Aegisub/aegisub/libass/ass_cache_template.c
Amar Takhar c2267bedcc Plug a bunch of memory leaks from uau in the mplayer2 repo: http://repo.or.cz/w/mplayer.git?a=commit;h=312d9e4b104741b834aa5d71b02228d0cd988a4e
libass: Fix cache lookup problem causing memory bloat

The cache code did hash lookups by storing key values in struct fields
and then hashing and comparing the struct as a single memory block. In
at least one case such a struct contained uninitialized padding bytes
which prevented the complete memory area of the struct from matching
even though the fields did. As a result the code failed to find
existing objects in the cache and stored new versions of them, causing
gigabytes of memory use in some circumstances. Initializing the struct
memory to zero before writing the fields avoided such memory use in
tests but is not guaranteed to work if I interpret the C standard
correctly (the compiler is allowed to write garbage over padding bytes
when changing struct member values).

Change the code to use struct-specific hashing and comparison
functions that work field by field to guarantee correct behavior.
Create these by replacing the struct definition with a template that
lists the fields and can be used the generate each of struct
definition, hash function and compare function with some preprocessor
magic (otherwise every field would need to be listed separately in all
three).

Originally committed to SVN as r2895.
2009-05-04 06:48:21 +00:00

88 lines
2.7 KiB
C

#ifdef CREATE_STRUCT_DEFINITIONS
#undef CREATE_STRUCT_DEFINITIONS
#define START(funcname, structname) \
typedef struct structname {
#define GENERIC(type, member) \
type member;
#define FTVECTOR(member) \
FT_Vector member;
#define END(typedefnamename) \
} typedefnamename;
#elif defined(CREATE_COMPARISON_FUNCTIONS)
#undef CREATE_COMPARISON_FUNCTIONS
#define START(funcname, structname) \
static int funcname##_compare(void *key1, void *key2, size_t key_size) \
{ \
struct structname *a = key1; \
struct structname *b = key2; \
return // conditions follow
#define GENERIC(type, member) \
a->member == b->member &&
#define FTVECTOR(member) \
a->member.x == b->member.x && a->member.y == b->member.y &&
#define END(typedefname) \
1; \
}
#elif defined(CREATE_HASH_FUNCTIONS)
#undef CREATE_HASH_FUNCTIONS
#define START(funcname, structname) \
static unsigned funcname##_hash(void *buf, size_t len) \
{ \
struct structname *p = buf; \
unsigned hval = FNV1_32A_INIT;
#define GENERIC(type, member) \
hval = fnv_32a_buf(&p->member, sizeof(p->member), hval);
#define FTVECTOR(member) GENERIC(, member.x); GENERIC(, member.y);
#define END(typedefname) \
return hval; \
}
#else
#error missing defines
#endif
// describes a bitmap; bitmaps with equivalents structs are considered identical
START(bitmap, bipmap_hash_key_s)
GENERIC(char, bitmap) // bool : true = bitmap, false = outline
GENERIC(ass_font_t *, font)
GENERIC(double, size) // font size
GENERIC(uint32_t, ch) // character code
GENERIC(unsigned, outline) // border width, 16.16 fixed point value
GENERIC(int, bold)
GENERIC(int, italic)
GENERIC(char, be) // blur edges
GENERIC(double, blur) // gaussian blur
GENERIC(unsigned, scale_x) // 16.16
GENERIC(unsigned, scale_y) // 16.16
GENERIC(int, frx) // signed 16.16
GENERIC(int, fry) // signed 16.16
GENERIC(int, frz) // signed 16.16
// shift vector that was added to glyph before applying rotation
// = 0, if frx = fry = frx = 0
// = (glyph base point) - (rotation origin), otherwise
GENERIC(int, shift_x)
GENERIC(int, shift_y)
FTVECTOR(advance) // subpixel shift vector
END(bitmap_hash_key_t)
// describes an outline glyph
START(glyph, glyph_hash_key_s)
GENERIC(ass_font_t *, font)
GENERIC(double, size) // font size
GENERIC(uint32_t, ch) // character code
GENERIC(int, bold)
GENERIC(int, italic)
GENERIC(unsigned, scale_x) // 16.16
GENERIC(unsigned, scale_y) // 16.16
FTVECTOR(advance) // subpixel shift vector
GENERIC(unsigned, outline) // border width, 16.16
END(glyph_hash_key_t)
#undef START
#undef GENERIC
#undef FTVECTOR
#undef END