buildenv: perl -> c++

8 files changed, 202 insertions, 172 deletions

diff --git a/.gitignore b/.gitignore
index a524e9b6a29b..2b90b549ba8a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -77,6 +77,9 @@ Makefile.config
 # /src/download-via-ssh/
 /src/download-via-ssh/download-via-ssh
 
+# /src/buildenv/
+/src/buildenv/buildenv
+
 # /tests/
 /tests/test-tmp
 /tests/common.sh
diff --git a/Makefile b/Makefile
index 90dca473f390..11b3309f80c2 100644
--- a/Makefile
+++ b/Makefile
@@ -12,6 +12,7 @@ makefiles = \
   src/nix-daemon/local.mk \
   src/nix-collect-garbage/local.mk \
   src/nix-prefetch-url/local.mk \
+  src/buildenv/local.mk \
   perl/local.mk \
   scripts/local.mk \
   corepkgs/local.mk \
diff --git a/corepkgs/buildenv.nix b/corepkgs/buildenv.nix
index 70981a752c3c..5e7b40eaa0cb 100644
--- a/corepkgs/buildenv.nix
+++ b/corepkgs/buildenv.nix
@@ -5,8 +5,7 @@ with import <nix/config.nix>;
 derivation {
   name = "user-environment";
   system = builtins.currentSystem;
-  builder = perl;
-  args = [ "-w" ./buildenv.pl ];
+  builder = nixLibexecDir + "/nix/buildenv";
 
   inherit manifest;
 
