From 696f960dee35889433adfa6c08a2dbfb6ea0724f Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Fri, 2 May 2014 14:31:15 +0200
Subject: [PATCH] Set up directories and permissions for multi-user install
 automatically

This automatically creates /nix/var/nix/profiles/per-user and sets the
permissions/ownership on /nix/store to 1775 and root:nixbld.
---
 src/libstore/local-store.cc | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 567706d09..5d210ae01 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -20,6 +20,7 @@
 #include <errno.h>
 #include <stdio.h>
 #include <time.h>
+#include <grp.h>
 
 #if HAVE_UNSHARE && HAVE_STATVFS && HAVE_SYS_MOUNT_H
 #include <sched.h>
@@ -237,7 +238,7 @@ LocalStore::LocalStore(bool reserveSpace)
     makeStoreWritable();
     createDirs(linksDir = settings.nixStore + "/.links");
     Path profilesDir = settings.nixStateDir + "/profiles";
-    createDirs(settings.nixStateDir + "/profiles");
+    createDirs(profilesDir);
     createDirs(settings.nixStateDir + "/temproots");
     createDirs(settings.nixDBPath);
     Path gcRootsDir = settings.nixStateDir + "/gcroots";
@@ -246,6 +247,32 @@ LocalStore::LocalStore(bool reserveSpace)
         createSymlink(profilesDir, gcRootsDir + "/profiles");
     }
 
+    /* Optionally, create directories and set permissions for a
+       multi-user install. */
+    if (getuid() == 0 && settings.buildUsersGroup != "") {
+
+        Path perUserDir = profilesDir + "/per-user";
+        createDirs(perUserDir);
+        if (chmod(perUserDir.c_str(), 01777) == -1)
+            throw SysError(format("could not set permissions on `%1%' to 1777") % perUserDir);
+
+        struct group * gr = getgrnam(settings.buildUsersGroup.c_str());
+        if (!gr)
+            throw Error(format("the group `%1%' specified in `build-users-group' does not exist")
+                % settings.buildUsersGroup);
+
+        struct stat st;
+        if (stat(settings.nixStore.c_str(), &st))
+            throw SysError(format("getting attributes of path `%1%'") % settings.nixStore);
+
+        if (st.st_uid != 0 || st.st_gid != gr->gr_gid || (st.st_mode & ~S_IFMT) != 01775) {
+            if (chown(settings.nixStore.c_str(), 0, gr->gr_gid) == -1)
+                throw SysError(format("changing ownership of path `%1%'") % settings.nixStore);
+            if (chmod(settings.nixStore.c_str(), 01775) == -1)
+                throw SysError(format("changing permissions on path `%1%'") % settings.nixStore);
+        }
+    }
+
     checkStoreNotSymlink();
 
     /* We can't open a SQLite database if the disk is full.  Since