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#include <iostream>
#include <sys/types.h>
#include <sys/wait.h>
#include "values.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");
}
};
static void copyFile(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");
}
static string absValuePath(string s)
{
return nixValues + "/" + s;
}
Hash addValue(string path)
{
path = absPath(path);
Hash hash = hashPath(path);
string name;
if (queryDB(nixDB, dbRefs, hash, name)) {
debug((string) hash + " already known");
return hash;
}
string baseName = baseNameOf(path);
string targetName = (string) hash + "-" + baseName;
copyFile(path, absValuePath(targetName));
setDB(nixDB, dbRefs, hash, targetName);
return hash;
}
#if 0
/* Download object referenced by the given URL into the sources
directory. Return the file name it was downloaded to. */
string fetchURL(string url)
{
string filename = baseNameOf(url);
string fullname = nixSourcesDir + "/" + filename;
struct stat st;
if (stat(fullname.c_str(), &st)) {
cerr << "fetching " << url << endl;
/* !!! quoting */
string shellCmd =
"cd " + nixSourcesDir + " && wget --quiet -N \"" + url + "\"";
int res = system(shellCmd.c_str());
if (WEXITSTATUS(res) != 0)
throw Error("cannot fetch " + url);
}
return fullname;
}
#endif
void deleteValue(Hash hash)
{
string name;
if (queryDB(nixDB, dbRefs, hash, name)) {
string fn = absValuePath(name);
deletePath(fn);
delDB(nixDB, dbRefs, hash);
}
}
/* !!! bad name, "query" implies no side effect => getValuePath() */
string queryValuePath(Hash hash)
{
bool checkedNet = false;
while (1) {
string name, url;
if (queryDB(nixDB, dbRefs, hash, name)) {
string fn = absValuePath(name);
/* Verify that the file hasn't changed. !!! race !!! slow */
if (hashPath(fn) != hash)
throw Error("file " + fn + " is stale");
return fn;
}
throw Error("a file with hash " + (string) hash + " is required, "
"but it is not known to exist locally or on the network");
#if 0
if (checkedNet)
throw Error("consistency problem: file fetched from " + url +
" should have hash " + (string) hash + ", but it doesn't");
if (!queryDB(nixDB, dbNetSources, hash, url))
throw Error("a file with hash " + (string) hash + " is required, "
"but it is not known to exist locally or on the network");
checkedNet = true;
fn = fetchURL(url);
setDB(nixDB, dbRefs, hash, fn);
#endif
}
}
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