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Fix overflow checking extension versions 

The easiest way to check for the version of an extension is to send the maximum
possible version numbers in the QueryVersion request. The X server overflows on
these as it assumes you will send a reasonable version number.

Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
This commit is contained in:
Robert Ancell 2014-05-22 10:43:52 +12:00 committed by Keith Packard
parent 4cbd3fabaa
commit 0df871cf34
1 changed files with 11 additions and 7 deletions
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18
include/misc.h
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@ -259,15 +259,19 @@ extern void FormatDouble(double dbl, char *string);
* or a value greater than 0 * or a value greater than 0
*/ */
static inline int static inline int
version_compare(uint16_t a_major, uint16_t a_minor, version_compare(uint32_t a_major, uint32_t a_minor,
uint16_t b_major, uint16_t b_minor) uint32_t b_major, uint32_t b_minor)
{ {
int a, b; if (a_major > b_major)
return 1;
if (a_major < b_major)
return -1;
if (a_minor > b_minor)
return 1;
if (a_minor < b_minor)
return -1;
a = a_major << 16 | a_minor; return 0;
b = b_major << 16 | b_minor;
return (a - b);
} }
/* some macros to help swap requests, replies, and events */ /* some macros to help swap requests, replies, and events */