Initial checkin

Imported from subversion report, converted to git. Updated all paths in
scripts and makefiles, reflecting the new directory hierarchy.

1 files changed, 1059 insertions, 0 deletions

diff --git a/rfc822/imaprefs.c b/rfc822/imaprefs.c
new file mode 100644
index 0000000..dc58869
--- /dev/null
+++ b/rfc822/imaprefs.c
@@ -0,0 +1,1059 @@
+/*
+** Copyright 2000-2003 Double Precision, Inc.
+** See COPYING for distribution information.
+*/
+
+/*
+*/
+
+#include	"config.h"
+
+#include	<stdio.h>
+#include	<stdlib.h>
+#include	<string.h>
+#include	<time.h>
+
+#include	"rfc822.h"
+#include	"imaprefs.h"
+
+static void swapmsgdata(struct imap_refmsg *a, struct imap_refmsg *b)
+{
+	char *cp;
+	char c;
+	time_t t;
+	unsigned long ul;
+
+#define swap(a,b,tmp) (tmp)=(a); (a)=(b); (b)=(tmp);
+
+	swap(a->msgid, b->msgid, cp);
+	swap(a->isdummy, b->isdummy, c);
+	swap(a->flag2, b->flag2, c);
+
+	swap(a->timestamp, b->timestamp, t);
+	swap(a->seqnum, b->seqnum, ul);
+
+#undef	swap
+}
+
+struct imap_refmsgtable *rfc822_threadalloc()
+{
+struct imap_refmsgtable *p;
+
+	p=(struct imap_refmsgtable *)malloc(sizeof(struct imap_refmsgtable));
+	if (p)
+		memset(p, 0, sizeof(*p));
+	return (p);
+}
+
+void rfc822_threadfree(struct imap_refmsgtable *p)
+{
+int i;
+struct imap_refmsghash *h;
+struct imap_subjlookup *s;
+struct imap_refmsg *m;
+
+	for (i=0; i<sizeof(p->hashtable)/sizeof(p->hashtable[0]); i++)
+		while ((h=p->hashtable[i]) != 0)
+		{
+			p->hashtable[i]=h->nexthash;
+			free(h);
+		}
+
+	for (i=0; i<sizeof(p->subjtable)/sizeof(p->subjtable[0]); i++)
+		while ((s=p->subjtable[i]) != 0)
+		{
+			p->subjtable[i]=s->nextsubj;
+			free(s->subj);
+			free(s);
+		}
+
+	while ((m=p->firstmsg) != 0)
+	{
+		p->firstmsg=m->next;
+		if (m->subj)
+			free(m->subj);
+		free(m);
+	}
+	free(p);
+}
+
+static int hashmsgid(const char *msgid)
+{
+unsigned long hashno=0;
+
+	while (*msgid)
+	{
+	unsigned long n= (hashno << 1);
+
+#define	HMIDS	(((struct imap_refmsgtable *)0)->hashtable)
+#define	HHMIDSS	( sizeof(HMIDS) / sizeof( HMIDS[0] ))
+
+		if (hashno & HHMIDSS )
+			n ^= 1;
+
+		hashno= n ^ (unsigned char)*msgid++;
+	}
+
+	return (hashno % HHMIDSS);
+}
+
+struct imap_refmsg *rfc822_threadallocmsg(struct imap_refmsgtable *mt,
+					  const char *msgid)
+{
+int n=hashmsgid(msgid);
+struct imap_refmsg *msgp= (struct imap_refmsg *)
+	malloc(sizeof(struct imap_refmsg)+1+strlen(msgid));
+struct imap_refmsghash *h, **hp;
+
+	if (!msgp)	return (0);
+	memset(msgp, 0, sizeof(*msgp));
+	strcpy ((msgp->msgid=(char *)(msgp+1)), msgid);
+
+	h=(struct imap_refmsghash *)malloc(sizeof(struct imap_refmsghash));
+	if (!h)
+	{
+		free(msgp);
+		return (0);
+	}
+
+	for (hp= &mt->hashtable[n]; *hp; hp= & (*hp)->nexthash)
+	{
+		if (strcmp( (*hp)->msg->msgid, msgp->msgid) > 0)
+			break;
+	}
+
+	h->nexthash= *hp;
+	*hp=h;
+	h->msg=msgp;
+
+	msgp->last=mt->lastmsg;
+
+	if (mt->lastmsg)
+		mt->lastmsg->next=msgp;
+	else
+		mt->firstmsg=msgp;
+
+	mt->lastmsg=msgp;
+	return (msgp);
+}
+
+struct imap_refmsg *rfc822_threadsearchmsg(struct imap_refmsgtable *mt,
