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elinks/src/encoding/bzip2.c
2022-01-16 19:38:30 +01:00

241 lines
5.3 KiB
C

/* Bzip2 encoding (ENCODING_BZIP2) backend */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdio.h>
#include <string.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <bzlib.h> /* Everything needs this after stdio.h */
#include <errno.h>
#include "elinks.h"
#include "encoding/bzip2.h"
#include "encoding/encoding.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
struct bz2_enc_data {
bz_stream fbz_stream;
/* The file descriptor from which we read. */
int fdread;
/* 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:1;
int after_end:1;
/* 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. */
char buf[ELINKS_BZ_BUFFER_LENGTH];
};
static int
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 = (struct bz2_enc_data *)mem_alloc(sizeof(*data));
int err;
stream->data = NULL;
if (!data) {
return -1;
}
/* 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->last_read = 0;
data->after_end = 0;
err = BZ2_bzDecompressInit(&data->fbz_stream, 0, 0);
if (err != BZ_OK) {
mem_free(data);
return -1;
}
stream->data = data;
return 0;
}
static int
bzip2_read(struct stream_encoded *stream, char *buf, int len)
{
struct bz2_enc_data *data = (struct bz2_enc_data *) stream->data;
int err = 0;
if (!data) return -1;
assert(len > 0);
if (data->last_read) return 0;
data->fbz_stream.avail_out = len;
data->fbz_stream.next_out = buf;
do {
if (data->fbz_stream.avail_in == 0) {
int l = safe_read(data->fdread, data->buf,
ELINKS_BZ_BUFFER_LENGTH);
if (l == -1) {
if (errno == EAGAIN)
break;
else
return -1; /* I/O error */
} else if (l == 0) {
/* EOF. It is error: we wait for more bytes */
return -1;
}
data->fbz_stream.next_in = data->buf;
data->fbz_stream.avail_in = l;
}
err = BZ2_bzDecompress(&data->fbz_stream);
if (err == BZ_STREAM_END) {
data->last_read = 1;
break;
} else if (err != BZ_OK) {
return -1;
}
} while (data->fbz_stream.avail_out > 0);
assert(len - data->fbz_stream.avail_out == data->fbz_stream.next_out - buf);
return len - data->fbz_stream.avail_out;
}
#ifdef CONFIG_SMALL
#define BZIP2_SMALL 1
#else
#define BZIP2_SMALL 0
#endif
static char *
bzip2_decode_buffer(struct stream_encoded *st, char *data, int len, int *new_len)
{
struct bz2_enc_data *enc_data = (struct bz2_enc_data *)st->data;
bz_stream *stream = &enc_data->fbz_stream;
char *buffer = NULL;
int error;
*new_len = 0; /* default, left there if an error occurs */
stream->next_in = data;
stream->avail_in = len;
stream->total_out_lo32 = 0;
stream->total_out_hi32 = 0;
do {
char *new_buffer;
size_t size = stream->total_out_lo32 + MAX_STR_LEN;
/* FIXME: support for 64 bit. real size is
*
* (total_in_hi32 << * 32) + total_in_lo32
*
* --jonas */
assertm(!stream->total_out_hi32, "64 bzip2 decoding not supported");
new_buffer = (char *)mem_realloc(buffer, size);
if (!new_buffer) {
error = BZ_MEM_ERROR;
break;
}
buffer = new_buffer;
stream->next_out = buffer + stream->total_out_lo32;
stream->avail_out = MAX_STR_LEN;
error = BZ2_bzDecompress(stream);
if (error == BZ_STREAM_END) {
break;
}
/* Apparently BZ_STREAM_END is not forced when the end of input
* is reached. At least lindi- reported that it caused a
* reproducable infinite loop. Maybe it has to do with decoding
* an incomplete file. */
} while (error == BZ_OK && stream->avail_in > 0);
if (error == BZ_STREAM_END) {
BZ2_bzDecompressEnd(stream);
enc_data->after_end = 1;
error = BZ_OK;
}
if (error == BZ_OK) {
*new_len = stream->total_out_lo32;
return buffer;
} else {
mem_free_if(buffer);
return NULL;
}
}
static void
bzip2_close(struct stream_encoded *stream)
{
struct bz2_enc_data *data = (struct bz2_enc_data *) stream->data;
if (data) {
if (!data->after_end) {
BZ2_bzDecompressEnd(&data->fbz_stream);
}
if (data->fdread != -1) {
close(data->fdread);
}
mem_free(data);
stream->data = 0;
}
}
const char *
get_bzip2_version(void)
{
static char version[16];
if (!version[0]) {
strncpy(version, BZ2_bzlibVersion(), 15);
size_t ok = strspn(version, "0123456789.");
version[ok] = '\0';
}
return version;
}
static const char *const bzip2_extensions[] = { ".bz2", ".tbz", NULL };
const struct decoding_backend bzip2_decoding_backend = {
"bzip2",
bzip2_extensions,
bzip2_open,
bzip2_read,
bzip2_decode_buffer,
bzip2_close,
};