xz: Don't fail if stdout doesn't support O_NONBLOCK.

This is similar to the case with stdin.

Thanks to Brad Smith for the bug report and testing
on OpenBSD.

diff --git a/src/xz/file_io.c b/src/xz/file_io.c
index 08288ebb459125d5f0967080fec5dc344c789fb4..7895ee0183a45fc33c4da8785abfc864fb56b794 100644 (file)
--- a/src/xz/file_io.c
+++ b/src/xz/file_io.c
@@ -713,17 +713,10 @@ io_open_dest_real(file_pair *pair)
                        return true;
                }
 
-               if ((stdout_flags & O_NONBLOCK) == 0) {
-                       if (fcntl(STDOUT_FILENO, F_SETFL,
-                                       stdout_flags | O_NONBLOCK) == -1) {
-                               message_error(_("Error setting O_NONBLOCK "
-                                               "on standard output: %s"),
-                                               strerror(errno));
-                               return true;
-                       }
-
-                       restore_stdout_flags = true;
-               }
+               if ((stdout_flags & O_NONBLOCK) == 0
+                               && fcntl(STDOUT_FILENO, F_SETFL,
+                                       stdout_flags | O_NONBLOCK) != -1)
+                               restore_stdout_flags = true;
 #endif
        } else {
                pair->dest_name = suffix_get_dest_name(pair->src_name);
@@ -827,23 +820,24 @@ io_open_dest_real(file_pair *pair)
                                if (lseek(STDOUT_FILENO, 0, SEEK_END) == -1)
                                        return false;
 
-                               // O_NONBLOCK was set earlier in this function
-                               // so it must be kept here too. If this
-                               // fcntl() call fails, we continue but won't
+                               // Construct the new file status flags.
+                               // If O_NONBLOCK was set earlier in this
+                               // function, it must be kept here too.
+                               int flags = stdout_flags & ~O_APPEND;
+                               if (restore_stdout_flags)
+                                       flags |= O_NONBLOCK;
+
+                               // If this fcntl() fails, we continue but won't
                                // try to create sparse output. The original
                                // flags will still be restored if needed (to
                                // unset O_NONBLOCK) when the file is finished.
-                               if (fcntl(STDOUT_FILENO, F_SETFL,
-                                               (stdout_flags | O_NONBLOCK)
-                                               & ~O_APPEND) == -1)
+                               if (fcntl(STDOUT_FILENO, F_SETFL, flags) == -1)
                                        return false;
 
                                // Disabling O_APPEND succeeded. Mark
                                // that the flags should be restored
-                               // in io_close_dest(). This quite likely was
-                               // already set when enabling O_NONBLOCK but
-                               // just in case O_NONBLOCK was already set,
-                               // set this again here.
+                               // in io_close_dest(). (This may have already
+                               // been set when enabling O_NONBLOCK.)
                                restore_stdout_flags = true;
 
                        } else if (lseek(STDOUT_FILENO, 0, SEEK_CUR)