+					   const char *msgid)
+{
+int n=hashmsgid(msgid);
+struct imap_refmsghash *h;
+
+	for (h= mt->hashtable[n]; h; h= h->nexthash)
+	{
+	int	rc=strcmp(h->msg->msgid, msgid);
+
+		if (rc == 0)	return (h->msg);
+		if (rc > 0)
+			break;
+	}
+	return (0);
+}
+
+static int findsubj(struct imap_refmsgtable *mt, const char *s, int *isrefwd,
+		    int create, struct imap_subjlookup **ptr)
+{
+	char *ss=rfc822_coresubj(s, isrefwd);
+	int n;
+	struct imap_subjlookup **h;
+	struct imap_subjlookup *newsubj;
+
+	if (!ss)	return (-1);
+	n=hashmsgid(ss);
+
+	for (h= &mt->subjtable[n]; *h; h= &(*h)->nextsubj)
+	{
+	int	rc=strcmp((*h)->subj, ss);
+
+		if (rc == 0)
+		{
+			free(ss);
+			*ptr= *h;
+			return (0);
+		}
+		if (rc > 0)
+			break;
+	}
+	if (!create)
+	{
+		free(ss);
+		*ptr=0;
+		return (0);
+	}
+
+	newsubj=malloc(sizeof(struct imap_subjlookup));
+	if (!newsubj)
+	{
+		free(ss);
+		return (-1);
+	}
+	memset(newsubj, 0, sizeof(*newsubj));
+	newsubj->subj=ss;
+	newsubj->nextsubj= *h;
+	newsubj->msgisrefwd= *isrefwd;
+	*h=newsubj;
+	*ptr=newsubj;
+	return (0);
+}
+
+static void linkparent(struct imap_refmsg *msg, struct imap_refmsg *lastmsg)
+{
+	msg->parent=lastmsg;
+	msg->prevsib=lastmsg->lastchild;
+	if (msg->prevsib)
+		msg->prevsib->nextsib=msg;
+	else
+		lastmsg->firstchild=msg;
+
+	lastmsg->lastchild=msg;
+	msg->nextsib=0;
+}
+
+
+static void breakparent(struct imap_refmsg *m)
+{
+	if (!m->parent)	return;
+
+	if (m->prevsib)	m->prevsib->nextsib=m->nextsib;
+	else		m->parent->firstchild=m->nextsib;
+
+	if (m->nextsib)	m->nextsib->prevsib=m->prevsib;
+	else		m->parent->lastchild=m->prevsib;
+	m->parent=0;
+}
+
+static struct imap_refmsg *dorefcreate(struct imap_refmsgtable *mt,
+				       const char *newmsgid,
+				       struct rfc822a *a)
+     /* a - references header */
+{
+struct imap_refmsg *lastmsg=0, *m;
+struct imap_refmsg *msg;
+int n;
+
+/*
+            (A) Using the Message-IDs in the message's references, link
+            the corresponding messages together as parent/child.  Make
+            the first reference the parent of the second (and the second
+            a child of the first), the second the parent of the third
+            (and the third a child of the second), etc.  The following
+            rules govern the creation of these links:
+
+               If no reference message can be found with a given
+               Message-ID, create a dummy message with this ID.  Use
+               this dummy message for all subsequent references to this
+               ID.
+*/
+
+	for (n=0; n<a->naddrs; n++)
+	{
+		char *msgid=a->addrs[n].tokens ? rfc822_getaddr(a, n):NULL;
+
+		msg=msgid ? rfc822_threadsearchmsg(mt, msgid):0;
+		if (!msg)
+		{
+			msg=rfc822_threadallocmsg(mt, msgid ? msgid:"");
+			if (!msg)
+			{
+				if (msgid)
+					free(msgid);
+
+				return (0);
+			}
+			msg->isdummy=1;
+		}
+
+		if (msgid)
+			free(msgid);
+
+/*
+               If a reference message already has a parent, don't change
+               the existing link.
