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Various comments and tweaks in bzip2 decoding.

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Do not assume that memset(ptr, 0, size) clears pointers to NULL.
The length of decoded data can be read in two ways; assert they match.
This commit is contained in:
Kalle Olavi Niemitalo 2007-02-24 22:51:12 +02:00 committed by Kalle Olavi Niemitalo
parent a75302caf2
commit 0e5b6af9b0
1 changed files with 30 additions and 6 deletions
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36
src/encoding/bzip2.c
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@ -20,29 +20,52 @@
#include "encoding/encoding.h" #include "encoding/encoding.h"
#include "util/memory.h" #include "util/memory.h"
/* How many bytes of compressed data to read before decompressing.
* This is currently defined as BZ_MAX_UNUSED to make the behaviour
* similar to BZ2_bzRead; but other values would work too. */
#define ELINKS_BZ_BUFFER_LENGTH BZ_MAX_UNUSED #define ELINKS_BZ_BUFFER_LENGTH BZ_MAX_UNUSED
struct bz2_enc_data { struct bz2_enc_data {
bz_stream fbz_stream; bz_stream fbz_stream;
/* The file descriptor from which we read. */
int fdread; int fdread;
int last_read; /* If err after last bzDecompress was BZ_STREAM_END.. */
unsigned char buf[ELINKS_BZ_BUFFER_LENGTH]; /* must be the last */ /* Initially 0; set to 1 when BZ2_bzDecompress indicates
* BZ_STREAM_END, which means it has found the bzip2-specific
* end-of-stream marker and all data has been decompressed.
* Then we neither read from the file nor call BZ2_bzDecompress
* any more. */
int last_read;
/* A buffer for data that has been read from the file but not
* yet decompressed. fbz_stream.next_in and fbz_stream.avail_in
* refer to this buffer. */
unsigned char buf[ELINKS_BZ_BUFFER_LENGTH];
}; };
static int static int
bzip2_open(struct stream_encoded *stream, int fd) bzip2_open(struct stream_encoded *stream, int fd)
{ {
/* A zero-initialized bz_stream. The compiler ensures that all
* pointer members in it are null. (Can't do this with memset
* because C99 does not require all-bits-zero to be a null
* pointer.) */
static const bz_stream null_bz_stream = {0};
struct bz2_enc_data *data = mem_alloc(sizeof(*data)); struct bz2_enc_data *data = mem_alloc(sizeof(*data));
int err; int err;
stream->data = 0; stream->data = NULL;
if (!data) { if (!data) {
return -1; return -1;
} }
memset(data, 0, sizeof(struct bz2_enc_data) - ELINKS_BZ_BUFFER_LENGTH);
data->last_read = 0; /* Initialize all members of *data, except data->buf[], which
* will be initialized on demand by bzip2_read. */
copy_struct(&data->fbz_stream, &null_bz_stream);
data->fdread = fd; data->fdread = fd;
data->last_read = 0;
err = BZ2_bzDecompressInit(&data->fbz_stream, 0, 0); err = BZ2_bzDecompressInit(&data->fbz_stream, 0, 0);
if (err != BZ_OK) { if (err != BZ_OK) {
@ -97,7 +120,8 @@ bzip2_read(struct stream_encoded *stream, unsigned char *buf, int len)
return -1; return -1;
} }
} while (data->fbz_stream.avail_out > 0); } while (data->fbz_stream.avail_out > 0);
assert(len - data->fbz_stream.avail_out == data->fbz_stream.next_out - (char *) buf);
return len - data->fbz_stream.avail_out; return len - data->fbz_stream.avail_out;
} }