X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;f=uid.c;h=8a775b9c63f48b60997f834f2d0f4f86f92bbe20;hb=91644ff0b2e6eb3b26c5544a4a769ca4aaf08a14;hp=6bf4bf1028e527abab06a07c32b50c28ecb250e7;hpb=17c363ec5e29760a99502afd70769d6a4c7ae63e;p=~andy%2Ffetchmail

diff --git a/uid.c b/uid.c
index 6bf4bf10..8a775b9c 100644
--- a/uid.c
+++ b/uid.c
@@ -1,11 +1,13 @@
-/*
- * uid.c -- UIDL handling for POP3 servers without LAST
+/**
+ * \file uid.c -- UIDL handling for POP3 servers without LAST
  *
  * For license terms, see the file COPYING in this directory.
  */
 
 #include "config.h"
 
+#include <sys/stat.h>
+#include <errno.h>
 #include <stdio.h>
 #include <limits.h>
 #if defined(STDC_HEADERS)
@@ -17,11 +19,13 @@
 #endif
 
 #include "fetchmail.h"
+#include "i18n.h"
+#include "sdump.h"
 
 /*
  * Machinery for handling UID lists live here.  This is mainly to support
- * RFC1725-conformant POP3 servers without a LAST command, but may also be
- * useful for making the IMAP4 querying logic UID-oriented, if a future
+ * RFC1725/RFC1939-conformant POP3 servers without a LAST command, but may also
+ * be useful for making the IMAP4 querying logic UID-oriented, if a future
  * revision of IMAP forces me to.
  *
  * These functions are also used by the rest of the code to maintain
@@ -36,7 +40,7 @@
  * This list is initially set up by initialize_saved_list() from the
  * .fetchids file.
  *
- * Early in the query, during the execution of the protocol-specific 
+ * Early in the query, during the execution of the protocol-specific
  * getrange code, the driver expects that the host's `newsaved' member
  * will be filled with a list of UIDs and message numbers representing
  * the mailbox state.  If this list is empty, the server did
@@ -60,22 +64,81 @@
  * be picked up by the next run.  If there are no un-expunged
  * messages, the file is deleted.
  *
- * Note: some comparisons (those used for DNS address lists) are caseblind!  
+ * One disadvantage of UIDL is that all the UIDs have to be downloaded
+ * before a search for new messages can be done. Typically, new messages
+ * are appended to mailboxes. Hence, downloading all UIDs just to download
+ * a few new mails is a waste of bandwidth. If new messages are always at
+ * the end of the mailbox, fast UIDL will decrease the time required to
+ * download new mails.
+ *
+ * During fast UIDL, the UIDs of all messages are not downloaded! The first
+ * unseen message is searched for by using a binary search on UIDs. UIDs
+ * after the first unseen message are downloaded as and when needed.
+ *
+ * The advantages of fast UIDL are (this is noticeable only when the
+ * mailbox has too many mails):
+ *
+ * - There is no need to download the UIDs of all mails right at the start.
+ * - There is no need to save all the UIDs in memory separately in
+ * `newsaved' list.
+ * - There is no need to download the UIDs of seen mail (except for the
+ * first binary search).
+ * - The first new mail is downloaded considerably faster.
+ *
+ * The disadvantages are:
+ *
+ * - Since all UIDs are not downloaded, it is not possible to swap old and
+ * new list. The current state of the mailbox is essentially a merged state
+ * of old and new mails.
+ * - If an intermediate mail has been temporarily refused (say, due to 4xx
+ * code from the smtp server), this mail may not get downloaded.
+ * - If 'flush' is used, such intermediate mails will also get deleted.
+ *
+ * The first two disadvantages can be overcome by doing a linear search
+ * once in a while (say, every 10th poll). Also, with flush, fast UIDL
+ * should be disabled.
+ *
+ * Note: some comparisons (those used for DNS address lists) are caseblind!
  */
 
-/* UIDs associated with un-queried hosts */
-static struct idlist *scratchlist;
+int dofastuidl = 0;
 
