* Improved Nix. Resources (package descriptors and other source

files) are now referenced using their cryptographic hashes.  

  This ensures that if two package descriptors have the same contents,
  then they describe the same package.  This property is not as
  trivial as it sounds: generally import relations cause this property
  not to hold w.r.t. temporality.  But since imports also use hashes
  to reference other packages, equality follows by induction.

pkg/aterm-2.0-build.sh

@@ -0,0 +1,13 @@
+#! /bin/sh
+
+export PATH=$utils/bin
+export LIBRARY_PATH=$glibc/lib
+export CC=$gcc/bin/gcc
+export CFLAGS="-isystem $glibc/include -isystem $kernel/include"
+
+top=`pwd`
+tar xvfz $src
+cd aterm-2.0
+./configure --prefix=$top
+make
+make install

pkg/aterm-2.0.nix

@@ -0,0 +1,11 @@
+# Dependencies.
+utils <- 5703121fe19cbeeaee7edd659cf4a25b # prog-bootstrap
+gcc <- 02212b3dc4e50349376975367d433929 # gcc-bootstrap
+glibc <- c0ce03ee0bab298babbe7e3b6159d36c # glibc-bootstrap
+kernel <- 3dc8333a2c2b4d627b892755417acf89 # kernel-bootstrap
+
+# Original sources.
+src = 853474e4bcf4a85f7d38a0676b36bded # aterm-2.0.tar.gz
+
+# Build script.
+build = ee7ae4ade69f846d2385871bf532ef7e # aterm-2.0-build.sh

src/nix.cc

@@ -1,6 +1,10 @@
 #include <iostream>
+#include <fstream>
 #include <memory>
 #include <string>
+#include <sstream>
+#include <list>
+#include <cstdio>
 
 #include <unistd.h>
 #include <sys/stat.h>
@@ -15,10 +19,16 @@ using namespace std;
 #define PKGINFO_PATH "/pkg/sys/var/pkginfo"
 
 
+static string dbRefs = "refs";
+static string dbInstPkgs = "pkginst";
+
+
 static string prog;
 static string dbfile = PKGINFO_PATH;
 
 
+/* Wrapper class that ensures that the database is closed upon
+   object destruction. */
 class Db2 : public Db 
 {
 public:
@@ -81,85 +91,250 @@ void delDB(const string & dbname, const string & key)
 }
 
 
-void getPkg(int argc, char * * argv)
+/* Verify that a reference is valid (that is, is a MD5 hash code). */
+void checkRef(const string & s)
 {
-    string pkg;
+    string err = "invalid reference: " + s;
-    string src;
+    if (s.length() != 32)
-    string inst;
+        throw err;
-    string cmd;
+    for (int i = 0; i < 32; i++) {
-    int res;
+        char c = s[i];
-
+        if (!((c >= '0' && c <= '9') ||
-    if (argc != 1)
+              (c >= 'a' && c <= 'f')))
-        throw string("arguments missing in get-pkg");
+            throw err;
-
-    pkg = argv[0];
-
-    if (queryDB("pkginst", pkg, inst)) {
-        cout << inst << endl;
-        return;
     }
-    
-    cerr << "package " << pkg << " is not yet installed\n";
-        
-    if (!queryDB("pkgsrc", pkg, src)) 
-        throw string("source of package " + string(pkg) + " is not known");
-
-    inst = "/pkg/" + pkg;
-
-    cmd = "rsync -a \"" + src + "\"/ \"" + inst + "\"";
-        
-    res = system(cmd.c_str());
-    if (!WIFEXITED(res) || WEXITSTATUS(res) != 0)
-        throw string("unable to copy sources");
-
-    if (chdir(inst.c_str()))
-        throw string("unable to chdir to package directory");
-
-    /* Prepare for building.  Clean the environment so that the
-       build process does not inherit things it shouldn't. */
-    setenv("PATH", "/pkg/sys/bin", 1);
-
-    res = system("./buildme");
-    if (!WIFEXITED(res) || WEXITSTATUS(res) != 0)
-        throw string("unable to build package");
-
-    setDB("pkginst", pkg, inst);
-
-    cout << inst << endl;
 }
 
 
-void registerPkg(int argc, char * * argv)
+/* Compute the MD5 hash of a file. */
+string makeRef(string filename)
 {
-    char * pkg;
+    char hash[33];
-    char * src;
 
-    if (argc != 2)
+    FILE * pipe = popen(("md5sum " + filename).c_str(), "r");
-        throw string("arguments missing in register-pkg");
+    if (!pipe) throw string("cannot execute md5sum");
 
