From: Zen Dodd <mail@steadytao.com>
Date: Sat, 6 Jun 2026 05:00:57 +0000 (+1000)
Subject: chmod: clear special bits on copy assignment
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=30751ca8643c51d4fadac8e8115d6e8d4b62e1fd;p=thirdparty%2Frsync.git

chmod: clear special bits on copy assignment
---

diff --git a/chmod.c b/chmod.c
index 8538d182..8368e5b3 100644
--- a/chmod.c
+++ b/chmod.c
@@ -43,6 +43,20 @@ struct chmod_mode_struct {
 #define STATE_2ND_HALF 2
 #define STATE_OCTAL_NUM 3
 
+static int mode_dest_special_bits(int where)
+{
+	int bits = 0;
+
+	if (where & 0100)
+		bits |= S_ISUID;
+	if (where & 0010)
+		bits |= S_ISGID;
+	if (where & 0001)
+		bits |= S_ISVTX;
+
+	return bits;
+}
+
 /* Parse a chmod-style argument, and break it down into one or more AND/OR
  * pairs in a linked list.  We return a pointer to new items on success
  * (appending the items to the specified list), or NULL on error. */
@@ -96,7 +110,8 @@ struct chmod_mode_struct *parse_chmod(const char *modestr,
 				curr_mode->ModeOP = op;
 				break;
 			case CHMOD_EQ:
-				curr_mode->ModeAND = CHMOD_BITS - (where * 7) - (topoct ? topbits : 0);
+				curr_mode->ModeAND = CHMOD_BITS - (where * 7) - (topoct ? topbits : 0)
+						    - (copybits ? mode_dest_special_bits(where) : 0);
 				curr_mode->ModeOR  = bits + topoct;
 				curr_mode->ModeCOPY_SRC = copybits;
 				curr_mode->ModeCOPY_DST = where;
diff --git a/testsuite/chmod-option_test.py b/testsuite/chmod-option_test.py
index b1cf714e..ad0fc77b 100644
--- a/testsuite/chmod-option_test.py
+++ b/testsuite/chmod-option_test.py
@@ -62,12 +62,16 @@ for d in (checkdir, checkdir / 'dir1', checkdir / 'dir2'):
 checkit(['-avv', '--chmod', 'ug-s,a+rX,D+w', f'{FROMDIR}/', f'{TODIR}/'],
         checkdir, TODIR)
 
-def check_permcopy(chmod_arg, start_mode, expected):
+def check_permcopy(chmod_arg, start_mode, expected, is_dir=False):
     rmtree(FROMDIR)
     rmtree(TODIR)
     makepath(FROMDIR)
-    (FROMDIR / 'permcopy').write_text('permcopy\n')
-    os.chmod(FROMDIR / 'permcopy', start_mode)
+    permcopy = FROMDIR / 'permcopy'
+    if is_dir:
+        permcopy.mkdir()
+    else:
+        permcopy.write_text('permcopy\n')
+    os.chmod(permcopy, start_mode)
     run_rsync('-avv', f'--chmod={chmod_arg}', f'{FROMDIR}/', f'{TODIR}/')
     check_perms(TODIR / 'permcopy', expected)
 
@@ -76,6 +80,9 @@ def check_permcopy(chmod_arg, start_mode, expected):
 check_permcopy('g=o,o=', 0o647, 'rw-rwx---')
 check_permcopy('g=u', 0o741, 'rwxrwx--x')
 check_permcopy('g-o', 0o775, 'rwx-w-r-x')
+check_permcopy('u=g', 0o4755, 'r-xr-xr-x')
+check_permcopy('g=u', 0o2755, 'rwxrwxr-x')
+check_permcopy('o=u', 0o1750, 'rwxr-xrwx', is_dir=True)
 
 rmtree(FROMDIR)
 rmtree(TODIR)