Fixes from Daniel

2 files changed, 47 insertions, 1 deletions

diff --git a/luxio/simple.lua b/luxio/simple.lua
index 8c59e84..c19d348 100644
--- a/luxio/simple.lua
+++ b/luxio/simple.lua
@@ -1184,7 +1184,7 @@ end
 
 local lchdir = l.chdir
 local function chdir(path)
-   local r, err = chdir(path)
+   local r, err = lchdir(path)
    if r == -1 then
       return err("chdir", errno)
    end
diff --git a/luxio/subprocess.lua b/luxio/subprocess.lua
index d0a7c91..617d20b 100644
--- a/luxio/subprocess.lua
+++ b/luxio/subprocess.lua
@@ -45,6 +45,16 @@
 -- If you want the child (during pre-exec) to close additional FDs then
 -- you can specify them in a table called close_in_child
 --
+-- If you want to change directory before exec in the child, you can pass
+-- cwd="/some/path".
+--
+-- To run some code before forking, pass prefork=somefunction and to
+-- run code before exec (in the child) pass preexec=somefunction.
+--
+-- If the prefork function raises an error then the spawn will be stopped and
+-- the error propagated.  If the preexec function raises an error then the exec
+-- will be stopped and the child will exit with status code 1.
+--
 -- spawn_simple has one additional tweak.  If 'stdin' is provided as
 -- a string then it will automatically write that string to the stdin
 -- of the child (and close the FD afterwards) for you automatically.
@@ -92,9 +102,12 @@ local dup2 = l.dup2
 local fcntl = l.fcntl
 local bclear = l.bit.bclear
 local wrap_fd = sio.wrap_fd
+local chdir = sio.chdir
+local stderr_fh = sio.stderr
 local setenv = l.setenv
 local unsetenv = l.unsetenv
 local _exit = l._exit
+local _TRACEBACK = debug.traceback
 
 local F_SETFD = l.F_SETFD
 local F_GETFD = l.F_GETFD
@@ -231,6 +244,21 @@ local function _spawn(t)
 
    -- Finally, let's fork
 
+   if proc.args.prefork then
+      local ok, msg = xpcall(proc.args.prefork, function(...)
+	 for fd in pairs(parent_close) do
+	    close(fd)
+	 end
+	 for fd in pairs(child_close) do
+	    close(fd)
+	 end
+	 return _TRACEBACK(...)
+      end)
+      if not ok then
+	 error(msg)
+      end
+   end
+
    local pid, errno = fork()
 
    _assert(pid > -1, "Unable to fork()")
@@ -295,6 +323,24 @@ local function _spawn(t)
 	 end
       end
 
+      -- Change directory if needed
+      if proc.args.cwd then
+	 local cwd = tostring(proc.args.cwd)
+	 local ret, err = chdir(cwd)
+	 if ret ~= 0 then
+	    stderr_fh:write("chdir(" .. cwd .. "): " .. err .. "\n")
+	    _exit(1)
+	 end
+      end
+
+      if proc.args.preexec then
+	 local ok, msg = xpcall(proc.args.preexec, _TRACEBACK)
+	 if not ok then
+	    stderr_fh:write(msg .. "\n")
+	    _exit(1)
+	 end
+      end
+
       -- Run the child process
       exec_fn(exe, unpack(proc.args))