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xz: O_SEARCH cannot be used for fsync() 

Opening a directory with O_SEARCH results in a file descriptor that can
be used with functions like openat(). Such a file descriptor cannot be
used with fsync(). Use O_RDONLY instead.

In musl, O_SEARCH becomes Linux-specific O_PATH. A file descriptor
from O_PATH doesn't allow fsync().

Seems that it's not possible to fsync() a directory that has write
and search permissions but not read permission.

Fixes: 2a9e91d796
This commit is contained in:
Lasse Collin 2025-01-05 21:43:11 +02:00
parent ad2b57cb47
commit 4014e2479c
No known key found for this signature in database
GPG Key ID: 38EE757D69184620
1 changed files with 10 additions and 11 deletions
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21
src/xz/file_io.c
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@ -69,10 +69,6 @@ static bool warn_fchown;
# define O_NOCTTY 0 # define O_NOCTTY 0
#endif #endif
#ifndef O_SEARCH
# define O_SEARCH O_RDONLY
#endif
#ifndef O_DIRECTORY #ifndef O_DIRECTORY
# define O_DIRECTORY 0 # define O_DIRECTORY 0
#endif #endif
@ -890,7 +886,7 @@ io_open_dest_real(file_pair *pair)
// to a directory. (We opened the source file // to a directory. (We opened the source file
// already but directories might have been renamed // already but directories might have been renamed
// after the source file was opened.) // after the source file was opened.)
pair->dir_fd = open(dir_name, O_SEARCH | O_DIRECTORY pair->dir_fd = open(dir_name, O_RDONLY | O_DIRECTORY
| O_NOCTTY | O_NONBLOCK); | O_NOCTTY | O_NONBLOCK);
if (pair->dir_fd == -1) { if (pair->dir_fd == -1) {
// Since we did open the source file // Since we did open the source file
@ -900,12 +896,15 @@ io_open_dest_real(file_pair *pair)
// //
// In an odd case, the directory has write // In an odd case, the directory has write
// and search permissions but not read // and search permissions but not read
// permission (d-wx------), and O_SEARCH is // permission (d-wx------). Then we would be
// actually O_RDONLY. Then we would be able // able to create a new file and only the
// to create a new file and only the directory // directory syncing would be impossible. But
// syncing would be impossible. But let's be // let's be strict about syncing and require
// strict about syncing and require users to // users to explicitly disable it if they
// explicitly disable it if they don't want it. // don't want it.
//
// NOTE: O_SEARCH doesn't allow fsync().
// musl maps O_SEARCH to O_PATH.
message_error(_("%s: Opening the directory " message_error(_("%s: Opening the directory "
"failed: %s"), "failed: %s"),
tuklib_mask_nonprint(dir_name), tuklib_mask_nonprint(dir_name),