[PATCH] libwbclient clear pointer on bad read

[Volker Lendecke]

On Sun, Jan 18, 2015 at 05:23:43PM +0000, Matthew Newton wrote:
> Hi,
> 
> On Sun, Jan 18, 2015 at 04:26:41PM +0100, Stefan (metze) Metzmacher wrote:
> > Am 17.01.2015 um 02:44 schrieb Matthew Newton:
> > > +	if ((fd_info = winbindd_fd_info()) == NULL) {
> > > +		return;
> > > +	}
> > 
> > Can you please change all changes like this into two lines:
> > 
> > fd_info = winbindd_fd_info();
> > if (fd_info == NULL) {
> > ...
> 
> No probs - I'll send updated patches.
> 
> Could you update README.Coding? It says both forms are acceptable
> so I guess maybe it's out of date.

Something like the attached patch?

Review appreciated! :-)

Thanks,

Volker

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-------------- next part --------------
From 3b648e1c308e93f10a0164b7da49dc96ab47dc84 Mon Sep 17 00:00:00 2001
From: Volker Lendecke <vl at samba.org>
Date: Mon, 19 Jan 2015 10:48:20 +0100
Subject: [PATCH] README.Coding: Add hint for if-statments

Signed-off-by: Volker Lendecke <vl at samba.org>
---
 README.Coding | 46 +++++++++++++++++++++++++++-------------------
 1 file changed, 27 insertions(+), 19 deletions(-)

diff --git a/README.Coding b/README.Coding
index 0bbba9f..f19399e 100644
--- a/README.Coding
+++ b/README.Coding
@@ -298,25 +298,6 @@ Good Examples:
 	}
 
 
-Checking Pointer Values
------------------------
-
-When invoking functions that return pointer values, either of the following
-are acceptable. Use your best judgement and choose the more readable option.
-Remember that many other persons will review it:
-
-	if ((x = malloc(sizeof(short)*10)) == NULL ) {
-		fprintf(stderr, "Unable to alloc memory!\n");
-	}
-
-or:
-
-	x = malloc(sizeof(short)*10);
-	if (!x) {
-		fprintf(stderr, "Unable to alloc memory!\n");
-	}
-
-
 Primitive Data Types
 --------------------
 
@@ -364,6 +345,33 @@ Bad Example:
 	ret = some_function_my_name(get_some_name());
 	...
 
+Please try to avoid passing function return values to if- or
+while-conditions. The reason for this is better handling of code under a
+debugger.
+
+Good example:
+
+	x = malloc(sizeof(short)*10);
+	if (!x) {
+		fprintf(stderr, "Unable to alloc memory!\n");
+	}
+
+Bad example:
+
+	if ((x = malloc(sizeof(short)*10)) == NULL ) {
+		fprintf(stderr, "Unable to alloc memory!\n");
+	}
+
+There are exceptions to this rule. One example is walking a data structure in
+an iterator style:
+
+	while ((opt = poptGetNextOpt(pc)) != -1) {
+		   ... do something with opt ...
+	}
+
+But in general, please try to avoid this pattern.
+
+
 Control-Flow changing macros
 ----------------------------
 
-- 
1.9.1