 #ifdef POP3_ENABLE
+/** UIDs associated with un-queried hosts */
+static struct idlist *scratchlist;
+
+/** Read saved IDs from \a idfile and attach to each host in \a hostlist. */
 void initialize_saved_lists(struct query *hostlist, const char *idfile)
-/* read file of saved IDs and attach to each host */
 {
+    struct stat statbuf;
     FILE	*tmpfp;
     struct query *ctl;
 
     /* make sure lists are initially empty */
-    for (ctl = hostlist; ctl; ctl = ctl->next)
-	ctl->skipped = ctl->oldsaved = ctl->newsaved = (struct idlist *)NULL;
+    for (ctl = hostlist; ctl; ctl = ctl->next) {
+	ctl->skipped = (struct idlist *)NULL;
+	ctl->oldsaved = (struct idlist *)NULL;
+	ctl->newsaved = (struct idlist *)NULL;
+	ctl->oldsavedend = &ctl->oldsaved;
+    }
+
+    errno = 0;
+
+    /*
+     * Croak if the uidl directory does not exist.
+     * This probably means an NFS mount failed and we can't
+     * see a uidl file that ought to be there.
+     * Question: is this a portable check? It's not clear
+     * that all implementations of lstat() will return ENOTDIR
+     * rather than plain ENOENT in this case...
+     */
+    if (lstat(idfile, &statbuf) < 0) {
+	if (errno == ENOTDIR)
+	{
+	    report(stderr, "lstat: %s: %s\n", idfile, strerror(errno));
+	    exit(PS_IOERR);
+	}
+    }
 
     /* let's get stored message UIDs from previous queries */
     if ((tmpfp = fopen(idfile, "r")) != (FILE *)NULL)
@@ -92,336 +155,319 @@ void initialize_saved_lists(struct query *hostlist, const char *idfile)
 
 	while (fgets(buf, POPBUFSIZE, tmpfp) != (char *)NULL)
 	{
-	  /*
-	   * At this point, we assume the bug has two fields -- a user@host 
-	   * part, and an ID part. Either field may contain spurious @ signs. 
-           * The previous version of this code presumed one could split at 
-           * the rightmost '@'.  This is not correct, as InterMail puts an 
-           * '@' in the UIDL.
-	   */
-	  
-	  /* very first, skip leading spaces */
-	  user = buf + strspn(buf, " \t");
-
-	  /* First, we split the buf into a userhost part and an id part */
-	  if ( (delimp1 = strpbrk(user, " \t")) != NULL ) {
-		id = delimp1 + strspn(delimp1, " \t");	/* set pointer to id */
-	  	saveddelim1 = *delimp1;	/* save char after token */
+	    /*
+	     * At this point, we assume the bug has two fields -- a user@host 
+	     * part, and an ID part. Either field may contain spurious @ signs.
+	     * The previous version of this code presumed one could split at 
+	     * the rightmost '@'.  This is not correct, as InterMail puts an 
+	     * '@' in the UIDL.
+	     */
+
+	    /* first, skip leading spaces */
+	    user = buf + strspn(buf, " \t");
+
+	    /*
+	     * First, we split the buf into a userhost part and an id
+	     * part ... but id doesn't necessarily start with a '<',
+	     * espescially if the POP server returns an X-UIDL header
+	     * instead of a Message-ID, as GMX's (www.gmx.net) POP3
+	     * StreamProxy V1.0 does.
+	     *
+	     * this is one other trick. The userhost part 
+	     * may contain ' ' in the user part, at least in
+	     * the lotus notes case.
+	     * So we start looking for the '@' after which the
+	     * host will follow with the ' ' separator with the id.
+	     *
+	     * XXX FIXME: There is a case this code cannot handle:
+	     * the user name cannot have blanks after a '@'.
+	     */
+	    if ((delimp1 = strchr(user, '@')) != NULL &&
+		(id = strchr(delimp1,' ')) != NULL)
+	    {
+	        for (delimp1 = id; delimp1 >= user; delimp1--)
+		    if ((*delimp1 != ' ') && (*delimp1 != '\t'))
+			break;
+
+		/* 
+		 * It should be safe to assume that id starts after
+		 * the " " - after all, we're writing the " "
+		 * ourselves in write_saved_lists() :-)
+		 */
+		id = id + strspn(id, " ");
+
+		delimp1++; /* but what if there is only white space ?!? */
+		/* we have at least one @, else we are not in this branch */
+		saveddelim1 = *delimp1;		/* save char after token */
 		*delimp1 = '\0';		/* delimit token with \0 */
-		if (id != NULL) {
-			/* now remove trainling white space chars from id */
-	  		if ( (delimp2 = strpbrk(id, " \t\n")) != NULL ) {
-				saveddelim2 = *delimp2;
-				*delimp2 = '\0';
-			}
-	      		atsign = strrchr(user, '@');
-	      		if (atsign) {
-				*atsign = '\0';
-				host = atsign + 1;
 
