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(RPNG) read_chunk_header - simplify code some more

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This commit is contained in:
twinaphex 2020-08-22 15:34:32 +02:00
parent 8b5b472a2d
commit 91345fe867
1 changed files with 49 additions and 37 deletions
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82
libretro-common/formats/png/rpng.c
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@ -83,7 +83,6 @@ struct idat_buffer
struct png_chunk struct png_chunk
{ {
uint32_t size; uint32_t size;
char type[4];
}; };
struct rpng_process struct rpng_process
@ -135,30 +134,6 @@ static INLINE uint32_t dword_be(const uint8_t *buf)
return (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | (buf[3] << 0); return (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | (buf[3] << 0);
} }
static enum png_chunk_type png_chunk_type(char chunk_type[4])
{
unsigned i;
struct
{
const char *id;
enum png_chunk_type type;
} static const chunk_map[] = {
{ "IHDR", PNG_CHUNK_IHDR },
{ "IDAT", PNG_CHUNK_IDAT },
{ "IEND", PNG_CHUNK_IEND },
{ "PLTE", PNG_CHUNK_PLTE },
{ "tRNS", PNG_CHUNK_tRNS },
};
for (i = 0; i < ARRAY_SIZE(chunk_map); i++)
{
if (!memcmp(chunk_type, chunk_map[i].id, 4))
return chunk_map[i].type;
}
return PNG_CHUNK_NOOP;
}
static bool png_process_ihdr(struct png_ihdr *ihdr) static bool png_process_ihdr(struct png_ihdr *ihdr)
{ {
unsigned i; unsigned i;
@ -951,16 +926,17 @@ error:
return NULL; return NULL;
} }
static bool read_chunk_header(uint8_t *buf, uint8_t *buf_end, static enum png_chunk_type read_chunk_header(uint8_t *buf, uint8_t *buf_end,
struct png_chunk *chunk) struct png_chunk *chunk)
{ {
unsigned i; unsigned i;
char type[4];
chunk->size = dword_be(buf); chunk->size = dword_be(buf);
/* Check whether chunk will overflow the data buffer */ /* Check whether chunk will overflow the data buffer */
if (buf + 8 + chunk->size > buf_end) if (buf + 8 + chunk->size > buf_end)
return false; return PNG_CHUNK_ERROR;
for (i = 0; i < 4; i++) for (i = 0; i < 4; i++)
{ {
@ -969,12 +945,51 @@ static bool read_chunk_header(uint8_t *buf, uint8_t *buf_end,
/* All four bytes of the chunk type must be /* All four bytes of the chunk type must be
* ASCII letters (codes 65-90 and 97-122) */ * ASCII letters (codes 65-90 and 97-122) */
if ((byte < 65) || ((byte > 90) && (byte < 97)) || (byte > 122)) if ((byte < 65) || ((byte > 90) && (byte < 97)) || (byte > 122))
return false; return PNG_CHUNK_ERROR;
type[i] = byte;
chunk->type[i] = byte;
} }
return true; if (
type[0] == 'I'
&& type[1] == 'H'
&& type[2] == 'D'
&& type[3] == 'R'
)
return PNG_CHUNK_IHDR;
else if
(
type[0] == 'I'
&& type[1] == 'D'
&& type[2] == 'A'
&& type[3] == 'T'
)
return PNG_CHUNK_IDAT;
else if
(
type[0] == 'I'
&& type[1] == 'E'
&& type[2] == 'N'
&& type[3] == 'D'
)
return PNG_CHUNK_IEND;
else if
(
type[0] == 'P'
&& type[1] == 'L'
&& type[2] == 'T'
&& type[3] == 'E'
)
return PNG_CHUNK_PLTE;
else if
(
type[0] == 't'
&& type[1] == 'R'
&& type[2] == 'N'
&& type[3] == 'S'
)
return PNG_CHUNK_tRNS;
return PNG_CHUNK_NOOP;
} }
static bool png_parse_ihdr(uint8_t *buf, static bool png_parse_ihdr(uint8_t *buf,
@ -1002,7 +1017,6 @@ bool rpng_iterate_image(rpng_t *rpng)
uint8_t *buf = (uint8_t*)rpng->buff_data; uint8_t *buf = (uint8_t*)rpng->buff_data;
chunk.size = 0; chunk.size = 0;
chunk.type[0] = 0;
/* Check whether data buffer pointer is valid */ /* Check whether data buffer pointer is valid */
if (buf > rpng->buff_end) if (buf > rpng->buff_end)
@ -1012,10 +1026,8 @@ bool rpng_iterate_image(rpng_t *rpng)
* the data buffer */ * the data buffer */
if (rpng->buff_end - buf < 8) if (rpng->buff_end - buf < 8)
return false; return false;
if (!read_chunk_header(buf, rpng->buff_end, &chunk))
return false;
switch (png_chunk_type(chunk.type)) switch (read_chunk_header(buf, rpng->buff_end, &chunk))
{ {
case PNG_CHUNK_NOOP: case PNG_CHUNK_NOOP:
default: default: