From 443743d2d8fc41604332edf014d876868e6b09fb Mon Sep 17 00:00:00 2001
From: Thomas Schmitt <scdbackup@gmx.net>
Date: Sun, 11 Aug 2024 12:30:50 +0200
Subject: [PATCH] New API call iso_util_get_effective_lfa_mask()

---
 libisofs/fs_local.c   |  9 ++-------
 libisofs/libisofs.h   | 21 +++++++++++++++++++++
 libisofs/libisofs.ver |  1 +
 libisofs/util.c       | 20 ++++++++++++++++++++
 4 files changed, 44 insertions(+), 7 deletions(-)

diff --git a/libisofs/fs_local.c b/libisofs/fs_local.c
index aee14a4..e67fcce 100644
--- a/libisofs/fs_local.c
+++ b/libisofs/fs_local.c
@@ -1003,10 +1003,8 @@ int iso_local_set_lfa_flags(char *disk_path, uint64_t lfa_flags, int max_bit,
 {
     int ret, old_max_bit;
     struct stat stbuf;
-    uint64_t known_user_mask, known_su_mask, non_settable, unknown, eff_flags;
+    uint64_t eff_flags;
 
-    iso_util_get_lfa_masks(&known_user_mask, &known_su_mask, &non_settable,
-                           &unknown);
     *os_errno = 0;
     if (flag & 32)
         ret = stat(disk_path, &stbuf);
@@ -1018,10 +1016,7 @@ int iso_local_set_lfa_flags(char *disk_path, uint64_t lfa_flags, int max_bit,
     }
     if ((stbuf.st_mode & S_IFMT) == S_IFLNK && !(flag & 32))
         return 3;
-    if (flag & 1)
-        change_mask &= ~known_su_mask;
-    if (flag & 2)
-        change_mask &= (known_user_mask | known_su_mask);
+    change_mask= iso_util_get_effective_lfa_mask(change_mask, flag & 3);
     if (change_mask == 0) {
         return 1;
     } else if (change_mask == ~((uint64_t) 0)) {
diff --git a/libisofs/libisofs.h b/libisofs/libisofs.h
index 9bcaa58..22ddcad 100644
--- a/libisofs/libisofs.h
+++ b/libisofs/libisofs.h
@@ -8187,6 +8187,27 @@ int iso_util_decode_lfa_flags(char *flags_text, uint64_t *lfa_flags, int flag);
  */
 void iso_util_get_lfa_masks(uint64_t *user_settable, uint64_t *su_settable,
                             uint64_t *non_settable, uint64_t *unknown);
+
+
+/**
+ * Return the effective change mask which will be used by
+ * iso_local_set_lfa_flags() with the same input of parameters change_mask
+ * and flag bits 0 and 1.
+ *      
+ * @param change_mask
+ *      Tells which bits of lfa_flags are meant to change attribute flags
+ *      of the file. Submit ~((uint64_t) 0) if all bits may cause changes.
+ *      The set of changeable bits may further be restricted by bit0 and bit1
+ *      of parameter flag.
+ * @param flag
+ *      Bitfield for control purposes
+ *      bit0= do not try to change known superuser flags
+ *      bit1= change only known chattr settable flags
+ *
+ * @since 1.5.8
+ */
+uint64_t iso_util_get_effective_lfa_mask(uint64_t change_mask, int flag);
+
  
 
 /* Default in case that the compile environment has no macro PATH_MAX.
diff --git a/libisofs/libisofs.ver b/libisofs/libisofs.ver
index 7c4dee9..b93d455 100644
--- a/libisofs/libisofs.ver
+++ b/libisofs/libisofs.ver
@@ -392,6 +392,7 @@ iso_node_get_lfa_flags;
 iso_node_set_lfa_flags;
 iso_util_decode_lfa_flags;
 iso_util_encode_lfa_flags;
+iso_util_get_effective_lfa_mask;
 iso_util_get_lfa_masks;
 } LIBISOFS6;
 
diff --git a/libisofs/util.c b/libisofs/util.c
index 9c6a08b..fc27f5b 100644
--- a/libisofs/util.c
+++ b/libisofs/util.c
@@ -2642,3 +2642,23 @@ void iso_util_get_lfa_masks(uint64_t *user_settable, uint64_t *su_settable,
     *unknown = 0xffffffff8d602200;
 }
 
+
+/*
+ * @param flag          Bitfield for control purposes
+ *      bit0= do not try to change known superuser flags
+ *      bit1= change only known chattr settable flags
+ */
+uint64_t iso_util_get_effective_lfa_mask(uint64_t change_mask, int flag)
+{
+    uint64_t known_user_mask, known_su_mask, non_settable, unknown;
+
+    iso_util_get_lfa_masks(&known_user_mask, &known_su_mask, &non_settable,
+                           &unknown);
+    if (flag & 1)
+        change_mask &= ~known_su_mask;
+    if (flag & 2)
+        change_mask &= (known_user_mask | known_su_mask);
+    return change_mask;
+}
+
+