[PATCH:xf86-video-modesetting] Include <alloca.h> on platforms that need it for alloca

[Jeremy Huddleston]

Can we please instead fix this by removing the alloca() calls?

--Jeremy

"""
BUGS
     alloca() is machine and compiler dependent; its use is discouraged.

     alloca() is slightly unsafe because it cannot ensure that the pointer returned points to a valid and usable
     block of memory.  The allocation made may exceed the bounds of the stack, or even go further into other
     objects in memory, and alloca() cannot determine such an error.  Avoid alloca() with large unbounded allo-
     cations.

     The use of C99 variable-length arrays and alloca() in the same function will cause the lifetime of alloca's
     storage to be limited to the block containing the alloca()
"""

On Apr 6, 2012, at 9:33 PM, Alan Coopersmith <alan.coopersmith at oracle.com> wrote:

> Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
> ---
> configure.ac |    1 +
> src/driver.c |    3 +++
> 2 files changed, 4 insertions(+)
> 
> diff --git a/configure.ac b/configure.ac
> index aa4ae9f..ddec78e 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -78,6 +78,7 @@ AM_CONDITIONAL(HAVE_XEXTPROTO_71, [ test "$HAVE_XEXTPROTO_71" = "yes" ])
> 
> # Checks for header files.
> AC_HEADER_STDC
> +AC_ALLOCA
> 
> PKG_CHECK_MODULES(DRM, [libdrm >= 2.2])
> PKG_CHECK_MODULES([PCIACCESS], [pciaccess >= 0.10])
> diff --git a/src/driver.c b/src/driver.c
> index 87431ff..514c423 100644
> --- a/src/driver.c
> +++ b/src/driver.c
> @@ -33,6 +33,9 @@
> #include "config.h"
> #endif
> 
> +#ifdef HAVE_ALLOCA_H
> +# include <alloca.h>
> +#endif
> #include <unistd.h>
> #include <fcntl.h>
> #include "xf86.h"
> -- 
> 1.7.9.2
> 
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