Check the lock directory is writable.

And, if it isn't, print more helpful debugging messages.

Fixes #1456.

1 files changed, 12 insertions, 3 deletions

diff --git a/Library/Homebrew/utils/lock.sh b/Library/Homebrew/utils/lock.sh
index cc041fa74..7f0638c1a 100644
--- a/Library/Homebrew/utils/lock.sh
+++ b/Library/Homebrew/utils/lock.sh
@@ -6,6 +6,14 @@ lock() {
   local lock_dir="$HOMEBREW_PREFIX/var/homebrew/locks"
   local lock_file="$lock_dir/$name"
   [[ -d "$lock_dir" ]] || mkdir -p "$lock_dir"
+  if ! [[ -w "$lock_dir" ]]
+  then
+    odie <<EOS
+Can't create $name lock in $lock_dir!
+Fix permissions by running:
+  sudo chown -R \$(whoami) $HOMEBREW_PREFIX/var/homebrew
+EOS
+  fi
   # 200 is the file descriptor used in the lock.
   # This FD should be used exclusively for lock purpose.
   # Any value except 0(stdin), 1(stdout) and 2(stderr) can do the job.
@@ -17,10 +25,10 @@ lock() {
   exec 200>&-
   # open the lock file to FD, so the shell process can hold the lock.
   exec 200>"$lock_file"
-  if ! _create_lock 200
+  if ! _create_lock 200 "$name"
   then
     odie <<EOS
-Another active Homebrew process is already in progress.
+Another active Homebrew $name process is already in progress.
 Please wait for it to finish or terminate it to continue.
 EOS
   fi
@@ -28,6 +36,7 @@ EOS
 
 _create_lock() {
   local lock_fd="$1"
+  local name="$2"
   local ruby="/usr/bin/ruby"
   [[ -x "$ruby" ]] || ruby="$(which ruby 2>/dev/null)"
 
@@ -38,6 +47,6 @@ _create_lock() {
   then
     flock -n "$lock_fd"
   else
-    onoe "Cannot create lock, please avoid running brew in parallel."
+    onoe "Cannot create $name lock, please avoid running Homebrew in parallel."
   fi
 }