+*/
+
+		if (lastmsg == 0 || msg->parent)
+		{
+			lastmsg=msg;
+			continue;
+		}
+
+/*
+               Do not create a parent/child link if creating that link
+               would introduce a loop.  For example, before making
+               message A the parent of B, make sure that A is not a
+               descendent of B.
+
+*/
+
+		for (m=lastmsg; m; m=m->parent)
+			if (strcmp(m->msgid, msg->msgid) == 0)
+				break;
+		if (m)
+		{
+			lastmsg=msg;
+			continue;
+		}
+
+		linkparent(msg, lastmsg);
+
+		lastmsg=msg;
+	}
+
+/*
+            (B) Create a parent/child link between the last reference
+            (or NIL if there are no references) and the current message.
+            If the current message has a parent already, break the
+            current parent/child link before creating the new one.  Note
+            that if this message has no references, that it will now
+            have no parent.
+
+               NOTE: The parent/child links MUST be kept consistent with
+               one another at ALL times.
+
+*/
+
+	msg=*newmsgid ? rfc822_threadsearchmsg(mt, newmsgid):0;
+
+	/*
+	       If a message does not contain a Message-ID header line,
+	       or the Message-ID header line does not contain a valid
+	       Message ID, then assign a unique Message ID to this
+	       message.
+
+	       Implementation note: empty msgid, plus dupe check below,
+	       implements that.
+	*/
+
+	if (msg && msg->isdummy)
+	{
+		msg->isdummy=0;
+		if (msg->parent)
+			breakparent(msg);
+	}
+	else
+	{
+#if 1
+		/*
+		** If two or more messages have the same Message ID, assign
+		** a unique Message ID to each of the duplicates.
+		**
+		** Implementation note: just unlink the existing message from
+		** it's parents/children.
+		*/
+		if (msg)
+		{
+			while (msg->firstchild)
+				breakparent(msg->firstchild);
+			breakparent(msg);
+			newmsgid="";
+
+			/* Create new entry with an empty msgid, if any more
+			** msgids come, they'll hit the dupe check again.
+			*/
+
+		}
+#endif
+		msg=rfc822_threadallocmsg(mt, newmsgid);
+		if (!msg)	return (0);
+	}
+
+	if (lastmsg)
+	{
+		for (m=lastmsg; m; m=m->parent)
+			if (strcmp(m->msgid, msg->msgid) == 0)
+				break;
+		if (!m)
+			linkparent(msg, lastmsg);
+	}
+	return (msg);
+}
+
+static struct imap_refmsg *threadmsg_common(struct imap_refmsg *m,
+					    const char *subjheader,
+					    const char *dateheader,
+					    time_t dateheader_tm,
+					    unsigned long seqnum);
+
+static struct imap_refmsg *rfc822_threadmsgaref(struct imap_refmsgtable *mt,
+					       const char *msgidhdr,
+					       struct rfc822a *refhdr,
+					       const char *subjheader,
+					       const char *dateheader,
+					       time_t dateheader_tm,
+					       unsigned long seqnum);
+
+struct imap_refmsg *rfc822_threadmsg(struct imap_refmsgtable *mt,
+				     const char *msgidhdr,
+				     const char *refhdr,
+				     const char *subjheader,
+				     const char *dateheader,
+				     time_t dateheader_tm,
+				     unsigned long seqnum)
+{
+	struct rfc822t *t;
+	struct rfc822a *a;
+	struct imap_refmsg *m;
+
+	t=rfc822t_alloc_new(refhdr ? refhdr:"", NULL, NULL);
+	if (!t)
+	{
+		return (0);
+	}
+
+	a=rfc822a_alloc(t);
+	if (!a)
+	{
+		rfc822t_free(t);
+		return (0);
+	}
+
+	m=rfc822_threadmsgaref(mt, msgidhdr, a, subjheader, dateheader,
+			       dateheader_tm, seqnum);
+
+	rfc822a_free(a);
+	rfc822t_free(t);
+	return m;
+}
+
+
+struct imap_refmsg *rfc822_threadmsgrefs(struct imap_refmsgtable *mt,
