imap4d.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

	return f;
}

/*
 * flags	: flag | flags ' ' flag
 * flag		: '\' atom | atom
 */
static int
flags(void)
{
	int ff, flags;
	char *s;
	int c;

	flags = 0;
	for(;;){
		c = peekc();
		if(c == '\\'){
			mustBe('\\');
			s = atomString(atomStop, "\\");
		}else if(strchr(atomStop, c) != nil)
			s = atom();
		else
			break;
		ff = mapFlag(s);
		if(ff == 0)
			parseErr("flag not supported");
		flags |= ff;
		if(peekc() != ' ')
			break;
		mustBe(' ');
	}
	if(flags == 0)
		parseErr("no flags given");
	return flags;
}

/*
 * storeWhat	: osign 'FLAGS' ' ' storeflags
 *		| osign 'FLAGS.SILENT' ' ' storeflags
 * osign	:
 *		| '+' | '-'
 * storeflags	: flagList | flags
 */
static Store*
storeWhat(void)
{
	int f;
	char *s;
	int c, w;

	c = peekc();
	if(c == '+' || c == '-')
		mustBe(c);
	else
		c = 0;
	s = atom();
	w = 0;
	if(cistrcmp(s, "flags") == 0)
		w = STFlags;
	else if(cistrcmp(s, "flags.silent") == 0)
		w = STFlagsSilent;
	else
		parseErr("illegal store attribute");
	mustBe(' ');
	if(peekc() == '(')
		f = flagList();
	else
		f = flags();
	return mkStore(c, w, f);
}

/*
 * fetchWhat	: "ALL" | "FULL" | "FAST" | fetchAtt | '(' fetchAtts ')'
 * fetchAtts	: fetchAtt | fetchAtts ' ' fetchAtt
 */
static char *fetchAtom	= "(){}%*\"\\[]";
static Fetch*
fetchWhat(void)
{
	Fetch *f;
	char *s;

	if(peekc() == '('){
		getc();
		f = nil;
		for(;;){
			s = atomString(fetchAtom, "");
			f = fetchAtt(s, f);
			if(peekc() == ')')
				break;
			mustBe(' ');
		}
		getc();
		return revFetch(f);
	}

	s = atomString(fetchAtom, "");
	if(cistrcmp(s, "all") == 0)
		f = mkFetch(FFlags, mkFetch(FInternalDate, mkFetch(FRfc822Size, mkFetch(FEnvelope, nil))));
	else if(cistrcmp(s, "fast") == 0)
		f = mkFetch(FFlags, mkFetch(FInternalDate, mkFetch(FRfc822Size, nil)));
	else if(cistrcmp(s, "full") == 0)
		f = mkFetch(FFlags, mkFetch(FInternalDate, mkFetch(FRfc822Size, mkFetch(FEnvelope, mkFetch(FBody, nil)))));
	else
		f = fetchAtt(s, nil);
	return f;
}

/*
 * fetchAtt	: "ENVELOPE" | "FLAGS" | "INTERNALDATE"
 *		| "RFC822" | "RFC822.HEADER" | "RFC822.SIZE" | "RFC822.TEXT"
 *		| "BODYSTRUCTURE"
 *		| "UID"
 *		| "BODY"
 *		| "BODY" bodysubs
 *		| "BODY.PEEK" bodysubs
 * bodysubs	: sect
 *		| sect '<' number '.' nz-number '>'
 * sect		: '[' sectSpec ']'
 * sectSpec	: sectMsgText
 *		| sectPart
 *		| sectPart '.' sectText
 * sectPart	: nz-number
 *		| sectPart '.' nz-number
 */
static Fetch*
fetchAtt(char *s, Fetch *f)
{
	NList *sect;
	int c;

	if(cistrcmp(s, "envelope") == 0)
		return mkFetch(FEnvelope, f);
	if(cistrcmp(s, "flags") == 0)
		return mkFetch(FFlags, f);
	if(cistrcmp(s, "internaldate") == 0)
		return mkFetch(FInternalDate, f);
	if(cistrcmp(s, "RFC822") == 0)
		return mkFetch(FRfc822, f);
	if(cistrcmp(s, "RFC822.header") == 0)
		return mkFetch(FRfc822Head, f);
	if(cistrcmp(s, "RFC822.size") == 0)
		return mkFetch(FRfc822Size, f);
	if(cistrcmp(s, "RFC822.text") == 0)
		return mkFetch(FRfc822Text, f);
	if(cistrcmp(s, "bodystructure") == 0)
		return mkFetch(FBodyStruct, f);
	if(cistrcmp(s, "uid") == 0)
		return mkFetch(FUid, f);

