aports/main/busybox/0025-find-fix-xdev-depth-and-delete.patch

From fdfcf5d1e3dd171f3175804dfae4247e995a0fd8 Mon Sep 17 00:00:00 2001
From: Dominique Martinet <dominique.martinet@atmark-techno.com>
Date: Fri, 27 Oct 2023 06:42:35 +0900
Subject: [PATCH] find: fix -xdev -depth (and -delete)
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find -xdev with -depth would check for same_fs after the subdirectory
has been processed (because the check is done in the file/dir action,
which is evaluated too late in the -depth case)
This renders `find -xdev -delete` useless, as reported in 2012 here:
https://bugs.busybox.net/show_bug.cgi?id=5756

The bug report suggested adding an extra hook, which would be required
if we were to keep the current xdev approach that allows all filesystems
given in argument, but GNU findutils and OpenBSD find actually stop on
the first filesystem boundary e.g. for the following tree:

$ find test -exec stat --format "%d %n"  {} +
27 test
27 test/file
59 test/tmpfs
27 test/tmpfs/bind
27 test/tmpfs/bind/file
59 test/tmpfs/file
(Where 'test/tmpfs' is a tmpfs, and 'test/tmpfs/bind' is a bind mount
to a neighboring directory in the same filesystem as 'test' -- also
tested with a symlink and -follow for openbsd which has no bind mount)

Then `find test test/tmpfs -xdev` does not print test/tmpfs/bind/file.

This makes the implementation much simpler (although it's a bit ugly to
carry the parent st_dev as an argument to the function) and smaller
code, and would allow for easy addition of rm/cp --one-file-system if
we want to do that later.

Note: this also no longer stores the stat result in 'status' in
recursive_action1 as that was not used and doing this saves 10 bytes

function                                             old     new   delta
recursive_action1                                    361     385     +24
parse_params                                        1503    1510      +7
recursive_action                                      63      65      +2
fileAction                                           206     127     -79
find_main                                            520     417    -103
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/2 up/down: 33/-182)          Total: -149 bytes
   text	   data	    bss	    dec	    hex	filename
  78267	   1582	   1552	  81401	  13df9	busybox_old
  78118	   1582	   1552	  81252	  13d64	busybox_unstripped
---
 findutils/find.c         | 44 ++--------------------------------------
 include/libbb.h          |  1 +
 libbb/recursive_action.c | 19 ++++++++++-------
 3 files changed, 15 insertions(+), 49 deletions(-)

diff --git a/findutils/find.c b/findutils/find.c
index 31c996988..a4a6bbc2d 100644
--- a/findutils/find.c
+++ b/findutils/find.c
@@ -501,7 +501,6 @@ struct globals {
 #endif
 	action ***actions;
 	smallint need_print;
-	smallint xdev_on;
 	smalluint exitstatus;
 	recurse_flags_t recurse_flags;
 	IF_FEATURE_FIND_EXEC_PLUS(unsigned max_argv_len;)
@@ -1015,26 +1014,10 @@ static int FAST_FUNC fileAction(
 		struct stat *statbuf)
 {
 	int r;
-	int same_fs = 1;
-
-#if ENABLE_FEATURE_FIND_XDEV
-	if (S_ISDIR(statbuf->st_mode) && G.xdev_count) {
-		int i;
-		for (i = 0; i < G.xdev_count; i++) {
-			if (G.xdev_dev[i] == statbuf->st_dev)
-				goto found;
-		}
-		//bb_error_msg("'%s': not same fs", fileName);
-		same_fs = 0;
- found: ;
-	}
-#endif
 
 #if ENABLE_FEATURE_FIND_MAXDEPTH
 	if (state->depth < G.minmaxdepth[0]) {
-		if (same_fs)
-			return TRUE; /* skip this, continue recursing */
-		return SKIP; /* stop recursing */
+		return TRUE; /* skip this, continue recursing */
 	}
 	if (state->depth > G.minmaxdepth[1])
 		return SKIP; /* stop recursing */
@@ -1051,11 +1034,6 @@ static int FAST_FUNC fileAction(
 			return SKIP;
 	}
 #endif
-	/* -xdev stops on mountpoints, but AFTER mountpoit itself
-	 * is processed as usual */
-	if (!same_fs) {
-		return SKIP;
-	}
 
 	/* Cannot return 0: our caller, recursive_action(),
 	 * will perror() and skip dirs (if called on dir) */
@@ -1295,7 +1273,7 @@ static action*** parse_params(char **argv)
 #if ENABLE_FEATURE_FIND_XDEV
 		else if (parm == OPT_XDEV) {
 			dbg("%d", __LINE__);
-			G.xdev_on = 1;
+			G.recurse_flags |= ACTION_XDEV;
 		}
 #endif
 #if ENABLE_FEATURE_FIND_MAXDEPTH
@@ -1718,24 +1696,6 @@ int find_main(int argc UNUSED_PARAM, char **argv)
 	G.actions = parse_params(&argv[firstopt]);
 	argv[firstopt] = NULL;
 