+					 const char *msgid_s,
+					 const char * const * msgidList,
+					 const char *subjheader,
+					 const char *dateheader,
+					 time_t dateheader_tm,
+					 unsigned long seqnum)
+{
+	struct imap_refmsg *m;
+	struct rfc822token *tArray;
+	struct rfc822addr *aArray;
+
+	struct rfc822a a;
+	size_t n, i;
+
+	for (n=0; msgidList[n]; n++)
+		;
+
+	if ((tArray=malloc((n+1) * sizeof(*tArray))) == NULL)
+		return NULL;
+
+	if ((aArray=malloc((n+1) * sizeof(*aArray))) == NULL)
+	{
+		free(tArray);
+		return NULL;
+	}
+
+	for (i=0; i<n; i++)
+	{
+		tArray[i].next=NULL;
+		tArray[i].token=0;
+		tArray[i].ptr=msgidList[i];
+		tArray[i].len=strlen(msgidList[i]);
+
+		aArray[i].name=NULL;
+		aArray[i].tokens=&tArray[i];
+	}
+
+	a.naddrs=n;
+	a.addrs=aArray;
+
+	m=rfc822_threadmsgaref(mt, msgid_s, &a, subjheader, dateheader,
+			       dateheader_tm, seqnum);
+
+	free(tArray);
+	free(aArray);
+	return m;
+}
+
+static struct imap_refmsg *rfc822_threadmsgaref(struct imap_refmsgtable *mt,
+						const char *msgidhdr,
+						struct rfc822a *refhdr,
+						const char *subjheader,
+						const char *dateheader,
+						time_t dateheader_tm,
+						unsigned long seqnum)
+{
+	struct rfc822t *t;
+	struct rfc822a *a;
+	struct imap_refmsg *m;
+
+	char *msgid_s;
+
+	t=rfc822t_alloc_new(msgidhdr ? msgidhdr:"", NULL, NULL);
+	if (!t)
+		return (0);
+	a=rfc822a_alloc(t);
+	if (!a)
+	{
+		rfc822t_free(t);
+		return (0);
+	}
+
+	msgid_s=a->naddrs > 0 ? rfc822_getaddr(a, 0):strdup("");
+
+	rfc822a_free(a);
+	rfc822t_free(t);
+
+	if (!msgid_s)
+		return (0);
+
+	m=dorefcreate(mt, msgid_s, refhdr);
+
+	free(msgid_s);
+
+	if (!m)
+		return (0);
+
+
+	return threadmsg_common(m, subjheader, dateheader,
+				dateheader_tm, seqnum);
+}
+
+static struct imap_refmsg *threadmsg_common(struct imap_refmsg *m,
+					    const char *subjheader,
+					    const char *dateheader,
+					    time_t dateheader_tm,
+					    unsigned long seqnum)
+{
+	if (subjheader && (m->subj=strdup(subjheader)) == 0)
+		return (0);	/* Cleanup in rfc822_threadfree() */
+
+	if (dateheader)
+		dateheader_tm=rfc822_parsedt(dateheader);
+
+	m->timestamp=dateheader_tm;
+
+	m->seqnum=seqnum;
+
+	return (m);
+}
+
+/*
+         (2) Gather together all of the messages that have no parents
+         and make them all children (siblings of one another) of a dummy
+         parent (the "root").  These messages constitute first messages
+         of the threads created thus far.
+
+*/
+
+struct imap_refmsg *rfc822_threadgetroot(struct imap_refmsgtable *mt)
+{
+	struct imap_refmsg *root, *m;
+
+	if (mt->rootptr)
+		return (mt->rootptr);
+
+	root=rfc822_threadallocmsg(mt, "(root)");
+
+	if (!root)	return (0);
+
+	root->parent=root;	/* Temporary */
+	root->isdummy=1;
+
+	for (m=mt->firstmsg; m; m=m->next)
+		if (!m->parent)
+		{
+			if (m->isdummy && m->firstchild == 0)
+				continue; /* Can happen in reference creation */
+
+			linkparent(m, root);
+		}
+	root->parent=NULL;
+	return (mt->rootptr=root);
+}
+
+/*
+** 
+**       (3) Prune dummy messages from the thread tree.  Traverse each
+**        thread under the root, and for each message:
+*/
+
+void rfc822_threadprune(struct imap_refmsgtable *mt)
+{
+	struct imap_refmsg *msg;
+
+	for (msg=mt->firstmsg; msg; msg=msg->next)
+	{
+		struct imap_refmsg *saveparent, *m;
+
+		if (!msg->parent)
+			continue;	/* The root, need it later. */
+
+		if (!msg->isdummy)
+			continue;
+
+		/*
+		**
+		** If it is a dummy message with NO children, delete it.