	if(cistrcmp(s, "body") == 0){
		if(peekc() != '[')
			return mkFetch(FBody, f);
		f = mkFetch(FBodySect, f);
	}else if(cistrcmp(s, "body.peek") == 0)
		f = mkFetch(FBodyPeek, f);
	else
		parseErr("illegal fetch attribute");

	mustBe('[');
	c = peekc();
	if(c >= '1' && c <= '9'){
		sect = mkNList(number(1), nil);
		while(peekc() == '.'){
			getc();
			c = peekc();
			if(c >= '1' && c <= '9'){
				sect = mkNList(number(1), sect);
			}else{
				break;
			}
		}
		f->sect = revNList(sect);
	}
	if(peekc() != ']')
		sectText(f, f->sect != nil);
	mustBe(']');

	if(peekc() != '<')
		return f;

	f->partial = 1;
	mustBe('<');
	f->start = number(0);
	mustBe('.');
	f->size = number(1);
	mustBe('>');
	return f;
}

/*
 * sectText	: sectMsgText | "MIME"
 * sectMsgText	: "HEADER"
 *		| "TEXT"
 *		| "HEADER.FIELDS" ' ' hdrList
 *		| "HEADER.FIELDS.NOT" ' ' hdrList
 * hdrList	: '(' hdrs ')'
 * hdrs:	: astring
 *		| hdrs ' ' astring
 */
static void
sectText(Fetch *f, int mimeOk)
{
	SList *h;
	char *s;

	s = atomString(fetchAtom, "");
	if(cistrcmp(s, "header") == 0){
		f->part = FPHead;
		return;
	}
	if(cistrcmp(s, "text") == 0){
		f->part = FPText;
		return;
	}
	if(mimeOk && cistrcmp(s, "mime") == 0){
		f->part = FPMime;
		return;
	}
	if(cistrcmp(s, "header.fields") == 0)
		f->part = FPHeadFields;
	else if(cistrcmp(s, "header.fields.not") == 0)
		f->part = FPHeadFieldsNot;
	else
		parseErr("illegal fetch section text");
	mustBe(' ');
	mustBe('(');
	h = nil;
	for(;;){
		h = mkSList(astring(), h);
		if(peekc() == ')')
			break;
		mustBe(' ');
	}
	mustBe(')');
	f->hdrs = revSList(h);
}

/*
 * searchWhat	: "CHARSET" ' ' astring searchkeys | searchkeys
 * searchkeys	: searchkey | searchkeys ' ' searchkey
 * searchkey	: "ALL" | "ANSWERED" | "DELETED" | "FLAGGED" | "NEW" | "OLD" | "RECENT"
 *		| "SEEN" | "UNANSWERED" | "UNDELETED" | "UNFLAGGED" | "DRAFT" | "UNDRAFT"
 *		| astrkey ' ' astring
 *		| datekey ' ' date
 *		| "KEYWORD" ' ' flag | "UNKEYWORD" flag
 *		| "LARGER" ' ' number | "SMALLER" ' ' number
 * 		| "HEADER" astring ' ' astring
 *		| set | "UID" ' ' set
 *		| "NOT" ' ' searchkey
 *		| "OR" ' ' searchkey ' ' searchkey
 *		| '(' searchkeys ')'
 * astrkey	: "BCC" | "BODY" | "CC" | "FROM" | "SUBJECT" | "TEXT" | "TO"
 * datekey	: "BEFORE" | "ON" | "SINCE" | "SENTBEFORE" | "SENTON" | "SENTSINCE"
 */
static NamedInt searchMap[] =
{
	{"ALL",		SKAll},
	{"ANSWERED",	SKAnswered},
	{"DELETED",	SKDeleted},
	{"FLAGGED",	SKFlagged},
	{"NEW",		SKNew},
	{"OLD",		SKOld},
	{"RECENT",	SKRecent},
	{"SEEN",	SKSeen},
	{"UNANSWERED",	SKUnanswered},
	{"UNDELETED",	SKUndeleted},
	{"UNFLAGGED",	SKUnflagged},
	{"DRAFT",	SKDraft},
	{"UNDRAFT",	SKUndraft},
	{"UNSEEN",	SKUnseen},
	{nil,		0}
};

