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#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include "util.h"
#include "zip.h"
#ifndef DISABLE_ZLIB
#include "zlib/zlib.h"
#endif
static const char cdfd_magic[4] = {'P', 'K', 1, 2};
static const char eocd_magic[4] = {'P', 'K', 5, 6};
#define MIN_EOCD_SIZE 22
#define MIN_CDFD_SIZE 46
#define ZIP_MAX_EOCD_OFFSET (64*1024+MIN_EOCD_SIZE)
enum {
ZIP_STORE = 0,
ZIP_DEFLATE = 8
};
zip_file *zip_open(const char *filename)
{
FILE *f = fopen(filename, "rb");
if (!f) {
return NULL;
}
long fsize = file_size(f);
if (fsize < MIN_EOCD_SIZE) {
//too small to be a zip file
goto fail;
}
long max_offset = fsize > ZIP_MAX_EOCD_OFFSET ? ZIP_MAX_EOCD_OFFSET : fsize;
fseek(f, -max_offset, SEEK_END);
uint8_t *buf = malloc(max_offset);
if (max_offset != fread(buf, 1, max_offset, f)) {
goto fail;
}
long current_offset;
uint32_t cd_start, cd_size;
uint16_t cd_count;
for (current_offset = max_offset - MIN_EOCD_SIZE; current_offset >= 0; current_offset--)
{
if (memcmp(eocd_magic, buf + current_offset, sizeof(eocd_magic))) {
continue;
}
uint16_t comment_size = buf[current_offset + 20] | buf[current_offset + 21] << 8;
if (comment_size != (max_offset - current_offset - MIN_EOCD_SIZE)) {
continue;
}
cd_start = buf[current_offset + 16] | buf[current_offset + 17] << 8
| buf[current_offset + 18] << 16 | buf[current_offset + 19] << 24;
if (cd_start > (fsize - (max_offset - current_offset))) {
continue;
}
cd_size = buf[current_offset + 12] | buf[current_offset + 13] << 8
| buf[current_offset + 14] << 16 | buf[current_offset + 15] << 24;
if ((cd_start + cd_size) > (fsize - (max_offset - current_offset))) {
continue;
}
cd_count = buf[current_offset + 10] | buf[current_offset + 11] << 8;
break;
}
free(buf);
if (current_offset < 0) {
//failed to find EOCD
goto fail;
}
buf = malloc(cd_size);
fseek(f, cd_start, SEEK_SET);
if (cd_size != fread(buf, 1, cd_size, f)) {
goto fail_free;
}
zip_entry *entries = calloc(cd_count, sizeof(zip_entry));
uint32_t cd_max_last = cd_size - MIN_CDFD_SIZE;
zip_entry *cur_entry = entries;
for (uint32_t off = 0; cd_count && off <= cd_max_last; cur_entry++, cd_count--)
{
if (memcmp(buf + off, cdfd_magic, sizeof(cdfd_magic))) {
goto fail_entries;
}
uint32_t name_length = buf[off + 28] | buf[off + 29] << 8;
uint32_t extra_length = buf[off + 30] | buf[off + 31] << 8;
//TODO: verify name length doesn't go past end of CD
cur_entry->name = malloc(name_length + 1);
memcpy(cur_entry->name, buf + off + MIN_CDFD_SIZE, name_length);
cur_entry->name[name_length] = 0;
cur_entry->compressed_size = buf[off + 20] | buf[off + 21] << 8
| buf[off + 22] << 16 | buf[off + 23] << 24;
cur_entry->size = buf[off + 24] | buf[off + 25] << 8
| buf[off + 26] << 16 | buf[off + 27] << 24;
cur_entry->local_header_off = buf[off + 42] | buf[off + 43] << 8
| buf[off + 44] << 16 | buf[off + 45] << 24;
cur_entry->compression_method = buf[off + 10] | buf[off + 11] << 8;
off += name_length + extra_length + MIN_CDFD_SIZE;
}
zip_file *z = malloc(sizeof(zip_file));
z->entries = entries;
z->file = f;
z->num_entries = cur_entry - entries;
return z;
fail_entries:
for (cur_entry--; cur_entry >= entries; cur_entry--)
{
free(cur_entry->name);
}
free(entries);
fail_free:
free(buf);
fail:
fclose(f);
return NULL;
}
uint8_t *zip_read(zip_file *f, uint32_t index, size_t *out_size)
{
fseek(f->file, f->entries[index].local_header_off + 26, SEEK_SET);
uint8_t tmp[4];
if (sizeof(tmp) != fread(tmp, 1, sizeof(tmp), f->file)) {
return NULL;
}
uint32_t local_variable = (tmp[0] | tmp[1] << 8) + (tmp[2] | tmp[3] << 8);
fseek(f->file, f->entries[index].local_header_off + local_variable + 30, SEEK_SET);
size_t int_size;
if (!out_size) {
out_size = &int_size;
int_size = f->entries[index].size;
}
uint8_t *buf = malloc(*out_size);
if (*out_size > f->entries[index].size) {
*out_size = f->entries[index].size;
}
switch(f->entries[index].compression_method)
{
case ZIP_STORE:
if (*out_size != fread(buf, 1, *out_size, f->file)) {
free(buf);
return NULL;
}
break;
#ifndef DISABLE_ZLIB
case ZIP_DEFLATE: {
//note in unzip.c in zlib/contrib suggests a dummy byte is needed, so we allocate an extra byte here
uint8_t *src_buf = malloc(f->entries[index].compressed_size + 1);
if (f->entries[index].compressed_size != fread(src_buf, 1, f->entries[index].compressed_size, f->file)) {
free(src_buf);
return NULL;
}
uLongf destLen = *out_size;
z_stream stream;
memset(&stream, 0, sizeof(stream));
stream.avail_in = f->entries[index].compressed_size + 1;
stream.next_in = src_buf;
stream.next_out = buf;
stream.avail_out = *out_size;
if (Z_OK == inflateInit2(&stream, -15)) {
int result = inflate(&stream, Z_FINISH);
*out_size = stream.total_out;
free(src_buf);
inflateEnd(&stream);
if (result != Z_OK && result != Z_STREAM_END && result != Z_BUF_ERROR) {
free(buf);
return NULL;
}
}
break;
}
#endif
default:
free(buf);
return NULL;
}
return buf;
}
void zip_close(zip_file *f)
{
fclose(f->file);
for (uint32_t i = 0; i < f->num_entries; i++)
{
free(f->entries[i].name);
}
free(f->entries);
free(f);
}
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