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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"
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");
}
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;
}
static string queryPathByHashPrefix(Hash hash, const string & prefix)
{
Strings paths;
if (!queryListDB(nixDB, dbHash2Paths, hash, paths))
throw Error(format("no paths known with hash `%1%'") % (string) hash);
/* Arbitrarily pick the first one that exists and still hash the
right hash. */
for (Strings::iterator it = paths.begin();
it != paths.end(); it++)
{
string path = *it;
try {
if (isInPrefix(path, prefix) && hashPath(path) == hash)
return path;
} catch (Error & e) {
debug(format("checking hash: %1%") % e.msg());
/* try next one */
}
}
throw Error(format("all paths with hash `%1%' are stale") % (string) hash);
}
string queryPathByHash(Hash hash)
{
return queryPathByHashPrefix(hash, "/");
}
void addToStore(string srcPath, string & dstPath, Hash & hash)
{
srcPath = absPath(srcPath);
hash = hashPath(srcPath);
try {
dstPath = queryPathByHashPrefix(hash, nixStore);
return;
} catch (...) {
}
string baseName = baseNameOf(srcPath);
dstPath = canonPath(nixStore + "/" + (string) hash + "-" + baseName);
copyPath(srcPath, dstPath);
registerPath(dstPath, hash);
}
void deleteFromStore(const string & path)
{
string prefix = nixStore + "/";
if (string(path, 0, prefix.size()) != prefix)
throw Error(format("path %1% is not in the store") % path);
unregisterPath(path);
deletePath(path);
}
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