static NamedInt searchMapStr[] =
{
	{"CHARSET",	SKCharset},
	{"BCC",		SKBcc},
	{"BODY",	SKBody},
	{"CC",		SKCc},
	{"FROM",	SKFrom},
	{"SUBJECT",	SKSubject},
	{"TEXT",	SKText},
	{"TO",		SKTo},
	{nil,		0}
};

static NamedInt searchMapDate[] =
{
	{"BEFORE",	SKBefore},
	{"ON",		SKOn},
	{"SINCE",	SKSince},
	{"SENTBEFORE",	SKSentBefore},
	{"SENTON",	SKSentOn},
	{"SENTSINCE",	SKSentSince},
	{nil,		0}
};

static NamedInt searchMapFlag[] =
{
	{"KEYWORD",	SKKeyword},
	{"UNKEYWORD",	SKUnkeyword},
	{nil,		0}
};

static NamedInt searchMapNum[] =
{
	{"SMALLER",	SKSmaller},
	{"LARGER",	SKLarger},
	{nil,		0}
};

static Search*
searchKeys(int first, Search *tail)
{
	Search *s;

	for(;;){
		if(peekc() == '('){
			getc();
			tail = searchKeys(0, tail);
			mustBe(')');
		}else{
			s = searchKey(first);
			tail->next = s;
			tail = s;
		}
		first = 0;
		if(peekc() != ' ')
			break;
		getc();
	}
	return tail;
}

static Search*
searchKey(int first)
{
	Search *sr, rock;
	Tm tm;
	char *a;
	int i, c;

	sr = binalloc(&parseBin, sizeof(Search), 1);
	if(sr == nil)
		parseErr("out of memory");

	c = peekc();
	if(c >= '0' && c <= '9'){
		sr->key = SKSet;
		sr->set = msgSet(0);
		return sr;
	}

	a = atom();
	if(i = mapInt(searchMap, a))
		sr->key = i;
	else if(i = mapInt(searchMapStr, a)){
		if(!first && i == SKCharset)
			parseErr("illegal search key");
		sr->key = i;
		mustBe(' ');
		sr->s = astring();
	}else if(i = mapInt(searchMapDate, a)){
		sr->key = i;
		mustBe(' ');
		c = peekc();
		if(c == '"')
			getc();
		a = atom();
		if(!imap4Date(&tm, a))
			parseErr("bad date format");
		sr->year = tm.year;
		sr->mon = tm.mon;
		sr->mday = tm.mday;
		if(c == '"')
			mustBe('"');
	}else if(i = mapInt(searchMapFlag, a)){
		sr->key = i;
		mustBe(' ');
		c = peekc();
		if(c == '\\'){
			mustBe('\\');
			a = atomString(atomStop, "\\");
		}else
			a = atom();
		i = mapFlag(a);
		if(i == 0)
			parseErr("flag not supported");
		sr->num = i;
	}else if(i = mapInt(searchMapNum, a)){
		sr->key = i;
		mustBe(' ');
		sr->num = number(0);
	}else if(cistrcmp(a, "HEADER") == 0){
		sr->key = SKHeader;
		mustBe(' ');
		sr->hdr = astring();
		mustBe(' ');
		sr->s = astring();
	}else if(cistrcmp(a, "UID") == 0){
		sr->key = SKUid;
		mustBe(' ');
		sr->set = msgSet(0);
	}else if(cistrcmp(a, "NOT") == 0){
		sr->key = SKNot;
		mustBe(' ');
		rock.next = nil;
		searchKeys(0, &rock);
		sr->left = rock.next;
	}else if(cistrcmp(a, "OR") == 0){
		sr->key = SKOr;
		mustBe(' ');
		rock.next = nil;
		searchKeys(0, &rock);
		sr->left = rock.next;
		mustBe(' ');
		rock.next = nil;
		searchKeys(0, &rock);
		sr->right = rock.next;
	}else
		parseErr("illegal search key");
	return sr;
}

/*
 * set	: seqno
 *	| seqno ':' seqno
 *	| set ',' set
 * seqno: nz-number
 *	| '*'
 *
 */
static MsgSet*
msgSet(int uids)
{
	MsgSet head, *last, *ms;
	ulong from, to;

	last = &head;
	head.next = nil;
	for(;;){
		from = uids ? uidNo() : seqNo();
		to = from;
		if(peekc() == ':'){
			getc();
			to = uids ? uidNo() : seqNo();
		}
		ms = binalloc(&parseBin, sizeof(MsgSet), 0);
		if(ms == nil)
			parseErr("out of memory");
		ms->from = from;
		ms->to = to;
		ms->next = nil;
		last->next = ms;
		last = ms;
		if(peekc() != ',')
			break;
		getc();
	}
	return head.next;
}

static ulong
seqNo(void)
{
	if(peekc() == '*'){
		getc();
		return ~0UL;
	}
	return number(1);
}

static ulong
uidNo(void)
{
	if(peekc() == '*'){
		getc();
		return ~0UL;
	}
	return number(0);
}