-			}
-			for (ctl = hostlist; ctl; ctl = ctl->next) {
-				if (ctl->server.truename &&
-			 	    strcasecmp(host, ctl->server.truename) == 0
-			 	    && strcasecmp(user, ctl->remotename) == 0) {
-	
-					save_str(&ctl->oldsaved, id, UID_SEEN);
-					break;
-				}
-			}
-			/* if it's not in a host we're querying,
-			** save it anyway */
-			if (ctl == (struct query *)NULL) {
-				/* restore string */
-				*delimp1 = saveddelim1;
-				*atsign = '@';
-	  			if (delimp2 != NULL) {
-					*delimp2 = saveddelim2;
-				}
-				save_str(&scratchlist, buf, UID_SEEN);
-			}
+		/* now remove trailing white space chars from id */
+		if ((delimp2 = strpbrk(id, " \t\n")) != NULL ) {
+		    saveddelim2 = *delimp2;
+		    *delimp2 = '\0';
+		}
+
+		atsign = strrchr(user, '@');
+		/* we have at least one @, else we are not in this branch */
+		*atsign = '\0';
+		host = atsign + 1;
+
+		/* find proper list and save it */
+		for (ctl = hostlist; ctl; ctl = ctl->next) {
+		    if (strcasecmp(host, ctl->server.queryname) == 0
+			    && strcasecmp(user, ctl->remotename) == 0) {
+			save_str(&ctl->oldsaved, id, UID_SEEN);
+			break;
+		    }
+		}
+		/* 
+		 * If it's not in a host we're querying,
+		 * save it anyway.  Otherwise we'd lose UIDL
+		 * information any time we queried an explicit
+		 * subset of hosts.
+		 */
+		if (ctl == (struct query *)NULL) {
+		    /* restore string */
+		    *delimp1 = saveddelim1;
+		    *atsign = '@';
+		    if (delimp2 != NULL) {
+			*delimp2 = saveddelim2;
+		    }
+		    save_str(&scratchlist, buf, UID_SEEN);
 		}
 	    }
 	}
-	fclose(tmpfp);
+	fclose(tmpfp);	/* not checking should be safe, mode was "r" */
     }
 
     if (outlevel >= O_DEBUG)
     {
 	struct idlist	*idp;
-	int uidlcount = 0;
 
 	for (ctl = hostlist; ctl; ctl = ctl->next)
-	    if (ctl->server.uidl)
 	    {
-		report_build(stdout, "Old UID list from %s:",ctl->server.pollname);
-		for (idp = ctl->oldsaved; idp; idp = idp->next)
-		    report_build(stdout, " %s", idp->id);
+		report_build(stdout, GT_("Old UID list from %s:"), 
+			     ctl->server.pollname);
+		idp = ctl->oldsaved;
 		if (!idp)
-		    report_build(stdout, " <empty>");
+		    report_build(stdout, GT_(" <empty>"));
+		else for (idp = ctl->oldsaved; idp; idp = idp->next) {
+		    char *t = sdump(idp->id, strlen(idp->id)-1);
+		    report_build(stdout, " %s\n", t);
+		    free(t);
+		}
 		report_complete(stdout, "\n");
-		uidlcount++;
 	    }
 
