size_t len, const char *name2, size_t len2)
{
	return (len == len2 && !strcasecmp(name, name2));
}

static void
xmlattr(XMLParser *p, const char *t, size_t tl, const char *n, size_t nl,
	const char *v, size_t vl)
{
	/* handles transforming inline XML to data */
	if (ISINCONTENT(ctx)) {
		if (ctx.contenttype == ContentTypeHTML)
			xmldata(p, v, vl);
		return;
	}

	if (ctx.feedtype == FeedTypeNone)
		return;

	/* content-type may be: Atom: text, xhtml, html or mime-type.
	   MRSS (media:description): plain, html. */
	if (ISCONTENTTAG(ctx)) {
		if (isattr(n, nl, STRP("type"))) {
			if (isattr(v, vl, STRP("html")) ||
			    isattr(v, vl, STRP("xhtml")) ||
			    isattr(v, vl, STRP("text/html")) ||
			    isattr(v, vl, STRP("text/xhtml"))) {
				ctx.contenttype = ContentTypeHTML;
			} else if (isattr(v, vl, STRP("text")) ||
			           isattr(v, vl, STRP("plain")) ||
				   isattr(v, vl, STRP("text/plain"))) {
				ctx.contenttype = ContentTypePlain;
			}
		}
		return;
	}

	if (ctx.feedtype == FeedTypeRSS) {
		if (ctx.tagid == RSSTagEnclosure &&
		    isattr(n, nl, STRP("url")) && ctx.field) {
			string_append(ctx.field, v, vl);
		} else if (ctx.tagid == RSSTagGuid &&
		           isattr(n, nl, STRP("ispermalink")) &&
		           !isattr(v, vl, STRP("true"))) {
			rssidpermalink = 0;
		}
	} else if (ctx.feedtype == FeedTypeAtom) {
		if (ctx.tagid == AtomTagLink &&
		           isattr(n, nl, STRP("rel"))) {
			/* empty or "alternate": other types could be
			   "enclosure", "related", "self" or "via" */
			if (!vl || isattr(v, vl, STRP("alternate")))
				atomlinktype = AtomTagLinkAlternate;
			else if (isattr(v, vl, STRP("enclosure")))
				atomlinktype = AtomTagLinkEnclosure;
			else
				atomlinktype = TagUnknown;
		} else if (ctx.tagid == AtomTagLink &&
		           isattr(n, nl, STRP("href"))) {
			string_append(&atomlink, v, vl);
		}
	}
}

static void
xmlattrend(XMLParser *p, const char *t, size_t tl, const char *n, size_t nl)
{
	if (!ISINCONTENT(ctx) || ctx.contenttype != ContentTypeHTML)
		return;

	/* handles transforming inline XML to data */
	xmldata(p, "\"", 1);
	ctx.attrcount = 0;
}

static void
xmlattrstart(XMLParser *p, const char *t, size_t tl, const char *n, size_t nl)
{
	if (!ISINCONTENT(ctx) || ctx.contenttype != ContentTypeHTML)
		return;

	/* handles transforming inline XML to data */
	if (!ctx.attrcount)
		xmldata(p, " ", 1);
	ctx.attrcount++;
	xmldata(p, n, nl);
	xmldata(p, "=\"", 2);
}

static void
xmlcdata(XMLParser *p, const char *s, size_t len)
{
	if (!ctx.field)
		return;

	string_append(ctx.field, s, len);
}

/* NOTE: this handler can be called multiple times if the data in this
 *       block is bigger than the buffer. */
static void
xmldata(XMLParser *p, const char *s, size_t len)
{
	if (!ctx.field)
		return;

	/* add only data from <name> inside <author> tag
	 * or any other non-<author> tag */
	if (ctx.tagid != AtomTagAuthor || istag(p->tag, p->taglen, STRP("name")))
		string_append(ctx.field, s, len);
}

static void
xmldataentity(XMLParser *p, const char *data, size_t datalen)
{
	char buf[16];
	ssize_t len;

	if (!ctx.field)
		return;

	/* try to translate entity, else just pass as data to
	 * xml_data_handler. */
	if ((len = xml_entitytostr(data, buf, sizeof(buf))) > 0)
		xmldata(p, buf, (size_t)len);
	else
		xmldata(p, data, datalen);
}

static void
xmltagstart(XMLParser *p, const char *t, size_t tl)
{
	enum TagId tagid;

	if (ISINCONTENT(ctx)) {
		ctx.attrcount = 0;
		if (ctx.contenttype == ContentTypeHTML) {
			xmldata(p, "<", 1);
			xmldata(p, t, tl);
		}
		return;
	}

	/* start of RSS or Atom item / entry */
	if (ctx.feedtype == FeedTypeNone) {
		if (istag(t, tl, STRP("entry")))
			ctx.feedtype = FeedTypeAtom;
		else if (istag(t, tl, STRP("item")))
			ctx.feedtype = FeedTypeRSS;
		return;
	}

	/* field tagid already set, nested tags are not allowed: return */
	if (ctx.tagid)
		return;

	/* in item */
	tagid = gettag(ctx.feedtype, t, tl);
	ctx.tagid = tagid;

