mirror of
https://github.com/rkd77/elinks.git
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247 lines
5.5 KiB
C
247 lines
5.5 KiB
C
/* deflate/gzip encoding backend */
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <stdio.h>
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#include <string.h>
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <zlib.h>
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#include <errno.h>
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#include "elinks.h"
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#include "encoding/encoding.h"
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#include "encoding/gzip.h"
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#include "util/memory.h"
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/* How many bytes of compressed data to read before decompressing. */
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#define ELINKS_DEFLATE_BUFFER_LENGTH 5000
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struct deflate_enc_data {
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z_stream deflate_stream;
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/* The file descriptor from which we read. */
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int fdread;
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size_t sent_pos;
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uint8_t *buffer;
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unsigned int decoded:1;
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unsigned int last_read:1;
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unsigned int after_first_read:1;
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unsigned int after_end:1;
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/* A buffer for data that has been read from the file but not
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* yet decompressed. z_stream.next_in and z_stream.avail_in
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* refer to this buffer. */
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unsigned char buf[ELINKS_DEFLATE_BUFFER_LENGTH];
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};
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static int
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deflate_open(int window_size, struct stream_encoded *stream, int fd)
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{
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/* A zero-initialized z_stream. The compiler ensures that all
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* pointer members in it are null. (Can't do this with memset
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* because C99 does not require all-bits-zero to be a null
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* pointer.) */
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static const z_stream null_z_stream = {0};
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int err;
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struct deflate_enc_data *data = (struct deflate_enc_data *)mem_alloc(sizeof(*data));
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stream->data = NULL;
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if (!data) {
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return -1;
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}
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/* Initialize all members of *data, except data->buf[], which
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* will be initialized on demand by deflate_read. */
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copy_struct(&data->deflate_stream, &null_z_stream);
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data->fdread = fd;
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data->last_read = 0;
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data->after_first_read = 0;
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data->after_end = 0;
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data->sent_pos = 0;
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data->decoded = 0;
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if (window_size > 0) {
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err = inflateInit2(&data->deflate_stream, window_size);
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} else {
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err = inflateInit(&data->deflate_stream);
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}
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if (err != Z_OK) {
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mem_free(data);
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return -1;
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}
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stream->data = data;
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return 0;
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}
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static int
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deflate_gzip_open(struct stream_encoded *stream, int fd)
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{
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/* detect gzip header, else assume zlib header */
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return deflate_open(MAX_WBITS + 32, stream, fd);
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}
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static char *deflate_gzip_decode_buffer(struct stream_encoded *st, char *data, int len, int *new_len);
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static int
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deflate_read(struct stream_encoded *stream, char *buf, int len)
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{
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struct deflate_enc_data *data = (struct deflate_enc_data *) stream->data;
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if (!data) return -1;
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assert(len > 0);
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if (!data->decoded) {
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size_t read_pos = 0;
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char *tmp_buf = (char *)mem_alloc(len);
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int new_len;
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if (!tmp_buf) {
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return 0;
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}
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do {
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int l = safe_read(data->fdread, tmp_buf + read_pos, len - read_pos);
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if (!l) break;
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if (l == -1 && errno == EAGAIN) {
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continue;
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}
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if (l == -1) {
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return -1;
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}
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read_pos += l;
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} while (1);
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if (deflate_gzip_decode_buffer(stream, tmp_buf, len, &new_len)) {
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data->decoded = 1;
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}
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mem_free(tmp_buf);
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}
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if (data->decoded) {
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int length = len < (data->deflate_stream.total_out - data->sent_pos) ? len : (data->deflate_stream.total_out - data->sent_pos);
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if (length <= 0) {
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mem_free_set(&data->buffer, NULL);
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} else {
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memcpy(buf, (void *)((char *)(data->buffer) + data->sent_pos), length);
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data->sent_pos += length;
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}
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return length;
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}
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return -1;
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}
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static char *
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deflate_decode_buffer(struct stream_encoded *st, int window_size, char *datac, int len, int *new_len)
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{
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unsigned char *data = (unsigned char *)datac;
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struct deflate_enc_data *enc_data = (struct deflate_enc_data *) st->data;
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z_stream *stream = &enc_data->deflate_stream;
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unsigned char *buffer = NULL;
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int error;
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*new_len = 0; /* default, left there if an error occurs */
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if (!len) return NULL;
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stream->next_in = data;
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stream->avail_in = len;
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stream->total_out = 0;
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do {
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unsigned char *new_buffer;
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size_t size = stream->total_out + MAX_STR_LEN;
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new_buffer = (unsigned char *)mem_realloc(buffer, size);
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if (!new_buffer) {
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error = Z_MEM_ERROR;
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break;
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}
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buffer = new_buffer;
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stream->next_out = buffer + stream->total_out;
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stream->avail_out = MAX_STR_LEN;
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restart2:
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error = inflate(stream, Z_SYNC_FLUSH);
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if (error == Z_STREAM_END) {
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break;
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}
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if (error == Z_DATA_ERROR && !enc_data->after_first_read) {
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(void)inflateEnd(stream);
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error = inflateInit2(stream, -MAX_WBITS);
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if (error == Z_OK) {
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enc_data->after_first_read = 1;
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stream->next_in = data;
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stream->avail_in = len;
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goto restart2;
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}
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}
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} while (error == Z_OK && stream->avail_in > 0);
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if (error == Z_STREAM_END) {
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inflateEnd(stream);
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enc_data->after_end = 1;
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error = Z_OK;
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}
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enc_data->buffer = (uint8_t *)buffer;
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if (error == Z_OK) {
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*new_len = stream->total_out;
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return (char *)buffer;
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} else {
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mem_free_set(&enc_data->buffer, NULL);
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return NULL;
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}
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}
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static char *
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deflate_gzip_decode_buffer(struct stream_encoded *st, char *data, int len, int *new_len)
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{
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/* detect gzip header, else assume zlib header */
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return deflate_decode_buffer(st, MAX_WBITS + 32, data, len, new_len);
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}
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static void
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deflate_close(struct stream_encoded *stream)
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{
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struct deflate_enc_data *data = (struct deflate_enc_data *) stream->data;
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if (data) {
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if (!data->after_end) {
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inflateEnd(&data->deflate_stream);
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}
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if (data->fdread != -1) {
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close(data->fdread);
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}
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mem_free(data);
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stream->data = 0;
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}
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}
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const char *
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get_gzip_version(void)
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{
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return zlibVersion();
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}
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static const char *const gzip_extensions[] = { ".gz", ".tgz", NULL };
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const struct decoding_backend gzip_decoding_backend = {
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"gzip",
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gzip_extensions,
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deflate_gzip_open,
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deflate_read,
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deflate_gzip_decode_buffer,
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deflate_close,
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};
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