[Libguestfs] [PATCH 3/3] Use an unsigned type (size_t) for all loop iterators.

[Matthew Booth]

On 16/07/10 13:05, Richard W.M. Jones wrote:
>> From 460031c9f9bcabd5e132aab22ab0d001ab14d33d Mon Sep 17 00:00:00 2001
> From: Richard Jones<rjones at redhat.com>
> Date: Fri, 16 Jul 2010 12:58:54 +0100
> Subject: [PATCH 3/3] Use an unsigned type (size_t) for all loop iterators.
>
> This resolves a warning from gcc 4.5:
>    assuming signed overflow does not occur when simplifying
>      conditional to constant
>
> This page explains the issues in some detail:
>    http://www.airs.com/blog/archives/120
> ---
>   configure.ac     |    1 -
>   src/generator.ml |   42 +++++++++++++++++++++---------------------
>   2 files changed, 21 insertions(+), 22 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index caf25ee..671fbb0 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -110,7 +110,6 @@ if test "$gl_gcc_warnings" = yes; then
>     nw="$nw -Wmissing-format-attribute" # daemon.h's asprintf_nowarn
>     nw="$nw -Winline"                 # daemon.h's asprintf_nowarn
>     nw="$nw -Wshadow"                 # numerous, plus we're not unanimous
> -  # ?? -Wstrict-overflow
>     nw="$nw -Wunsafe-loop-optimizations" # just a warning that an optimization
>                                       # was not possible, safe to ignore
>     nw="$nw -Wpacked"                 # Allow attribute((packed)) on structs
> diff --git a/src/generator.ml b/src/generator.ml
> index cb3f773..8fc619f 100755
> --- a/src/generator.ml
> +++ b/src/generator.ml

...

> @@ -9354,7 +9354,7 @@ put_handle (guestfs_h *g)
>   static char **
>   get_string_list (PyObject *obj)
>   {
> -  int i, len;
> +  size_t i, len;
>     char **r;
>
>     assert (obj);

This isn't safe. len is assigned later:

   len = PyList_Size (obj);

PyList_Size returns Py_ssize_t, which is a signed type. This may also 
mean that the later code may also need a second look, as it doesn't 
check for a negative return value.

The rest all look fine, though.

Matt
-- 
Matthew Booth, RHCA, RHCSS
Red Hat Engineering, Virtualisation Team

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