* A function to restore from a Nix archive.

* addValue() can now import any dumpable FS object.

1 files changed, 75 insertions, 3 deletions

diff --git a/src/values.cc b/src/values.cc
index 7cef5d3def..22f84c83e6 100644
--- a/src/values.cc
+++ b/src/values.cc
@@ -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");
 }