From: Jeff King <peff@peff.net>
Date: Tue, 7 Aug 2012 04:10:26 +0000 (-0400)
Subject: terminal: seek when switching between reading and writing
X-Git-Tag: v1.7.12-rc3~5^2~1
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=67ba123fd1fcb9a7699ae85f05f1229513322c1c;p=git.git

terminal: seek when switching between reading and writing

When a stdio stream is opened in update mode (e.g., "w+"),
the C standard forbids switching between reading or writing
without an intervening positioning function. Many
implementations are lenient about this, but Solaris libc
will flush the recently-read contents to the output buffer.
In this instance, that meant writing the non-echoed password
that the user just typed to the terminal.

Fix it by inserting a no-op fseek between the read and
write.

The opposite direction (writing followed by reading) is also
disallowed, but our intervening fflush is an acceptable
positioning function for that alternative.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

diff --git a/compat/terminal.c b/compat/terminal.c
index 6d16c8fba..bbb038dd0 100644
--- a/compat/terminal.c
+++ b/compat/terminal.c
@@ -59,6 +59,7 @@ char *git_terminal_prompt(const char *prompt, int echo)
 
 	r = strbuf_getline(&buf, fh, '\n');
 	if (!echo) {
+		fseek(fh, SEEK_CUR, 0);
 		putc('\n', fh);
 		fflush(fh);
 	}