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