diff --git a/corepkgs/buildenv.pl b/corepkgs/buildenv.pl
deleted file mode 100644
index dacc53701a01..000000000000
--- a/corepkgs/buildenv.pl
+++ /dev/null
@@ -1,168 +0,0 @@
-use strict;
-use Cwd;
-use IO::Handle;
-use utf8;
-
-STDOUT->autoflush(1);
-
-my $out = $ENV{"out"};
-mkdir "$out", 0755 || die "error creating $out";
-
-
-my $symlinks = 0;
-
-my %priorities;
-
-
-# For each activated package, create symlinks.
-
-sub createLinks {
-    my $srcDir = shift;
-    my $dstDir = shift;
-    my $priority = shift;
-
-    my @srcFiles = glob("$srcDir/*");
-
-    foreach my $srcFile (@srcFiles) {
-        my $baseName = $srcFile;
-        $baseName =~ s/^.*\///g; # strip directory
-        my $dstFile = "$dstDir/$baseName";
-
-        # The files below are special-cased so that they don't show up
-        # in user profiles, either because they are useless, or
-        # because they would cause pointless collisions (e.g., each
-        # Python package brings its own
-        # `$out/lib/pythonX.Y/site-packages/easy-install.pth'.)
-        # Urgh, hacky...
-        if ($srcFile =~ /\/propagated-build-inputs$/ ||
-            $srcFile =~ /\/nix-support$/ ||
-            $srcFile =~ /\/perllocal.pod$/ ||
-            $srcFile =~ /\/info\/dir$/ ||
-            $srcFile =~ /\/log$/)
-        {
-            # Do nothing.
-        }
-
-        elsif (-d $srcFile) {
-
-            lstat $dstFile;
-
-            if (-d _) {
-                createLinks($srcFile, $dstFile, $priority);
-            }
-
-            elsif (-l _) {
-                my $target = readlink $dstFile or die;
-                if (!-d $target) {
-                    die "collision between directory ‘$srcFile’ and non-directory ‘$target’";
-                }
-                unlink $dstFile or die "error unlinking ‘$dstFile’: $!";
-                mkdir $dstFile, 0755 ||
-                    die "error creating directory ‘$dstFile’: $!";
-                createLinks($target, $dstFile, $priorities{$dstFile});
-                createLinks($srcFile, $dstFile, $priority);
-            }
-
-            else {
-                symlink($srcFile, $dstFile) ||
-                    die "error creating link ‘$dstFile’: $!";
-                $priorities{$dstFile} = $priority;
-                $symlinks++;
-            }
-        }
-
-        else {
-
-            if (-l $dstFile) {
-                my $target = readlink $dstFile;
-                my $prevPriority = $priorities{$dstFile};
-                die("collision between ‘$srcFile’ and ‘$target’; " .
-                    "use ‘nix-env --set-flag priority NUMBER PKGNAME’ " .
-                    "to change the priority of one of the conflicting packages\n")
-                    if $prevPriority == $priority;
-                next if $prevPriority < $priority;
-                unlink $dstFile or die;
-            }
-
-            symlink($srcFile, $dstFile) ||
-                die "error creating link ‘$dstFile’: $!";
-            $priorities{$dstFile} = $priority;
-            $symlinks++;
-        }
-    }
-}
-
-
-my %done;
-my %postponed;
-
-sub addPkg;
-sub addPkg {
-    my $pkgDir = shift;
-    my $priority = shift;
-
-    return if (defined $done{$pkgDir});
-    $done{$pkgDir} = 1;
-
-#    print "symlinking $pkgDir\n";
-    createLinks("$pkgDir", "$out", $priority);
-
-    my $propagatedFN = "$pkgDir/nix-support/propagated-user-env-packages";
-    if (-e $propagatedFN) {
-        open PROP, "<$propagatedFN" or die;
-        my $propagated = <PROP>;
-        close PROP;
-        my @propagated = split ' ', $propagated;
-        foreach my $p (@propagated) {
-            $postponed{$p} = 1 unless defined $done{$p};
-        }
-    }
-}
-
-
-# Convert the stuff we get from the environment back into a coherent
-# data type.
-my @pkgs;
-my @derivations = split ' ', $ENV{"derivations"};
-while (scalar @derivations) {
-    my $active = shift @derivations;
-    my $priority = shift @derivations;
-    my $outputs = shift @derivations;
-    for (my $n = 0; $n < $outputs; $n++) {
-        my $path = shift @derivations;
-        push @pkgs,
-            { path => $path
-            , active => $active ne "false"
-            , priority => int($priority) };
-    }
-}
-
-
-# Symlink to the packages that have been installed explicitly by the
-# user.  Process in priority order to reduce unnecessary
-# symlink/unlink steps.
-@pkgs = sort { $a->{priority} <=> $b->{priority} || $a->{path} cmp $b->{path} } @pkgs;
-foreach my $pkg (@pkgs) {
-    #print $pkg, " ", $pkgs{$pkg}->{priority}, "\n";
-    addPkg($pkg->{path}, $pkg->{priority}) if $pkg->{active};
-}
-
-
-# Symlink to the packages that have been "propagated" by packages
-# installed by the user (i.e., package X declares that it wants Y
-# installed as well).  We do these later because they have a lower
-# priority in case of collisions.
-my $priorityCounter = 1000; # don't care about collisions
-while (scalar(keys %postponed) > 0) {
-    my @pkgDirs = keys %postponed;
-    %postponed = ();
-    foreach my $pkgDir (sort @pkgDirs) {
-        addPkg($pkgDir, $priorityCounter++);
-    }
-}
-
-
-print STDERR "created $symlinks symlinks in user environment\n";
-
-
-symlink($ENV{"manifest"}, "$out/manifest.nix") or die "cannot create manifest";
diff --git a/corepkgs/config.nix.in b/corepkgs/config.nix.in
index 90e8edbea833..f0f4890a32fd 100644
--- a/corepkgs/config.nix.in
+++ b/corepkgs/config.nix.in
@@ -3,7 +3,6 @@ let
     let val = builtins.getEnv var; in
     if val != "" then val else def;
 in rec {
-  perl = "@perl@";
   shell = "@bash@";
   coreutils = "@coreutils@";
   bzip2 = "@bzip2@";
@@ -14,6 +13,7 @@ in rec {
   tr = "@tr@";
   nixBinDir = fromEnv "NIX_BIN_DIR" "@bindir@";
   nixPrefix = "@prefix@";
+  nixLibexecDir = fromEnv "NIX_LIBEXEC_DIR" "@libexecdir@";
 