-#if ENABLE_FEATURE_FIND_XDEV
-	if (G.xdev_on) {
-		struct stat stbuf;
-
-		G.xdev_count = firstopt;
-		G.xdev_dev = xzalloc(G.xdev_count * sizeof(G.xdev_dev[0]));
-		for (i = 0; argv[i]; i++) {
-			/* not xstat(): shouldn't bomb out on
-			 * "find not_exist exist -xdev" */
-			if (stat(argv[i], &stbuf) == 0)
-				G.xdev_dev[i] = stbuf.st_dev;
-			/* else G.xdev_dev[i] stays 0 and
-			 * won't match any real device dev_t
-			 */
-		}
-	}
-#endif
-
 	for (i = 0; argv[i]; i++) {
 		if (!recursive_action(argv[i],
 				G.recurse_flags,/* flags */
diff --git a/include/libbb.h b/include/libbb.h
index 0dddc8b8a..66fe9ecf7 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -519,6 +519,7 @@ enum {
 	ACTION_DEPTHFIRST     = (1 << 3),
 	ACTION_QUIET          = (1 << 4),
 	ACTION_DANGLING_OK    = (1 << 5),
+	ACTION_XDEV           = (1 << 6),
 };
 typedef uint8_t recurse_flags_t;
 typedef struct recursive_state {
diff --git a/libbb/recursive_action.c b/libbb/recursive_action.c
index b1c4bfad7..d4b40afde 100644
--- a/libbb/recursive_action.c
+++ b/libbb/recursive_action.c
@@ -62,13 +62,15 @@ static int FAST_FUNC true_action(struct recursive_state *state UNUSED_PARAM,
  * ACTION_FOLLOWLINKS mainly controls handling of links to dirs.
  * 0: lstat(statbuf). Calls fileAction on link name even if points to dir.
  * 1: stat(statbuf). Calls dirAction and optionally recurse on link to dir.
+ *
+ * If ACTION_XDEV, stop on different filesystem _after_ it has been processed
  */
 
-static int recursive_action1(recursive_state_t *state, const char *fileName)
+static int recursive_action1(recursive_state_t *state, const char *fileName, dev_t parentDev)
 {
 	struct stat statbuf;
 	unsigned follow;
-	int status;
+	int status = TRUE;
 	DIR *dir;
 	struct dirent *next;
 
@@ -76,8 +78,7 @@ static int recursive_action1(recursive_state_t *state, const char *fileName)
 	if (state->depth == 0)
 		follow = ACTION_FOLLOWLINKS | ACTION_FOLLOWLINKS_L0;
 	follow &= state->flags;
-	status = (follow ? stat : lstat)(fileName, &statbuf);
-	if (status < 0) {
+	if ((follow ? stat : lstat)(fileName, &statbuf) < 0) {
 #ifdef DEBUG_RECURS_ACTION
 		bb_error_msg("status=%d flags=%x", status, state->flags);
 #endif
@@ -114,6 +115,10 @@ static int recursive_action1(recursive_state_t *state, const char *fileName)
 			return TRUE;
 	}
 
+	/* skip cross devices -- we still need to process action */
+	if ((state->flags & ACTION_XDEV) && parentDev != 0 && statbuf.st_dev != parentDev)
+		goto skip_recurse;
+
 	dir = opendir(fileName);
 	if (!dir) {
 		/* findutils-4.1.20 reports this */
@@ -121,7 +126,6 @@ static int recursive_action1(recursive_state_t *state, const char *fileName)
 		/* To trigger: "find -exec rm -rf {} \;" */
 		goto done_nak_warn;
 	}
-	status = TRUE;
 	while ((next = readdir(dir)) != NULL) {
 		char *nextFile;
 		int s;
@@ -132,7 +136,7 @@ static int recursive_action1(recursive_state_t *state, const char *fileName)
 
 		/* process every file (NB: ACTION_RECURSE is set in flags) */
 		state->depth++;
-		s = recursive_action1(state, nextFile);
+		s = recursive_action1(state, nextFile, statbuf.st_dev);
 		if (s == FALSE)
 			status = FALSE;
 		free(nextFile);
@@ -146,6 +150,7 @@ static int recursive_action1(recursive_state_t *state, const char *fileName)
 	}
 	closedir(dir);
 
+skip_recurse:
 	if (state->flags & ACTION_DEPTHFIRST) {
 		if (!state->dirAction(state, fileName, &statbuf))
 			goto done_nak_warn;
@@ -177,5 +182,5 @@ int FAST_FUNC recursive_action(const char *fileName,
 	state.fileAction = fileAction ? fileAction : true_action;
 	state.dirAction  =  dirAction ?  dirAction : true_action;
 
-	return recursive_action1(&state, fileName);
+	return recursive_action1(&state, fileName, 0);
 }