lix/src/libutil/tarfile.cc
2019-12-07 18:12:21 +00:00

127 lines
3.4 KiB
C++

#include "rust-ffi.hh"
#include "compression.hh"
#include <archive.h>
#include <archive_entry.h>
#include "finally.hh"
namespace nix {
struct TarArchive {
struct archive *archive;
Source *source;
unsigned char buffer[4096];
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) {
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)");
}
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) {
TarArchive *self = (TarArchive *)_self;
*buffer = self->buffer;
try {
return self->source->read(self->buffer, 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)
std::cerr << "warning: popd failed to chdir";
/* 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);
struct archive_entry *entry;
int flags = ARCHIVE_EXTRACT_FFLAGS | ARCHIVE_EXTRACT_PERM;
for(;;) {
int r = archive_read_next_header(archive.archive, &entry);
if (r == ARCHIVE_EOF) break;
else if (r == ARCHIVE_WARN)
std::cerr << "warning: " << archive_error_string(archive.archive) << std::endl;
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);
}
}