In initdb, ensure stdout/stderr buffering behavior is what we expect.

Since this program may print to either stdout or stderr, the relative
ordering of its messages depends on the buffering behavior of those files.
Force stdout to be line-buffered and stderr to be unbuffered, ensuring
that the behavior will match standard Unix interactive behavior, even
when stdout and stderr are rerouted to a file.

Per complaint from Tomas Vondra.  The particular case he pointed out is
new in HEAD, but issues of the same sort could arise in any branch with
other error messages, so back-patch to all branches.

I'm unsure whether we might not want to do this in other client programs
as well.  For the moment, just fix initdb.

diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 091b13f3e4d1b44479e33405012e2fe8270598b7..40852a33b9a6713ffe8965ace25457dfe943d4ec 100644 (file)
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -2551,6 +2551,15 @@ main(int argc, char *argv[])
                "pg_stat_tmp"
        };
 
+       /*
+        * Ensure that buffering behavior of stdout and stderr matches what it is
+        * in interactive usage (at least on most platforms).  This prevents
+        * unexpected output ordering when, eg, output is redirected to a file.
+        * POSIX says we must do this before any other usage of these files.
+        */
+       setvbuf(stdout, NULL, _IOLBF, 0);
+       setvbuf(stderr, NULL, _IONBF, 0);
+
        progname = get_progname(argv[0]);
        set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("initdb"));