Add sanity check to is_actual_binary.

Should fix crash in 'luarocks pack' reported by Alexander Gladysh,
or at least give better diagnostics.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/luarocks/fs/unix.lua b/src/luarocks/fs/unix.lua
index f2290412..c5769bac 100644
--- a/src/luarocks/fs/unix.lua
+++ b/src/luarocks/fs/unix.lua
@@ -101,6 +101,11 @@ function is_actual_binary(filename)
    if file then
       local found = false
       local first = file:read()
+      if not first then
+         file:close()
+         print("Warning: could not read "..filename)
+         return false
+      end
       if first:match("#!.*lua") then
          file:close()
          return true