Add string flag to number convience function

1 files changed, 53 insertions, 1 deletions

diff --git a/luxio/simple.lua b/luxio/simple.lua
index 22ecfd4..8d1dbd0 100644
--- a/luxio/simple.lua
+++ b/luxio/simple.lua
@@ -190,7 +190,13 @@
 --         nil, errmsg, errno
 -- getcwd()
 --         Returns the current working directory, or nil, errmsg, errno
-
+--
+-- flags()
+--         Parses a list of comma-seperated flag strings, looks them up
+--         as UNIX constants, and ORs them together.
+--         Common suffixes are optional, and the system is case-insensitive.
+--         For example, flags("rdrw,creat,excl") would be the same as ORing
+--         together O_RDWR, O_CREAT, and O_EXCL.
 
 local l = require "luxio"
 
@@ -288,6 +294,50 @@ local function err(s, errno)
     return nil, ("%s: %s"):format(s, strerror(errno)), errno
 end
 
+local flag_prefixes = {
+    "O_", "SEEK_", "SPLICE_F_", "S_", "F_", "PF_", "AF_", "IPPROTO_", "SOCK_",
+    "SHUT_", "SO_", "TCP_", "AI_", "POLL", "LOG_", "EXIT_"
+}
+
+local function flags_find_flag(f)
+    for flag in pairs(l) do
+        if type(l[flag]) == "number" then
+            if f == flag or f == flag:lower() then return flag end
+            -- now look for both lower and upper using a set of prefixes
+            for _, prefix in ipairs(flag_prefixes) do
+                local try = prefix .. f
+                if try == flag or try:upper() == flag:upper() then return flag end
+            end
+        end
+    end
+    
+    return nil
+end
+
+local flag_cache = { }
+
+local function flags(...)
+    local r = 0
+    local f = table.concat({ ... }, ",")
+    
+    if flag_cache[f] then return flag_cache[f] end
+    
+    
+    for i in f:gmatch("([^,]*)") do
+        if i ~= "" then
+            local flag = flags_find_flag(i)
+            if not flag then
+                error("unknown flag " .. i)
+            end
+            r = l_bit_bor(r, luxio[flag])
+        end
+    end
+    
+    flag_cache[f] = r
+    
+    return r
+end
+
 local function sio_perm_flags_help(s, read, write, execute, sid)
     local c = { }
     for l in s:gmatch "." do
@@ -1251,6 +1301,8 @@ return {
     stderr = sio_wrap_mt(l.STDERR_FILENO, true, "<stderr>"),
 
     luxio = l,
+    
+    flags = flags,
 
     _VERSION = "Luxio Simple Interface " .. tostring(l._RELEASE),
     _COPYRIGHT = "Copyright 2012 Rob Kendrick <rjek+luxio@rjek.com>",