From 91750dff8f2c654ff636f12a2acdffe5492374b3 Mon Sep 17 00:00:00 2001 From: Lasse Collin Date: Fri, 28 Jun 2013 17:36:47 +0300 Subject: [PATCH] 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. --- src/xz/file_io.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/src/xz/file_io.c b/src/xz/file_io.c index f9b7f305..4fd6855d 100644 --- a/src/xz/file_io.c +++ b/src/xz/file_io.c @@ -41,9 +41,10 @@ static bool warn_fchown; 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 @@ -634,11 +635,11 @@ io_open_dest_real(file_pair *pair) 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 @@ -660,9 +661,10 @@ io_open_dest_real(file_pair *pair) 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) { @@ -703,11 +705,11 @@ io_close_dest(file_pair *pair, bool success) { #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 "