-    pkg = argv[0];
+    if (fread(hash, 32, 1, pipe) != 1)
-    src = argv[1];
+        throw string("cannot read hash from md5sum");
+    hash[32] = 0;
 
-    setDB("pkgsrc", pkg, src);
+    pclose(pipe);
+
+    checkRef(hash);
+    return hash;
+}
+
+
+struct Dep
+{
+    string name;
+    string ref;
+    Dep(string _name, string _ref)
+    {
+        name = _name;
+        ref = _ref;
+    }
+};
+
+typedef list<Dep> DepList;
+
+
+void readPkgDescr(const string & pkgfile,
+    DepList & pkgImports, DepList & fileImports)
+{
+    ifstream file;
+    file.exceptions(ios::badbit);
+    file.open(pkgfile.c_str());
+    
+    while (!file.eof()) {
+        string line;
+        getline(file, line);
+
+        int n = line.find('#');
+        if (n >= 0) line = line.erase(n);
+
+        if ((int) line.find_first_not_of(" ") < 0) continue;
+        
+        istringstream str(line);
+
+        string name, op, ref;
+        str >> name >> op >> ref;
+
+        checkRef(ref);
+
+        if (op == "<-") 
+            pkgImports.push_back(Dep(name, ref));
+        else if (op == "=")
+            fileImports.push_back(Dep(name, ref));
+        else throw string("invalid operator " + op);
+    }
+}
+
+
+string getPkg(string pkgref);
+
+
+typedef pair<string, string> EnvPair;
+typedef list<EnvPair> Environment;
+
+
+void installPkg(string pkgref)
+{
+    string pkgfile;
+    string src;
+    string path;
+    string cmd;
+    string builder;
+
+    if (!queryDB("refs", pkgref, pkgfile))
+        throw string("unknown package " + pkgref);
+
+    cerr << "installing package " + pkgref + " from " + pkgfile + "\n";
+
+    /* Verify that the file hasn't changed. !!! race */
+    if (makeRef(pkgfile) != pkgref)
+        throw string("file " + pkgfile + " is stale");
+
+    /* Read the package description file. */
+    DepList pkgImports, fileImports;
+    readPkgDescr(pkgfile, pkgImports, fileImports);
+
+    /* Recursively fetch all the dependencies, filling in the
+       environment as we go along. */
+    Environment env;
+
+    for (DepList::iterator it = pkgImports.begin();
+         it != pkgImports.end(); it++)
+    {
+        cerr << "fetching package dependency "
+             << it->name << " <- " << it->ref
+             << endl;
+        env.push_back(EnvPair(it->name, getPkg(it->ref)));
+    }
+
+    for (DepList::iterator it = fileImports.begin();
+         it != fileImports.end(); it++)
+    {
+        cerr << "fetching file dependency "
+             << it->name << " = " << it->ref
+             << endl;
+
+        string file;
+
+        if (!queryDB("refs", it->ref, file))
+            throw string("unknown file " + it->ref);
+
+        if (makeRef(file) != it->ref)
+            throw string("file " + file + " is stale");
+
+        if (it->name == "build")
+            builder = file;
+        else
+            env.push_back(EnvPair(it->name, file));
+    }
+
+    if (builder == "")
+        throw string("no builder specified");
+
+    /* Construct a path for the installed package. */
+    path = "/pkg/" + pkgref;
+
+    /* Create the path. */
+    if (mkdir(path.c_str(), 0777))
+        throw string("unable to create directory " + path);
+
+    /* Fork a child to build the package. */
+    pid_t pid;
+    switch (pid = fork()) {
+
+    case -1:
+        throw string("unable to fork");
+
+    case 0: /* child */
+
+        /* Go to the build directory. */
+        if (chdir(path.c_str())) {
+            cout << "unable to chdir to package directory\n";
+            _exit(1);
+        }
+
+        /* Fill in the environment.  We don't bother freeing the
+           strings, since we'll exec or die soon anyway. */
+        const char * env2[env.size() + 1];
+        int i = 0;
+        for (Environment::iterator it = env.begin();
+             it != env.end(); it++, i++)
+            env2[i] = (new string(it->first + "=" + it->second))->c_str();
+        env2[i] = 0;
+
+        /* Execute the builder.  This should not return. */
+        execle(builder.c_str(), builder.c_str(), 0, env2);
+
+        cout << strerror(errno) << endl;
+
+        cout << "unable to execute builder\n";
+        _exit(1);
+    }
+
+    /* parent */
+
+    /* Wait for the child to finish. */
+    int status;
+    if (waitpid(pid, &status, 0) != pid)
+        throw string("unable to wait for child");
+    
+    if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
+        throw string("unable to build package");
+
+    setDB(dbInstPkgs, pkgref, path);
+}
+
+
+string getPkg(string pkgref)
+{
+    string path;
+    checkRef(pkgref);
+    while (!queryDB(dbInstPkgs, pkgref, path))
+        installPkg(pkgref);
+    return path;
+}
+
+
+string absPath(string filename)
+{
+    if (filename[0] != '/') {
+        char buf[PATH_MAX];
+        if (!getcwd(buf, sizeof(buf)))
+            throw string("cannot get cwd");
+        filename = string(buf) + "/" + filename;
+        /* !!! canonicalise */
+    }
+    return filename;
+}
+
+
+void registerFile(string filename)
+{
+    filename = absPath(filename);
+    setDB(dbRefs, makeRef(filename), filename);
 }
 
