[PATCH for gui-staging] xpdf: revert used by unitialized warning

[Michal H. <ms...@gm...>]

On Wed, Jan 25, 2012 at 06:28:17PM +0100, Michal Hocko wrote:
> Hi,
> I have looked at the xpdf changes introduced by pdfeditor project
> (http://code.google.com/p/pdfeditor/). 
> 
> I would like to clarify some of them before mergin:
> 
[...]
> diff --git a/src/xpdf/xpdf/Gfx.cc b/src/xpdf/xpdf/Gfx.cc
> index fe1c465..1a29de4 100644
> --- a/src/xpdf/xpdf/Gfx.cc
> +++ b/src/xpdf/xpdf/Gfx.cc
> @@ -703,10 +703,8 @@ void Gfx::execOp(const Object *cmd, Object args[], int numArgs) {
>  }
>  
>  Operator *Gfx::findOp(const char *name) {
> -  int a, b, m, cmp;
> +  int a = -1, b = numOps, m = 0, cmp = 0;
>  
> -  a = -1;
> -  b = numOps;

I have double checked this one. The full function looks as follows
  int a, b, m, cmp;

  a = -1;
  b = numOps;
  // invariant: opTab[a] < name < opTab[b]
  while (b - a > 1) {
    m = (a + b) / 2;
    cmp = strcmp(opTab[m].name, name);
    if (cmp < 0)
      a = m;
    else if (cmp > 0)
      b = m;
    else
      a = b = m;
  }
  if (cmp != 0)
    return NULL;
  return &opTab[a];

gcc doesn't seem to complain even with -Wall. Anyway, the only issue
seems to be that cmp might be used uninitialized if numOps <= 0
but this can never happen because it is defined as sizeof(opTab) /
sizeof(Operator).
So I would be for reverting this change:
---
>From 53f1b1a3d6165dfd63f77937adc7910f3e6f458d Mon Sep 17 00:00:00 2001
From: Michal Hocko <ms...@gm...>
Date: Sun, 29 Jan 2012 21:38:09 +0100
Subject: [PATCH] xpdf: revert used by unitialized warning

We do not have to initialize m and cmp variables because they can never
be used uninitialized because numOps would have to be <= 0 which is not
possible as it is defined as sizeof(opTab) / sizeof(Operator).
So revert the original fix so that we are closer with the master branch.
---
 src/xpdf/xpdf/Gfx.cc |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/src/xpdf/xpdf/Gfx.cc b/src/xpdf/xpdf/Gfx.cc
index 1a29de4..a64454b 100644
--- a/src/xpdf/xpdf/Gfx.cc
+++ b/src/xpdf/xpdf/Gfx.cc
@@ -703,8 +703,10 @@ void Gfx::execOp(const Object *cmd, Object args[], int numArgs) {
 }
 
 Operator *Gfx::findOp(const char *name) {
-  int a = -1, b = numOps, m = 0, cmp = 0;
+  int a, b, m, cmp;
 
+  a = -1;
+  b = numOps;
   // invariant: opTab[a] < name < opTab[b]
   while (b - a > 1) {
     m = (a + b) / 2;
-- 
1.7.8.3


-- 
Michal Hocko