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author | Oleg Oshmyan <chortos@inbox.lv> | 2017-02-03 21:34:13 +0200 |
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committer | Oleg Oshmyan <chortos@inbox.lv> | 2017-02-14 19:43:04 +0200 |
commit | 81ba39f0d28a9ea9d284b031517ebd0f2684d4ff (patch) | |
tree | 33f35989c06d0992f8b59c9a982d21d72c0fe9dd /libass | |
parent | 08092bdfb42abee2c3763b30dcd9905c45f7318e (diff) | |
download | libass-81ba39f0d28a9ea9d284b031517ebd0f2684d4ff.tar.bz2 libass-81ba39f0d28a9ea9d284b031517ebd0f2684d4ff.tar.xz |
Fix parsing of unusual Alignment values in ASS style definitions
Handle large and negative values except INT32_MIN like VSFilter.
This avoids both overflow and inconsistent internal state.
This fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=523.
VSFilter handles INT32_MIN like a mix of \an1, \an2 and \an3:
* Vertical alignment is bottom.
* Lines within the event are center-aligned.
* Without \pos or \move, the center of the event is aligned
with the right edge of the screen minus MarginR.
* With \pos or \move, the left edge of the event is aligned
with the position point.
* Without \org, the rotation origin is aligned
with the horizontal center of the event.
* (With \org, the rotation origin is as specified.)
If we wanted to emulate this in libass, the cleanest way would be to
introduce a new horizontal alignment constant for this purpose that
would be used only for ASS style definitions with Alignment INT32_MIN.
This commit makes no attempt to do this and instead arbitrarily picks
\an2 for style definitions with Alignment -INT_MAX-1, which equals
INT32_MIN if int is int32_t. The fact that int is platform-dependent
is one of the reasons for this. We could change Alignment to be int32_t
instead of int for perfect VSFilter compatibility, but the same applies
to many other fields that currently use platform-dependent types.
Diffstat (limited to 'libass')
-rw-r--r-- | libass/ass.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/libass/ass.c b/libass/ass.c index e8cefc50..3a942909 100644 --- a/libass/ass.c +++ b/libass/ass.c @@ -24,6 +24,7 @@ #include <string.h> #include <assert.h> #include <errno.h> +#include <limits.h> #include <sys/types.h> #include <sys/stat.h> #include <inttypes.h> @@ -241,12 +242,20 @@ static long long string2timecode(ASS_Library *library, char *p) */ static int numpad2align(int val) { - int res, v; - v = (val - 1) / 3; // 0, 1 or 2 for vertical alignment - if (v != 0) - v = 3 - v; - res = ((val - 1) % 3) + 1; // horizontal alignment - res += v * 4; + if (val < -INT_MAX) + // Pick an alignment somewhat arbitrarily. VSFilter handles + // INT32_MIN as a mix of 1, 2 and 3, so prefer one of those values. + val = 2; + else if (val < 0) + val = -val; + + int res = ((val - 1) % 3) + 1; // horizontal alignment + if (val <= 3) + res |= VALIGN_SUB; + else if (val <= 6) + res |= VALIGN_CENTER; + else + res |= VALIGN_TOP; return res; } |