util-lib: when copying files make sure to apply some chattrs early, some late

Some chattrs only work sensible if you set them right after opening a
file for create (think: FS_NOCOW_FL). Others only work when they are
applied when the file is fully written (think: FS_IMMUTABLE_FL). Let's
take that into account when copying files and applying a chattr to them.

3 files changed, 32 insertions, 10 deletions

diff --git a/src/basic/chattr-util.h b/src/basic/chattr-util.h
index 7570bba2fa..eb6bfbe461 100644
--- a/src/basic/chattr-util.h
+++ b/src/basic/chattr-util.h
@@ -1,6 +1,20 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 #pragma once
 
+#include <linux/fs.h>
+
+#include "missing_fs.h"
+
+/* The chattr() flags to apply when creating a new file *before* writing to it. In particular, flags such as
+ * FS_NOCOW_FL don't work if applied a-posteriori. All other flags are fine (or even necessary, think
+ * FS_IMMUTABLE_FL!) to apply after writing to the files. */
+#define CHATTR_EARLY_FL                         \
+        (FS_NOATIME_FL |                        \
+         FS_COMPR_FL   |                        \
+         FS_NOCOW_FL   |                        \
+         FS_NOCOMP_FL  |                        \
+         FS_PROJINHERIT_FL)
+
 int chattr_fd(int fd, unsigned value, unsigned mask, unsigned *previous);
 int chattr_path(const char *p, unsigned value, unsigned mask, unsigned *previous);
 
diff --git a/src/basic/copy.c b/src/basic/copy.c
index 2f36c8eb87..eed9cfdff7 100644
--- a/src/basic/copy.c
+++ b/src/basic/copy.c
@@ -755,6 +755,7 @@ int copy_file_full(
                 int flags,
                 mode_t mode,
                 unsigned chattr_flags,
+                unsigned chattr_mask,
                 CopyFlags copy_flags,
                 copy_progress_bytes_t progress_bytes,
                 void *userdata) {
@@ -770,8 +771,8 @@ int copy_file_full(
                         return -errno;
         }
 
-        if (chattr_flags != 0)
-                (void) chattr_fd(fdt, chattr_flags, (unsigned) -1, NULL);
+        if (chattr_mask != 0)
+                (void) chattr_fd(fdt, chattr_flags, chattr_mask & CHATTR_EARLY_FL, NULL);
 
         r = copy_file_fd_full(from, fdt, copy_flags, progress_bytes, userdata);
         if (r < 0) {
@@ -780,6 +781,9 @@ int copy_file_full(
                 return r;
         }
 
+        if (chattr_mask != 0)
+                (void) chattr_fd(fdt, chattr_flags, chattr_mask & ~CHATTR_EARLY_FL, NULL);
+
         if (close(fdt) < 0) {
                 unlink_noerrno(to);
                 return -errno;
@@ -793,6 +797,7 @@ int copy_file_atomic_full(
                 const char *to,
                 mode_t mode,
                 unsigned chattr_flags,
+                unsigned chattr_mask,
                 CopyFlags copy_flags,
                 copy_progress_bytes_t progress_bytes,
                 void *userdata) {
@@ -826,8 +831,8 @@ int copy_file_atomic_full(
                         return fdt;
         }
 
-        if (chattr_flags != 0)
-                (void) chattr_fd(fdt, chattr_flags, (unsigned) -1, NULL);
+        if (chattr_mask != 0)
+                (void) chattr_fd(fdt, chattr_flags, chattr_mask & CHATTR_EARLY_FL, NULL);
 
         r = copy_file_fd_full(from, fdt, copy_flags, progress_bytes, userdata);
         if (r < 0)
@@ -845,6 +850,9 @@ int copy_file_atomic_full(
                         return r;
         }
 
+        if (chattr_mask != 0)
+                (void) chattr_fd(fdt, chattr_flags, chattr_mask & ~CHATTR_EARLY_FL, NULL);
+
         t = mfree(t);
         return 0;
 }
diff --git a/src/basic/copy.h b/src/basic/copy.h
index a33546d3ab..51ea4d51eb 100644
--- a/src/basic/copy.h
+++ b/src/basic/copy.h
@@ -25,14 +25,14 @@ static inline int copy_file_fd(const char *from, int to, CopyFlags copy_flags) {
         return copy_file_fd_full(from, to, copy_flags, NULL, NULL);
 }
 
-int copy_file_full(const char *from, const char *to, int open_flags, mode_t mode, unsigned chattr_flags, CopyFlags copy_flags, copy_progress_bytes_t progress, void *userdata);
-static inline int copy_file(const char *from, const char *to, int open_flags, mode_t mode, unsigned chattr_flags, CopyFlags copy_flags) {
-        return copy_file_full(from, to, open_flags, mode, chattr_flags, copy_flags, NULL, NULL);
+int copy_file_full(const char *from, const char *to, int open_flags, mode_t mode, unsigned chattr_flags, unsigned chattr_mask, CopyFlags copy_flags, copy_progress_bytes_t progress, void *userdata);
+static inline int copy_file(const char *from, const char *to, int open_flags, mode_t mode, unsigned chattr_flags, unsigned chattr_mask, CopyFlags copy_flags) {
+        return copy_file_full(from, to, open_flags, mode, chattr_flags, chattr_mask, copy_flags, NULL, NULL);
 }
 
-int copy_file_atomic_full(const char *from, const char *to, mode_t mode, unsigned chattr_flags, CopyFlags copy_flags, copy_progress_bytes_t progress, void *userdata);
-static inline int copy_file_atomic(const char *from, const char *to, mode_t mode, unsigned chattr_flags, CopyFlags copy_flags) {
-        return copy_file_atomic_full(from, to, mode, chattr_flags, copy_flags, NULL, NULL);
+int copy_file_atomic_full(const char *from, const char *to, mode_t mode, unsigned chattr_flags, unsigned chattr_mask, CopyFlags copy_flags, copy_progress_bytes_t progress, void *userdata);
+static inline int copy_file_atomic(const char *from, const char *to, mode_t mode, unsigned chattr_flags, unsigned chattr_mask, CopyFlags copy_flags) {
+        return copy_file_atomic_full(from, to, mode, chattr_flags, chattr_mask, copy_flags, NULL, NULL);
 }
 
 int copy_tree_at_full(int fdf, const char *from, int fdt, const char *to, uid_t override_uid, gid_t override_gid, CopyFlags copy_flags, copy_progress_path_t progress_path, copy_progress_bytes_t progress_bytes, void *userdata);