Mesa (master): mesa: new MESA_EXTENSION_MAX_YEAR env var
Brian Paul
brianp at kemper.freedesktop.org
Thu Mar 24 17:49:35 UTC 2011
Module: Mesa
Branch: master
Commit: 82dd62fb22c8f88d62e3c77666c6805a2ac6ecd3
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=82dd62fb22c8f88d62e3c77666c6805a2ac6ecd3
Author: Brian Paul <brianp at vmware.com>
Date: Thu Mar 24 11:39:21 2011 -0600
mesa: new MESA_EXTENSION_MAX_YEAR env var
If set to year X, only report extensions up to that year. This is a
work-around for games that try to copy the extensions string to a fixed
size buffer and overflow. If a game was released in year X, setting
MESA_EXTENSION_MAX_YEAR to that year will likely fix the problem.
---
docs/envvars.html | 9 +++++++++
src/mesa/main/extensions.c | 20 +++++++++++++++++---
2 files changed, 26 insertions(+), 3 deletions(-)
diff --git a/docs/envvars.html b/docs/envvars.html
index c8be843..986d2f8 100644
--- a/docs/envvars.html
+++ b/docs/envvars.html
@@ -49,6 +49,15 @@ Setting this variable automatically sets the MESA_TEX_PROG variable as well.
<li>MESA_EXTENSION_OVERRIDE - can be used to enable/disable extensions.
A value such as "GL_EXT_foo -GL_EXT_bar" will enable the GL_EXT_foo extension
and disable the GL_EXT_bar extension.
+<li>MESA_EXTENSION_MAX_YEAR - The GL_EXTENSIONS string returned by Mesa is sorted
+by extension year.
+If this variable is set to year X, only extensions defined on or before year
+X will be reported.
+This is to work-around a bug in some games where the extension string is
+copied into a fixed-size buffer without truncating.
+If the extension string is too long, the buffer overrun can cause the game
+to crash.
+This is a work-around for that.
<li>MESA_GLSL - <a href="shading.html#envvars">shading language compiler options</a>
</ul>
diff --git a/src/mesa/main/extensions.c b/src/mesa/main/extensions.c
index 4b6e91c..728c73c 100644
--- a/src/mesa/main/extensions.c
+++ b/src/mesa/main/extensions.c
@@ -875,12 +875,24 @@ _mesa_make_extension_string(struct gl_context *ctx)
GLboolean *base = (GLboolean *) &ctx->Extensions;
const struct extension *i;
unsigned j;
-
+ unsigned maxYear = ~0;
+
+ /* Check if the MESA_EXTENSION_MAX_YEAR env var is set */
+ {
+ const char *env = getenv("MESA_EXTENSION_MAX_YEAR");
+ if (env) {
+ maxYear = atoi(env);
+ _mesa_debug(ctx, "Note: limiting GL extensions to %u or earlier\n",
+ maxYear);
+ }
+ }
/* Compute length of the extension string. */
count = 0;
for (i = extension_table; i->name != 0; ++i) {
- if (base[i->offset] && (i->api_set & (1 << ctx->API))) {
+ if (base[i->offset] &&
+ i->year <= maxYear &&
+ (i->api_set & (1 << ctx->API))) {
length += strlen(i->name) + 1; /* +1 for space */
++count;
}
@@ -908,7 +920,9 @@ _mesa_make_extension_string(struct gl_context *ctx)
*/
j = 0;
for (i = extension_table; i->name != 0; ++i) {
- if (base[i->offset] && (i->api_set & (1 << ctx->API))) {
+ if (base[i->offset] &&
+ i->year <= maxYear &&
+ (i->api_set & (1 << ctx->API))) {
extension_indices[j++] = i - extension_table;
}
}
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