+		*/
+
+		if (msg->firstchild == 0)
+		{
+			breakparent(msg);
+			/*
+			** Don't free the node, it'll be done on msgtable
+			** purge.
+			*/
+			continue;
+		}
+
+		/*
+		** If it is a dummy message with children, delete it, but
+		** promote its children to the current level.  In other words,
+		** splice them in with the dummy's siblings.
+		**
+		** Do not promote the children if doing so would make them
+		** children of the root, unless there is only one child.
+		*/
+
+		if (msg->firstchild->nextsib &&
+		    msg->parent->parent)
+			continue;
+
+		saveparent=msg->parent;
+		breakparent(msg);
+
+		while ((m=msg->firstchild) != 0)
+		{
+			breakparent(m);
+			linkparent(m, saveparent);
+		}
+	}
+}
+
+static int cmp_msgs(const void *, const void *);
+
+int rfc822_threadsortsubj(struct imap_refmsg *root)
+{
+	struct imap_refmsg *toproot;
+
+/*
+** (4) Sort the messages under the root (top-level siblings only)
+** by sent date.  In the case of an exact match on sent date or if
+** either of the Date: headers used in a comparison can not be
+** parsed, use the order in which the messages appear in the
+** mailbox (that is, by sequence number) to determine the order.
+** In the case of a dummy message, sort its children by sent date
+** and then use the first child for the top-level sort.
+*/
+	size_t cnt, i;
+	struct imap_refmsg **sortarray;
+
+	for (cnt=0, toproot=root->firstchild; toproot;
+	     toproot=toproot->nextsib)
+	{
+		if (toproot->isdummy)
+			rfc822_threadsortsubj(toproot);
+		++cnt;
+	}
+
+	if ((sortarray=malloc(sizeof(struct imap_refmsg *)*(cnt+1))) == 0)
+		return (-1);
+
+	for (cnt=0; (toproot=root->firstchild) != NULL; ++cnt)
+	{
+		sortarray[cnt]=toproot;
+		breakparent(toproot);
+	}
+
+	qsort(sortarray, cnt, sizeof(*sortarray), cmp_msgs);
+
+	for (i=0; i<cnt; i++)
+		linkparent(sortarray[i], root);
+	free(sortarray);
+	return (0);
+}
+
+int rfc822_threadgathersubj(struct imap_refmsgtable *mt,
+			    struct imap_refmsg *root)
+{
+	struct imap_refmsg *toproot, *p;
+
+/*
+** (5) Gather together messages under the root that have the same
+** extracted subject text.
+**
+** (A) Create a table for associating extracted subjects with
+** messages.
+**
+** (B) Populate the subject table with one message per
+** extracted subject.  For each message under the root:
+*/
+
+	for (toproot=root->firstchild; toproot; toproot=toproot->nextsib)
+	{
+		const char *subj;
+		struct imap_subjlookup *subjtop;
+		int isrefwd;
+
+		/*
+		** (i) Find the subject of this thread by extracting the
+		** base subject from the current message, or its first child
+		** if the current message is a dummy.
+		*/
+
+		p=toproot;
+		if (p->isdummy)
+			p=p->firstchild;
+
+		subj=p->subj ? p->subj:"";
+
+
+		/*
+		** (ii) If the extracted subject is empty, skip this
+		** message.
+		*/
+
+		if (*subj == 0)
+			continue;
+
+		/*
+		** (iii) Lookup the message associated with this extracted
+		** subject in the table.
+		*/
+
+		if (findsubj(mt, subj, &isrefwd, 1, &subjtop))
+			return (-1);
+
+		/*
+		**
+		** (iv) If there is no message in the table with this
+		** subject, add the current message and the extracted
+		** subject to the subject table.
+		*/
+
+		if (subjtop->msg == 0)
+		{
+			subjtop->msg=toproot;
+			subjtop->msgisrefwd=isrefwd;
+			continue;
+		}
+
+		/*
+		** Otherwise, replace the message in the table with the
+		** current message if the message in the table is not a
+		** dummy AND either of the following criteria are true:
+		*/
+
+		if (!subjtop->msg->isdummy)
+		{
+			/*
+			** The current message is a dummy
+			**
+			*/
+
+			if (toproot->isdummy)
+			{
+				subjtop->msg=toproot;
+				subjtop->msgisrefwd=isrefwd;
+				continue;
+			}
+
+			/*
+			** The message in the table is a reply or forward (its
+			** original subject contains a subj-refwd part and/or a
+			** "(fwd)" subj-trailer) and the current message is
+			not.
