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Use fewer flags when opening directories

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This doesn’t change behavior; it is a refactoring for
compatibility with a future patch that will use Linux’s
openat2 syscall, which is pickier about flags.
* src/tar.c (decode_options): When searching directories,
do not use O_NOCTTY, O_NONBLOCK, and O_NOATIME.
openat2 rejects all three flags if O_PATH is used.
The first two flags are definitely irrelevant for directories,
and O_NOATIME probably doesn’t matter either.
This commit is contained in:
Paul Eggert 2025-11-13 13:18:27 -08:00
parent 915a8077af
commit e1445cfdf0
1 changed files with 15 additions and 11 deletions
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26
src/tar.c
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@ -2692,21 +2692,25 @@ decode_options (int argc, char **argv)
if (recursive_unlink_option)
old_files_option = UNLINK_FIRST_OLD_FILES;
/* Flags for accessing files to be read from or copied into. POSIX says
O_NONBLOCK has unspecified effect on most types of files, but in
practice it never harms and sometimes helps. */
/* Flags for accessing files to be read from, searched, or statted. */
{
int base_open_flags =
(O_BINARY | O_CLOEXEC | O_NOCTTY | O_NONBLOCK
| (dereference_option ? 0 : O_NOFOLLOW)
| (atime_preserve_option == system_atime_preserve ? O_NOATIME : 0));
open_read_flags = O_RDONLY | base_open_flags;
int noatime_flag = (atime_preserve_option == system_atime_preserve
? O_NOATIME : 0);
int nofollow_flag = dereference_option ? 0 : O_NOFOLLOW;
/* POSIX says O_NONBLOCK has unspecified effect on most types of
files, but in practice it harms only with O_PATH and sometimes
helps otherwise. */
open_read_flags = (O_RDONLY | O_BINARY | O_CLOEXEC | O_NOCTTY | O_NONBLOCK
| noatime_flag | nofollow_flag);
#if defined O_PATH && O_SEARCH == O_RDONLY
int open_search_flag = O_PATH;
int search_flags = O_PATH; /* openat2 rejects O_PATH | O_NOATIME. */
#else
int open_search_flag = O_SEARCH;
int search_flags = O_SEARCH | noatime_flag;
#endif
open_searchdir_flags = open_search_flag | O_DIRECTORY | base_open_flags;
open_searchdir_flags = (search_flags | O_BINARY | O_CLOEXEC | O_DIRECTORY
| nofollow_flag);
}
fstatat_flags = dereference_option ? 0 : AT_SYMLINK_NOFOLLOW;