-	if (uidlcount)
-	{
-	    report_build(stdout, "Scratch list of UIDs:");
-	    for (idp = scratchlist; idp; idp = idp->next)
-		report_build(stdout, " %s", idp->id);
-	    if (!idp)
-		report_build(stdout, " <empty>");
-	    report_complete(stdout, "\n");
+	report_build(stdout, GT_("Scratch list of UIDs:"));
+	if (!scratchlist)
+		report_build(stdout, GT_(" <empty>"));
+	else for (idp = scratchlist; idp; idp = idp->next) {
+		char *t = sdump(idp->id, strlen(idp->id)-1);
+		report_build(stdout, " %s\n", t);
+		free(t);
 	}
+	report_complete(stdout, "\n");
     }
 }
-#endif /* POP3_ENABLE */
-
-struct idlist *save_str(struct idlist **idl, const char *str, flag status)
-/* save a number/UID pair on the given UID list */
-{
-    struct idlist **end;
-
-    /* do it nonrecursively so the list is in the right order */
-    for (end = idl; *end; end = &(*end)->next)
-	continue;
-
-    *end = (struct idlist *)xmalloc(sizeof(struct idlist));
-    (*end)->val.status.mark = status;
-    (*end)->id = str ? xstrdup(str) : (char *)NULL;
-    (*end)->next = NULL;
-
-    return(*end);
-}
-
-void free_str_list(struct idlist **idl)
-/* free the given UID list */
-{
-    if (*idl == (struct idlist *)NULL)
-	return;
 
-    free_str_list(&(*idl)->next);
-    free ((*idl)->id);
-    free(*idl);
-    *idl = (struct idlist *)NULL;
-}
-
-void save_str_pair(struct idlist **idl, const char *str1, const char *str2)
-/* save an ID pair on the given list */
-{
-    struct idlist **end;
-
-    /* do it nonrecursively so the list is in the right order */
-    for (end = idl; *end; end = &(*end)->next)
-	continue;
-
-    *end = (struct idlist *)xmalloc(sizeof(struct idlist));
-    (*end)->id = str1 ? xstrdup(str1) : (char *)NULL;
-    if (str2)
-	(*end)->val.id2 = xstrdup(str2);
-    else
-	(*end)->val.id2 = (char *)NULL;
-    (*end)->next = (struct idlist *)NULL;
-}
-
-#ifdef __UNUSED__
-void free_str_pair_list(struct idlist **idl)
-/* free the given ID pair list */
-{
-    if (*idl == (struct idlist *)NULL)
-	return;
-
-    free_idpair_list(&(*idl)->next);
-    free ((*idl)->id);
-    free ((*idl)->val.id2);
-    free(*idl);
-    *idl = (struct idlist *)NULL;
-}
-#endif
-
-int str_in_list(struct idlist **idl, const char *str, const flag caseblind)
-/* is a given ID in the given list? (comparison may be caseblind) */
-{
-    if (*idl == (struct idlist *)NULL || str == (char *) NULL)
-	return(0);
-    else if (!caseblind && strcmp(str, (*idl)->id) == 0)
-	return(1);
-    else if (caseblind && strcasecmp(str, (*idl)->id) == 0)
-	return(1);
-    else
-	return(str_in_list(&(*idl)->next, str, caseblind));
-}
-
-int str_nr_in_list( struct idlist **idl, const char *str )
-  /* return the position of str in idl */
-{
-    int nr;
-    struct idlist *walk;
-    if ( !str )
-        return -1;
-    for( walk = *idl, nr = 0; walk; nr ++, walk = walk->next )
-        if( strcmp( str, walk->id) == 0 )
-	    return nr;
-    return -1;
-}
-
-int str_nr_last_in_list( struct idlist **idl, const char *str)
-/* return the last position of str in idl */
+/** Assert that all UIDs marked deleted in query \a ctl have actually been
+expunged. */
+void expunge_uids(struct query *ctl)
 {
-    int nr, ret = -1;
-    struct idlist *walk;
-    if ( !str )
-        return -1;
-    for( walk = *idl, nr = 0; walk; nr ++, walk = walk->next )
-        if( strcmp( str, walk->id) == 0 )
-	    ret = nr;
-    return ret;
-}
+    struct idlist *idl;
 
