In base backup, only include our own tablespace version directory.

If you have clusters of different versions pointing to the same tablespace
location, we would incorrectly include all the data belonging to the other
versions, too.

Fixes bug #7986, reported by Sergey Burladyan.

src/backend/replication/basebackup.c

@@ -19,6 +19,7 @@
 
 #include "access/xlog_internal.h"		/* for pg_start/stop_backup */
 #include "catalog/pg_type.h"
+#include "common/relpath.h"
 #include "lib/stringinfo.h"
 #include "libpq/libpq.h"
 #include "libpq/pqformat.h"
@@ -45,6 +46,7 @@ typedef struct
 
 
 static int64 sendDir(char *path, int basepathlen, bool sizeonly);
+static int64 sendTablespace(char *path, bool sizeonly);
 static bool sendFile(char *readfilename, char *tarfilename,
 		 struct stat * statbuf, bool missing_ok);
 static void sendFileWithContent(const char *filename, const char *content);
@@ -146,7 +148,7 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
 			ti = palloc(sizeof(tablespaceinfo));
 			ti->oid = pstrdup(de->d_name);
 			ti->path = pstrdup(linkpath);
-			ti->size = opt->progress ? sendDir(linkpath, strlen(linkpath), true) : -1;
+			ti->size = opt->progress ? sendTablespace(fullpath, true) : -1;
 			tablespaces = lappend(tablespaces, ti);
 #else
 
@@ -181,29 +183,26 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
 			pq_sendint(&buf, 0, 2);		/* natts */
 			pq_endmessage(&buf);
 
-			/* In the main tar, include the backup_label first. */
-			if (ti->path == NULL)
-				sendFileWithContent(BACKUP_LABEL_FILE, labelfile);
-
-			sendDir(ti->path == NULL ? "." : ti->path,
-					ti->path == NULL ? 1 : strlen(ti->path),
-					false);
-
-			/* In the main tar, include pg_control last. */
 			if (ti->path == NULL)
 			{
 				struct stat statbuf;
 
+				/* In the main tar, include the backup_label first... */
+				sendFileWithContent(BACKUP_LABEL_FILE, labelfile);
+
+				/* ... then the bulk of the files ... */
+				sendDir(".", 1, false);
+
+				/* ... and pg_control after everything else. */
 				if (lstat(XLOG_CONTROL_FILE, &statbuf) != 0)
-				{
 					ereport(ERROR,
 							(errcode_for_file_access(),
 							 errmsg("could not stat control file \"%s\": %m",
 									XLOG_CONTROL_FILE)));
-				}
-
 				sendFile(XLOG_CONTROL_FILE, XLOG_CONTROL_FILE, &statbuf, false);
 			}
+			else
+				sendTablespace(ti->path, false);
 
 			/*
 			 * If we're including WAL, and this is the main data directory we
@@ -728,6 +727,49 @@ sendFileWithContent(const char *filename, const char *content)
 	}
 }
 
+/*
+ * Include the tablespace directory pointed to by 'path' in the output tar
+ * stream.  If 'sizeonly' is true, we just calculate a total length and return
+ * it, without actually sending anything.
+ */
+static int64
+sendTablespace(char *path, bool sizeonly)
+{
+	int64		size;
+	char		pathbuf[MAXPGPATH];
+	struct stat statbuf;
+
+	/*
+	 * 'path' points to the tablespace location, but we only want to include
+	 * the version directory in it that belongs to us.
+	 */
+	snprintf(pathbuf, sizeof(pathbuf), "%s/%s", path,
+			 TABLESPACE_VERSION_DIRECTORY);
+
+	/*
+	 * Store a directory entry in the tar file so we get the permissions right.
+	 */
+	if (lstat(pathbuf, &statbuf) != 0)
+	{
+		if (errno != ENOENT)
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not stat file or directory \"%s\": %m",
+							pathbuf)));
+
+		/* If the tablespace went away while scanning, it's no error. */
+		return 0;
+	}
+	if (!sizeonly)
+		_tarWriteHeader(TABLESPACE_VERSION_DIRECTORY, NULL, &statbuf);
+	size = 512;		/* Size of the header just added */
+
+	/* Send all the files in the tablespace version directory */
+	size += sendDir(pathbuf, strlen(path), sizeonly);
+
+	return size;
+}
+
 /*
  * Include all files from the given directory in the output tar stream. If
  * 'sizeonly' is true, we just calculate a total length and return it, without