1 files changed, 40 insertions, 1 deletions
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 90bcccd243a7..50c59c1314d9 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -20,6 +20,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/utsname.h>
+#include <sys/select.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <errno.h>
@@ -1786,8 +1787,10 @@ void DerivationGoal::startBuilder()
     if (useChroot) {
 
         string defaultChrootDirs;
+#if CHROOT_ENABLED
         if (isInStore(BASH_PATH))
             defaultChrootDirs = "/bin/sh=" BASH_PATH;
+#endif
 
         /* Allow a user-configurable set of directories from the
            host file system. */
@@ -1895,7 +1898,7 @@ void DerivationGoal::startBuilder()
            build user. */
         Path chrootStoreDir = chrootRootDir + settings.nixStore;
         createDirs(chrootStoreDir);
-        chmod_(chrootStoreDir, 0730);
+        chmod_(chrootStoreDir, 01775);
 
         if (chown(chrootStoreDir.c_str(), 0, buildUser.getGID()) == -1)
             throw SysError(format("cannot change ownership of ‘%1%’") % chrootStoreDir);
@@ -1969,6 +1972,42 @@ void DerivationGoal::startBuilder()
                 }
     }
 
+    if (settings.preBuildHook != "") {
+        printMsg(lvlChatty, format("executing pre-build hook ‘%1%’")
+            % settings.preBuildHook);
+        auto args = useChroot ? Strings({drvPath, chrootRootDir}) :
+            Strings({ drvPath });
+        enum BuildHookState {
+            stBegin,
+            stExtraChrootDirs
+        };
+        auto state = stBegin;
+        auto lines = runProgram(settings.preBuildHook, false, args);
+        auto lastPos = std::string::size_type{0};
+        for (auto nlPos = lines.find('\n'); nlPos != string::npos;
+                nlPos = lines.find('\n', lastPos)) {
+            auto line = std::string{lines, lastPos, nlPos};
+            lastPos = nlPos + 1;
+            if (state == stBegin) {
+                if (line == "extra-chroot-dirs") {
+                    state = stExtraChrootDirs;
+                } else {
+                    throw Error(format("unknown pre-build hook command ‘%1%’")
+                        % line);
+                }
+            } else if (state == stExtraChrootDirs) {
+                if (line == "") {
+                    state = stBegin;
+                } else {
+                    auto p = line.find('=');
+                    if (p == string::npos)
+                        dirsInChroot[line] = line;
+                    else
+                        dirsInChroot[string(line, 0, p)] = string(line, p + 1);
+                }
+            }
+        }
+    }
 
     /* Run the builder. */
     printMsg(lvlChatty, format("executing builder ‘%1%’") % drv.builder);