* Refactoring on the file names.
This commit is contained in:
Eelco Dolstra
parent
7952a8053c
commit
224c585aba
7 changed files with 17 additions and 60 deletions
340
src/fstate.cc
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340
src/fstate.cc
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@ -0,0 +1,340 @@
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#include <map>
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#include <iostream>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include "fstate.hh"
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#include "globals.hh"
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#include "store.hh"
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#include "db.hh"
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/* A Unix environment is a mapping from strings to strings. */
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typedef map<string, string> Environment;
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/* Return true iff the given path exists. */
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bool pathExists(const string & path)
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{
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int res;
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struct stat st;
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res = stat(path.c_str(), &st);
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if (!res) return true;
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if (errno != ENOENT)
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throw SysError(format("getting status of %1%") % path);
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return false;
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}
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/* Run a program. */
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static void runProgram(const string & program, Environment env)
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{
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/* Create a log file. */
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string logFileName = nixLogDir + "/run.log";
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/* !!! auto-pclose on exit */
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FILE * logFile = popen(("tee " + logFileName + " >&2").c_str(), "w"); /* !!! escaping */
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if (!logFile)
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throw SysError(format("unable to create log file %1%") % logFileName);
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/* Fork a child to build the package. */
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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:
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try { /* child */
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#if 0
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/* Try to use a prebuilt. */
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string prebuiltHashS, prebuiltFile;
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if (queryDB(nixDB, dbPrebuilts, hash, prebuiltHashS)) {
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try {
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prebuiltFile = getFile(parseHash(prebuiltHashS));
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} catch (Error e) {
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cerr << "cannot obtain prebuilt (ignoring): " << e.what() << endl;
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goto build;
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}
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cerr << "substituting prebuilt " << prebuiltFile << endl;
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int res = system(("tar xfj " + prebuiltFile + " 1>&2").c_str()); // !!! escaping
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if (WEXITSTATUS(res) != 0)
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/* This is a fatal error, because path may now
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have clobbered. */
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throw Error("cannot unpack " + prebuiltFile);
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_exit(0);
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}
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#endif
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// build:
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/* Fill in the environment. We don't bother freeing
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the strings, since we'll exec or die soon
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anyway. */
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const char * env2[env.size() + 1];
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int i = 0;
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for (Environment::iterator it = env.begin();
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it != env.end(); it++, i++)
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env2[i] = (new string(it->first + "=" + it->second))->c_str();
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env2[i] = 0;
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/* Dup the log handle into stderr. */
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if (dup2(fileno(logFile), STDERR_FILENO) == -1)
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throw SysError("cannot pipe standard error into log file");
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/* Dup stderr to stdin. */
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if (dup2(STDERR_FILENO, STDOUT_FILENO) == -1)
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throw SysError("cannot dup stderr into stdout");
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/* Make the program executable. !!! hack. */
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if (chmod(program.c_str(), 0755))
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throw SysError("cannot make program executable");
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/* Execute the program. This should not return. */
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execle(program.c_str(), baseNameOf(program).c_str(), 0, env2);
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throw SysError(format("unable to execute %1%") % program);
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} catch (exception & e) {
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cerr << format("build error: %1%\n") % e.what();
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}
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_exit(1);
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}
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/* parent */
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/* Close the logging pipe. Note that this should not cause
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the logger to exit until builder exits (because the latter
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has an open file handle to the former). */
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pclose(logFile);
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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 Error("unable to wait for child");
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if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
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throw Error("unable to build package");
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}
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/* Throw an exception if the given platform string is not supported by
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the platform we are executing on. */
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static void checkPlatform(const string & platform)
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{
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if (platform != thisSystem)
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throw Error(format("a `%1%' is required, but I am a `%2%'")
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% platform % thisSystem);
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}
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string printTerm(ATerm t)
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{
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char * s = ATwriteToString(t);
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return s;
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}
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Error badTerm(const format & f, ATerm t)
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{
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return Error(format("%1%, in `%2%'") % f.str() % printTerm(t));
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}
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Hash hashTerm(ATerm t)
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{
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return hashString(printTerm(t));
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}
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struct RStatus
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{
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/* !!! the comparator of this hash should match the semantics of
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the file system */
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// map<string, Hash> paths;
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};
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static ATerm termFromHash(const Hash & hash)
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{
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string path = queryFromStore(hash);
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ATerm t = ATreadFromNamedFile(path.c_str());
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if (!t) throw Error(format("cannot read aterm %1%") % path);
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return t;
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}
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Hash writeTerm(ATerm t)
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{
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string path = nixStore + "/tmp.nix"; /* !!! */
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if (!ATwriteToNamedTextFile(t, path.c_str()))
