From 9afa363f46406be3ba45faebf414b649ecfa02b8 Mon Sep 17 00:00:00 2001
From: Simon Schubert <corecode@dragonflybsd.org>
Date: Mon, 20 Jul 2009 21:53:32 +0200
Subject: [PATCH] dma: rewrite file management

Close files as early as possible, possibly re-open them later.  This is
so that we avoid filedesc sharing problems completely and that we won't
run out of fdesc in case of a large queue.
---
 libexec/dma/dma.c   |  68 ++++++++++----------
 libexec/dma/dma.h   |  12 ++--
 libexec/dma/spool.c | 147 ++++++++++++++++++++++++++------------------
 3 files changed, 128 insertions(+), 99 deletions(-)

diff --git a/libexec/dma/dma.c b/libexec/dma/dma.c
index 448ff3730d..d9b5d49a07 100644
--- a/libexec/dma/dma.c
+++ b/libexec/dma/dma.c
@@ -66,12 +66,11 @@ struct aliases aliases = LIST_HEAD_INITIALIZER(aliases);
 struct strlist tmpfs = SLIST_HEAD_INITIALIZER(tmpfs);
 struct virtusers virtusers = LIST_HEAD_INITIALIZER(virtusers);
 struct authusers authusers = LIST_HEAD_INITIALIZER(authusers);
-static int daemonize = 1;
 struct config *config;
-static const char *username;
-static uid_t uid;
-static const char *logident_base;
+const char *username;
 
+static int daemonize = 1;
+static const char *logident_base;
 
 const char *
 hostname(void)
@@ -151,6 +150,7 @@ set_username(void)
 {
 	struct passwd *pwd;
 	char *u = NULL;
+	uid_t uid;
 
 	uid = getuid();
 	username = check_username(getlogin(), uid);
@@ -358,26 +358,24 @@ readmail(struct queue *queue, const char *sender, int nodot)
 {
 	char line[1000];	/* by RFC2822 */
 	size_t linelen;
-	int error;
+	size_t error;
 	int had_headers = 0;
 	int had_from = 0;
 	int had_messagid = 0;
 	int had_date = 0;
 
-	error = snprintf(line, sizeof(line),
+	error = fprintf(queue->mailf,
 		"Received: from %s (uid %d)\n"
 		"\t(envelope-from %s)\n"
 		"\tid %s\n"
 		"\tby %s (%s)\n"
 		"\t%s\n",
-		username, uid,
+		username, getuid(),
 		sender,
 		queue->id,
 		hostname(), VERSION,
 		rfc822date());
-	if (error < 0 || (size_t)error >= sizeof(line))
-		return (-1);
-	if (write(queue->mailfd, line, error) != error)
+	if ((ssize_t)error < 0)
 		return (-1);
 
 	while (!feof(stdin)) {
@@ -411,21 +409,16 @@ readmail(struct queue *queue, const char *sender, int nodot)
 					had_from = 1;
 					snprintf(line, sizeof(line), "From: <%s>\n", sender);
 				}
-				if ((size_t)write(queue->mailfd, line, strlen(line)) != strlen(line))
+				if (fwrite(line, strlen(line), 1, queue->mailf) != 1)
 					return (-1);
 			}
 			strcpy(line, "\n");
 		}
 		if (!nodot && linelen == 2 && line[0] == '.')
 			break;
-		if ((size_t)write(queue->mailfd, line, linelen) != linelen)
+		if (fwrite(line, strlen(line), 1, queue->mailf) != 1)
 			return (-1);
 	}
-	if (fsync(queue->mailfd) != 0)
-		return (-1);
-
-	syslog(LOG_INFO, "new mail from user=%s uid=%d envelope_from=<%s>",
-	       username, uid, sender);
 
 	return (0);
 }
@@ -450,10 +443,8 @@ go_background(struct queue *queue)
 
 	LIST_FOREACH(it, &queue->queue, next) {
 		/* No need to fork for the last dest */
-		if (LIST_NEXT(it, next) == NULL) {
-			setlogident("%s", it->queueid);
-			return (it);
-		}
+		if (LIST_NEXT(it, next) == NULL)
+			goto retit;
 
 		pid = fork();
 		switch (pid) {
@@ -468,7 +459,16 @@ go_background(struct queue *queue)
 			 *
 			 * return and deliver mail
 			 */
+retit:
+			/*
+			 * If necessary, aquire the queue and * mail files.
+			 * If this fails, we probably were raced by another
+			 * process.
+			 */
 			setlogident("%s", it->queueid);
+			if (aquirespool(it) < 0)
+				exit(1);
+			dropspool(queue, it);
 			return (it);
 
 		default:
@@ -501,16 +501,13 @@ bounce(struct qitem *it, const char *reason)
 	}
 
 	LIST_INIT(&bounceq.queue);
-	if (add_recp(&bounceq, it->sender, "", 1) != 0)
-		goto fail;
 	if (newspoolf(&bounceq, "") != 0)
 		goto fail;
 
 	syslog(LOG_ERR, "delivery failed, bouncing as %s", bounceq.id);
 	setlogident("%s", bounceq.id);
 
