* Descriptor importing in Fix.

src/fix.cc

@@ -2,6 +2,7 @@
 #include <map>
 
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <sys/wait.h>
 
 extern "C" {
@@ -15,9 +16,17 @@ static string nixDescriptorDir;
 static string nixSourcesDir;
 
 
+/* Mapping of Fix file names to the hashes of the resulting Nix
+   descriptors. */
 typedef map<string, string> DescriptorMap;
 
 
+/* Forward declarations. */
+
+string instantiateDescriptor(string filename,
+    DescriptorMap & done);
+
+
 void registerFile(string filename)
 {
     int res = system(("nix regfile " + filename).c_str());
@@ -52,12 +61,15 @@ string fetchURL(string url)
 {
     string filename = baseNameOf(url);
     string fullname = nixSourcesDir + "/" + filename;
-    /* !!! quoting */
-    string shellCmd =
-        "cd " + nixSourcesDir + " && wget --quiet -N \"" + url + "\"";
-    int res = system(shellCmd.c_str());
-    if (WEXITSTATUS(res) != 0)
-        throw Error("cannot fetch " + url);
+    struct stat st;
+    if (stat(fullname.c_str(), &st)) {
+        /* !!! 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;
 }
 
@@ -101,17 +113,21 @@ string evaluateFile(ATerm e, string dir)
             throw Error("cannot copy " + filename);
         registerFile(nixSourcesDir + "/" + baseNameOf(filename));
         return hashFile(filename);
-    } else throw Error("invalid hash expression");
+    } else throw Error("invalid file expression");
 }
 
 
-string evaluatePkg(ATerm e, DescriptorMap & done)
+string evaluatePkg(ATerm e, string dir, DescriptorMap & done)
 {
     char * s;
+    ATerm t;
     if (ATmatch(e, "<str>", &s)) {
         checkHash(s);
         return s;
-    } else throw Error("invalid hash expression");
+    } else if (ATmatch(e, "Fix(<term>)", &t)) {
+        string filename = absPath(evaluateStr(t), dir); /* !!! */
+        return instantiateDescriptor(filename, done);
+    } else throw Error("invalid pkg expression");
 }
 
 
@@ -125,7 +141,7 @@ ATerm evaluate(ATerm e, string dir, DescriptorMap & done)
     else if (ATmatch(e, "File(<term>)", &t))
         return ATmake("File(<str>)", evaluateFile(t, dir).c_str());
     else if (ATmatch(e, "Pkg(<term>)", &t))
-        return ATmake("Pkg(<str>)", evaluatePkg(t, done).c_str());
+        return ATmake("Pkg(<str>)", evaluatePkg(t, dir, done).c_str());
     else throw Error("invalid expression type");
 }
 
@@ -215,8 +231,8 @@ string instantiateDescriptor(string filename,
     /* Register it with Nix. */
     registerFile(outFilename);
 
-    done[filename] = outFilename;
-    return outFilename;
+    done[filename] = outHash;
+    return outHash;
 }
 
 

src/nix-populate

@@ -1,89 +0,0 @@
-#! /usr/bin/perl -w
-
-use strict;
-
-my $pkglist = $ENV{"NIX_ACTIVATIONS"};
-$pkglist or die "NIX_ACTIVATIONS not set";
-my $linkdir = $ENV{"NIX_LINKS"};
-$linkdir or die "NIX_LINKS not set";
-my @dirs = ("bin", "sbin", "lib", "include");
-
-# Figure out a generation number.
-my $nr = 1;
-while (-e "$linkdir/$nr") { $nr++; }
-my $gendir = "$linkdir/$nr";
-print "populating $gendir\n";
-
-# Create the subdirectories.
-mkdir $gendir;
-foreach my $dir (@dirs) {
-    mkdir "$gendir/$dir";
-}
-
-# For each activated package, create symlinks.
-
-sub createLinks {
-    my $srcdir = shift;
-    my $dstdir = shift;
-
-    my @srcfiles = glob("$srcdir/*");
-
-    foreach my $srcfile (@srcfiles) {
-	my $basename = $srcfile;
-	$basename =~ s/^.*\///g; # strip directory
-	my $dstfile = "$dstdir/$basename";
-	if (-d $srcfile) {
-	    # !!! hack for resolving name clashes
-	    if (!-e $dstfile) {
-		mkdir($dstfile) or 
-		    die "error creating directory $dstfile";
-	    }
-	    -d $dstfile or die "$dstfile is not a directory";
-	    createLinks($srcfile, $dstfile);
-	} elsif (-l $dstfile) {
-	    my $target = readlink($dstfile);
-	    die "collission between $srcfile and $target";
-	} else {
-	    print "linking $dstfile to $srcfile\n";
-	    symlink($srcfile, $dstfile) or
-		die "error creating link $dstfile";
-	}
-    }
-}
-
-
-open PKGS, "< $pkglist";
-
-while (<PKGS>) {
-    chomp;
-    my $hash = $_;
-    
-    my $pkgdir = `nix getpkg $hash`;
-    if ($?) { die "`nix getpkg' failed"; }
-    chomp $pkgdir;
-
-    print "merging $pkgdir\n";
-
-    foreach my $dir (@dirs) {
-	createLinks("$pkgdir/$dir", "$gendir/$dir");
-    }
-}
-
-close PKGS;
-
-# Make $gendir the current generation by pointing $linkdir/current to
-# it.  The rename() system call is supposed to be essentially atomic
-# on Unix.  That is, if we have links `current -> X' and `new_current
-# -> Y', and we rename new_current to current, a process accessing
-# current will see X or Y, but never a file-not-found or other error
-# condition.  This is sufficient to atomically switch the current link
-# tree.
-
-my $current = "$linkdir/current";
-
-print "switching $current to $gendir\n"; 
-
-my $tmplink = "$linkdir/new_current";
-symlink($gendir, $tmplink) or die "cannot create $tmplink";
-rename($tmplink, $current) or die "cannot rename $tmplink";
-