-void str_set_mark( struct idlist **idl, const char *str, const flag val)
-/* update the mark on an of an id to given value */
-{
-    int nr;
-    struct idlist *walk;
-    if (!str)
-        return;
-    for(walk = *idl, nr = 0; walk; nr ++, walk = walk->next)
-        if (strcmp(str, walk->id) == 0)
-	    walk->val.status.mark = val;
+    for (idl = dofastuidl ? ctl->oldsaved : ctl->newsaved; idl; idl = idl->next)
+	if (idl->val.status.mark == UID_DELETED)
+	    idl->val.status.mark = UID_EXPUNGED;
 }
 
-int count_list( struct idlist **idl)
-/* count the number of elements in the list */
+static const char *str_uidmark(int mark)
 {
-  if( !*idl )
-    return 0;
-  return 1 + count_list( &(*idl)->next );
+	static char buf[20];
+
+	switch(mark) {
+		case UID_UNSEEN:
+			return "UNSEEN";
+		case UID_SEEN:
+			return "SEEN";
+		case UID_EXPUNGED:
+			return "EXPUNGED";
+		case UID_DELETED:
+			return "DELETED";
+		default:
+			if (snprintf(buf, sizeof(buf), "MARK=%d", mark) < 0)
+				return "ERROR";
+			else
+				return buf;
+	}
 }
 
-char *str_from_nr_list(struct idlist **idl, int number)
-/* return the number'th string in idl */
+static void dump_list(const struct idlist *idp)
 {
-    if( !*idl  || number < 0)
-        return 0;
-    if( number == 0 )
-        return (*idl)->id;
-    return str_from_nr_list(&(*idl)->next, number-1);
+	if (!idp) {
+		report_build(stdout, GT_(" <empty>"));
+	} else while (idp) {
+	    char *t = sdump(idp->id, strlen(idp->id));
+	    report_build(stdout, " %s = %s%s", t, str_uidmark(idp->val.status.mark), idp->next ? "," : "");
+	    free(t);
+	    idp = idp->next;
+	}
 }
 
-    
-char *str_find(struct idlist **idl, int number)
-/* return the id of the given number in the given list. */
+/* finish a query */
+void uid_swap_lists(struct query *ctl) 
 {
-    if (*idl == (struct idlist *) 0)
-	return((char *) 0);
-    else if (number == (*idl)->val.status.num)
-	return((*idl)->id);
-    else
-	return(str_find(&(*idl)->next, number));
-}
+    /* debugging code */
+    if (outlevel >= O_DEBUG)
+    {
+	if (dofastuidl) {
+	    report_build(stdout, GT_("Merged UID list from %s:"), ctl->server.pollname);
+	    dump_list(ctl->oldsaved);
+	} else {
+	    report_build(stdout, GT_("New UID list from %s:"), ctl->server.pollname);
+	    dump_list(ctl->newsaved);
+	}
+	report_complete(stdout, "\n");
+    }
 