+			*/
+
+			if (subjtop->msgisrefwd && !isrefwd)
+			{
+				subjtop->msg=toproot;
+				subjtop->msgisrefwd=isrefwd;
+			}
+		}
+	}
+	return (0);
+}
+
+/*
+** (C) Merge threads with the same subject.  For each message
+** under the root:
+*/
+
+int rfc822_threadmergesubj(struct imap_refmsgtable *mt,
+			   struct imap_refmsg *root)
+{
+	struct imap_refmsg *toproot, *p, *q, *nextroot;
+	char *str;
+
+	for (toproot=root->firstchild; toproot; toproot=nextroot)
+	{
+		const char *subj;
+		struct imap_subjlookup *subjtop;
+		int isrefwd;
+
+		nextroot=toproot->nextsib;
+
+		/*
+		** (i) Find the subject of this thread as in step 4.B.i
+		** above.
+		*/
+
+		p=toproot;
+		if (p->isdummy)
+			p=p->firstchild;
+
+		subj=p->subj ? p->subj:"";
+
+		/*
+		** (ii) If the extracted subject is empty, skip this
+		** message.
+		*/
+
+		if (*subj == 0)
+			continue;
+
+		/*
+		** (iii) Lookup the message associated with this extracted
+		** subject in the table.
+		*/
+
+		if (findsubj(mt, subj, &isrefwd, 0, &subjtop) || subjtop == 0)
+			return (-1);
+
+		/*
+		** (iv) If the message in the table is the current message,
+		** skip it.
+		*/
+
+		/* NOTE - ptr comparison IS NOT LEGAL */
+
+		subjtop->msg->flag2=1;
+		if (toproot->flag2)
+		{
+			toproot->flag2=0;
+			continue;
+		}
+		subjtop->msg->flag2=0;
+
+		/*
+		** Otherwise, merge the current message with the one in the
+		** table using the following rules:
+		**
+		** If both messages are dummies, append the current
+		** message's children to the children of the message in
+		** the table (the children of both messages become
+		** siblings), and then delete the current message.
+		*/
+
+		if (subjtop->msg->isdummy && toproot->isdummy)
+		{
+			while ((p=toproot->firstchild) != 0)
+			{
+				breakparent(p);
+				linkparent(p, subjtop->msg);
+			}
+			breakparent(toproot);
+			continue;
+		}
+
+		/*
+		** If the message in the table is a dummy and the current
+		** message is not, make the current message a child of
+		** the message in the table (a sibling of it's children).
+		*/
+
+		if (subjtop->msg->isdummy)
+		{
+			breakparent(toproot);
+			linkparent(toproot, subjtop->msg);
+			continue;
+		}
+
+		/*
+		** If the current message is a reply or forward and the
+		** message in the table is not, make the current message
+		** a child of the message in the table (a sibling of it's
+		** children).
+		*/
+
+		if (isrefwd)
+		{
+			p=subjtop->msg;
+			if (p->isdummy)
+				p=p->firstchild;
+
+			subj=p->subj ? p->subj:"";
+
+			str=rfc822_coresubj(subj, &isrefwd);
+
+			if (!str)
+				return (-1);
+			free(str);	/* Don't really care */
+
+			if (!isrefwd)
+			{
+				breakparent(toproot);
+				linkparent(toproot, subjtop->msg);
+				continue;
+			}
+		}
+
+		/*
+		** Otherwise, create a new dummy container and make both
+		** messages children of the dummy, and replace the
+		** message in the table with the dummy message.
+		*/
+
+		/* What we do is create a new message, then move the
+		** contents of subjtop->msg (including its children)
+		** to the new message, then make the new message a child
+		** of subjtop->msg, and mark subjtop->msg as a dummy msg.
