archive: rename archiver data field to filter_command

The void pointer "data" in struct archiver is only used to store filter
commands to pass tar archives to, like gzip.  Rename it accordingly and
also turn it into a char pointer to document the fact that it's a string
reference.

Signed-off-by: René Scharfe <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: rscharfe

archive-tar.c

@@ -383,8 +383,8 @@ static int tar_filter_config(const char *var, const char *value, void *data)
 	if (!strcmp(type, "command")) {
 		if (!value)
 			return config_error_nonbool(var);
-		free(ar->data);
-		ar->data = xstrdup(value);
+		free(ar->filter_command);
+		ar->filter_command = xstrdup(value);
 		return 0;
 	}
 	if (!strcmp(type, "remote")) {
@@ -432,10 +432,10 @@ static int write_tar_filter_archive(const struct archiver *ar,
 	struct child_process filter = CHILD_PROCESS_INIT;
 	int r;
 
-	if (!ar->data)
+	if (!ar->filter_command)
 		BUG("tar-filter archiver called with no filter defined");
 
-	strbuf_addstr(&cmd, ar->data);
+	strbuf_addstr(&cmd, ar->filter_command);
 	if (args->compression_level >= 0)
 		strbuf_addf(&cmd, " -%d", args->compression_level);
 
@@ -478,7 +478,7 @@ void init_tar_archiver(void)
 	git_config(git_tar_config, NULL);
 	for (i = 0; i < nr_tar_filters; i++) {
 		/* omit any filters that never had a command configured */
-		if (tar_filters[i]->data)
+		if (tar_filters[i]->filter_command)
 			register_archiver(tar_filters[i]);
 	}
 }

archive.h

@@ -43,7 +43,7 @@ struct archiver {
 	const char *name;
 	int (*write_archive)(const struct archiver *, struct archiver_args *);
 	unsigned flags;
-	void *data;
+	char *filter_command;
 };
 void register_archiver(struct archiver *);