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* A function to restore from a Nix archive.

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* addValue() can now import any dumpable FS object.
This commit is contained in:
Eelco Dolstra 2003-06-23 13:27:59 +00:00
parent 85effedca3
commit 5f5cab0ac7
6 changed files with 293 additions and 14 deletions
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78
src/values.cc
View file

@ -1,13 +1,85 @@
#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)
{
int res = system(("cat " + src + " > " + dst).c_str()); /* !!! escape */
if (WEXITSTATUS(res) != 0)
throw Error("cannot copy " + src + " to " + 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");
}