xz: Fix use of wrong variable in a fcntl() call.
Due to a wrong variable name, when writing a sparse file
to standard output, *all* file status flags were cleared
(to the extent the operating system allowed it) instead of
only clearing the O_APPEND flag. In practice this worked
fine in the common situations on GNU/Linux, but I didn't
check how it behaved elsewhere.
The original flags were still restored correctly. I still
changed the code to use a separate boolean variable to
indicate when the flags should be restored instead of
relying on a special value in stdout_flags.
diff --git a/src/xz/file_io.c b/src/xz/file_io.c
index 61b10f9..df758fd 100644
--- a/src/xz/file_io.c
+++ b/src/xz/file_io.c
@@ -41,9 +41,10 @@
static bool try_sparse = true;
#ifndef TUKLIB_DOSLIKE
-/// File status flags of standard output. This is used by io_open_dest()
-/// and io_close_dest().
-static int stdout_flags = 0;
+/// Original file status flags of standard output. This is used by
+/// io_open_dest() and io_close_dest() to save and restore the flags.
+static int stdout_flags;
+static bool restore_stdout_flags = false;
#endif
@@ -676,11 +677,11 @@
if (!S_ISREG(pair->dest_st.st_mode))
return false;
- const int flags = fcntl(STDOUT_FILENO, F_GETFL);
- if (flags == -1)
+ stdout_flags = fcntl(STDOUT_FILENO, F_GETFL);
+ if (stdout_flags == -1)
return false;
- if (flags & O_APPEND) {
+ if (stdout_flags & O_APPEND) {
// Creating a sparse file is not possible
// when O_APPEND is active (it's used by
// shell's >> redirection). As I understand
@@ -702,9 +703,10 @@
stdout_flags & ~O_APPEND))
return false;
- // Remember the flags so that io_close_dest()
- // can restore them.
- stdout_flags = flags;
+ // Disabling O_APPEND succeeded. Mark
+ // that the flags should be restored
+ // in io_close_dest().
+ restore_stdout_flags = true;
} else if (lseek(STDOUT_FILENO, 0, SEEK_CUR)
!= pair->dest_st.st_size) {
@@ -745,11 +747,11 @@
{
#ifndef TUKLIB_DOSLIKE
// If io_open_dest() has disabled O_APPEND, restore it here.
- if (stdout_flags != 0) {
+ if (restore_stdout_flags) {
assert(pair->dest_fd == STDOUT_FILENO);
const int fail = fcntl(STDOUT_FILENO, F_SETFL, stdout_flags);
- stdout_flags = 0;
+ restore_stdout_flags = false;
if (fail) {
message_error(_("Error restoring the O_APPEND flag "
