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pixz/read.c

335 lines
9.4 KiB
C

#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <lzma.h>
#include <libkern/OSByteOrder.h>
#pragma mark DEFINES
#define CHUNKSIZE 4096
#define MEMLIMIT (64L * 1024 * 1024 * 1024) // crazy high
#pragma mark TYPES
struct file_index_t {
char *name;
off_t offset;
struct file_index_t *next;
};
typedef struct file_index_t file_index_t;
typedef struct {
lzma_block block;
lzma_filter filters[LZMA_FILTERS_MAX + 1];
} block_wrapper_t;
#pragma mark GLOBALS
FILE *gInFile = NULL;
lzma_stream gStream = LZMA_STREAM_INIT;
lzma_check gCheck = LZMA_CHECK_NONE;
lzma_index *gIndex = NULL;
file_index_t *gFileIndex = NULL, *gLastFile = NULL;
uint8_t *gFileIndexBuf = NULL;
size_t gFIBSize = CHUNKSIZE, gFIBPos = 0;
lzma_ret gFIBErr = LZMA_OK;
uint8_t gFIBInputBuf[CHUNKSIZE];
size_t gMoved = 0;
#pragma mark FUNCTION DECLARATIONS
void die(const char *fmt, ...);
void decode_index(void);
void *decode_block_start(off_t block_seek);
void dump_file_index(void);
void free_file_index(void);
void read_file_index(void);
char *read_file_index_name(void);
void read_file_index_make_space(void);
void read_file_index_data(void);
void extract_file(const char *target);
void extract_block(off_t block_seek, off_t skip, off_t size);
#pragma mark FUNCTION DEFINITIONS
int main(int argc, char **argv) {
if (argc != 3)
die("Need two arguments");
if (!(gInFile = fopen(argv[1], "r")))
die("Can't open input file");
char *target = argv[2];
decode_index();
read_file_index();
extract_file(target);
free_file_index();
lzma_index_end(gIndex, NULL);
return 0;
}
void die(const char *fmt, ...) {
va_list args;
va_start(args, fmt);
vfprintf(stderr, fmt, args);
fprintf(stderr, "\n");
fflush(stderr);
va_end(args);
exit(1);
}
void decode_index(void) {
if (fseek(gInFile, -LZMA_STREAM_HEADER_SIZE, SEEK_END) == -1)
die("Error seeking to stream footer");
uint8_t hdrbuf[LZMA_STREAM_HEADER_SIZE];
if (fread(hdrbuf, LZMA_STREAM_HEADER_SIZE, 1, gInFile) != 1)
die("Error reading stream footer");
lzma_stream_flags flags;
if (lzma_stream_footer_decode(&flags, hdrbuf) != LZMA_OK)
die("Error decoding stream footer");
gCheck = flags.check;
size_t index_seek = -LZMA_STREAM_HEADER_SIZE - flags.backward_size;
if (fseek(gInFile, index_seek, SEEK_CUR) == -1)
die("Error seeking to index");
if (lzma_index_decoder(&gStream, &gIndex, MEMLIMIT) != LZMA_OK)
die("Error creating index decoder");
uint8_t ibuf[CHUNKSIZE];
gStream.avail_in = 0;
lzma_ret err = LZMA_OK;
while (err != LZMA_STREAM_END) {
if (gStream.avail_in == 0) {
gStream.avail_in = fread(ibuf, 1, CHUNKSIZE, gInFile);
if (ferror(gInFile))
die("Error reading index");
gStream.next_in = ibuf;
}
err = lzma_code(&gStream, LZMA_RUN);
if (err != LZMA_OK && err != LZMA_STREAM_END)
die("Error decoding index");
}
}
void *decode_block_start(off_t block_seek) {
if (fseeko(gInFile, block_seek, SEEK_SET) == -1)
die("Error seeking to block");
block_wrapper_t *bw = malloc(sizeof(block_wrapper_t));
bw->block = (lzma_block){ .check = gCheck, .filters = bw->filters };
int b = fgetc(gInFile);
if (b == EOF || b == 0)
die("Error reading block size");
bw->block.header_size = lzma_block_header_size_decode(b);
uint8_t hdrbuf[bw->block.header_size];
hdrbuf[0] = (uint8_t)b;
if (fread(hdrbuf + 1, bw->block.header_size - 1, 1, gInFile) != 1)
die("Error reading block header");
if (lzma_block_header_decode(&bw->block, NULL, hdrbuf) != LZMA_OK)
die("Error decoding file index block header");
if (lzma_block_decoder(&gStream, &bw->block) != LZMA_OK)
die("Error initializing file index stream");
return bw;
}
void read_file_index(void) {
// find the last block
lzma_vli loc = lzma_index_uncompressed_size(gIndex) - 1;
lzma_index_record rec;
if (lzma_index_locate(gIndex, &rec, loc))
die("Can't locate file index block");
void *bdata = decode_block_start(rec.stream_offset);
gFileIndexBuf = malloc(gFIBSize);
gStream.avail_out = gFIBSize;
gStream.avail_in = 0;
while (true) {
