From: Jeff King <peff@peff.net>
To: git@vger.kernel.org
Subject: [PATCH 1/4] wt-status: fix possible use of uninitialized variable
Date: Thu, 21 Mar 2013 07:05:28 -0400 [thread overview]
Message-ID: <20130321110527.GA18819@sigill.intra.peff.net> (raw)
In-Reply-To: <20130321110338.GA18552@sigill.intra.peff.net>
In wt_status_print_change_data, we accept a change_type flag
that is meant to be either WT_STATUS_UPDATED or
WT_STATUS_CHANGED. We then switch() on this value to set
the local variable "status" for each case, but do not
provide a fallback "default" label to the switch statement.
As a result, the compiler realizes that "status" might be
unset, and complains with a warning. To silence this
warning, we use the "int status = status" trick. This is
correct with the current code, as all callers provide one of
the two expected change_type flags. However, it's also a
maintenance trap, as there is nothing to prevent future
callers from passing another flag, nor to document this
assumption.
Instead of using the "x = x" hack, let's handle the default
case in the switch() statement with a die("BUG"). That tells
the compiler and any readers of the code exactly what the
function's input assumptions are.
We could also convert the flag to an enum, which would
provide a compile-time check on the function input. However,
since these flags are part of a larger enum, that would make
the code unnecessarily complex (we would have to make a new
enum with just the two flags, and then convert it to the old
enum for passing to sub-functions).
Signed-off-by: Jeff King <peff@peff.net>
---
wt-status.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/wt-status.c b/wt-status.c
index ef405d0..7555817 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -264,7 +264,7 @@ static void wt_status_print_change_data(struct wt_status *s,
{
struct wt_status_change_data *d = it->util;
const char *c = color(change_type, s);
- int status = status;
+ int status;
char *one_name;
char *two_name;
const char *one, *two;
@@ -292,6 +292,9 @@ static void wt_status_print_change_data(struct wt_status *s,
}
status = d->worktree_status;
break;
+ default:
+ die("BUG: unhandled change_type %d in wt_status_print_change_data",
+ change_type);
}
one = quote_path(one_name, -1, &onebuf, s->prefix);
--
1.8.2.rc2.8.g2161951
next prev parent reply other threads:[~2013-03-21 11:06 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-21 11:03 [PATCH 0/4] drop some "int x = x" hacks to silence gcc warnings Jeff King
2013-03-21 11:05 ` Jeff King [this message]
2013-03-21 19:49 ` [PATCH 1/4] wt-status: fix possible use of uninitialized variable Jonathan Nieder
2013-03-21 19:55 ` Junio C Hamano
2013-03-21 19:58 ` Jonathan Nieder
2013-03-22 16:15 ` Jeff King
2013-03-21 11:08 ` [PATCH 2/4] fast-import: use pointer-to-pointer to keep list tail Jeff King
2013-03-21 20:43 ` Jonathan Nieder
2013-03-21 11:10 ` [PATCH 3/4] drop some obsolete "x = x" compiler warning hacks Jeff King
2013-03-21 15:16 ` Erik Faye-Lund
2013-03-21 20:47 ` Jonathan Nieder
2013-03-24 7:17 ` Torsten Bögershausen
2013-03-21 11:13 ` [PATCH 4/4] transport: drop "int cmp = cmp" hack Jeff King
2013-03-21 20:59 ` Jonathan Nieder
2013-03-24 4:00 ` Junio C Hamano
2013-03-24 9:32 ` Jeff King
2013-03-24 14:54 ` Torsten Bögershausen
2013-03-25 19:50 ` Junio C Hamano
2013-03-25 21:06 ` Jeff King
2013-03-25 21:55 ` Junio C Hamano
2013-03-21 11:45 ` [PATCH 0/4] drop some "int x = x" hacks to silence gcc warnings Johannes Sixt
2013-03-21 11:55 ` Jeff King
2013-03-21 14:58 ` Junio C Hamano
2013-03-21 15:19 ` Junio C Hamano
2013-03-21 15:44 ` Jeff King
2013-03-21 15:44 ` [PATCH 5/4] fast-import: clarify "inline" logic in file_change_m Jeff King
2013-03-21 15:45 ` [PATCH 6/4] run-command: always set failed_errno in start_command Jeff King
2013-03-21 21:02 ` [PATCH 0/4] drop some "int x = x" hacks to silence gcc warnings Jonathan Nieder
2013-03-22 16:18 ` Jeff King
2013-03-22 16:19 ` [PATCH 7/4] submodule: clarify logic in show_submodule_summary Jeff King
2013-03-22 21:10 ` Junio C Hamano
2013-03-22 16:21 ` [PATCH 8/4] match-trees: drop "x = x" initializations Jeff King
2013-03-22 21:26 ` Junio C Hamano
2013-03-22 21:33 ` Junio C Hamano
2013-03-22 21:36 ` Jeff King
2013-03-23 18:57 ` René Scharfe
2013-03-24 4:55 ` Junio C Hamano
2013-03-24 10:01 ` Jeff King
2013-03-24 22:46 ` René Scharfe
2013-03-25 16:10 ` Junio C Hamano
2013-03-21 13:44 ` [PATCH 0/4] drop some "int x = x" hacks to silence gcc warnings Joachim Schmitz
2013-03-21 13:56 ` Joachim Schmitz
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