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GitPack.cpp
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GitPack.cpp
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#include "GitPack.h"
#include "GitPackIdxV2.h"
#include <QDebug>
#include <QFile>
#include <zlib.h>
void GitPack::decodeTree(QByteArray *out)
{
if (out && out->size() > 0) {
QByteArray ba;
uint8_t const *begin = (uint8_t const *)out->data();
uint8_t const *end = begin + out->size();
uint8_t const *ptr = begin;
while (ptr < end) {
int mode = 0;
while (ptr < end) {
int c = *ptr & 0xff;
ptr++;
if (isdigit(c & 0xff)) {
mode = mode * 10 + (c - '0');
} else if (c == ' ') {
break;
}
}
uint8_t const *left = ptr;
while (ptr < end && *ptr) {
ptr++;
}
std::string name(left, ptr);
if (ptr + 20 < end) {
ptr++;
char tmp[100];
sprintf(tmp, "%06u %s ", mode, mode < 100000 ? "tree" : "blob");
char *p = tmp + 12;
for (int i = 0; i < 20; i++) {
sprintf(p, "%02x", ptr[i]);
p += 2;
}
ba.append(tmp, p - tmp);
ba.append('\t');
ba.append(name.c_str(), name.size());
ba.append('\n');
ptr += 20;
} else {
break;
}
}
*out = std::move(ba);
}
}
Git::Object::Type GitPack::stripHeader(QByteArray *out)
{
if (out) {
int n = out->size();
if (n > 0) {
char const *p = out->data();
if (n > 16) n = 16;
for (int i = 0; i < n; i++) {
if (p[i] == 0) {
Git::Object::Type type = Git::Object::Type::UNKNOWN;
if (strncmp(p, "blob ", 5) == 0) {
type = Git::Object::Type::BLOB;
} else if (strncmp(p, "tree ", 5) == 0) {
type = Git::Object::Type::TREE;
} else if (strncmp(p, "commit ", 7) == 0) {
type = Git::Object::Type::COMMIT;
} else if (strncmp(p, "tag ", 4) == 0) {
type = Git::Object::Type::TAG;
}
if (type != Git::Object::Type::UNKNOWN) {
*out = out->mid(i + 1);
}
return type;
}
}
}
}
return Git::Object::Type::UNKNOWN;
}
bool GitPack::decompress(QIODevice *in, size_t expanded_size, QByteArray *out, size_t *consumed, uint32_t *crc)
{
if (consumed) *consumed = 0;
try {
int err;
z_stream d_stream;
d_stream.zalloc = nullptr;
d_stream.zfree = nullptr;
d_stream.opaque = nullptr;
d_stream.avail_in = 0;
err = inflateInit(&d_stream);
if (err != Z_OK) {
throw QString("failed: inflateInit");
}
int flush = Z_NO_FLUSH;
while (1) {
uint8_t ibuf[65536];
uint8_t obuf[65536];
size_t ilen = d_stream.avail_in;
d_stream.next_in = ibuf;
d_stream.next_out = obuf;
d_stream.avail_out = sizeof(obuf);
err = ::inflate(&d_stream, flush);
if (err == Z_BUF_ERROR) {
if (flush == Z_FINISH) {
throw QString("failed: inflate");
}
d_stream.avail_in = in->read((char *)ibuf, sizeof(ibuf));
if (d_stream.avail_in == 0) {
flush = Z_FINISH;
}
continue;
}
ilen -= d_stream.avail_in;
if (consumed) *consumed += ilen;
if (crc) *crc = crc32(*crc, ibuf, ilen);
if (ilen > 0 && d_stream.avail_in > 0) {
memmove(ibuf, ibuf + ilen, d_stream.avail_in);
}
size_t n = sizeof(obuf) - d_stream.avail_out;
out->append((char const *)obuf, n);
if (err == Z_STREAM_END) {
break;
}
if (err != Z_OK) {
throw QString("failed: inflate");
}
if (expanded_size > 0 && (size_t)out->size() > expanded_size) {
throw QString("file too large");
}
}
err = inflateEnd(&d_stream);
if (err != Z_OK) {
throw QString("failed: inflateEnd");
}
return true;
} catch (QString const &e) {
qDebug() << e;
}
return false;
}
bool GitPack::seekPackedObject(QIODevice *file, GitPackIdxItem const *item, Info *out)
{
try {
Info info;
auto Read = [&](void *ptr, size_t len){
const auto l = file->read((char *)ptr, len);
if (l < 0 || ((size_t)(l)) != len) {
throw QString("failed to read");
}
info.checksum = crc32(info.checksum, (uint8_t const *)ptr, len);
};
file->seek(0);
uint32_t header[3];
Read(header, sizeof(int32_t) * 3);
if (memcmp(header, "PACK", 4) != 0) throw QString("invalid pack file");
uint32_t version = read_uint32_be(header + 1);
if (version < 2) throw QString("invalid pack file version");
/*int count = */read_uint32_be(header + 2);
file->seek(item->offset);
info.checksum = 0;
// cf. https://github.com/github/git-msysgit/blob/master/builtin/unpack-objects.c
{
size_t size = 0;
char c;
Read(&c, 1);
info.type = (Git::Object::Type)((c >> 4) & 7);
size = c & 0x0f;
int shift = 4;
while (c & 0x80) {
Read(&c, 1);
size |= (c & 0x7f) << shift;
shift += 7;
}
info.expanded_size = size;
}
if (info.type == Git::Object::Type::OFS_DELTA) {
uint64_t offset = 0;
char c;
Read(&c, 1);
offset = c & 0x7f;
while (c & 0x80) {
Read(&c, 1);
offset = ((offset + 1) << 7) | (c & 0x7f);
}
info.offset = offset;
} else if (info.type == Git::Object::Type::REF_DELTA) {
char bin[20];
Read(bin, 20);
char tmp[41];
for (int i = 0; i < 20; i++) {
sprintf(tmp + i * 2, "%02x", bin[i] & 0xff);
}
info.ref_id = QString::fromLatin1(tmp, GIT_ID_LENGTH);
}
*out = info;
return true;
} catch (QString const &e) {
qDebug() << e;
}
return false;
}
bool GitPack::load(QIODevice *file, GitPackIdxItem const *item, Object *out)
{
*out = Object();
try {
seekPackedObject(file, item, out);
if (decompress(file, out->expanded_size, &out->content, &out->packed_size, &out->checksum)) {
out->expanded_size = out->expanded_size;
return true;
}
} catch (QString const &e) {
qDebug() << e;
}
return false;
}
bool GitPack::load(QString const &packfile, GitPackIdxItem const *item, GitPack::Object *out)
{
QFile file(packfile);
if (file.open(QFile::ReadOnly)) {
if (load(&file, item, out)) {
return true;
}
}
return false;
}

File Metadata

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text/x-c
Expires
Sun, Nov 15, 12:06 AM (1 d, 14 h)
Storage Engine
blob
Storage Format
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Storage Handle
132319
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GitPack.cpp (5 KB)

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