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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 Hash & srcHash, const Hash & subHash)
{
Strings subs;
queryListDB(nixDB, dbSubstitutes, srcHash, subs); /* non-existence = ok */
for (Strings::iterator it = subs.begin(); it != subs.end(); it++)
if (parseHash(*it) == subHash) return;
subs.push_back(subHash);
setListDB(nixDB, dbSubstitutes, srcHash, subs);
}
Hash registerPath(const string & _path, Hash hash)
{
string path(canonPath(_path));
if (hash == Hash()) hash = hashPath(path);
Strings paths;
queryListDB(nixDB, dbHash2Paths, hash, paths); /* non-existence = ok */
for (Strings::iterator it = paths.begin();
it != paths.end(); it++)
if (*it == path) goto exists;
paths.push_back(path);
setListDB(nixDB, dbHash2Paths, hash, paths);
exists:
return hash;
}
void unregisterPath(const string & _path)
{
string path(canonPath(_path));
Hash hash = hashPath(path);
Strings paths, paths2;
queryListDB(nixDB, dbHash2Paths, hash, 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, dbHash2Paths, hash, paths2);
}
bool isInPrefix(const string & path, const string & _prefix)
{
string prefix = canonPath(_prefix + "/");
return string(path, 0, prefix.size()) == prefix;
}
string expandHash(const Hash & hash, const string & target,
const string & prefix)
{
Strings paths;
if (!target.empty() && !isInPrefix(target, prefix))
abort();
queryListDB(nixDB, dbHash2Paths, hash, paths);
/* !!! we shouldn't check for staleness by default --- too slow */
/* Pick one equal to `target'. */
if (!target.empty()) {
for (Strings::iterator i = paths.begin();
i != paths.end(); i++)
{
string path = *i;
try {
if (path == target && hashPath(path) == hash)
return path;
} catch (Error & e) {
debug(format("stale path: %1%") % e.msg());
/* try next one */
}
}
}
/* Arbitrarily pick the first one that exists and isn't stale. */
for (Strings::iterator it = paths.begin();
it != paths.end(); it++)
{
string path = *it;
try {
if (isInPrefix(path, prefix) && hashPath(path) == hash) {
if (target.empty())
return path;
else {
copyPath(path, target);
return target;
}
}
} catch (Error & e) {
debug(format("stale path: %1%") % e.msg());
/* try next one */
}
}
/* Try to realise the substitutes. */
Strings subs;
queryListDB(nixDB, dbSubstitutes, hash, subs); /* non-existence = ok */
for (Strings::iterator it = subs.begin(); it != subs.end(); it++) {
StringSet dummy;
FState nf = realiseFState(hash2fstate(parseHash(*it)), dummy);
string path = fstatePath(nf);
if (hashPath(path) != hash)
throw Error(format("bad substitute in `%1%'") % (string) path);
if (target.empty())
return path; /* !!! prefix */
else {
if (path != target) {
copyPath(path, target);
registerPath(target, hash);
}
return target;
}
}
throw Error(format("cannot expand hash `%1%'") % (string) hash);
}
void addToStore(string srcPath, string & dstPath, Hash & hash,
bool deterministicName)
{
srcPath = absPath(srcPath);
hash = hashPath(srcPath);
string baseName = baseNameOf(srcPath);
dstPath = canonPath(nixStore + "/" + (string) hash + "-" + baseName);
try {
/* !!! should not use the substitutes! */
dstPath = expandHash(hash, deterministicName ? dstPath : "", nixStore);
return;
} catch (...) {
}
copyPath(srcPath, dstPath);
registerPath(dstPath, hash);
}
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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