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