-char *idpair_find(struct idlist **idl, const char *id)
-/* return the id of the given id in the given list (caseblind comparison) */
-{
-    if (*idl == (struct idlist *) 0)
-	return((char *) 0);
-    else if (strcasecmp(id, (*idl)->id) == 0)
-	return((*idl)->val.id2 ? (*idl)->val.id2 : (*idl)->id);
-    else
-	return(idpair_find(&(*idl)->next, id));
+    /*
+     * Don't swap UID lists unless we've actually seen UIDLs.
+     * This is necessary in order to keep UIDL information
+     * from being heedlessly deleted later on.
+     *
+     * Older versions of fetchmail did
+     *
+     *     free_str_list(&scratchlist);
+     *
+     * after swap.  This was wrong; we need to preserve the UIDL information
+     * from unqueried hosts.  Unfortunately, not doing this means that
+     * under some circumstances UIDLs can end up being stored forever --
+     * specifically, if a user description is removed from .fetchmailrc
+     * with UIDLs from that account in .fetchids, there is no way for
+     * them to ever get garbage-collected.
+     */
+    if (ctl->newsaved)
+    {
+	/* old state of mailbox may now be irrelevant */
+	struct idlist *temp = ctl->oldsaved;
+	if (outlevel >= O_DEBUG)
+	    report(stdout, GT_("swapping UID lists\n"));
+	ctl->oldsaved = ctl->newsaved;
+	ctl->newsaved = (struct idlist *) NULL;
+	free_str_list(&temp);
+    }
+    /* in fast uidl, there is no need to swap lists: the old state of
+     * mailbox cannot be discarded! */
+    else if (outlevel >= O_DEBUG && !dofastuidl)
+	report(stdout, GT_("not swapping UID lists, no UIDs seen this query\n"));
 }
 
-int delete_str(struct idlist **idl, int num)
-/* delete given message from given list */
+/* finish a query which had errors */
+void uid_discard_new_list(struct query *ctl)
 {
-    struct idlist	*idp;
-
-    for (idp = *idl; idp; idp = idp->next)
-	if (idp->val.status.num == num)
-	{
-	    idp->val.status.mark = UID_DELETED;
-	    return(1);
-	}
-    return(0);
-}
+    /* debugging code */
+    if (outlevel >= O_DEBUG)
+    {
+	/* this is now a merged list! the mails which were seen in this
+	 * poll are marked here. */
+	report_build(stdout, GT_("Merged UID list from %s:"), ctl->server.pollname);
+	dump_list(ctl->oldsaved);
+	report_complete(stdout, "\n");
+    }
 
-void append_str_list(struct idlist **idl, struct idlist **nidl)
-/* append nidl to idl (does not copy *) */
-{
-    if ((*nidl) == (struct idlist *)NULL || *nidl == *idl)
-	return;
-    else if ((*idl) == (struct idlist *)NULL)
-	*idl = *nidl;
-    else if ((*idl)->next == (struct idlist *)NULL)
-	(*idl)->next = *nidl;
-    else if ((*idl)->next != *nidl)
-	append_str_list(&(*idl)->next, nidl);
+    if (ctl->newsaved)
+    {
+	/* new state of mailbox is not reliable */
+	if (outlevel >= O_DEBUG)
+	    report(stdout, GT_("discarding new UID list\n"));
+	free_str_list(&ctl->newsaved);
+	ctl->newsaved = (struct idlist *) NULL;
+    }
 }
 
-#ifdef POP3_ENABLE
-void expunge_uids(struct query *ctl)
-/* assert that all UIDs marked deleted have actually been expunged */
+/** Reset the number associated with each id */
+void uid_reset_num(struct query *ctl)
 {
-    struct idlist *idl;
-
-    for (idl = ctl->newsaved; idl; idl = idl->next)
-	if (idl->val.status.mark == UID_DELETED)
-	    idl->val.status.mark = UID_EXPUNGED;
+    struct idlist *idp;
+    for (idp = ctl->oldsaved; idp; idp = idp->next)
+	idp->val.status.num = 0;
 }
 
+/** Write list of seen messages, at end of run. */
 void write_saved_lists(struct query *hostlist, const char *idfile)
-/* perform end-of-run write of seen-messages list */
 {
-    int		idcount;
+    long	idcount;
     FILE	*tmpfp;
     struct query *ctl;
     struct idlist *idp;
 
