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Fix crash in GNUstep font coverage check

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* src/nsfont.m (ns_charset_covers): Check coverage more accurately and
don't automatically assume the buffer is 8192 bytes long.
This commit is contained in:
Alan Third 2021-06-28 19:50:31 +01:00
parent 0382aa1148
commit 28fcdb5219
1 changed files with 25 additions and 19 deletions
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44
src/nsfont.m
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@ -277,30 +277,36 @@ ns_ascii_average_width (NSFont *sfont)
/* Return whether set1 covers set2 to a reasonable extent given by pct.
We check, out of each 16 Unicode char range containing chars in set2,
whether at least one character is present in set1.
This must be true for pct of the pairs to consider it covering. */
The GNUstep bitmap representation doesn't match Apple's
description. It appears to be a single block of bytes, not broken
up into planes, where the last byte contains the highest character
the character set supports. */
static BOOL
ns_charset_covers(NSCharacterSet *set1, NSCharacterSet *set2, float pct)
{
const unsigned short *bytes1 = [[set1 bitmapRepresentation] bytes];
const unsigned short *bytes2 = [[set2 bitmapRepresentation] bytes];
int i, off = 0, tot = 0;
NSData *font = [set1 bitmapRepresentation];
NSData *script = [set2 bitmapRepresentation];
/* Work around what appears to be a GNUstep bug.
See <https://bugs.gnu.org/11853>. */
if (! (bytes1 && bytes2))
return NO;
uint8_t *fontPlane = (uint8_t *)[font bytes];
uint8_t *scriptPlane = (uint8_t *)[script bytes];
for (i=0; i<4096; i++, bytes1++, bytes2++)
if (*bytes2)
{
tot++;
if (*bytes1 == 0) // *bytes1 & *bytes2 != *bytes2
off++;
}
// fprintf(stderr, "off = %d\ttot = %d\n", off,tot);
return (float)off / tot < 1.0F - pct;
int covered = 0, total = 0;
for (ptrdiff_t b = 0 ; b < [script length] ; b++)
for (int i = 0 ; i < 8 ; i++)
{
if (*(scriptPlane + b) & (1 << i))
{
total++;
if (b < [font length]
&& *(fontPlane + b) & (1 << i))
covered++;
}
}
return (float)covered / total >= 1.0F - pct;
}