-	bit = LIST_FIRST(&bounceq.queue);
-	error = fprintf(bit->mailf,
+	error = fprintf(bounceq.mailf,
 		"Received: from MAILER-DAEMON\n"
 		"\tid %s\n"
 		"\tby %s (%s)\n"
@@ -545,14 +542,15 @@ bounce(struct qitem *it, const char *reason)
 		    "Message headers follow.");
 	if (error < 0)
 		goto fail;
-	if (fflush(bit->mailf) != 0)
+
+	if (add_recp(&bounceq, it->sender, "", 1) != 0)
 		goto fail;
 
 	if (fseek(it->mailf, it->hdrlen, SEEK_SET) != 0)
 		goto fail;
 	if (config->features & FULLBOUNCE) {
 		while ((pos = fread(line, 1, sizeof(line), it->mailf)) > 0) {
-			if ((size_t)write(bounceq.mailfd, line, pos) != pos)
+			if (fwrite(line, 1, pos, bounceq.mailf) != pos)
 				goto fail;
 		}
 	} else {
@@ -561,13 +559,12 @@ bounce(struct qitem *it, const char *reason)
 				break;
 			if (line[0] == '\n')
 				break;
-			if ((size_t)write(bounceq.mailfd, line, strlen(line)) != strlen(line))
+			if (fwrite(line, strlen(line), 1, bounceq.mailf) != 1)
 				goto fail;
 		}
 	}
-	if (fsync(bounceq.mailfd) != 0)
-		goto fail;
-	if (linkspool(&bounceq) != 0)
+
+	if (linkspool(&bounceq, "MAILER-DAEMON") != 0)
 		goto fail;
 	/* bounce is safe */
 
@@ -651,6 +648,7 @@ static void
 show_queue(struct queue *queue)
 {
 	struct qitem *it;
+	int locked = 0;	/* XXX */
 
 	if (LIST_EMPTY(&queue->queue)) {
 		printf("Mail queue is empty\n");
@@ -663,7 +661,7 @@ show_queue(struct queue *queue)
 		       "To\t: %s\n"
 		       "--\n",
 		       it->queueid,
-		       it->locked ? "*" : "",
+		       locked ? "*" : "",
 		       it->sender, it->addr);
 	}
 }
@@ -794,13 +792,13 @@ skipopts:
 		err(1, "can not read SMTP authentication file");
 
 	if (showq) {
-		load_queue(&lqueue, 1);
+		load_queue(&lqueue);
 		show_queue(&lqueue);
 		return (0);
 	}
 
 	if (doqueue) {
-		load_queue(&lqueue, 0);
+		load_queue(&lqueue);
 		run_queue(&lqueue);
 		return (0);
 	}
@@ -827,7 +825,7 @@ skipopts:
 	if (readmail(&queue, sender, nodot) != 0)
 		err(1, "can not read mail");
 
-	if (linkspool(&queue) != 0)
+	if (linkspool(&queue, sender) != 0)
 		err(1, "can not create spools");
 
 	/* From here on the mail is safe. */
diff --git a/libexec/dma/dma.h b/libexec/dma/dma.h
index bbb6e50ec2..75ce1cccaf 100644
--- a/libexec/dma/dma.h
+++ b/libexec/dma/dma.h
@@ -94,18 +94,17 @@ struct qitem {
 	char *queuefn;
 	char *mailfn;
 	char *queueid;
+	FILE *queuef;
 	FILE *mailf;
-	int queuefd;
 	off_t hdrlen;
 	int remote;
-	int locked;
 };
 LIST_HEAD(queueh, qitem);
 
 struct queue {
 	struct queueh queue;
 	char *id;
-	int mailfd;
+	FILE *mailf;
 	char *tmpf;
 };
 
@@ -146,6 +145,7 @@ extern struct config *config;
 extern struct strlist tmpfs;
 extern struct virtusers virtusers;
 extern struct authusers authusers;
+extern const char *username;
 
 extern char neterr[BUF_SIZE];
 
@@ -181,9 +181,11 @@ const char *hostname(void);
 
 /* spool.c */
 int newspoolf(struct queue *, const char *);
-int linkspool(struct queue *);
-void load_queue(struct queue *, int);
+int linkspool(struct queue *, const char *);
+void load_queue(struct queue *);
 void delqueue(struct qitem *);
+int aquirespool(struct qitem *);
+void dropspool(struct queue *, struct qitem *);
 