-    /* old state of mailbox is now irrelevant */
-    free_str_list(&ctl->oldsaved);
-    free_str_list(&scratchlist);
-    ctl->oldsaved = ctl->newsaved;
-    ctl->newsaved = (struct idlist *) NULL;
-
-    /* debugging code */
-    if (ctl->server.uidl && outlevel >= O_DEBUG)
-    {
-	struct idlist *idp;
-
-	report_build(stdout, "New UID list from %s:", ctl->server.pollname);
-	for (idp = ctl->oldsaved; idp; idp = idp->next)
-	    report_build(stdout, " %s = %d", idp->id, idp->val.status.mark);
-	if (!idp)
-	    report_build(stdout, " <empty>");
-	report_complete(stdout, "\n");
-    }
-
     /* if all lists are empty, nuke the file */
     idcount = 0;
     for (ctl = hostlist; ctl; ctl = ctl->next) {
-	if (ctl->oldsaved)
-	    idcount++;
+	for (idp = ctl->oldsaved; idp; idp = idp->next)
+	    if (idp->val.status.mark == UID_SEEN
+		    || idp->val.status.mark == UID_DELETED)
+		idcount++;
     }
 
     /* either nuke the file or write updated last-seen IDs */
     if (!idcount && !scratchlist)
     {
+	if (outlevel >= O_DEBUG) {
+	    if (access(idfile, F_OK) == 0)
+		    report(stdout, GT_("Deleting fetchids file.\n"));
+	}
+	if (unlink(idfile) && errno != ENOENT)
+	    report(stderr, GT_("Error deleting %s: %s\n"), idfile, strerror(errno));
+    } else {
+	char *newnam = (char *)xmalloc(strlen(idfile) + 2);
+	strcpy(newnam, idfile);
+	strcat(newnam, "_");
 	if (outlevel >= O_DEBUG)
-	    report(stdout, "Deleting fetchids file.\n");
-	unlink(idfile);
-    }
-    else
-	if ((tmpfp = fopen(idfile, "w")) != (FILE *)NULL) {
+	    report(stdout, GT_("Writing fetchids file.\n"));
+	(void)unlink(newnam); /* remove file/link first */
+	if ((tmpfp = fopen(newnam, "w")) != (FILE *)NULL) {
+	    int errflg = 0;
 	    for (ctl = hostlist; ctl; ctl = ctl->next) {
 		for (idp = ctl->oldsaved; idp; idp = idp->next)
 		    if (idp->val.status.mark == UID_SEEN
 				|| idp->val.status.mark == UID_DELETED)
-			fprintf(tmpfp, "%s@%s %s\n", 
-			    ctl->remotename, ctl->server.truename, idp->id);
+			if (fprintf(tmpfp, "%s@%s %s\n",
+			    ctl->remotename, ctl->server.queryname, idp->id) < 0) {
+			    int e = errno;
+			    report(stderr, GT_("Write error on fetchids file %s: %s\n"), newnam, strerror(e));
+			    errflg = 1;
+			    goto bailout;
+			}
 	    }
 	    for (idp = scratchlist; idp; idp = idp->next)
-		fputs(idp->id, tmpfp);
+		if (EOF == fputs(idp->id, tmpfp)) {
+			    int e = errno;
+			    report(stderr, GT_("Write error on fetchids file %s: %s\n"), newnam, strerror(e));
+			    errflg = 1;
+			    goto bailout;
+		}
+
+bailout:
+	    (void)fflush(tmpfp); /* return code ignored, we check ferror instead */
+	    errflg |= ferror(tmpfp);
 	    fclose(tmpfp);
+	    /* if we could write successfully, move into place;
+	     * otherwise, drop */
+	    if (errflg) {
+		report(stderr, GT_("Error writing to fetchids file %s, old file left in place.\n"), newnam);
+		unlink(newnam);
+	    } else {
+		if (rename(newnam, idfile)) {
+		    report(stderr, GT_("Cannot rename fetchids file %s to %s: %s\n"), newnam, idfile, strerror(errno));
+		}
+	    }
+	} else {
+	    report(stderr, GT_("Cannot open fetchids file %s for writing: %s\n"), newnam, strerror(errno));
 	}
+	free(newnam);
+    }
 }
 #endif /* POP3_ENABLE */