/*
 * 7 bit, non-ctl chars, no (){%*"\
 * NIL is special case for nstring or parenlist
 */
static char *
atom(void)
{
	return atomString(atomStop, "");
}

/*
 * like an atom, but no +
 */
static char *
tag(void)
{
	return atomString("+(){%*\"\\", "");
}

/*
 * string or atom allowing %*
 */
static char *
listmbox(void)
{
	int c;

	c = peekc();
	if(c == '{')
		return literal();
	if(c == '"')
		return quoted();
	return atomString("(){\"\\", "");
}

/*
 * string or atom
 */
static char *
astring(void)
{
	int c;

	c = peekc();
	if(c == '{')
		return literal();
	if(c == '"')
		return quoted();
	return atom();
}

/*
 * 7 bit, non-ctl chars, none from exception list
 */
static char *
atomString(char *disallowed, char *initial)
{
	char *s;
	int c, ns, as;

	ns = strlen(initial);
	s = binalloc(&parseBin, ns + StrAlloc, 0);
	if(s == nil)
		parseErr("out of memory");
	strcpy(s, initial);
	as = ns + StrAlloc;
	for(;;){
		c = getc();
		if(c <= ' ' || c >= 0x7f || strchr(disallowed, c) != nil){
			ungetc();
			break;
		}
		s[ns++] = c;
		if(ns >= as){
			s = bingrow(&parseBin, s, as, as + StrAlloc, 0);
			if(s == nil)
				parseErr("out of memory");
			as += StrAlloc;
		}
	}
	if(ns == 0)
		badsyn();
	s[ns] = '\0';
	return s;
}

/*
 * quoted: '"' chars* '"'
 * chars:	1-128 except \r and \n
 */
static char *
quoted(void)
{
	char *s;
	int c, ns, as;

	mustBe('"');
	s = binalloc(&parseBin, StrAlloc, 0);
	if(s == nil)
		parseErr("out of memory");
	as = StrAlloc;
	ns = 0;
	for(;;){
		c = getc();
		if(c == '"')
			break;
		if(c < 1 || c > 0x7f || c == '\r' || c == '\n')
			badsyn();
		if(c == '\\'){
			c = getc();
			if(c != '\\' && c != '"')
				badsyn();
		}
		s[ns++] = c;
		if(ns >= as){
			s = bingrow(&parseBin, s, as, as + StrAlloc, 0);
			if(s == nil)
				parseErr("out of memory");
			as += StrAlloc;
		}
	}
	s[ns] = '\0';
	return s;
}

/*
 * litlen: {number}\r\n
 */
static ulong
litlen(void)
{
	ulong v;

	mustBe('{');
	v = number(0);
	mustBe('}');
	crnl();
	return v;
}

/*
 * literal: litlen data<0:litlen>
 */
static char *
literal(void)
{
	char *s;
	ulong v;

	v = litlen();
	s = binalloc(&parseBin, v+1, 0);
	if(s == nil)
		parseErr("out of memory");
	Bprint(&bout, "+ Ready for literal data\r\n");
	if(Bflush(&bout) < 0)
		writeErr();
	if(v != 0 && Bread(&bin, s, v) != v)
		badsyn();
	s[v] = '\0';
	return s;
}

/*
 * digits; number is 32 bits
 */
static ulong
number(int nonzero)
{
	ulong v;
	int c, first;

	v = 0;
	first = 1;
	for(;;){
		c = getc();
		if(c < '0' || c > '9'){
			ungetc();
			if(first)
				badsyn();
			break;
		}
		if(nonzero && first && c == '0')
			badsyn();
		c -= '0';
		first = 0;
		if(v > UlongMax/10 || v == UlongMax/10 && c > UlongMax%10)
			parseErr("number out of range\r\n");
		v = v * 10 + c;
	}
	return v;
}

static int
getc(void)
{
	return Bgetc(&bin);
}

static void
ungetc(void)
{
	Bungetc(&bin);
}

static int
peekc(void)
{
	int c;

	c = Bgetc(&bin);
	Bungetc(&bin);
	return c;
}