	/* without a rel attribute the default link type is "alternate" */
	if (tagid == AtomTagLink) {
		atomlinktype = AtomTagLinkAlternate;
		string_clear(&atomlink); /* reuse and clear temporary link */
	} else if (tagid == RSSTagGuid) {
		/* without a ispermalink attribute the default value is "true" */
		rssidpermalink = 1;
	}

	/* map tag type to field: unknown or lesser priority is ignored,
	   when tags of the same type are repeated only the first is used. */
	if (fieldmap[tagid] == -1 || tagid <= ctx.fields[fieldmap[tagid]].tagid) {
		ctx.field = NULL;
		return;
	}

	if (fieldmap[ctx.tagid] == FeedFieldContent) {
		/* handle default content-type per tag, Atom, RSS, MRSS. */
		switch (tagid) {
		case RSSTagContentEncoded:
		case RSSTagDescription:
			ctx.contenttype = ContentTypeHTML;
			break;
		default:
			ctx.contenttype = ContentTypePlain;
		}
		ctx.iscontenttag = 1;
	} else {
		ctx.iscontenttag = 0;
	}

	ctx.field = &(ctx.fields[fieldmap[ctx.tagid]].str);
	ctx.fields[fieldmap[ctx.tagid]].tagid = tagid;
	/* clear field */
	string_clear(ctx.field);
}

static void
xmltagstartparsed(XMLParser *p, const char *tag, size_t taglen, int isshort)
{
	if (ctx.iscontenttag) {
		ctx.iscontent = 1;
		ctx.iscontenttag = 0;
		return;
	}

	/* don't read field value in Atom <link> tag */
	if (ctx.tagid == AtomTagLink)
		ctx.field = NULL;

	if (!ISINCONTENT(ctx) || ctx.contenttype != ContentTypeHTML)
		return;

	if (isshort)
		xmldata(p, "/>", 2);
	else
		xmldata(p, ">", 1);
}

static void
xmltagend(XMLParser *p, const char *t, size_t tl, int isshort)
{
	size_t i;

	if (ctx.feedtype == FeedTypeNone)
		return;

	if (ISINCONTENT(ctx)) {
		/* not close content field */
		if (gettag(ctx.feedtype, t, tl) != ctx.tagid) {
			if (!isshort && ctx.contenttype == ContentTypeHTML) {
				xmldata(p, "</", 2);
				xmldata(p, t, tl);
				xmldata(p, ">", 1);
			}
			return;
		}
	} else if (ctx.tagid == AtomTagLink) {
		/* map tag type to field: unknown or lesser priority is ignored,
		   when tags of the same type are repeated only the first is used. */
		if (atomlinktype && atomlinktype > ctx.fields[fieldmap[atomlinktype]].tagid) {
			string_append(&ctx.fields[fieldmap[atomlinktype]].str,
			              atomlink.data, atomlink.len);
			ctx.fields[fieldmap[atomlinktype]].tagid = atomlinktype;
		}
	} else if (ctx.tagid == RSSTagGuid && rssidpermalink) {
		if (ctx.tagid > ctx.fields[FeedFieldLink].tagid) {
			string_clear(&ctx.fields[FeedFieldLink].str);
			string_append(&ctx.fields[FeedFieldLink].str,
			             ctx.fields[FeedFieldId].str.data,
			             ctx.fields[FeedFieldId].str.len);
			ctx.fields[FeedFieldLink].tagid = ctx.tagid;
		}
	} else if (!ctx.tagid && ((ctx.feedtype == FeedTypeAtom &&
	   istag(t, tl, STRP("entry"))) || /* Atom */
	   (ctx.feedtype == FeedTypeRSS &&
	   istag(t, tl, STRP("item"))))) /* RSS */
	{
		/* end of RSS or Atom entry / item */
		printfields();

		/* clear strings */
		for (i = 0; i < FeedFieldLast; i++) {
			string_clear(&ctx.fields[i].str);
			ctx.fields[i].tagid = TagUnknown;
		}
		ctx.contenttype = ContentTypeNone;
		/* allow parsing of Atom and RSS concatenated in one XML stream. */
		ctx.feedtype = FeedTypeNone;
	} else if (!ctx.tagid ||
	           gettag(ctx.feedtype, t, tl) != ctx.tagid) {
		/* not end of field */
		return;
	}
	/* close field */
	ctx.iscontent = 0;
	ctx.tagid = TagUnknown;
	ctx.field = NULL;
}

int
main(int argc, char *argv[])
{
	if (pledge("stdio", NULL) == -1)
		err(1, "pledge");

	if (argc > 1)
		baseurl = argv[1];

	parser.xmlattr = xmlattr;
	parser.xmlattrend = xmlattrend;
	parser.xmlattrstart = xmlattrstart;
	parser.xmlcdata = xmlcdata;
	parser.xmldata = xmldata;
	parser.xmldataentity = xmldataentity;
	parser.xmltagend = xmltagend;
	parser.xmltagstart = xmltagstart;
	parser.xmltagstartparsed = xmltagstartparsed;

	/* NOTE: getnext is defined in xml.h for inline optimization */
	xml_parse(&parser);

	return 0;
}