 
 /* This is primarily used for bootstrapping. */
-void registerInstalledPkg(int argc, char * * argv)
+void registerInstalledPkg(string pkgref, string path)
 {
-    string pkg;
+    checkRef(pkgref);
-    string inst;
+    if (path == "")
-    
+        delDB(dbInstPkgs, pkgref);
-    if (argc != 2)
-        throw string("arguments missing in register-installed-pkg");
-
-    pkg = argv[0];
-    inst = argv[1];
-    
-    if (inst == "")
-        delDB("pkginst", pkg);
     else
-        setDB("pkginst", pkg, inst);
+        setDB(dbInstPkgs, pkgref, path);
+}
+
+
+void initDB()
+{
+    openDB(dbRefs, false);
+    openDB(dbInstPkgs, false);
 }
 
 
@@ -168,18 +343,29 @@ void run(int argc, char * * argv)
     string cmd;
 
     if (argc < 1)
-        throw string("command not specified\n");
+        throw string("command not specified");
 
     cmd = argv[0];
     argc--, argv++;
 
-    if (cmd == "get-pkg")
+    if (cmd == "init") {
-        getPkg(argc, argv);
+        if (argc != 0)
-    else if (cmd == "register-pkg")
+            throw string("init doesn't have arguments");
-        registerPkg(argc, argv);
+        initDB();
-    else if (cmd == "register-installed-pkg")
+    } else if (cmd == "getpkg") {
-        registerInstalledPkg(argc, argv);
+        if (argc != 1)
-    else
+            throw string("arguments missing in getpkg");
+        string path = getPkg(argv[0]);
+        cout << path << endl;
+    } else if (cmd == "reg") {
+        if (argc != 1)
+            throw string("arguments missing in reg");
+        registerFile(argv[0]);
+    } else if (cmd == "regpkg") {
+        if (argc != 2)
+            throw string("arguments missing in regpkg");
+        registerInstalledPkg(argv[0], argv[1]);
+    } else
         throw string("unknown command: " + string(cmd));
 }
     
@@ -190,31 +376,38 @@ int main(int argc, char * * argv)
 
     prog = argv[0];
 
-    while ((c = getopt(argc, argv, "d:")) != EOF) {
+    umask(0022);
-        
-        switch (c) {
-
-        case 'd':
-            dbfile = optarg;
-            break;
-
-        default:
-            cerr << "unknown option\n";
-            break;
-        }
-
-    }
-
-    argc -= optind, argv += optind;
 
     try {
+
+        while ((c = getopt(argc, argv, "d:")) != EOF) {
+        
+            switch (c) {
+
+            case 'd':
+                dbfile = optarg;
+                break;
+
+            default:
+                throw string("unknown option");
+                break;
+
+            }
+        }
+
+        argc -= optind, argv += optind;
         run(argc, argv);
-        return 0;
+
     } catch (DbException e) {
         cerr << "db exception: " << e.what() << endl;
         return 1;
+    } catch (exception e) {
+        cerr << e.what() << endl;
+        return 1;
     } catch (string s) {
         cerr << s << endl;
         return 1;
     }
+
+    return 0;
 }

