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#include <archive.h>
#include <archive_entry.h>
#include "serialise.hh"
namespace nix {
struct TarArchive {
struct archive * archive;
Source * source;
std::vector<unsigned char> buffer;
void check(int err, const char * reason = "failed to extract archive: %s")
{
if (err == ARCHIVE_EOF)
throw EndOfFile("reached end of archive");
else if (err != ARCHIVE_OK)
throw Error(reason, archive_error_string(this->archive));
}
TarArchive(Source & source) : buffer(4096)
{
this->archive = archive_read_new();
this->source = &source;
archive_read_support_filter_all(archive);
archive_read_support_format_all(archive);
check(archive_read_open(archive,
(void *)this,
TarArchive::callback_open,
TarArchive::callback_read,
TarArchive::callback_close),
"failed to open archive: %s");
}
TarArchive(const Path & path)
{
this->archive = archive_read_new();
archive_read_support_filter_all(archive);
archive_read_support_format_all(archive);
check(archive_read_open_filename(archive, path.c_str(), 16384), "failed to open archive: %s");
}
TarArchive(const TarArchive &) = delete;
void close()
{
check(archive_read_close(archive), "failed to close archive: %s");
}
~TarArchive()
{
if (this->archive) archive_read_free(this->archive);
}
private:
static int callback_open(struct archive *, void * self) {
return ARCHIVE_OK;
}
static ssize_t callback_read(struct archive * archive, void * _self, const void * * buffer)
{
auto self = (TarArchive *)_self;
*buffer = self->buffer.data();
try {
return self->source->read(self->buffer.data(), 4096);
} catch (EndOfFile &) {
return 0;
} catch (std::exception & err) {
archive_set_error(archive, EIO, "source threw exception: %s", err.what());
return -1;
}
}
static int callback_close(struct archive *, void * self) {
return ARCHIVE_OK;
}
};
struct PushD {
char * oldDir;
PushD(const std::string &newDir) {
oldDir = getcwd(0, 0);
if (!oldDir) throw SysError("getcwd");
int r = chdir(newDir.c_str());
if (r != 0) throw SysError("changing directory to tar output path");
}
~PushD() {
int r = chdir(oldDir);
free(oldDir);
if (r != 0)
warn("failed to change directory back after tar extraction");
/* can't throw out of a destructor */
}
};
static void extract_archive(TarArchive & archive, const Path & destDir)
{
// need to chdir back *after* archive closing
PushD newDir(destDir);
int flags = ARCHIVE_EXTRACT_FFLAGS
| ARCHIVE_EXTRACT_PERM
| ARCHIVE_EXTRACT_SECURE_SYMLINKS
| ARCHIVE_EXTRACT_SECURE_NODOTDOT
| ARCHIVE_EXTRACT_SECURE_NOABSOLUTEPATHS;
for (;;) {
struct archive_entry * entry;
int r = archive_read_next_header(archive.archive, &entry);
if (r == ARCHIVE_EOF) break;
else if (r == ARCHIVE_WARN)
warn(archive_error_string(archive.archive));
else
archive.check(r);
archive.check(archive_read_extract(archive.archive, entry, flags));
}
archive.close();
}
void unpackTarfile(Source & source, const Path & destDir)
{
auto archive = TarArchive(source);
createDirs(destDir);
extract_archive(archive, destDir);
}
void unpackTarfile(const Path & tarFile, const Path & destDir)
{
auto archive = TarArchive(tarFile);
createDirs(destDir);
extract_archive(archive, destDir);
}
}
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