326 lines
7.6 KiB
C++
326 lines
7.6 KiB
C++
#include <vector>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <dirent.h>
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#include <fcntl.h>
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#include "archive.hh"
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#include "util.hh"
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static string archiveVersion1 = "nix-archive-1";
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static void writePadding(unsigned int len, DumpSink & sink)
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{
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if (len % 8) {
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unsigned char zero[8];
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memset(zero, 0, sizeof(zero));
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sink(zero, 8 - (len % 8));
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}
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}
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static void writeInt(unsigned int n, DumpSink & sink)
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{
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unsigned char buf[8];
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memset(buf, 0, sizeof(buf));
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buf[0] = n & 0xff;
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buf[1] = (n >> 8) & 0xff;
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buf[2] = (n >> 16) & 0xff;
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buf[3] = (n >> 24) & 0xff;
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sink(buf, sizeof(buf));
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}
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static void writeString(const string & s, DumpSink & sink)
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{
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unsigned int len = s.length();
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writeInt(len, sink);
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sink((const unsigned char *) s.c_str(), len);
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writePadding(len, sink);
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}
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static void dump(const string & path, DumpSink & sink);
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static void dumpEntries(const string & path, DumpSink & sink)
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{
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DIR * dir = opendir(path.c_str());
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if (!dir) throw SysError("opening directory " + path);
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vector<string> names;
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struct dirent * dirent;
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while (errno = 0, dirent = readdir(dir)) {
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string name = dirent->d_name;
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if (name == "." || name == "..") continue;
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names.push_back(name);
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}
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if (errno) throw SysError("reading directory " + path);
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sort(names.begin(), names.end());
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for (vector<string>::iterator it = names.begin();
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it != names.end(); it++)
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{
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writeString("entry", sink);
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writeString("(", sink);
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writeString("name", sink);
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writeString(*it, sink);
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writeString("node", sink);
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dump(path + "/" + *it, sink);
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writeString(")", sink);
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}
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closedir(dir); /* !!! close on exception */
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}
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static void dumpContents(const string & path, unsigned int size,
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DumpSink & sink)
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{
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writeString("contents", sink);
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writeInt(size, sink);
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int fd = open(path.c_str(), O_RDONLY);
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if (!fd) throw SysError("opening file " + path);
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unsigned char buf[65536];
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unsigned int total = 0;
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ssize_t n;
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while ((n = read(fd, buf, sizeof(buf)))) {
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if (n == -1) throw SysError("reading file " + path);
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total += n;
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sink(buf, n);
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}
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if (total != size)
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throw SysError("file changed while reading it: " + path);
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writePadding(size, sink);
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close(fd); /* !!! close on exception */
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}
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static void dump(const string & path, DumpSink & sink)
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{
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struct stat st;
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if (lstat(path.c_str(), &st))
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throw SysError("getting attributes of path " + path);
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writeString("(", sink);
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if (S_ISREG(st.st_mode)) {
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writeString("type", sink);
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writeString("regular", sink);
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dumpContents(path, st.st_size, sink);
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}
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else if (S_ISDIR(st.st_mode)) {
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writeString("type", sink);
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writeString("directory", sink);
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dumpEntries(path, sink);
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}
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else if (S_ISLNK(st.st_mode)) {
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writeString("type", sink);
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writeString("symlink", sink);
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char buf[st.st_size];
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if (readlink(path.c_str(), buf, st.st_size) != st.st_size)
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throw SysError("reading symbolic link " + path);
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writeString("target", sink);
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writeString(string(buf, st.st_size), sink);
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}
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else throw Error("unknown file type: " + path);
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writeString(")", sink);
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}
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void dumpPath(const string & path, DumpSink & sink)
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{
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writeString(archiveVersion1, sink);
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dump(path, sink);
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}
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static Error badArchive(string s)
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{
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return Error("bad archive: " + s);
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}
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static void readPadding(unsigned int len, RestoreSource & source)
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{
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if (len % 8) {
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unsigned char zero[8];
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unsigned int n = 8 - (len % 8);
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source(zero, n);
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for (unsigned int i = 0; i < n; i++)
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if (zero[i]) throw badArchive("non-zero padding");
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}
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}
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static unsigned int readInt(RestoreSource & source)
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{
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unsigned char buf[8];
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source(buf, sizeof(buf));
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if (buf[4] || buf[5] || buf[6] || buf[7])
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throw Error("implementation cannot deal with > 32-bit integers");
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return
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buf[0] |
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(buf[1] << 8) |
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(buf[2] << 16) |
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(buf[3] << 24);
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}
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static string readString(RestoreSource & source)
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{
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unsigned int len = readInt(source);
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char buf[len];
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source((const unsigned char *) buf, len);
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readPadding(len, source);
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return string(buf, len);
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}
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static void skipGeneric(RestoreSource & source)
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{
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if (readString(source) == "(") {
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while (readString(source) != ")")
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skipGeneric(source);
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}
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}
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static void restore(const string & path, RestoreSource & source);
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static void restoreEntry(const string & path, RestoreSource & source)
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{
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string s, name;
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s = readString(source);
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if (s != "(") throw badArchive("expected open tag");
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while (1) {
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s = readString(source);
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if (s == ")") {
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break;
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} else if (s == "name") {
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name = readString(source);
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} else if (s == "node") {
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if (s == "") throw badArchive("entry name missing");
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restore(path + "/" + name, source);
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} else {
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throw badArchive("unknown field " + s);
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skipGeneric(source);
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}
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}
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}
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static void restoreContents(int fd, const string & path, RestoreSource & source)
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{
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unsigned int size = readInt(source);
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unsigned int left = size;
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unsigned char buf[65536];
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while (left) {
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unsigned int n = sizeof(buf);
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if (n > left) n = left;
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source(buf, n);
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if (write(fd, buf, n) != (ssize_t) n)
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throw SysError("writing file " + path);
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left -= n;
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}
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readPadding(size, source);
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}
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static void restore(const string & path, RestoreSource & source)
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{
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string s;
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s = readString(source);
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if (s != "(") throw badArchive("expected open tag");
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enum { tpUnknown, tpRegular, tpDirectory, tpSymlink } type = tpUnknown;
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int fd = -1; /* !!! close on exception */
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while (1) {
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s = readString(source);
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if (s == ")") {
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break;
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}
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else if (s == "type") {
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if (type != tpUnknown)
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throw badArchive("multiple type fields");
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string t = readString(source);
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if (t == "regular") {
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type = tpRegular;
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fd = open(path.c_str(), O_CREAT | O_EXCL | O_WRONLY, 0666);
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if (fd == -1)
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throw SysError("creating file " + path);
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}
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else if (t == "directory") {
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type = tpDirectory;
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if (mkdir(path.c_str(), 0777) == -1)
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throw SysError("creating directory " + path);
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}
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else if (t == "symlink") {
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type = tpSymlink;
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}
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else throw badArchive("unknown file type " + t);
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}
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else if (s == "contents" && type == tpRegular) {
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restoreContents(fd, path, source);
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}
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else if (s == "entry" && type == tpDirectory) {
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restoreEntry(path, source);
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}
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else if (s == "target" && type == tpSymlink) {
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string target = readString(source);
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if (symlink(target.c_str(), path.c_str()) == -1)
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throw SysError("creating symlink " + path);
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}
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else {
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throw badArchive("unknown field " + s);
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skipGeneric(source);
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}
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}
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if (fd != -1) close(fd);
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}
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void restorePath(const string & path, RestoreSource & source)
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{
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if (readString(source) != archiveVersion1)
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throw badArchive("expected Nix archive");
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restore(path, source);
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}
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