* A function to restore from a Nix archive.
* addValue() can now import any dumpable FS object.
This commit is contained in:
parent
85effedca3
commit
5f5cab0ac7
196
src/archive.cc
196
src/archive.cc
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@ -10,7 +10,10 @@
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#include "util.hh"
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#include "util.hh"
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static void pad(unsigned int len, DumpSink & sink)
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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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{
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if (len % 8) {
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if (len % 8) {
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unsigned char zero[8];
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unsigned char zero[8];
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@ -37,10 +40,13 @@ static void writeString(const string & s, DumpSink & sink)
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unsigned int len = s.length();
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unsigned int len = s.length();
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writeInt(len, sink);
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writeInt(len, sink);
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sink((const unsigned char *) s.c_str(), len);
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sink((const unsigned char *) s.c_str(), len);
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pad(len, sink);
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writePadding(len, sink);
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}
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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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static void dumpEntries(const string & path, DumpSink & sink)
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{
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{
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DIR * dir = opendir(path.c_str());
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DIR * dir = opendir(path.c_str());
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@ -65,8 +71,8 @@ static void dumpEntries(const string & path, DumpSink & sink)
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writeString("(", sink);
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writeString("(", sink);
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writeString("name", sink);
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writeString("name", sink);
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writeString(*it, sink);
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writeString(*it, sink);
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writeString("file", sink);
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writeString("node", sink);
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dumpPath(path + "/" + *it, sink);
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dump(path + "/" + *it, sink);
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writeString(")", sink);
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writeString(")", sink);
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}
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}
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@ -96,13 +102,13 @@ static void dumpContents(const string & path, unsigned int size,
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if (total != size)
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if (total != size)
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throw SysError("file changed while reading it: " + path);
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throw SysError("file changed while reading it: " + path);
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pad(size, sink);
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writePadding(size, sink);
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close(fd); /* !!! close on exception */
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close(fd); /* !!! close on exception */
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}
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}
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void dumpPath(const string & path, DumpSink & sink)
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static void dump(const string & path, DumpSink & sink)
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{
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{
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struct stat st;
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struct stat st;
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if (lstat(path.c_str(), &st))
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if (lstat(path.c_str(), &st))
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@ -138,6 +144,182 @@ void dumpPath(const string & path, DumpSink & sink)
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}
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}
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void restorePath(const string & path, ReadSource & source)
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void dumpPath(const string & path, DumpSink & sink)
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{
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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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}
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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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@ -48,7 +48,7 @@ struct DumpSink
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void dumpPath(const string & path, DumpSink & sink);
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void dumpPath(const string & path, DumpSink & sink);
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struct ReadSource
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struct RestoreSource
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{
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{
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/* The callee should store exactly *len bytes in the buffer
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/* The callee should store exactly *len bytes in the buffer
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pointed to by data. It should block if that much data is not
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pointed to by data. It should block if that much data is not
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@ -56,3 +56,5 @@ struct ReadSource
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available. */
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available. */
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virtual void operator () (const unsigned char * data, unsigned int len) = 0;
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virtual void operator () (const unsigned char * data, unsigned int len) = 0;
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};
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};
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void restorePath(const string & path, RestoreSource & source);
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@ -123,8 +123,8 @@ static Hash computeDerived(Hash sourceHash, string targetName,
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} catch (exception & e) {
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} catch (exception & e) {
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cerr << "build error: " << e.what() << endl;
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cerr << "build error: " << e.what() << endl;
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_exit(1);
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}
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}
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_exit(1);
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}
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}
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@ -133,7 +133,8 @@ struct StdoutSink : DumpSink
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(const unsigned char * data, unsigned int len)
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(const unsigned char * data, unsigned int len)
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{
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{
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/* Don't use cout, it's slow as hell! */
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/* Don't use cout, it's slow as hell! */
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write(STDOUT_FILENO, (char *) data, len);
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if (write(STDOUT_FILENO, (char *) data, len) != len)
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throw SysError("writing to stdout");
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}
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}
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};
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};
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24
src/test.cc
24
src/test.cc
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@ -23,7 +23,21 @@ struct MySink : DumpSink
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virtual void operator () (const unsigned char * data, unsigned int len)
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virtual void operator () (const unsigned char * data, unsigned int len)
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{
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{
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/* Don't use cout, it's slow as hell! */
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/* Don't use cout, it's slow as hell! */
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write(STDOUT_FILENO, (char *) data, len);
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if (write(STDOUT_FILENO, (char *) data, len) != (ssize_t) len)
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throw SysError("writing to stdout");
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}
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};
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struct MySource : RestoreSource
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{
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virtual void operator () (const unsigned char * data, unsigned int len)
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{
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ssize_t res = read(STDIN_FILENO, (char *) data, len);
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if (res == -1)
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throw SysError("reading from stdin");
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if (res != (ssize_t) len)
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throw Error("not enough data available on stdin");
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}
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}
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};
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};
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@ -53,6 +67,14 @@ void runTests()
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cout << (string) hashPath("scratch") << endl;
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cout << (string) hashPath("scratch") << endl;
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#endif
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#endif
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/* Restoring. */
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#if 1
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MySource source;
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restorePath("outdir", source);
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cout << (string) hashPath("outdir") << endl;
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return;
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#endif
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/* Set up the test environment. */
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/* Set up the test environment. */
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mkdir("scratch", 0777);
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mkdir("scratch", 0777);
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@ -1,13 +1,85 @@
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#include <iostream>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include "values.hh"
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#include "values.hh"
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#include "globals.hh"
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#include "globals.hh"
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#include "db.hh"
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#include "db.hh"
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#include "archive.hh"
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struct CopySink : DumpSink
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{
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int fd;
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virtual void operator () (const unsigned char * data, unsigned int len)
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{
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if (write(fd, (char *) data, len) != (ssize_t) len)
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throw SysError("writing to child");
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}
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};
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struct CopySource : RestoreSource
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{
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int fd;
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virtual void operator () (const unsigned char * data, unsigned int len)
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{
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ssize_t res = read(fd, (char *) data, len);
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if (res == -1)
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throw SysError("reading from parent");
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if (res != (ssize_t) len)
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throw Error("not enough data available on parent");
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}
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};
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static void copyFile(string src, string dst)
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static void copyFile(string src, string dst)
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{
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{
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int res = system(("cat " + src + " > " + dst).c_str()); /* !!! escape */
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/* Unfortunately C++ doesn't support coprocedures, so we have no
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if (WEXITSTATUS(res) != 0)
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nice way to chain CopySink and CopySource together. Instead we
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throw Error("cannot copy " + src + " to " + dst);
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fork off a child to run the sink. (Fork-less platforms should
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use a thread). */
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/* Create a pipe. */
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int fds[2];
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if (pipe(fds) == -1) throw SysError("creating pipe");
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/* Fork. */
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pid_t pid;
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switch (pid = fork()) {
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case -1:
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throw SysError("unable to fork");
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case 0: /* child */
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try {
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close(fds[1]);
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CopySource source;
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source.fd = fds[0];
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restorePath(dst, source);
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_exit(0);
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} catch (exception & e) {
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cerr << "error: " << e.what() << endl;
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}
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_exit(1);
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}
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close(fds[0]);
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/* Parent. */
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CopySink sink;
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sink.fd = fds[1];
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dumpPath(src, sink);
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/* Wait for the child to finish. */
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int status;
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if (waitpid(pid, &status, 0) != pid)
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throw SysError("waiting for child");
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if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
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throw Error("cannot copy file: child died");
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}
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}
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Loading…
Reference in a new issue