libshare: nfs: share nfs_is_shared()

Reviewed-by: Don Brady <don.brady@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12067

lib/libshare/nfs.c

@@ -148,38 +148,29 @@ nfs_fini_tmpfile(const char *exports, struct tmpfile *tmpf)
 	return (SA_OK);
 }
 
-/*
- * Copy all entries from the exports file to newfp,
- * omitting any entries for the specified mountpoint.
- */
 static int
-nfs_copy_entries(FILE *newfp, const char *exports, const char *mountpoint)
+nfs_process_exports(const char *exports, const char *mountpoint,
+    boolean_t (*cbk)(void *userdata, char *line, boolean_t found_mountpoint),
+    void *userdata)
 {
 	int error = SA_OK;
+	boolean_t cont = B_TRUE;
 
-	fputs(FILE_HEADER, newfp);
-
-	/*
-	 * ZFS_EXPORTS_FILE may not exist yet.
-	 * If that's the case, then just write out the new file.
-	 */
 	FILE *oldfp = fopen(exports, "re");
 	if (oldfp != NULL) {
 		char *buf = NULL, *sep;
 		size_t buflen = 0, mplen = strlen(mountpoint);
 
-		while (getline(&buf, &buflen, oldfp) != -1) {
-
+		while (cont && getline(&buf, &buflen, oldfp) != -1) {
 			if (buf[0] == '\n' || buf[0] == '#')
 				continue;
 
-			if ((sep = strpbrk(buf, "\t \n")) != NULL &&
+			cont = cbk(userdata, buf,
+			    (sep = strpbrk(buf, "\t \n")) != NULL &&
 			    sep - buf == mplen &&
-			    strncmp(buf, mountpoint, mplen) == 0)
-					continue;
-
-			fputs(buf, newfp);
+			    strncmp(buf, mountpoint, mplen) == 0);
 		}
+		free(buf);
 
 		if (ferror(oldfp) != 0)
 			error = ferror(oldfp);
@@ -189,10 +180,32 @@ nfs_copy_entries(FILE *newfp, const char *exports, const char *mountpoint)
 			    exports, strerror(errno));
 			error = error != SA_OK ? error : SA_SYSTEM_ERR;
 		}
-
-		free(buf);
 	}
 
+	return (error);
+}
+
+static boolean_t
+nfs_copy_entries_cb(void *userdata, char *line, boolean_t found_mountpoint)
+{
+	FILE *newfp = userdata;
+	if (!found_mountpoint)
+		fputs(line, newfp);
+	return (B_TRUE);
+}
+
+/*
+ * Copy all entries from the exports file (if it exists) to newfp,
+ * omitting any entries for the specified mountpoint.
+ */
+static int
+nfs_copy_entries(FILE *newfp, const char *exports, const char *mountpoint)
+{
+	fputs(FILE_HEADER, newfp);
+
+	int error = nfs_process_exports(
+	    exports, mountpoint, nfs_copy_entries_cb, newfp);
+
 	if (error == SA_OK && ferror(newfp) != 0)
 		error = ferror(newfp);
 
@@ -233,3 +246,20 @@ fullerr:
 	nfs_exports_unlock(lockfile);
 	return (error);
 }
+
+static boolean_t
+nfs_is_shared_cb(void *userdata, char *line, boolean_t found_mountpoint)
+{
+	boolean_t *found = userdata;
+	*found = found_mountpoint;
+	return (!found_mountpoint);
+}
+
+boolean_t
+nfs_is_shared_impl(const char *exports, sa_share_impl_t impl_share)
+{
+	boolean_t found = B_FALSE;
+	nfs_process_exports(exports, impl_share->sa_mountpoint,
+	    nfs_is_shared_cb, &found);
+	return (found);
+}

lib/libshare/nfs.h

@@ -30,6 +30,7 @@
 
 void libshare_nfs_init(void);
 
+boolean_t nfs_is_shared_impl(const char *exports, sa_share_impl_t impl_share);
 int nfs_toggle_share(const char *lockfile, const char *exports,
     const char *expdir, sa_share_impl_t impl_share,
     int(*cbk)(sa_share_impl_t impl_share, FILE *tmpfile));

lib/libshare/os/freebsd/nfs.c

@@ -148,35 +148,7 @@ nfs_disable_share(sa_share_impl_t impl_share)
 static boolean_t
 nfs_is_shared(sa_share_impl_t impl_share)
 {
-	char *s, last, line[MAXLINESIZE];
-	size_t len;
-	char *mntpoint = impl_share->sa_mountpoint;
-	size_t mntlen = strlen(mntpoint);
-
-	FILE *fp = fopen(ZFS_EXPORTS_FILE, "re");
-	if (fp == NULL)
-		return (B_FALSE);
-
-	for (;;) {
-		s = fgets(line, sizeof (line), fp);
-		if (s == NULL)
-			return (B_FALSE);
-		/* Skip empty lines and comments. */
-		if (line[0] == '\n' || line[0] == '#')
-			continue;
-		len = strlen(line);
-		if (line[len - 1] == '\n')
-			line[len - 1] = '\0';
-		last = line[mntlen];
-		/* Skip the given mountpoint. */
-		if (strncmp(mntpoint, line, mntlen) == 0 &&
-		    (last == '\t' || last == ' ' || last == '\0')) {
-			fclose(fp);
-			return (B_TRUE);
-		}
-	}
-	fclose(fp);
-	return (B_FALSE);
+	return (nfs_is_shared_impl(ZFS_EXPORTS_FILE, impl_share));
 }
 
 static int

lib/libshare/os/linux/nfs.c

@@ -467,31 +467,7 @@ nfs_disable_share(sa_share_impl_t impl_share)
 static boolean_t
 nfs_is_shared(sa_share_impl_t impl_share)
 {
-	size_t buflen = 0;
-	char *buf = NULL;
-
-	FILE *fp = fopen(ZFS_EXPORTS_FILE, "re");
-	if (fp == NULL) {
-		return (B_FALSE);
-	}
-	while ((getline(&buf, &buflen, fp)) != -1) {
-		char *space = NULL;
-
-		if ((space = strchr(buf, ' ')) != NULL) {
-			int mountpoint_len = strlen(impl_share->sa_mountpoint);
-
-			if (space - buf == mountpoint_len &&
-			    strncmp(impl_share->sa_mountpoint, buf,
-			    mountpoint_len) == 0) {
-				fclose(fp);
-				free(buf);
-				return (B_TRUE);
-			}
-		}
-	}
-	free(buf);
-	fclose(fp);
-	return (B_FALSE);
+	return (nfs_is_shared_impl(ZFS_EXPORTS_FILE, impl_share));
 }
 
 /*