sys/bootstrap

@@ -26,7 +26,7 @@ mkdir -m 1777 $target/tmp
 pkgdb=$target/pkg/sys/var/pkginfo
 
 # Copy some programs and its libraries.
-utils="/usr/bin/vi /bin/sh /bin/mount /bin/umount /bin/ls /bin/ln /bin/cp /bin/mv /bin/rm /bin/cat /bin/df /bin/pwd /usr/bin/ld /usr/bin/as /bin/sed /bin/chmod /bin/chown /usr/bin/expr /bin/mkdir /bin/rmdir /usr/bin/sort /usr/bin/uniq /bin/uname /usr/bin/grep /bin/sleep /usr/bin/rsync /usr/bin/make /usr/bin/cmp /bin/date /usr/bin/tr /usr/bin/ar /usr/bin/ranlib /usr/bin/basename /usr/bin/less ../src/nix"
+utils="/usr/bin/vi /bin/sh /bin/mount /bin/umount /bin/ls /bin/ln /bin/cp /bin/mv /bin/rm /bin/cat /bin/df /bin/pwd /usr/bin/ld /usr/bin/as /bin/sed /bin/chmod /bin/chown /usr/bin/expr /bin/mkdir /bin/rmdir /usr/bin/sort /usr/bin/uniq /bin/uname /usr/bin/grep /bin/sleep /bin/gzip /usr/bin/make /usr/bin/cmp /bin/date /usr/bin/tr /usr/bin/ar /usr/bin/ranlib /usr/bin/basename /usr/bin/less /usr/bin/md5sum /bin/tar ../src/nix"
 bootlib=/pkg/prog-bootstrap/lib
 bootbin=/pkg/prog-bootstrap/bin
 mkdir -p $target/$bootlib
@@ -36,27 +36,27 @@ libs=`ldd $utils | awk '{ print $3 }' | sort | uniq`
 echo $libs
 cp -p $libs $target/$bootlib
 for i in libc.so.6 libdl.so.2 libpthread.so.0 librt.so.1 libresolv.so.2 ld-linux.so.2; do rm $target/$bootlib/$i; done
-../src/nix -d $pkgdb register-installed-pkg prog-bootstrap /pkg/prog-bootstrap
+../src/nix -d $pkgdb regpkg 5703121fe19cbeeaee7edd659cf4a25b /pkg/prog-bootstrap
 
 mv $target/$bootbin/nix $target/pkg/sys/bin
-../src/nix -d $pkgdb register-installed-pkg sys /pkg/sys
+../src/nix -d $pkgdb regpkg 36bcbb801f5052739af8220c6ea51434 /pkg/sys
 
 # Copy the bootstrap gcc.
 echo Copying gcc...
 rsync -a ../bootstrap/gcc/inst/pkg $target
-../src/nix -d $pkgdb register-installed-pkg gcc-bootstrap /pkg/gcc-bootstrap
+../src/nix -d $pkgdb regpkg 02212b3dc4e50349376975367d433929 /pkg/gcc-bootstrap
 
 # Copy the bootstrap glibc.
 echo Copying glibc...
 glibcdir=/pkg/glibc-bootstrap
 rsync -a ../bootstrap/glibc/inst/pkg $target
-../src/nix -d $pkgdb register-installed-pkg glibc-bootstrap $glibcdir
+../src/nix -d $pkgdb regpkg c0ce03ee0bab298babbe7e3b6159d36c $glibcdir
 
 # Copy the bootstrap kernel header files.
 echo Copying kernel headers...
 kerneldir=/pkg/kernel-bootstrap
 rsync -a ../bootstrap/kernel/inst/pkg $target
-../src/nix -d $pkgdb register-installed-pkg kernel-bootstrap $kerneldir
+../src/nix -d $pkgdb regpkg 3dc8333a2c2b4d627b892755417acf89 $kerneldir
 
 # Compatibility.
 rm -rf $target/lib
@@ -75,7 +75,7 @@ $target/$glibcdir/sbin/ldconfig -r $target
 
 # Source repository.
 rm -f $target/src
-ln -sf /mnt/host/`pwd`/../src $target/src
+ln -sf /mnt/host/`pwd`/../pkg $target/src
 
 # Copy boot script.
 cp -p ./start $target/pkg/sys/bin

sys/start

@@ -4,7 +4,7 @@
 export PATH=/pkg/sys/bin
 
 # Add in the utilities needed for booting.
-export PATH=$PATH:`nix get-pkg prog-bootstrap`/bin
+export PATH=$PATH:`nix getpkg 5703121fe19cbeeaee7edd659cf4a25b`/bin
 
 echo
 echo Starting up...
@@ -14,17 +14,15 @@ mount -n -o remount,rw /dev/root /
 mount -n -t proc none /proc
 mount -n -t hostfs none /mnt/host 
 
-echo Registering available src packages...
+echo Registering available sources...
-( cd /src
+( if cd /src; then
-  for i in *; do
+    for i in *; do
-    if test -d $i; then
+      nix reg $i
-      echo "  $i"
+    done
-      nix register-pkg $i /src/$i
+  fi
-    fi
-  done
 )
 
-export PATH=`nix get-pkg coreutils-4.5.7`/bin:$PATH
+export PATH=`nix getpkg coreutils-4.5.7`/bin:$PATH
 
 echo
 echo "=== starting interactive shell ==="