180 lines
4.1 KiB
C++
180 lines
4.1 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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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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void copyPath(string src, string dst)
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{
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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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Hash registerPath(const string & _path, Hash hash)
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{
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string path(canonPath(_path));
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if (hash == Hash()) hash = hashPath(path);
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Strings paths;
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queryListDB(nixDB, dbRefs, hash, 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) goto exists;
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paths.push_back(path);
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setListDB(nixDB, dbRefs, hash, paths);
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exists:
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return hash;
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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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static string queryPathByHashPrefix(Hash hash, const string & prefix)
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{
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Strings paths;
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if (!queryListDB(nixDB, dbRefs, hash, paths))
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throw Error(format("no paths known with hash `%1%'") % (string) hash);
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/* Arbitrarily pick the first one that exists and still hash the
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right hash. */
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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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debug(*it);
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string path = *it;
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try {
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debug(path);
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debug(prefix);
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if (isInPrefix(path, prefix) && hashPath(path) == hash)
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return path;
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} catch (Error & e) {
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debug(format("checking hash: %1%") % e.msg());
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/* try next one */
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}
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}
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throw Error(format("all paths with hash `%1%' are stale") % (string) hash);
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}
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string queryPathByHash(Hash hash)
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{
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return queryPathByHashPrefix(hash, "/");
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}
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void addToStore(string srcPath, string & dstPath, Hash & hash)
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{
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srcPath = absPath(srcPath);
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hash = hashPath(srcPath);
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try {
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dstPath = queryPathByHashPrefix(hash, nixStore);
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return;
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} catch (...) {
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}
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string baseName = baseNameOf(srcPath);
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dstPath = nixStore + "/" + (string) hash + "-" + baseName;
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copyPath(srcPath, dstPath);
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registerPath(dstPath, hash);
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}
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void deleteFromStore(const string & path)
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{
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string prefix = nixStore + "/";
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if (string(path, 0, prefix.size()) != prefix)
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throw Error(format("path %1% is not in the store") % path);
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deletePath(path);
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// delDB(nixDB, dbRefs, hash);
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}
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