 /* local.c */
 int deliver_local(struct qitem *, const char **errmsg);
diff --git a/libexec/dma/spool.c b/libexec/dma/spool.c
index ae3c9879a3..0013a72b14 100644
--- a/libexec/dma/spool.c
+++ b/libexec/dma/spool.c
@@ -66,54 +66,47 @@
 int
 newspoolf(struct queue *queue, const char *sender)
 {
-	char line[1000];	/* by RFC2822 */
 	char fn[PATH_MAX+1];
 	struct stat st;
 	struct stritem *t;
 	struct qitem *it;
-	FILE *mailf;
 	off_t hdrlen;
-	int error;
+	int fd;
 
 	if (snprintf(fn, sizeof(fn), "%s/%s", config->spooldir, "tmp_XXXXXXXXXX") <= 0)
 		return (-1);
 
-	queue->mailfd = mkstemp(fn);
-	if (queue->mailfd < 0)
-		return (-1);
-	if (flock(queue->mailfd, LOCK_EX) == -1)
+	fd = mkstemp(fn);
+	if (fd < 0)
 		return (-1);
-
+	if (flock(fd, LOCK_EX) == -1)
+		goto fail;
 	queue->tmpf = strdup(fn);
 	if (queue->tmpf == NULL)
 		goto fail;
 
-	error = snprintf(line, sizeof(line), "%s\n", sender);
-	if (error < 0 || (size_t)error >= sizeof(line)) {
-		errno = E2BIG;
+	/*
+	 * Assign queue id
+	 */
+	if (fstat(fd, &st) != 0)
 		goto fail;
-	}
-	if (write(queue->mailfd, line, error) != error)
+	if (asprintf(&queue->id, "%"PRIxMAX, st.st_ino) < 0)
 		goto fail;
 
-	hdrlen = lseek(queue->mailfd, 0, SEEK_CUR);
+	queue->mailf = fdopen(fd, "r+");
+	if (queue->mailf == NULL)
+		goto fail;
 
-	mailf = fdopen(queue->mailfd, "r+");
-	if (mailf == NULL)
+	if (fprintf(queue->mailf, "%s\n", sender) < 0)
 		goto fail;
+
+	hdrlen = ftello(queue->mailf);
+
 	LIST_FOREACH(it, &queue->queue, next) {
-		it->mailf = mailf;
+		it->mailf = queue->mailf;
 		it->hdrlen = hdrlen;
 	}
 
-	/*
-	 * Assign queue id
-	 */
-	if (fstat(queue->mailfd, &st) != 0)
-		return (-1);
-	if (asprintf(&queue->id, "%"PRIxMAX, st.st_ino) < 0)
-		return (-1);
-
 	t = malloc(sizeof(*t));
 	if (t != NULL) {
 		t->str = queue->tmpf;
@@ -122,20 +115,28 @@ newspoolf(struct queue *queue, const char *sender)
 	return (0);
 
 fail:
-	close(queue->mailfd);
+	if (queue->mailf != NULL)
+		fclose(queue->mailf);
+	close(fd);
 	unlink(fn);
 	return (-1);
 }
 
 int
-linkspool(struct queue *queue)
+linkspool(struct queue *queue, const char *sender)
 {
 	char line[1000];	/* by RFC2822 */
 	struct stat st;
-	int error;
+	size_t error;
 	int queuefd;
 	struct qitem *it;
 
+	if (fflush(queue->mailf) != 0 || fsync(fileno(queue->mailf)) != 0)
+		goto delfiles;
+
+	syslog(LOG_INFO, "new mail from user=%s uid=%d envelope_from=<%s>",
+	       username, getuid(), sender);
+
 	LIST_FOREACH(it, &queue->queue, next) {
 		if (asprintf(&it->queueid, "%s.%"PRIxPTR, queue->id, (uintptr_t)it) <= 0)
 			goto delfiles;
@@ -149,16 +150,20 @@ linkspool(struct queue *queue)
 			goto delfiles;
 
 		error = snprintf(line, sizeof(line), "%s %s\n", it->queueid, it->addr);
-		if (error < 0 || (size_t)error >= sizeof(line))
+		if ((ssize_t)error < 0 || error >= sizeof(line))
 			goto delfiles;
+
 		queuefd = open_locked(it->queuefn, O_CREAT|O_EXCL|O_RDWR, 0600);
 		if (queuefd == -1)
 			goto delfiles;
-		if (write(queuefd, line, error) != error) {
-			close(queuefd);
+		it->queuef = fdopen(queuefd, "w+");
+		if (it->queuef == NULL)
+			goto delfiles;
+
+		if (fwrite(line, strlen(line), 1, it->queuef) != 1)
+			goto delfiles;
+		if (fflush(it->queuef) != 0 || fsync(fileno(it->queuef)) != 0)
 			goto delfiles;
-		}
-		it->queuefd = queuefd;
 
