X-Git-Url: https://git.decadent.org.uk/gitweb/?p=nfs-utils.git;a=blobdiff_plain;f=support%2Fexport%2Fxtab.c;h=510765a3f0d59b5517e06b0542f1eb8d0d702f03;hp=4289d7ce5fc1537c6ce5b8d05e4088a761916f27;hb=4cacc965afc4fb03a465ffcc6cb3078aeadc3818;hpb=8b7ad01b14df1e7529b9ba8a1ea17df0d6004ef9

diff --git a/support/export/xtab.c b/support/export/xtab.c
index 4289d7c..510765a 100644
--- a/support/export/xtab.c
+++ b/support/export/xtab.c
@@ -6,7 +6,9 @@
  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
  */
 
-#include "config.h"
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
 
 #include <sys/fcntl.h>
 #include <unistd.h>
@@ -18,9 +20,15 @@
 #include "xio.h"
 #include "xlog.h"
 
+static void cond_rename(char *newfile, char *oldfile);
+
 static int
 xtab_read(char *xtab, int is_export)
 {
+    /* is_export == 0  => reading /proc/fs/nfs/exports - we know these things are exported to kernel
+     * is_export == 1  => reading /var/lib/nfs/etab - these things are allowed to be exported
+     * is_export == 2  => reading /var/lib/nfs/xtab - these things might be known to kernel
+     */
 	struct exportent	*xp;
 	nfs_export		*exp;
 	int			lockid;
@@ -28,16 +36,23 @@ xtab_read(char *xtab, int is_export)
 	if ((lockid = xflock(xtab, "r")) < 0)
 		return 0;
 	setexportent(xtab, "r");
-	while ((xp = getexportent()) != NULL) {
-		if (!(exp = export_lookup(xp->e_hostname, xp->e_path)) &&
-		    !(exp = export_create(xp))) {
+	while ((xp = getexportent(is_export==0, 0)) != NULL) {
+		if (!(exp = export_lookup(xp->e_hostname, xp->e_path, is_export != 1)) &&
+		    !(exp = export_create(xp, is_export!=1))) {
 			continue;
 		}
-		if (is_export) {
+		switch (is_export) {
+		case 0:
+			exp->m_exported = 1;
+			break;
+		case 1:
 			exp->m_xtabent = 1;
 			exp->m_mayexport = 1;
-		} else
-			exp->m_exported = 1;
+			break;
+		case 2:
+			exp->m_exported = -1;/* may be exported */
+			break;
+		}
 	}
 	endexportent();
 	xfunlock(lockid);
@@ -52,8 +67,11 @@ xtab_mount_read(void)
 	if ((fd=open(_PATH_PROC_EXPORTS, O_RDONLY))>=0) {
 		close(fd);
 		return xtab_read(_PATH_PROC_EXPORTS, 0);
+	} else if ((fd=open(_PATH_PROC_EXPORTS_ALT, O_RDONLY) >= 0)) {
+		close(fd);
+		return xtab_read(_PATH_PROC_EXPORTS_ALT, 0);
 	} else
-		return xtab_read(_PATH_XTAB, 0);
+		return xtab_read(_PATH_XTAB, 2);
 }
 
 int
@@ -62,6 +80,12 @@ xtab_export_read(void)
 	return xtab_read(_PATH_ETAB, 1);
 }
 
+/*
+ * mountd now keeps an open fd for the etab at all times to make sure that the
+ * inode number changes when the xtab_export_write is done. If you change the
+ * routine below such that the files are edited in place, then you'll need to
+ * fix the auth_reload logic as well...
+ */
 static int
 xtab_write(char *xtab, char *xtabtmp, int is_export)
 {
@@ -76,7 +100,7 @@ xtab_write(char *xtab, char *xtabtmp, int is_export)
 	setexportent(xtabtmp, "w");
 
 	for (i = 0; i < MCL_MAXTYPES; i++) {
-		for (exp = exportlist[i]; exp; exp = exp->m_next) {
+		for (exp = exportlist[i].p_head; exp; exp = exp->m_next) {
 			if (is_export && !exp->m_xtabent)
 				continue;
 			if (!is_export && ! exp->m_exported)
@@ -84,16 +108,13 @@ xtab_write(char *xtab, char *xtabtmp, int is_export)
 
 			/* write out the export entry using the FQDN */
 			xe = exp->m_export;
-			strncpy(xe.e_hostname,
-				exp->m_client->m_hostname,
-				sizeof (xe.e_hostname) - 1);
-			xe.e_hostname[sizeof (xe.e_hostname) - 1] = '\0';
+			xe.e_hostname = exp->m_client->m_hostname;
 			putexportent(&xe);
 		}
 	}
 	endexportent();
 
-	rename(xtabtmp, xtab);
+	cond_rename(xtabtmp, xtab);
 
 	xfunlock(lockid);
 
@@ -122,12 +143,53 @@ xtab_append(nfs_export *exp)
 		return;
 	setexportent(_PATH_XTAB, "a");
 	xe = exp->m_export;
-	strncpy(xe.e_hostname, exp->m_client->m_hostname,
-	       sizeof (xe.e_hostname) - 1);
-	xe.e_hostname[sizeof (xe.e_hostname) - 1] = '\0';
+	xe.e_hostname = exp->m_client->m_hostname;
 	putexportent(&xe);
 	endexportent();
 	xfunlock(lockid);
 	exp->m_xtabent = 1;
 }
 
+/*
+ * rename newfile onto oldfile unless
+ * they are identical
+ */
+static void cond_rename(char *newfile, char *oldfile)
+{
+	int nfd, ofd;
+	char nbuf[4096], obuf[4096];
+	int ncnt, ocnt;
+
+	nfd = open(newfile, 0);
+	if (nfd < 0)
+		return;
+	ofd = open(oldfile, 0);
+	if (ofd < 0) {
+		close(nfd);
+		rename(newfile, oldfile);
+		return;
+	}
+
+	do {
+		ncnt = read(nfd, nbuf, sizeof(nbuf));
+		if (ncnt < 0)
+			break;
+		ocnt = read(ofd, obuf, sizeof(obuf));
+		if (ocnt < 0)
+			break;
+		if (ncnt != ocnt)
+			break;
+		if (ncnt == 0) {
+			close(nfd);
+			close(ofd);
+			unlink(newfile);
+			return;
+		}
+	} while (memcmp(obuf, nbuf, ncnt) == 0);
+
+	/* some mis-match */
+	close(nfd);
+	close(ofd);
+	rename(newfile, oldfile);
+	return;
+}