libbb: shrink recursive_action() by reducing memory pressure

function old new delta recursive_action1 - 316 +316 file_action_grep 161 164 +3 add_to_prg_cache_if_socket 202 205 +3 depmod_main 509 511 +2 writeFileToTarball 488 489 +1 parse_module 281 282 +1 fileAction 207 208 +1 act 189 190 +1 add_to_dirlist 65 64 -1 writeTarFile 196 194 -2 uuidcache_init 47 45 -2 uuidcache_check_device 109 107 -2 true_action 8 6 -2 run_parts_main 310 308 -2 netstat_main 534 532 -2 lsusb_main 29 27 -2 lspci_main 45 43 -2 initial_scan 138 136 -2 grep_main 845 843 -2 find_main 482 480 -2 config_file_action 437 435 -2 chmod_main 142 140 -2 dirAction 14 10 -4 diff_main 1544 1540 -4 chown_main 154 148 -6 skip_dir 136 129 -7 dir_act 191 184 -7 recursive_action 453 69 -384 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 7/20 up/down: 328/-439) Total: -111 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2020-10-01 21:52:16 +02:00
parent 3c3928fc65
commit 689d0650ab
19 changed files with 159 additions and 150 deletions
--- a/libbb/recursive_action.c
+++ b/libbb/recursive_action.c
@@ -21,10 +21,9 @@
 * is so stinking huge.
 */

-static int FAST_FUNC true_action(const char *fileName UNUSED_PARAM,
-		struct stat *statbuf UNUSED_PARAM,
-		void* userData UNUSED_PARAM,
-		int depth UNUSED_PARAM)
+static int FAST_FUNC true_action(struct recursive_state *state UNUSED_PARAM,
+		const char *fileName UNUSED_PARAM,
+		struct stat *statbuf UNUSED_PARAM)
 {
 	return TRUE;
 }
@@ -65,12 +64,7 @@ static int FAST_FUNC true_action(const char *fileName UNUSED_PARAM,
 * 1: stat(statbuf). Calls dirAction and optionally recurse on link to dir.
 */

-int FAST_FUNC recursive_action(const char *fileName,
-		unsigned flags,
-		int FAST_FUNC (*fileAction)(const char *fileName, struct stat *statbuf, void* userData, int depth),
-		int FAST_FUNC (*dirAction)(const char *fileName, struct stat *statbuf, void* userData, int depth),
-		void* userData,
-		unsigned depth)
+static int recursive_action1(recursive_state_t *state, const char *fileName)
 {
 	struct stat statbuf;
 	unsigned follow;
@@ -78,24 +72,21 @@ int FAST_FUNC recursive_action(const char *fileName,
 	DIR *dir;
 	struct dirent *next;

-	if (!fileAction) fileAction = true_action;
-	if (!dirAction) dirAction = true_action;
-
 	follow = ACTION_FOLLOWLINKS;
-	if (depth == 0)
+	if (state->depth == 0)
 		follow = ACTION_FOLLOWLINKS | ACTION_FOLLOWLINKS_L0;
-	follow &= flags;
+	follow &= state->flags;
 	status = (follow ? stat : lstat)(fileName, &statbuf);
 	if (status < 0) {
 #ifdef DEBUG_RECURS_ACTION
-		bb_error_msg("status=%d flags=%x", status, flags);
+		bb_error_msg("status=%d flags=%x", status, state->flags);
 #endif
-		if ((flags & ACTION_DANGLING_OK)
+		if ((state->flags & ACTION_DANGLING_OK)
 		 && errno == ENOENT
 		 && lstat(fileName, &statbuf) == 0
 		) {
 			/* Dangling link */
-			return fileAction(fileName, &statbuf, userData, depth);
+			return state->fileAction(state, fileName, &statbuf);
 		}
 		goto done_nak_warn;
 	}
@@ -103,20 +94,20 @@ int FAST_FUNC recursive_action(const char *fileName,
 	/* If S_ISLNK(m), then we know that !S_ISDIR(m).
 	 * Then we can skip checking first part: if it is true, then
 	 * (!dir) is also true! */
-	if ( /* (!(flags & ACTION_FOLLOWLINKS) && S_ISLNK(statbuf.st_mode)) || */
+	if ( /* (!(state->flags & ACTION_FOLLOWLINKS) && S_ISLNK(statbuf.st_mode)) || */
 	 !S_ISDIR(statbuf.st_mode)
 	) {
-		return fileAction(fileName, &statbuf, userData, depth);
+		return state->fileAction(state, fileName, &statbuf);
 	}

 	/* It's a directory (or a link to one, and followLinks is set) */

-	if (!(flags & ACTION_RECURSE)) {
-		return dirAction(fileName, &statbuf, userData, depth);
+	if (!(state->flags & ACTION_RECURSE)) {
+		return state->dirAction(state, fileName, &statbuf);
 	}

-	if (!(flags & ACTION_DEPTHFIRST)) {
-		status = dirAction(fileName, &statbuf, userData, depth);
+	if (!(state->flags & ACTION_DEPTHFIRST)) {
+		status = state->dirAction(state, fileName, &statbuf);
 		if (status == FALSE)
 			goto done_nak_warn;
 		if (status == SKIP)
@@ -140,11 +131,13 @@ int FAST_FUNC recursive_action(const char *fileName,
 			continue;

 		/* process every file (NB: ACTION_RECURSE is set in flags) */
-		s = recursive_action(nextFile, flags, fileAction, dirAction,
-						userData, depth + 1);
+		state->depth++;
+		s = recursive_action1(state, nextFile);
 		if (s == FALSE)
 			status = FALSE;
 		free(nextFile);
+		state->depth--;
+
 //#define RECURSE_RESULT_ABORT -1
 //		if (s == RECURSE_RESULT_ABORT) {
 //			closedir(dir);
@@ -153,15 +146,36 @@ int FAST_FUNC recursive_action(const char *fileName,
 	}
 	closedir(dir);

-	if (flags & ACTION_DEPTHFIRST) {
-		if (!dirAction(fileName, &statbuf, userData, depth))
+	if (state->flags & ACTION_DEPTHFIRST) {
+		if (!state->dirAction(state, fileName, &statbuf))
 			goto done_nak_warn;
 	}

 	return status;

 done_nak_warn:
-	if (!(flags & ACTION_QUIET))
+	if (!(state->flags & ACTION_QUIET))
 		bb_simple_perror_msg(fileName);
 	return FALSE;
 }
+
+int FAST_FUNC recursive_action(const char *fileName,
+		unsigned flags,
+		int FAST_FUNC (*fileAction)(struct recursive_state *state, const char *fileName, struct stat* statbuf),
+		int FAST_FUNC  (*dirAction)(struct recursive_state *state, const char *fileName, struct stat* statbuf),
+		void *userData)
+{
+	/* Keeping a part of variables of recusive descent in a "state structure"
+	 * instead of passing ALL of them down as parameters of recursive_action1()
+	 * relieves register pressure, both in recursive_action1()
+	 * and in every file/dirAction().
+	 */
+	recursive_state_t state;
+	state.flags = flags;
+	state.depth = 0;
+	state.userData = userData;
+	state.fileAction = fileAction ? fileAction : true_action;
+	state.dirAction  =  dirAction ?  dirAction : true_action;
+
+	return recursive_action1(&state, fileName);
+}