X-Git-Url: https://git.decadent.org.uk/gitweb/?p=nfs-utils.git;a=blobdiff_plain;f=utils%2Fmountd%2Frmtab.c;h=8c4a5a978de904888bf9a5495b52095774fffeac;hp=170d8594e4371f7373f50b7ba78cfd6d620d3a8e;hb=37716a53f77e53afe99695f838545374beabc0e3;hpb=70a0e44cc77a7d8fc78c5514889bcd5d4fde3599

diff --git a/utils/mountd/rmtab.c b/utils/mountd/rmtab.c
index 170d859..8c4a5a9 100644
--- a/utils/mountd/rmtab.c
+++ b/utils/mountd/rmtab.c
@@ -8,7 +8,9 @@
 
 #include "config.h"
 
+#include <sys/types.h>
 #include <sys/stat.h>
+#include <unistd.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <netdb.h>
@@ -18,6 +20,31 @@
 #include "xio.h"
 #include "mountd.h"
 
+#include <limits.h> /* PATH_MAX */
+
+/* If new path is a link do not destroy it but place the
+ * file where the link points.
+ */
+
+static int 
+slink_safe_rename(const char * oldpath, const char * newpath)
+{
+	int r;
+	struct stat s;
+	char slink_path[PATH_MAX];
+	const char *real_newpath = newpath;
+
+	if ((lstat(newpath, &s) == 0) && S_ISLNK(s.st_mode)) {
+		/* New path is a symbolic link, do not destroy but follow */
+		if ((r = readlink(newpath, slink_path, PATH_MAX - 1)) == -1)
+			return -1;
+		slink_path[r] = '\0';
+		real_newpath = slink_path;
+	}
+
+	return rename(oldpath, real_newpath);
+}
+
 void
 mountlist_add(nfs_export *exp, const char *path)
 {
@@ -82,7 +109,7 @@ mountlist_del(nfs_export *exp, const char *path)
 		if (!match || rep->r_count)
 			fputrmtabent(fp, rep, NULL);
 	}
-	if (rename(_PATH_RMTABTMP, _PATH_RMTAB) < 0) {
+	if (slink_safe_rename(_PATH_RMTABTMP, _PATH_RMTAB) < 0) {
 		xlog(L_ERROR, "couldn't rename %s to %s",
 				_PATH_RMTABTMP, _PATH_RMTAB);
 	}
@@ -130,7 +157,7 @@ mountlist_del_all(struct sockaddr_in *sin)
 		}
 		fputrmtabent(fp, rep, NULL);
 	}
-	if (rename(_PATH_RMTABTMP, _PATH_RMTAB) < 0) {
+	if (slink_safe_rename(_PATH_RMTABTMP, _PATH_RMTAB) < 0) {
 		xlog(L_ERROR, "couldn't rename %s to %s",
 				_PATH_RMTABTMP, _PATH_RMTAB);
 	}