char *name = read_file_index_name();
if (!name)
break;
file_index_t *f = malloc(sizeof(file_index_t));
f->name = strlen(name) ? strdup(name) : NULL;
f->offset = OSReadLittleInt64(gFileIndexBuf, gFIBPos);
gFIBPos += sizeof(uint64_t);
if (gLastFile) {
gLastFile->next = f;
} else {
gFileIndex = f;
}
gLastFile = f;
}
free(gFileIndexBuf);
lzma_end(&gStream);
free(bdata);
}
char *read_file_index_name(void) {
while (true) {
// find a nul that ends a name
uint8_t *eos, *haystack = gFileIndexBuf + gFIBPos;
ssize_t len = gFIBSize - gStream.avail_out - gFIBPos - sizeof(uint64_t);
if (len > 0 && (eos = memchr(haystack, '\0', len))) { // found it
gFIBPos += eos - haystack + 1;
return (char*)haystack;
} else if (gFIBErr == LZMA_STREAM_END) { // nothing left
return NULL;
} else { // need more data
if (gStream.avail_out == 0)
read_file_index_make_space();
read_file_index_data();
}
}
}
void read_file_index_make_space(void) {
bool expand = (gFIBPos == 0);
if (gFIBPos != 0) { // clear more space
size_t move = gFIBSize - gStream.avail_out - gFIBPos;
memmove(gFileIndexBuf, gFileIndexBuf + gFIBPos, move);
gMoved += move;
gStream.avail_out += gFIBPos;
gFIBPos = 0;
}
// Try to reduce number of moves by expanding proactively
if (expand || gMoved >= gFIBSize) { // malloc more space
gStream.avail_out += gFIBSize;
gFIBSize *= 2;
gFileIndexBuf = realloc(gFileIndexBuf, gFIBSize);
}
}
void read_file_index_data(void) {
gStream.next_out = gFileIndexBuf + gFIBSize - gStream.avail_out;
while (gFIBErr != LZMA_STREAM_END && gStream.avail_out) {
if (gStream.avail_in == 0) {
// It's ok to read past the end of the block, we'll still
// get LZMA_STREAM_END at the right place
gStream.avail_in = fread(gFIBInputBuf, 1, CHUNKSIZE, gInFile);
if (ferror(gInFile))
die("Error reading file index data");
gStream.next_in = gFIBInputBuf;
}
gFIBErr = lzma_code(&gStream, LZMA_RUN);
if (gFIBErr != LZMA_OK && gFIBErr != LZMA_STREAM_END)
die("Error decoding file index data");
}
}
void dump_file_index(void) {
for (file_index_t *f = gFileIndex; f != NULL; f = f->next) {
printf("%10llx %s\n", f->offset, f->name ? f->name : "");
}
}
void free_file_index(void) {
for (file_index_t *f = gFileIndex; f != NULL; ) {
file_index_t *next = f->next;
free(f->name);
free(f);
f = next;
}
gFileIndex = gLastFile = NULL;
}
void extract_file(const char *target) {
// find it in the index
file_index_t *f;
for (f = gFileIndex; f != NULL; f = f->next) {
if (f->name && strcmp(f->name, target) == 0)
break;
}
if (!f)
die("Can't find target file");
off_t fstart = f->offset, fsize = f->next->offset - fstart;
// extract the data
lzma_index_record rec;
lzma_index_rewind(gIndex);
while (fsize && !lzma_index_read(gIndex, &rec)) {
off_t bstart = rec.uncompressed_offset,
bsize = rec.uncompressed_size;
if (fstart > bstart + bsize)
continue;
off_t dstart = fstart > bstart ? fstart - bstart : 0;
bsize -= dstart;
off_t dsize = fsize > bsize ? bsize : fsize;
fsize -= dsize;
extract_block(rec.stream_offset, dstart, dsize);
}
if (fsize)
die("Block with file contents missing");
}
void extract_block(off_t block_seek, off_t skip, off_t size) {
void *bdata = decode_block_start(block_seek);
uint8_t ibuf[CHUNKSIZE], obuf[CHUNKSIZE];
gStream.avail_in = 0;
lzma_ret err = LZMA_OK;
while (size && err != LZMA_STREAM_END) {
gStream.next_out = obuf;
gStream.avail_out = CHUNKSIZE;
if (gStream.avail_in == 0) {
gStream.avail_in = fread(ibuf, 1, CHUNKSIZE, gInFile);
if (ferror(gInFile))
die("Error reading block data");
gStream.next_in = ibuf;
}
err = lzma_code(&gStream, LZMA_RUN);
if (err != LZMA_OK && err != LZMA_STREAM_END)
die("Error decoding block");
// do we want to write?
uint8_t *start = obuf;
size_t out = gStream.next_out - obuf;
if (out <= skip) {
skip -= out;
continue;
}
// what do we want to write?
start += skip;
out -= skip;
skip = 0;
if (out > size)
out = size;
if (fwrite(start, out, 1, stdout) != 1)
die("Error writing output");
size -= out;
}
if (size)
die("Block data missing");
lzma_end(&gStream);
free(bdata);
}