+		*/
+
+		q=rfc822_threadallocmsg(mt, "(dummy)");
+		if (!q)
+			return (-1);
+
+		q->isdummy=1;
+
+		swapmsgdata(q, subjtop->msg);
+
+		while ((p=subjtop->msg->firstchild) != 0)
+		{
+			breakparent(p);
+			linkparent(p, q);
+		}
+		linkparent(q, subjtop->msg);
+
+		breakparent(toproot);
+		linkparent(toproot, subjtop->msg);
+	}
+	return (0);
+}
+
+/*
+** (6) Traverse the messages under the root and sort each set of
+** siblings by sent date.  Traverse the messages in such a way
+** that the "youngest" set of siblings are sorted first, and the
+** "oldest" set of siblings are sorted last (grandchildren are
+** sorted before children, etc).  In the case of an exact match on
+** sent date or if either of the Date: headers used in a
+** comparison can not be parsed, use the order in which the
+** messages appear in the mailbox (that is, by sequence number) to
+** determine the order.  In the case of a dummy message (which can
+** only occur with top-level siblings), use its first child for
+** sorting.
+*/
+
+static int cmp_msgs(const void *a, const void *b)
+{
+	struct imap_refmsg *ma=*(struct imap_refmsg **)a;
+	struct imap_refmsg *mb=*(struct imap_refmsg **)b;
+	time_t ta, tb;
+	unsigned long na, nb;
+
+	while (ma && ma->isdummy)
+		ma=ma->firstchild;
+
+	while (mb && mb->isdummy)
+		mb=mb->firstchild;
+
+	ta=tb=0;
+	na=nb=0;
+	if (ma)
+	{
+		ta=ma->timestamp;
+		na=ma->seqnum;
+	}
+	if (mb)
+	{
+		tb=mb->timestamp;
+		nb=mb->seqnum;
+	}
+
+	return (ta && tb && ta != tb ? ta < tb ? -1: 1:
+		na < nb ? -1: na > nb ? 1:0);
+}
+
+struct imap_threadsortinfo {
+	struct imap_refmsgtable *mt;
+	struct imap_refmsg **sort_table;
+	size_t sort_table_cnt;
+} ;
+
+static int dothreadsort(struct imap_threadsortinfo *,
+			struct imap_refmsg *);
+
+int rfc822_threadsortbydate(struct imap_refmsgtable *mt)
+{
+	struct imap_threadsortinfo itsi;
+	int rc;
+
+	itsi.mt=mt;
+	itsi.sort_table=0;
+	itsi.sort_table_cnt=0;
+
+	rc=dothreadsort(&itsi, mt->rootptr);
+
+	if (itsi.sort_table)
+		free(itsi.sort_table);
+	return (rc);
+}
+
+static int dothreadsort(struct imap_threadsortinfo *itsi,
+			struct imap_refmsg *p)
+{
+	struct imap_refmsg *q;
+	size_t i, n;
+
+	for (q=p->firstchild; q; q=q->nextsib)
+		dothreadsort(itsi, q);
+
+	n=0;
+	for (q=p->firstchild; q; q=q->nextsib)
+		++n;
+
+	if (n > itsi->sort_table_cnt)
+	{
+		struct imap_refmsg **new_array=(struct imap_refmsg **)
+			(itsi->sort_table ?
+			 realloc(itsi->sort_table,
+				 sizeof(struct imap_refmsg *)*n)
+			 :malloc(sizeof(struct imap_refmsg *)*n));
+
+		if (!new_array)
+			return (-1);
+
+		itsi->sort_table=new_array;
+		itsi->sort_table_cnt=n;
+	}
+
+	n=0;
+	while ((q=p->firstchild) != 0)
+	{
+		breakparent(q);
+		itsi->sort_table[n++]=q;
+	}
+
+	qsort(itsi->sort_table, n, sizeof(struct imap_refmsg *), cmp_msgs);
+
+	for (i=0; i<n; i++)
+		linkparent(itsi->sort_table[i], p);
+	return (0);
+}
+
+struct imap_refmsg *rfc822_thread(struct imap_refmsgtable *mt)
+{
+	if (!mt->rootptr)
+	{
+		rfc822_threadprune(mt);
+		if ((mt->rootptr=rfc822_threadgetroot(mt)) == 0)
+			return (0);
+		if (rfc822_threadsortsubj(mt->rootptr) ||
+		    rfc822_threadgathersubj(mt, mt->rootptr) ||
+		    rfc822_threadmergesubj(mt, mt->rootptr) ||
+		    rfc822_threadsortbydate(mt))
+		{
+			mt->rootptr=0;
+			return (0);
+		}
+	}
+
+	return (mt->rootptr);
+}