mpd/src/SongFilter.cxx

/*
 * Copyright (C) 2003-2014 The Music Player Daemon Project
 * http://www.musicpd.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "config.h"
#include "SongFilter.hxx"
#include "db/LightSong.hxx"
#include "DetachedSong.hxx"
#include "tag/Tag.hxx"
#include "util/ConstBuffer.hxx"
#include "util/ASCII.hxx"
#include "util/UriUtil.hxx"
#include "lib/icu/Collate.hxx"

#include <assert.h>
#include <string.h>
#include <stdlib.h>

#define LOCATE_TAG_FILE_KEY     "file"
#define LOCATE_TAG_FILE_KEY_OLD "filename"
#define LOCATE_TAG_ANY_KEY      "any"

unsigned
locate_parse_type(const char *str)
{
	if (StringEqualsCaseASCII(str, LOCATE_TAG_FILE_KEY) ||
	    StringEqualsCaseASCII(str, LOCATE_TAG_FILE_KEY_OLD))
		return LOCATE_TAG_FILE_TYPE;

	if (StringEqualsCaseASCII(str, LOCATE_TAG_ANY_KEY))
		return LOCATE_TAG_ANY_TYPE;

	if (strcmp(str, "base") == 0)
		return LOCATE_TAG_BASE_TYPE;

	if (strcmp(str, "modified-since") == 0)
		return LOCATE_TAG_MODIFIED_SINCE;

	return tag_name_parse_i(str);
}

gcc_pure
static std::string
ImportString(const char *p, bool fold_case)
{
	return fold_case
		? IcuCaseFold(p)
		: std::string(p);
}

SongFilter::Item::Item(unsigned _tag, const char *_value, bool _fold_case)
	:tag(_tag), fold_case(_fold_case),
	 value(ImportString(_value, _fold_case))
{
}

SongFilter::Item::Item(unsigned _tag, time_t _time)
	:tag(_tag), time(_time)
{
}

bool
SongFilter::Item::StringMatch(const char *s) const
{
	assert(s != nullptr);

	if (fold_case) {
		const std::string folded = IcuCaseFold(s);
		return folded.find(value) != folded.npos;
	} else {
		return s == value;
	}
}

bool
SongFilter::Item::Match(const TagItem &item) const
{
	return (tag == LOCATE_TAG_ANY_TYPE || (unsigned)item.type == tag) &&
		StringMatch(item.value);
}

bool
SongFilter::Item::Match(const Tag &_tag) const
{
	bool visited_types[TAG_NUM_OF_ITEM_TYPES];
	std::fill_n(visited_types, size_t(TAG_NUM_OF_ITEM_TYPES), false);

	for (const auto &i : _tag) {
		visited_types[i.type] = true;

		if (Match(i))
			return true;
	}

	if (tag < TAG_NUM_OF_ITEM_TYPES && !visited_types[tag]) {
		/* If the search critieron was not visited during the
		   sweep through the song's tag, it means this field
		   is absent from the tag or empty. Thus, if the
		   searched string is also empty
		   then it's a match as well and we should return
		   true. */
		if (value.empty())
			return true;

		if (tag == TAG_ALBUM_ARTIST && visited_types[TAG_ARTIST]) {
			/* if we're looking for "album artist", but
			   only "artist" exists, use that */
			for (const auto &item : _tag)
				if (item.type == TAG_ARTIST &&
				    StringMatch(item.value))
					return true;
		}
	}

	return false;
}

bool
SongFilter::Item::Match(const DetachedSong &song) const
{
	if (tag == LOCATE_TAG_BASE_TYPE)
		return uri_is_child_or_same(value.c_str(), song.GetURI());

	if (tag == LOCATE_TAG_MODIFIED_SINCE)
		return song.GetLastModified() >= time;

	if (tag == LOCATE_TAG_FILE_TYPE)
		return StringMatch(song.GetURI());

	return Match(song.GetTag());
}

bool
SongFilter::Item::Match(const LightSong &song) const
{
	if (tag == LOCATE_TAG_BASE_TYPE) {
		const auto uri = song.GetURI();
		return uri_is_child_or_same(value.c_str(), uri.c_str());
	}

	if (tag == LOCATE_TAG_MODIFIED_SINCE)
		return song.mtime >= time;

	if (tag == LOCATE_TAG_FILE_TYPE) {
		const auto uri = song.GetURI();
		return StringMatch(uri.c_str());
	}

	return Match(*song.tag);
}

SongFilter::SongFilter(unsigned tag, const char *value, bool fold_case)
{
	items.push_back(Item(tag, value, fold_case));
}

SongFilter::~SongFilter()
{
	/* this destructor exists here just so it won't get inlined */
}

#if !defined(__GLIBC__) && !defined(WIN32)

/**
 * Determine the time zone offset in a portable way.
 */
gcc_const
static time_t
GetTimeZoneOffset()
{
	time_t t = 1234567890;
	struct tm tm;
	tm.tm_isdst = 0;
	gmtime_r(&t, &tm);
	return t - mktime(&tm);
}

#endif

gcc_pure
static time_t
ParseTimeStamp(const char *s)
{
	assert(s != nullptr);

	char *endptr;
	unsigned long long value = strtoull(s, &endptr, 10);
	if (*endptr == 0 && endptr > s)
		/* it's an integral UNIX time stamp */
		return (time_t)value;

#ifdef WIN32
	/* TODO: emulate strptime()? */
	return 0;
#else
	/* try ISO 8601 */

	struct tm tm;
	const char *end = strptime(s, "%FT%TZ", &tm);
	if (end == nullptr || *end != 0)
		return 0;

#ifdef __GLIBC__
	/* timegm() is a GNU extension */
	return timegm(&tm);
#else
	tm.tm_isdst = 0;
	return mktime(&tm) + GetTimeZoneOffset();
#endif /* !__GLIBC__ */

#endif /* !WIN32 */
}

bool
SongFilter::Parse(const char *tag_string, const char *value, bool fold_case)
{
	unsigned tag = locate_parse_type(tag_string);
	if (tag == TAG_NUM_OF_ITEM_TYPES)
		return false;

	if (tag == LOCATE_TAG_BASE_TYPE) {
		if (!uri_safe_local(value))
			return false;

		/* case folding doesn't work with "base" */
		fold_case = false;
	}

	if (tag == LOCATE_TAG_MODIFIED_SINCE) {
		time_t t = ParseTimeStamp(value);
		if (t == 0)
			return false;

		items.push_back(Item(tag, t));
		return true;
	}

	items.push_back(Item(tag, value, fold_case));
	return true;
}

bool
SongFilter::Parse(ConstBuffer<const char *> args, bool fold_case)
{
	if (args.size == 0 || args.size % 2 != 0)
		return false;

	for (unsigned i = 0; i < args.size; i += 2)
		if (!Parse(args[i], args[i + 1], fold_case))
			return false;

	return true;
}

bool
SongFilter::Match(const DetachedSong &song) const
{
	for (const auto &i : items)
		if (!i.Match(song))
			return false;

	return true;
}

bool
SongFilter::Match(const LightSong &song) const
{
	for (const auto &i : items)
		if (!i.Match(song))
			return false;

	return true;
}

bool
SongFilter::HasOtherThanBase() const
{
	for (const auto &i : items)
		if (i.GetTag() != LOCATE_TAG_BASE_TYPE)
			return true;

	return false;
}

std::string
SongFilter::GetBase() const
{
	for (const auto &i : items)
		if (i.GetTag() == LOCATE_TAG_BASE_TYPE)
			return i.GetValue();

	return std::string();
}