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#include <iostream>
#include <sys/types.h>
#include <sys/wait.h>
#include "store.hh"
#include "globals.hh"
#include "db.hh"
#include "archive.hh"
#include "fstate.hh"
struct CopySink : DumpSink
{
int fd;
virtual void operator () (const unsigned char * data, unsigned int len)
{
if (write(fd, (char *) data, len) != (ssize_t) len)
throw SysError("writing to child");
}
};
struct CopySource : RestoreSource
{
int fd;
virtual void operator () (const unsigned char * data, unsigned int len)
{
ssize_t res = read(fd, (char *) data, len);
if (res == -1)
throw SysError("reading from parent");
if (res != (ssize_t) len)
throw Error("not enough data available on parent");
}
};
void copyPath(string src, string dst)
{
/* Unfortunately C++ doesn't support coprocedures, so we have no
nice way to chain CopySink and CopySource together. Instead we
fork off a child to run the sink. (Fork-less platforms should
use a thread). */
/* Create a pipe. */
int fds[2];
if (pipe(fds) == -1) throw SysError("creating pipe");
/* Fork. */
pid_t pid;
switch (pid = fork()) {
case -1:
throw SysError("unable to fork");
case 0: /* child */
try {
close(fds[1]);
CopySource source;
source.fd = fds[0];
restorePath(dst, source);
_exit(0);
} catch (exception & e) {
cerr << "error: " << e.what() << endl;
}
_exit(1);
}
close(fds[0]);
/* Parent. */
CopySink sink;
sink.fd = fds[1];
dumpPath(src, sink);
/* Wait for the child to finish. */
int status;
if (waitpid(pid, &status, 0) != pid)
throw SysError("waiting for child");
if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
throw Error("cannot copy file: child died");
}
void registerSubstitute(const FSId & srcId, const FSId & subId)
{
#if 0
Strings subs;
queryListDB(nixDB, dbSubstitutes, srcId, subs); /* non-existence = ok */
for (Strings::iterator it = subs.begin(); it != subs.end(); it++)
if (parseHash(*it) == subId) return;
subs.push_back(subId);
setListDB(nixDB, dbSubstitutes, srcId, subs);
#endif
/* For now, accept only one substitute per id. */
Strings subs;
subs.push_back(subId);
setListDB(nixDB, dbSubstitutes, srcId, subs);
}
void registerPath(const string & _path, const FSId & id)
{
string path(canonPath(_path));
setDB(nixDB, dbPath2Id, path, id);
Strings paths;
queryListDB(nixDB, dbId2Paths, id, paths); /* non-existence = ok */
for (Strings::iterator it = paths.begin();
it != paths.end(); it++)
if (*it == path) return;
paths.push_back(path);
setListDB(nixDB, dbId2Paths, id, paths);
}
void unregisterPath(const string & _path)
{
string path(canonPath(_path));
string _id;
if (!queryDB(nixDB, dbPath2Id, path, _id))
return;
FSId id(parseHash(_id));
delDB(nixDB, dbPath2Id, path);
/* begin transaction */
Strings paths, paths2;
queryListDB(nixDB, dbId2Paths, id, paths); /* non-existence = ok */
bool changed = false;
for (Strings::iterator it = paths.begin();
it != paths.end(); it++)
if (*it != path) paths2.push_back(*it); else changed = true;
if (changed)
setListDB(nixDB, dbId2Paths, id, paths2);
/* end transaction */
}
bool isInPrefix(const string & path, const string & _prefix)
{
string prefix = canonPath(_prefix + "/");
return string(path, 0, prefix.size()) == prefix;
}
string expandId(const FSId & id, const string & target,
const string & prefix)
{
Strings paths;
if (!target.empty() && !isInPrefix(target, prefix))
abort();
queryListDB(nixDB, dbId2Paths, id, paths);
/* Pick one equal to `target'. */
if (!target.empty()) {
for (Strings::iterator i = paths.begin();
i != paths.end(); i++)
{
string path = *i;
if (path == target && pathExists(path))
return path;
}
}
/* Arbitrarily pick the first one that exists and isn't stale. */
for (Strings::iterator it = paths.begin();
it != paths.end(); it++)
{
string path = *it;
if (isInPrefix(path, prefix) && pathExists(path)) {
if (target.empty())
return path;
else {
copyPath(path, target);
registerPath(target, id);
return target;
}
}
}
/* Try to realise the substitutes. */
Strings subs;
queryListDB(nixDB, dbSubstitutes, id, subs); /* non-existence = ok */
for (Strings::iterator it = subs.begin(); it != subs.end(); it++) {
FSId subId = parseHash(*it);
Slice slice = normaliseFState(subId);
realiseSlice(slice);
Strings paths = fstatePaths(subId, true);
if (paths.size() != 1)
throw Error("substitute created more than 1 path");
string path = *(paths.begin());
if (target.empty())
return path; /* !!! prefix */
else {
if (path != target) {
copyPath(path, target);
registerPath(target, id);
}
return target;
}
}
throw Error(format("cannot expand id `%1%'") % (string) id);
}
void addToStore(string srcPath, string & dstPath, FSId & id,
bool deterministicName)
{
srcPath = absPath(srcPath);
id = hashPath(srcPath);
string baseName = baseNameOf(srcPath);
dstPath = canonPath(nixStore + "/" + (string) id + "-" + baseName);
try {
/* !!! should not use the substitutes! */
dstPath = expandId(id, deterministicName ? dstPath : "", nixStore);
return;
} catch (...) {
}
copyPath(srcPath, dstPath);
registerPath(dstPath, id);
}
void deleteFromStore(const string & path)
{
string prefix = + "/";
if (!isInPrefix(path, nixStore))
throw Error(format("path %1% is not in the store") % path);
unregisterPath(path);
deletePath(path);
}
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