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throw Error(format("cannot write aterm %1%") % path);
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Hash hash = hashPath(path);
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string path2 = nixStore + "/" + (string) hash + ".nix";
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if (rename(path.c_str(), path2.c_str()) == -1)
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throw SysError(format("renaming %1% to %2%") % path % path2);
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setDB(nixDB, dbRefs, hash, path2);
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return hash;
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}
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static FState realise(RStatus & status, FState fs)
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{
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char * s1, * s2, * s3;
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Content content;
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ATermList refs, ins, bnds;
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/* First repeatedly try to substitute $fs$ by any known successors
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in order to speed up the rewrite process. */
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{
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string fsHash, scHash;
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while (queryDB(nixDB, dbSuccessors, fsHash = hashTerm(fs), scHash)) {
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debug(format("successor %1% -> %2%") % (string) fsHash % scHash);
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FState fs2 = termFromHash(parseHash(scHash));
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if (fs == fs2) {
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debug(format("successor cycle detected in %1%") % printTerm(fs));
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break;
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}
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fs = fs2;
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}
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}
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/* Fall through. */
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if (ATmatch(fs, "Include(<str>)", &s1)) {
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return realise(status, termFromHash(parseHash(s1)));
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}
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else if (ATmatch(fs, "Path(<str>, <term>, [<list>])", &s1, &content, &refs)) {
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string path(s1);
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msg(format("realising atomic path %1%") % path);
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Nest nest(true);
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if (path[0] != '/')
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throw Error(format("path `%1% is not absolute") % path);
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/* Realise referenced paths. */
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ATermList refs2 = ATempty;
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while (!ATisEmpty(refs)) {
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refs2 = ATinsert(refs2, realise(status, ATgetFirst(refs)));
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refs = ATgetNext(refs);
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}
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refs2 = ATreverse(refs2);
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if (!ATmatch(content, "Hash(<str>)", &s1))
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throw badTerm("hash expected", content);
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Hash hash = parseHash(s1);
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/* Normal form. */
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ATerm nf = ATmake("Path(<str>, <term>, <term>)",
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path.c_str(), content, refs2);
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/* Register the normal form. */
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if (fs != nf) {
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Hash nfHash = writeTerm(nf);
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setDB(nixDB, dbSuccessors, hashTerm(fs), nfHash);
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}
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/* Perhaps the path already exists and has the right hash? */
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if (pathExists(path)) {
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if (hash == hashPath(path)) {
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debug(format("path %1% already has hash %2%")
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% path % (string) hash);
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return nf;
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}
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throw Error(format("path %1% exists, but does not have hash %2%")
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% path % (string) hash);
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}
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/* Do we know a path with that hash? If so, copy it. */
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string path2 = queryFromStore(hash);
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copyPath(path2, path);
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return nf;
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}
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else if (ATmatch(fs, "Derive(<str>, <str>, [<list>], <str>, [<list>])",
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&s1, &s2, &ins, &s3, &bnds))
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{
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string platform(s1), builder(s2), outPath(s3);
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msg(format("realising derivate path %1%") % outPath);
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Nest nest(true);
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checkPlatform(platform);
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/* Realise inputs. */
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ATermList ins2 = ATempty;
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while (!ATisEmpty(ins)) {
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ins2 = ATinsert(ins2, realise(status, ATgetFirst(ins)));
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ins = ATgetNext(ins);
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}
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ins2 = ATreverse(ins2);
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/* Build the environment. */
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Environment env;
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while (!ATisEmpty(bnds)) {
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ATerm bnd = ATgetFirst(bnds);
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if (!ATmatch(bnd, "(<str>, <str>)", &s1, &s2))
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throw badTerm("tuple of strings expected", bnd);
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env[s1] = s2;
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bnds = ATgetNext(bnds);
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}
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/* Check whether the target already exists. */
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if (pathExists(outPath))
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deleteFromStore(outPath);
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// throw Error(format("path %1% already exists") % outPath);
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/* Run the builder. */
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runProgram(builder, env);
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/* Check whether the result was created. */
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if (!pathExists(outPath))
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throw Error(format("program %1% failed to create a result in %2%")
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% builder % outPath);
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#if 0
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/* Remove write permission from the value. */
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int res = system(("chmod -R -w " + targetPath).c_str()); // !!! escaping
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if (WEXITSTATUS(res) != 0)
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throw Error("cannot remove write permission from " + targetPath);
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#endif
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/* Hash the result. */
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Hash outHash = hashPath(outPath);
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/* Register targetHash -> targetPath. !!! this should be in
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values.cc. */
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setDB(nixDB, dbRefs, outHash, outPath);
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/* Register the normal form of fs. */
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FState nf = ATmake("Path(<str>, Hash(<str>), <term>)",
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outPath.c_str(), ((string) outHash).c_str(), ins2);
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Hash nfHash = writeTerm(nf);
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setDB(nixDB, dbSuccessors, hashTerm(fs), nfHash);
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return nf;
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}
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throw badTerm("bad fstate expression", fs);
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}
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FState realiseFState(FState fs)
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{
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RStatus status;
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return realise(status, fs);
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}
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