   # If Nix is installed in the Nix store, then automatically add it as
   # a dependency to the core packages. This ensures that they work
diff --git a/corepkgs/local.mk b/corepkgs/local.mk
index 19c1d06962c0..8ea66a7c3e2f 100644
--- a/corepkgs/local.mk
+++ b/corepkgs/local.mk
@@ -1,4 +1,4 @@
-corepkgs_FILES = nar.nix buildenv.nix buildenv.pl unpack-channel.nix derivation.nix fetchurl.nix imported-drv-to-derivation.nix
+corepkgs_FILES = nar.nix buildenv.nix unpack-channel.nix derivation.nix fetchurl.nix imported-drv-to-derivation.nix
 
 $(foreach file,config.nix $(corepkgs_FILES),$(eval $(call install-data-in,$(d)/$(file),$(datadir)/nix/corepkgs)))
 
diff --git a/src/buildenv/buildenv.cc b/src/buildenv/buildenv.cc
new file mode 100644
index 000000000000..f997096eddbb
--- /dev/null
+++ b/src/buildenv/buildenv.cc
@@ -0,0 +1,186 @@
+#include "shared.hh"
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <algorithm>
+
+using namespace nix;
+
+typedef std::map<Path,int> Priorities;
+
+static bool isDirectory (const Path & path)
+{
+    struct stat st;
+    if (stat(path.c_str(), &st) == -1)
+        throw SysError(format("getting status of ‘%1%’") % path);
+    return S_ISDIR(st.st_mode);
+}
+
+static auto priorities = Priorities{};
+
+static auto symlinks = 0;
+
+/* For each activated package, create symlinks */
+static void createLinks(const Path & srcDir, const Path & dstDir, int priority)
+{
+    auto srcFiles = readDirectory(srcDir);
+    for (const auto & ent : srcFiles) {
+        if (ent.name[0] == '.')
+            /* not matched by glob */
+            continue;
+        const auto & srcFile = srcDir + "/" + ent.name;
+        auto dstFile = dstDir + "/" + ent.name;
+
+        /* The files below are special-cased to that they don't show up
+         * in user profiles, either because they are useless, or
+         * because they would cauase pointless collisions (e.g., each
+         * Python package brings its own
+         * `$out/lib/pythonX.Y/site-packages/easy-install.pth'.)
+         */
+        if (hasSuffix(srcFile, "/propagated-build-inputs") ||
+            hasSuffix(srcFile, "/nix-support") ||
+            hasSuffix(srcFile, "/perllocal.pod") ||
+            hasSuffix(srcFile, "/info/dir") ||
+            hasSuffix(srcFile, "/log")) {
+            continue;
+        } else if (isDirectory(srcFile)) {
+            struct stat dstSt;
+            auto res = lstat(dstFile.c_str(), &dstSt);
+            if (res == 0) {
+                if (S_ISDIR(dstSt.st_mode)) {
+                    createLinks(srcFile, dstFile, priority);
+                    continue;
+                } else if (S_ISLNK(dstSt.st_mode)) {
+                    auto target = readLink(dstFile);
+                    if (!isDirectory(target))
+                        throw Error(format("collision between ‘%1%’ and non-directory ‘%2%’")
+                            % srcFile % target);
+                    if (unlink(dstFile.c_str()) == -1)
+                        throw SysError(format("unlinking ‘%1%’") % dstFile);
+                    if (mkdir(dstFile.c_str(), 0755) == -1)
+                        throw SysError(format("creating directory ‘%1%’"));
+                    createLinks(target, dstFile, priorities[dstFile]);
+                    createLinks(srcFile, dstFile, priority);
+                    continue;
+                }
+            } else if (errno != ENOENT)
+                throw SysError(format("getting status of ‘%1%’") % dstFile);
+        } else {
+            struct stat dstSt;
+            auto res = lstat(dstFile.c_str(), &dstSt);
+            if (res == 0) {
+                if (S_ISLNK(dstSt.st_mode)) {
+                    auto target = readLink(dstFile);
+                    auto prevPriority = priorities[dstFile];
+                    if (prevPriority == priority)
+                        throw Error(format(
+                                "collision between ‘%1%’ and ‘%2%’; "
+                                "use ‘nix-env --set-flag priority NUMBER PKGNAME’ "
+                                "to change the priority of one of the conflicting packages"
+                                ) % srcFile % target);