 		if (link(queue->tmpf, it->mailfn) != 0)
 			goto delfiles;
@@ -181,7 +186,7 @@ delfiles:
 }
 
 void
-load_queue(struct queue *queue, int ignorelock)
+load_queue(struct queue *queue)
 {
 	struct qitem *it;
 	//struct queue queue, itmqueue;
@@ -197,8 +202,6 @@ load_queue(struct queue *queue, int ignorelock)
 	char *queuefn;
 	char *mailfn;
 	off_t hdrlen;
-	int fd;
-	int locked;
 
 	LIST_INIT(&queue->queue);
 
@@ -207,13 +210,11 @@ load_queue(struct queue *queue, int ignorelock)
 		err(1, "reading queue");
 
 	while ((de = readdir(spooldir)) != NULL) {
-		fd = -1;
 		sender = NULL;
 		queuef = NULL;
 		mailf = NULL;
 		queueid = NULL;
 		queuefn = NULL;
-		locked = 1;
 		LIST_INIT(&itmqueue.queue);
 
 		/* ignore temp files */
@@ -226,20 +227,6 @@ load_queue(struct queue *queue, int ignorelock)
 		if (asprintf(&mailfn, "%s/M%s", config->spooldir, de->d_name + 1) < 0)
 			goto fail;
 
-		fd = open_locked(queuefn, O_RDONLY|O_NONBLOCK);
-		if (ignorelock) {
-			if (fd < 0)
-				fd = open(queuefn, O_RDONLY);
-			else
-				locked = 0;
-		}
-		if (fd < 0) {
-			/* Ignore locked files */
-			if (errno == EWOULDBLOCK)
-				continue;
-			goto skip_item;
-		}
-
 		mailf = fopen(mailfn, "r");
 		if (mailf == NULL)
 			goto skip_item;
@@ -252,7 +239,7 @@ load_queue(struct queue *queue, int ignorelock)
 
 		hdrlen = ftell(mailf);
 
-		queuef = fdopen(fd, "r");
+		queuef = fopen(queuefn, "r");
 		if (queuef == NULL)
 			goto skip_item;
 
@@ -269,16 +256,18 @@ load_queue(struct queue *queue, int ignorelock)
 
 		if (add_recp(&itmqueue, addr, sender, 0) != 0)
 			goto skip_item;
+
 		it = LIST_FIRST(&itmqueue.queue);
-		it->queuefd = fd;
-		it->mailf = mailf;
 		it->queueid = queueid;
 		it->queuefn = queuefn;
 		it->mailfn = mailfn;
 		it->hdrlen = hdrlen;
-		it->locked = locked;
 		LIST_INSERT_HEAD(&queue->queue, it, next);
 
+		if (queuef != NULL)
+			fclose(queuef);
+		if (mailf != NULL)
+			fclose(mailf);
 		continue;
 
 skip_item:
@@ -295,7 +284,6 @@ skip_item:
 			fclose(queuef);
 		if (mailf != NULL)
 			fclose(mailf);
-		close(fd);
 	}
 	closedir(spooldir);
 	return;
@@ -308,8 +296,49 @@ void
 delqueue(struct qitem *it)
 {
 	unlink(it->queuefn);
-	close(it->queuefd);
 	unlink(it->mailfn);
-	fclose(it->mailf);
+	if (it->queuef != NULL)
+		fclose(it->queuef);
+	if (it->mailf != NULL)
+		fclose(it->mailf);
 	free(it);
 }
+
+int
+aquirespool(struct qitem *it)
+{
+	int queuefd;
+
+	if (it->queuef == NULL) {
+		queuefd = open_locked(it->queuefn, O_RDWR);
+		if (queuefd < 0)
+			return (-1);
+		it->queuef = fdopen(queuefd, "r+");
+		if (it->queuef == NULL)
+			return (-1);
+	}
+
+	if (it->mailf == NULL) {
+		it->mailf = fopen(it->mailfn, "r");
+		if (it->mailf == NULL)
+			return (-1);
+	}
+
+	return (0);
+}
+
+void
+dropspool(struct queue *queue, struct qitem *keep)
+{
+	struct qitem *it;
+
+	LIST_FOREACH(it, &queue->queue, next) {
+		if (it == keep)
+			continue;
+
+		if (it->queuef != NULL)
+			fclose(it->queuef);
+		if (it->mailf != NULL)
+			fclose(it->mailf);
+	}
+}
-- 
2.41.0