forked from lix-project/lix
412 lines
10 KiB
C++
412 lines
10 KiB
C++
#include <iostream>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include "store.hh"
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#include "globals.hh"
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#include "db.hh"
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#include "archive.hh"
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#include "normalise.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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writeFull(fd, data, len);
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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 () (unsigned char * data, unsigned int len)
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{
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readFull(fd, data, len);
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}
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};
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void copyPath(string src, string dst)
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{
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debug(format("copying `%1%' to `%2%'") % src % dst);
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/* Unfortunately C++ doesn't support coprocedures, so we have no
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nice way to chain CopySink and CopySource together. Instead we
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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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void registerSubstitute(const FSId & srcId, const FSId & subId)
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{
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#if 0
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Strings subs;
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queryListDB(nixDB, dbSubstitutes, srcId, subs); /* non-existence = ok */
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for (Strings::iterator it = subs.begin(); it != subs.end(); it++)
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if (parseHash(*it) == subId) return;
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subs.push_back(subId);
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setListDB(nixDB, dbSubstitutes, srcId, subs);
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#endif
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/* For now, accept only one substitute per id. */
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Strings subs;
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subs.push_back(subId);
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Transaction txn(nixDB);
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nixDB.setStrings(txn, dbSubstitutes, srcId, subs);
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txn.commit();
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}
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void registerPath(const string & _path, const FSId & id)
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{
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string path(canonPath(_path));
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Transaction txn(nixDB);
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debug(format("registering path `%1%' with id %2%")
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% path % (string) id);
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string oldId;
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if (nixDB.queryString(txn, dbPath2Id, path, oldId)) {
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txn.abort();
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if (id != parseHash(oldId))
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throw Error(format("path `%1%' already contains id %2%")
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% path % oldId);
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return;
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}
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nixDB.setString(txn, dbPath2Id, path, id);
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Strings paths;
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nixDB.queryStrings(txn, dbId2Paths, id, paths); /* non-existence = ok */
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paths.push_back(path);
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nixDB.setStrings(txn, dbId2Paths, id, paths);
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txn.commit();
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}
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void unregisterPath(const string & _path)
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{
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string path(canonPath(_path));
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Transaction txn(nixDB);
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debug(format("unregistering path `%1%'") % path);
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string _id;
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if (!nixDB.queryString(txn, dbPath2Id, path, _id)) {
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txn.abort();
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return;
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}
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FSId id(parseHash(_id));
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nixDB.delPair(txn, dbPath2Id, path);
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Strings paths, paths2;
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nixDB.queryStrings(txn, dbId2Paths, id, paths); /* non-existence = ok */
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for (Strings::iterator it = paths.begin();
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it != paths.end(); it++)
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if (*it != path) paths2.push_back(*it);
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nixDB.setStrings(txn, dbId2Paths, id, paths2);
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txn.commit();
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}
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bool queryPathId(const string & path, FSId & id)
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{
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string s;
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if (!nixDB.queryString(noTxn, dbPath2Id, absPath(path), s)) return false;
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id = parseHash(s);
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return true;
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}
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bool isInPrefix(const string & path, const string & _prefix)
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{
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string prefix = canonPath(_prefix + "/");
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return string(path, 0, prefix.size()) == prefix;
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}
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string expandId(const FSId & id, const string & target,
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const string & prefix, FSIdSet pending, bool ignoreSubstitutes)
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{
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Nest nest(lvlDebug, format("expanding %1%") % (string) id);
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Strings paths;
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if (!target.empty() && !isInPrefix(target, prefix))
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abort();
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nixDB.queryStrings(noTxn, dbId2Paths, id, paths);
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/* Pick one equal to `target'. */
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if (!target.empty()) {
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for (Strings::iterator i = paths.begin();
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i != paths.end(); i++)
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{
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string path = *i;
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if (path == target && pathExists(path))
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return path;
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}
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}
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/* Arbitrarily pick the first one that exists and isn't stale. */
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for (Strings::iterator it = paths.begin();
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it != paths.end(); it++)
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{
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string path = *it;
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if (isInPrefix(path, prefix) && pathExists(path)) {
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if (target.empty())
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return path;
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else {
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copyPath(path, target);
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registerPath(target, id);
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return target;
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}
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}
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}
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if (!ignoreSubstitutes) {
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if (pending.find(id) != pending.end())
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throw Error(format("id %1% already being expanded") % (string) id);
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pending.insert(id);
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/* Try to realise the substitutes, but only if this id is not
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already being realised by a substitute. */
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Strings subs;
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nixDB.queryStrings(noTxn, dbSubstitutes, id, subs); /* non-existence = ok */