+                    if (prevPriority < priority)
+                        continue;
+                    if (unlink(dstFile.c_str()) == -1)
+                        throw SysError(format("unlinking ‘%1%’") % dstFile);
+                }
+            } else if (errno != ENOENT)
+                throw SysError(format("getting status of ‘%1%’") % dstFile);
+        }
+        createSymlink(srcFile, dstFile);
+        priorities[dstFile] = priority;
+        symlinks++;
+    }
+}
+
+typedef std::set<Path> FileProp;
+
+static auto done = FileProp{};
+static auto postponed = FileProp{};
+
+static auto out = string{};
+
+static void addPkg(const Path & pkgDir, int priority)
+{
+    if (done.find(pkgDir) != done.end())
+        return;
+    done.insert(pkgDir);
+    createLinks(pkgDir, out, priority);
+    auto propagatedFN = pkgDir + "/nix-support/propagated-user-env-packages";
+    auto propagated = string{};
+    {
+        AutoCloseFD fd = open(propagatedFN.c_str(), O_RDONLY | O_CLOEXEC);
+        if (!fd) {
+            if (errno == ENOENT)
+                return;
+            throw SysError(format("opening ‘%1%’") % propagatedFN);
+        }
+        propagated = readLine(fd.get());
+    }
+    for (const auto & p : tokenizeString<std::vector<string>>(propagated, " "))
+        if (done.find(p) == done.end())
+            postponed.insert(p);
+}
+
+struct Package {
+    Path path;
+    bool active;
+    int priority;
+    Package(Path path, bool active, int priority) : path{std::move(path)}, active{active}, priority{priority} {}
+};
+
+typedef std::vector<Package> Packages;
+
+int main(int argc, char ** argv)
+{
+    return handleExceptions(argv[0], [&]() {
+        initNix();
+        out = getEnv("out");
+        if (mkdir(out.c_str(), 0755) == -1)
+            throw SysError(format("creating %1%") % out);
+
+        /* Convert the stuff we get from the environment back into a coherent
+         * data type.
+         */
+        auto pkgs = Packages{};
+        auto derivations = tokenizeString<Strings>(getEnv("derivations"));
+        while (!derivations.empty()) {
+            /* !!! We're trusting the caller to structure derivations env var correctly */
+            auto active = derivations.front(); derivations.pop_front();
+            auto priority = stoi(derivations.front()); derivations.pop_front();
+            auto outputs = stoi(derivations.front()); derivations.pop_front();
+            for (auto n = 0; n < outputs; n++) {
+                auto path = derivations.front(); derivations.pop_front();
+                pkgs.emplace_back(path, active != "false", priority);
+            }
+        }
+
+        /* Symlink to the packages that have been installed explicitly by the
+         * user. Process in priority order to reduce unnecessary
+         * symlink/unlink steps.
+         */
+        std::sort(pkgs.begin(), pkgs.end(), [](const Package & a, const Package & b) {
+            return a.priority < b.priority || (a.priority == b.priority && a.path < b.path);
+        });
+        for (const auto & pkg : pkgs)
+            if (pkg.active)
+                addPkg(pkg.path, pkg.priority);
+
+        /* Symlink to the packages that have been "propagated" by packages
+         * installed by the user (i.e., package X declares that it wants Y
+         * installed as well). We do these later because they have a lower
+         * priority in case of collisions.
+         */
+        auto priorityCounter = 1000;
+        while (!postponed.empty()) {
+            auto pkgDirs = postponed;
+            postponed = FileProp{};
+            for (const auto & pkgDir : pkgDirs)
+                addPkg(pkgDir, priorityCounter++);
+        }
+
+        std::cerr << "created " << symlinks << " symlinks in user environment\n";
+
+        createSymlink(getEnv("manifest"), out + "/manifest.nix");
+    });
+}
+
diff --git a/src/buildenv/local.mk b/src/buildenv/local.mk
new file mode 100644
index 000000000000..493acfadfb45
--- /dev/null
+++ b/src/buildenv/local.mk
@@ -0,0 +1,9 @@
+programs += buildenv
+
+buildenv_DIR := $(d)
+
+buildenv_INSTALL_DIR := $(libexecdir)/nix
+
+buildenv_LIBS = libmain libutil libformat
+
+buildenv_SOURCES := $(d)/buildenv.cc