[Git][freetype/freetype][master] [gzip] Use exact type for `ft_gzip_alloc` and `ft_gzip_free`.

[Werner Lemberg (@wl)]

Werner Lemberg pushed to branch master at FreeType / FreeType

Commits:

• 06e21ffe
  by Ben Wagner at 2021-05-19T09:07:33+02:00

  [gzip] Use exact type for `ft_gzip_alloc` and `ft_gzip_free`.
  
  While a function pointer may be cast to another function pointer
  type, it is required to cast the function pointer back to the
  original function pointer type before calling it.  If a parameter is
  a pointer the exact pointer type is required.  Using a pointer to a
  different underlying type is technically undefined behavior.  The
  wrapper functions `ft_gzip_alloc` and `ft_gzip_free` took
  `FT_Memory` (a `FT_MemoryRec_*`) instead of `voidpf` (`void*`), so
  when gzip calls these callbacks through `alloc_func` or `free_func`
  it invokes undefined behavior.  On most platforms this works out as
  expected, but newer undefined behavior detectors and targets like
  wasm can detect this and will produce an error.
  
  * src/gzip/ftgzip.c (ft_gzip_alloc, ft_gzip_free): Update signatures
  to exactly match `alloc_func` and `free_func`, respectively.
  Internally, cast the `void*` opaque pointer to `FT_Memory`.
  

2 changed files:

• ChangeLog
• src/gzip/ftgzip.c

Changes:

ChangeLog

---

	1	+2021-05-19 Ben Wagner <bungeman@chromium.org>
	2	+
	3	+ [gzip] Use exact type for `ft_gzip_alloc` and `ft_gzip_free`.
	4	+
	5	+ While a function pointer may be cast to another function pointer
	6	+ type, it is required to cast the function pointer back to the
	7	+ original function pointer type before calling it. If a parameter is
	8	+ a pointer the exact pointer type is required. Using a pointer to a
	9	+ different underlying type is technically undefined behavior. The
	10	+ wrapper functions `ft_gzip_alloc` and `ft_gzip_free` took
	11	+ `FT_Memory` (a `FT_MemoryRec_*`) instead of `voidpf` (`void*`), so
	12	+ when gzip calls these callbacks through `alloc_func` or `free_func`
	13	+ it invokes undefined behavior. On most platforms this works out as
	14	+ expected, but newer undefined behavior detectors and targets like
	15	+ wasm can detect this and will produce an error.
	16	+
	17	+ * src/gzip/ftgzip.c (ft_gzip_alloc, ft_gzip_free): Update signatures
	18	+ to exactly match `alloc_func` and `free_func`, respectively.
	19	+ Internally, cast the `void*` opaque pointer to `FT_Memory`.
	20	+
1	21	2021-05-18 Alexei Podtelezhnikov <apodtele@gmail.com>
2	22
3	23	Prioritize the anti-aliasing renderer module.

src/gzip/ftgzip.c

---

...	...	@@ -121,13 +121,14 @@
121	121	'malloc/free' */
122	122
123	123	static voidpf
124		- ft_gzip_alloc( FT_Memory memory,
125		- uInt items,
126		- uInt size )
	124	+ ft_gzip_alloc( voidpf opaque,
	125	+ uInt items,
	126	+ uInt size )
127	127	{
128		- FT_ULong sz = (FT_ULong)size * items;
	128	+ FT_Memory memory = (FT_Memory)opaque;
	129	+ FT_ULong sz = (FT_ULong)size * items;
129	130	FT_Error error;
130		- FT_Pointer p = NULL;
	131	+ FT_Pointer p = NULL;
131	132
132	133
133	134	/* allocate and zero out */
...	...	@@ -137,9 +138,12 @@
137	138
138	139
139	140	static void
140		- ft_gzip_free( FT_Memory memory,
141		- voidpf address )
	141	+ ft_gzip_free( voidpf opaque,
	142	+ voidpf address )
142	143	{
	144	+ FT_Memory memory = (FT_Memory)opaque;
	145	+
	146	+
143	147	FT_MEM_FREE( address );
144	148	}
145	149
...	...	@@ -151,14 +155,14 @@
151	155	unsigned items,
152	156	unsigned size )
153	157	{
154		- return ft_gzip_alloc( (FT_Memory)opaque, items, size );
	158	+ return ft_gzip_alloc( opaque, items, size );
155	159	}
156	160
157	161	local void
158	162	zcfree( voidpf opaque,
159	163	voidpf ptr )
160	164	{
161		- ft_gzip_free( (FT_Memory)opaque, ptr );
	165	+ ft_gzip_free( opaque, ptr );
162	166	}
163	167
164	168	#endif /* !SYSTEM_ZLIB && !USE_ZLIB_ZCALLOC */
...	...	@@ -305,8 +309,8 @@
305	309	}
306	310
307	311	/* initialize zlib -- there is no zlib header in the compressed stream */
308		- zstream->zalloc = (alloc_func)ft_gzip_alloc;
309		- zstream->zfree = (free_func) ft_gzip_free;
	312	+ zstream->zalloc = ft_gzip_alloc;
	313	+ zstream->zfree = ft_gzip_free;
310	314	zstream->opaque = stream->memory;
311	315
312	316	zstream->avail_in = 0;
...	...	@@ -742,8 +746,8 @@
742	746	stream.next_out = output;
743	747	stream.avail_out = (uInt)*output_len;
744	748
745		- stream.zalloc = (alloc_func)ft_gzip_alloc;
746		- stream.zfree = (free_func) ft_gzip_free;
	749	+ stream.zalloc = ft_gzip_alloc;
	750	+ stream.zfree = ft_gzip_free;
747	751	stream.opaque = memory;
748	752
749	753	/* This is a temporary fix and will be removed once the internal

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