Fix multiple bugs and infelicities in pg_rewind.

Bugs all spotted by Coverity, including wrong realloc() size request
and memory leaks.  Cosmetic improvements by me.

The usage of the global variable "filemap" here is still pretty awful,
but at least I got rid of the gratuitous aliasing in several routines
(which was helping to annoy Coverity, as well as being a bug risk).

src/bin/pg_rewind/filemap.c

@@ -30,12 +30,12 @@ static char *datasegpath(RelFileNode rnode, ForkNumber forknum,
 			BlockNumber segno);
 static int	path_cmp(const void *a, const void *b);
 static int	final_filemap_cmp(const void *a, const void *b);
-static void filemap_list_to_array(void);
+static void filemap_list_to_array(filemap_t *map);
 
 /*
- * Create a new file map.
+ * Create a new file map (stored in the global pointer "filemap").
  */
-filemap_t *
+void
 filemap_create(void)
 {
 	filemap_t  *map;
@@ -48,8 +48,6 @@ filemap_create(void)
 
 	Assert(filemap == NULL);
 	filemap = map;
-
-	return map;
 }
 
 /*
@@ -271,7 +269,10 @@ process_local_file(const char *path, file_type_t type, size_t oldsize,
 			pg_fatal("remote file list is empty\n");
 		}
 
-		filemap_list_to_array();
+		filemap_list_to_array(map);
+
+		Assert(map->array != NULL);
+
 		qsort(map->array, map->narray, sizeof(file_entry_t *), path_cmp);
 	}
 
@@ -284,8 +285,8 @@ process_local_file(const char *path, file_type_t type, size_t oldsize,
 
 	key.path = (char *) path;
 	key_ptr = &key;
-	exists = bsearch(&key_ptr, map->array, map->narray, sizeof(file_entry_t *),
-					 path_cmp) != NULL;
+	exists = (bsearch(&key_ptr, map->array, map->narray, sizeof(file_entry_t *),
+					  path_cmp) != NULL);
 
 	/* Remove any file or folder that doesn't exist in the remote system. */
 	if (!exists)
@@ -335,7 +336,7 @@ process_block_change(ForkNumber forknum, RelFileNode rnode, BlockNumber blkno)
 	filemap_t  *map = filemap;
 	file_entry_t **e;
 
-	Assert(filemap->array);
+	Assert(map->array);
 
 	segno = blkno / RELSEG_SIZE;
 	blkno_inseg = blkno % RELSEG_SIZE;
@@ -395,38 +396,40 @@ process_block_change(ForkNumber forknum, RelFileNode rnode, BlockNumber blkno)
 }
 
 /*
- * Convert the linked list of entries in filemap->first/last to the array,
- * filemap->array.
+ * Convert the linked list of entries in map->first/last to the array,
+ * map->array.
  */
 static void
-filemap_list_to_array(void)
+filemap_list_to_array(filemap_t *map)
 {
 	int			narray;
 	file_entry_t *entry,
 			   *next;
 
-	filemap->array =
-		pg_realloc(filemap->array,
-				   (filemap->nlist + filemap->narray) * sizeof(file_entry_t));
+	map->array = (file_entry_t **)
+		pg_realloc(map->array,
+				   (map->nlist + map->narray) * sizeof(file_entry_t *));
 
-	narray = filemap->narray;
-	for (entry = filemap->first; entry != NULL; entry = next)
+	narray = map->narray;
+	for (entry = map->first; entry != NULL; entry = next)
 	{
-		filemap->array[narray++] = entry;
+		map->array[narray++] = entry;
 		next = entry->next;
 		entry->next = NULL;
 	}
-	Assert(narray == filemap->nlist + filemap->narray);
-	filemap->narray = narray;
-	filemap->nlist = 0;
-	filemap->first = filemap->last = NULL;
+	Assert(narray == map->nlist + map->narray);
+	map->narray = narray;
+	map->nlist = 0;
+	map->first = map->last = NULL;
 }
 
 void
 filemap_finalize(void)
 {
-	filemap_list_to_array();
-	qsort(filemap->array, filemap->narray, sizeof(file_entry_t *),
+	filemap_t  *map = filemap;
+
+	filemap_list_to_array(map);
+	qsort(map->array, map->narray, sizeof(file_entry_t *),
 		  final_filemap_cmp);
 }
 