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for (Strings::iterator it = subs.begin(); it != subs.end(); it++) {
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FSId subId = parseHash(*it);
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debug(format("trying substitute %1%") % (string) subId);
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realiseSlice(normaliseFState(subId, pending), pending);
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return expandId(id, target, prefix, pending);
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}
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}
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throw Error(format("cannot expand id `%1%'") % (string) id);
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}
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void addToStore(string srcPath, string & dstPath, FSId & id,
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bool deterministicName)
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{
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debug(format("adding `%1%' to the store") % srcPath);
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srcPath = absPath(srcPath);
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id = hashPath(srcPath);
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string baseName = baseNameOf(srcPath);
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dstPath = canonPath(nixStore + "/" + (string) id + "-" + baseName);
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try {
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/* !!! should not use the substitutes! */
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dstPath = expandId(id, deterministicName ? dstPath : "",
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nixStore, FSIdSet(), true);
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return;
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} catch (...) {
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}
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copyPath(srcPath, dstPath);
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registerPath(dstPath, id);
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}
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void deleteFromStore(const string & path)
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{
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string prefix = + "/";
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if (!isInPrefix(path, nixStore))
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throw Error(format("path %1% is not in the store") % path);
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unregisterPath(path);
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deletePath(path);
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}
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void verifyStore()
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{
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Transaction txn(nixDB);
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/* !!! verify that the result is consistent */
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Strings paths;
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nixDB.enumTable(txn, dbPath2Id, paths);
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for (Strings::iterator i = paths.begin();
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i != paths.end(); i++)
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{
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bool erase = true;
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string path = *i;
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if (!pathExists(path)) {
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debug(format("path `%1%' disappeared") % path);
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}
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else {
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string id;
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if (!nixDB.queryString(txn, dbPath2Id, path, id)) abort();
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Strings idPaths;
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nixDB.queryStrings(txn, dbId2Paths, id, idPaths);
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bool found = false;
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for (Strings::iterator j = idPaths.begin();
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j != idPaths.end(); j++)
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if (path == *j) {
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found = true;
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break;
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}
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if (found)
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erase = false;
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else
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/* !!! perhaps we should add path to idPaths? */
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debug(format("reverse mapping for path `%1%' missing") % path);
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}
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if (erase) nixDB.delPair(txn, dbPath2Id, path);
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}
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Strings ids;
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nixDB.enumTable(txn, dbId2Paths, ids);
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for (Strings::iterator i = ids.begin();
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i != ids.end(); i++)
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{
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FSId id = parseHash(*i);
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Strings idPaths;
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nixDB.queryStrings(txn, dbId2Paths, id, idPaths);
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for (Strings::iterator j = idPaths.begin();
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j != idPaths.end(); )
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{
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string id2;
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if (!nixDB.queryString(txn, dbPath2Id, *j, id2) ||
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id != parseHash(id2)) {
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debug(format("erasing path `%1%' from mapping for id %2%")
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% *j % (string) id);
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j = idPaths.erase(j);
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} else j++;
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}
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nixDB.setStrings(txn, dbId2Paths, id, idPaths);
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}
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Strings subs;
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nixDB.enumTable(txn, dbSubstitutes, subs);
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for (Strings::iterator i = subs.begin();
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i != subs.end(); i++)
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{
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FSId srcId = parseHash(*i);
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Strings subIds;
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nixDB.queryStrings(txn, dbSubstitutes, srcId, subIds);
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for (Strings::iterator j = subIds.begin();
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j != subIds.end(); )
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{
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FSId subId = parseHash(*j);
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Strings subPaths;
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nixDB.queryStrings(txn, dbId2Paths, subId, subPaths);
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if (subPaths.size() == 0) {
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debug(format("erasing substitute %1% for %2%")
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% (string) subId % (string) srcId);
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j = subIds.erase(j);
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} else j++;
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}
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nixDB.setStrings(txn, dbSubstitutes, srcId, subIds);
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}
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Strings sucs;
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nixDB.enumTable(txn, dbSuccessors, sucs);
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for (Strings::iterator i = sucs.begin();
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i != sucs.end(); i++)
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{
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FSId id1 = parseHash(*i);
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string id2;
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if (!nixDB.queryString(txn, dbSuccessors, id1, id2)) abort();
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Strings id2Paths;
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nixDB.queryStrings(txn, dbId2Paths, id2, id2Paths);
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if (id2Paths.size() == 0) {
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Strings id2Subs;
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nixDB.queryStrings(txn, dbSubstitutes, id2, id2Subs);
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if (id2Subs.size() == 0) {
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debug(format("successor %1% for %2% missing")
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% id2 % (string) id1);
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nixDB.delPair(txn, dbSuccessors, (string) id1);
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}
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}
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}
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txn.commit();
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}
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