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xfree86: Fix fallback driver sort order for Xorg -configure (v2) 

The intent here was that fallback drivers would be at the end of the
list in order, but if a fallback driver happened to be at the end of the
list already that's not what would happen. Rather than open-code
something smarter, just use qsort.

Note that qsort puts things in ascending order, so somewhat backwardsly
fallbacks are greater than native drivers, and vesa is greater than
modesetting.

v2: Use strcmp to compare non-fallback drivers so we get a predictable
result if your libc's qsort isn't stable (Keith Packard)

Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Adam Jackson <ajax@redhat.com>
This commit is contained in:
Adam Jackson 2016-07-12 10:04:18 -04:00
parent 4926845a57
commit 32a9504c69
1 changed files with 40 additions and 19 deletions
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59
hw/xfree86/common/xf86Config.c
View File

@ -518,33 +518,54 @@ xf86InputDriverlistFromConfig(void)
return modulearray;
}
static int
is_fallback(const char *s)
{
/* later entries are less preferred */
const char *fallback[5] = { "modesetting", "fbdev", "vesa", "wsfb", NULL };
int i;
for (i = 0; fallback[i]; i++)
if (strstr(s, fallback[i]))
return i;
return -1;
}
static int
driver_sort(const void *_l, const void *_r)
{
const char *l = *(const char **)_l;
const char *r = *(const char **)_r;
int left = is_fallback(l);
int right = is_fallback(r);
/* neither is a fallback, asciibetize */
if (left == -1 && right == -1)
return strcmp(l, r);
/* left is a fallback */
if (left >= 0)
return 1;
/* right is a fallback */
if (right >= 0)
return -1;
/* both are fallbacks, which is worse */
return left - right;
}
static void
fixup_video_driver_list(const char **drivers)
{
static const char *fallback[5] = { "modesetting", "fbdev", "vesa", "wsfb", NULL };
const char **end, **drv;
const char *x;
int i;
const char **end;
/* walk to the end of the list */
for (end = drivers; *end && **end; end++);
end--;
/*
* for each of the fallback drivers, if we find it in the list,
* swap it with the last available non-fallback driver.
*/
for (i = 0; fallback[i]; i++) {
for (drv = drivers; drv != end; drv++) {
if (strstr(*drv, fallback[i])) {
x = *drv;
*drv = *end;
*end = x;
end--;
break;
}
}
}
qsort(drivers, end - drivers, sizeof(const char *), driver_sort);
}
static const char **