@@ -466,9 +469,9 @@ calculate_totals(void)
 	map->total_size = 0;
 	map->fetch_size = 0;
 
-	for (i = 0; i < filemap->narray; i++)
+	for (i = 0; i < map->narray; i++)
 	{
-		entry = filemap->array[i];
+		entry = map->array[i];
 
 		if (entry->type != FILE_TYPE_REGULAR)
 			continue;
@@ -501,12 +504,13 @@ calculate_totals(void)
 void
 print_filemap(void)
 {
+	filemap_t  *map = filemap;
 	file_entry_t *entry;
 	int			i;
 
-	for (i = 0; i < filemap->narray; i++)
+	for (i = 0; i < map->narray; i++)
 	{
-		entry = filemap->array[i];
+		entry = map->array[i];
 		if (entry->action != FILE_ACTION_NONE ||
 			entry->pagemap.bitmapsize > 0)
 		{

src/bin/pg_rewind/filemap.h

@@ -29,8 +29,7 @@ typedef enum
 	FILE_ACTION_NONE,		/* no action (we might still copy modified blocks
 							 * based on the parsed WAL) */
 	FILE_ACTION_TRUNCATE,	/* truncate local file to 'newsize' bytes */
-	FILE_ACTION_REMOVE,		/* remove local file / directory / symlink */
-
+	FILE_ACTION_REMOVE		/* remove local file / directory / symlink */
 } file_action_t;
 
 typedef enum
@@ -40,7 +39,7 @@ typedef enum
 	FILE_TYPE_SYMLINK
 } file_type_t;
 
-struct file_entry_t
+typedef struct file_entry_t
 {
 	char	   *path;
 	file_type_t type;
@@ -58,11 +57,9 @@ struct file_entry_t
 	char		*link_target;
 
 	struct file_entry_t *next;
-};
-
-typedef struct file_entry_t file_entry_t;
+} file_entry_t;
 
-struct filemap_t
+typedef struct filemap_t
 {
 	/*
 	 * New entries are accumulated to a linked list, in process_remote_file
@@ -70,7 +67,7 @@ struct filemap_t
 	 */
 	file_entry_t *first;
 	file_entry_t *last;
-	int			nlist;
+	int			nlist;			/* number of entries currently in list */
 
 	/*
 	 * After processing all the remote files, the entries in the linked list
@@ -80,7 +77,7 @@ struct filemap_t
 	 * the array, and the linked list is empty.
 	 */
 	file_entry_t **array;
-	int			narray;
+	int			narray;			/* current length of array */
 
 	/*
 	 * Summary information. total_size is the total size of the source cluster,
@@ -88,14 +85,11 @@ struct filemap_t
 	 */
 	uint64		total_size;
 	uint64		fetch_size;
-};
-
-typedef struct filemap_t filemap_t;
-
-extern filemap_t * filemap;
+} filemap_t;
 
-extern filemap_t *filemap_create(void);
+extern filemap_t *filemap;
 
+extern void filemap_create(void);
 extern void calculate_totals(void);
 extern void print_filemap(void);
 

src/bin/pg_rewind/libpq_fetch.c

@@ -285,6 +285,10 @@ receiveFileChunks(const char *sql)
 		open_target_file(filename, false);
 
 		write_target_range(chunk, chunkoff, chunksize);
+
+		pg_free(filename);
+
+		PQclear(res);
 	}
 }
 

src/bin/pg_rewind/pg_rewind.c

@@ -248,7 +248,7 @@ main(int argc, char **argv)
 	/*
 	 * Build the filemap, by comparing the remote and local data directories.
 	 */
-	(void) filemap_create();
+	filemap_create();
 	pg_log(PG_PROGRESS, "reading source file list\n");
 	fetchRemoteFileList();
 	pg_log(PG_PROGRESS, "reading target file list\n");