Paired down OS Lua library

Pretty much removed everything except for time operations. File operations steps on the toes of the IO library, and the others were useless or invasive. The only one I wasn't sure about was `os.tmpname()`, but I think that's something that could be implemented for IO library instead if necessary.

The main reason I want this is because os.time provides an OK way to initially seed RNG on game first boot. But it would also be cute to let Lua modders be able to re-implement Christmas mode / day&night cycles themselves :p

src/blua/Sourcefile

@@ -23,3 +23,4 @@ lstring.c
 ltable.c
 ltm.c
 lvm.c
+loslib.c

src/blua/linit.c

@@ -18,6 +18,7 @@ static const luaL_Reg lualibs[] = {
   {"", luaopen_base},
   {LUA_TABLIBNAME, luaopen_table},
   {LUA_IOLIBNAME, luaopen_io},
+  {LUA_OSLIBNAME, luaopen_os},
   {LUA_STRLIBNAME, luaopen_string},
   {NULL, NULL}
 };

src/blua/loslib.c

@@ -0,0 +1,167 @@
+/*
+** $Id: loslib.c,v 1.19.1.3 2008/01/18 16:38:18 roberto Exp $
+** Standard Operating System library
+** See Copyright Notice in lua.h
+*/
+
+
+#include <errno.h>
+#include <locale.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#define loslib_c
+#define LUA_LIB
+
+#include "lua.h"
+
+#include "lauxlib.h"
+#include "lualib.h"
+
+
+static int os_clock (lua_State *L) {
+  lua_pushnumber(L, ((lua_Number)clock())/(lua_Number)CLOCKS_PER_SEC);
+  return 1;
+}
+
+
+/*
+** {======================================================
+** Time/Date operations
+** { year=%Y, month=%m, day=%d, hour=%H, min=%M, sec=%S,
+**   wday=%w+1, yday=%j, isdst=? }
+** =======================================================
+*/
+
+static void setfield (lua_State *L, const char *key, int value) {
+  lua_pushinteger(L, value);
+  lua_setfield(L, -2, key);
+}
+
+static void setboolfield (lua_State *L, const char *key, int value) {
+  if (value < 0)  /* undefined? */
+    return;  /* does not set field */
+  lua_pushboolean(L, value);
+  lua_setfield(L, -2, key);
+}
+
+static int getboolfield (lua_State *L, const char *key) {
+  int res;
+  lua_getfield(L, -1, key);
+  res = lua_isnil(L, -1) ? -1 : lua_toboolean(L, -1);
+  lua_pop(L, 1);
+  return res;
+}
+
+
+static int getfield (lua_State *L, const char *key, int d) {
+  int res;
+  lua_getfield(L, -1, key);
+  if (lua_isnumber(L, -1))
+    res = (int)lua_tointeger(L, -1);
+  else {
+    if (d < 0)
+      return luaL_error(L, "field " LUA_QS " missing in date table", key);
+    res = d;
+  }
+  lua_pop(L, 1);
+  return res;
+}
+
+
+static int os_date (lua_State *L) {
+  const char *s = luaL_optstring(L, 1, "%c");
+  time_t t = luaL_opt(L, (time_t)luaL_checknumber, 2, time(NULL));
+  struct tm *stm;
+  if (*s == '!') {  /* UTC? */
+    stm = gmtime(&t);
+    s++;  /* skip `!' */
+  }
+  else
+    stm = localtime(&t);
+  if (stm == NULL)  /* invalid date? */
+    lua_pushnil(L);
+  else if (strcmp(s, "*t") == 0) {
+    lua_createtable(L, 0, 9);  /* 9 = number of fields */
+    setfield(L, "sec", stm->tm_sec);
+    setfield(L, "min", stm->tm_min);
+    setfield(L, "hour", stm->tm_hour);
+    setfield(L, "day", stm->tm_mday);
+    setfield(L, "month", stm->tm_mon+1);
+    setfield(L, "year", stm->tm_year+1900);
+    setfield(L, "wday", stm->tm_wday+1);
+    setfield(L, "yday", stm->tm_yday+1);
+    setboolfield(L, "isdst", stm->tm_isdst);
+  }
+  else {
+    char cc[3];
+    luaL_Buffer b;
+    cc[0] = '%'; cc[2] = '\0';
+    luaL_buffinit(L, &b);
+    for (; *s; s++) {
+      if (*s != '%' || *(s + 1) == '\0')  /* no conversion specifier? */
+        luaL_addchar(&b, *s);
+      else {
+        size_t reslen;
+        char buff[200];  /* should be big enough for any conversion result */
+        cc[1] = *(++s);
+        reslen = strftime(buff, sizeof(buff), cc, stm);
+        luaL_addlstring(&b, buff, reslen);
+      }
+    }
+    luaL_pushresult(&b);
+  }
+  return 1;
+}
+
+
+static int os_time (lua_State *L) {
+  time_t t;
+  if (lua_isnoneornil(L, 1))  /* called without args? */
+    t = time(NULL);  /* get current time */
+  else {
+    struct tm ts;
+    luaL_checktype(L, 1, LUA_TTABLE);
+    lua_settop(L, 1);  /* make sure table is at the top */
+    ts.tm_sec = getfield(L, "sec", 0);
+    ts.tm_min = getfield(L, "min", 0);
+    ts.tm_hour = getfield(L, "hour", 12);
+    ts.tm_mday = getfield(L, "day", -1);
+    ts.tm_mon = getfield(L, "month", -1) - 1;
+    ts.tm_year = getfield(L, "year", -1) - 1900;
+    ts.tm_isdst = getboolfield(L, "isdst");
+    t = mktime(&ts);
+  }
+  if (t == (time_t)(-1))
+    lua_pushnil(L);
+  else
+    lua_pushnumber(L, (lua_Number)t);
+  return 1;
+}
+
+
+static int os_difftime (lua_State *L) {
+  lua_pushnumber(L, difftime((time_t)(luaL_checknumber(L, 1)),
+                             (time_t)(luaL_optnumber(L, 2, 0))));
+  return 1;
+}
+
+/* }====================================================== */
+
+static const luaL_Reg syslib[] = {
+  {"clock",     os_clock},
+  {"date",      os_date},
+  {"difftime",  os_difftime},
+  {"time",      os_time},
+  {NULL, NULL}
+};
+
+/* }====================================================== */
+
+
+
+LUALIB_API int luaopen_os (lua_State *L) {
+  luaL_register(L, LUA_OSLIBNAME, syslib);
+  return 1;
+}

src/blua/lualib.h

@@ -24,6 +24,9 @@ LUALIB_API int (luaopen_table) (lua_State *L);
 #define LUA_IOLIBNAME	"io"
 LUALIB_API int (luaopen_io) (lua_State *L);
 
+#define LUA_OSLIBNAME	"os"
+LUALIB_API int (luaopen_os) (lua_State *L);
+
 #define LUA_STRLIBNAME	"string"
 LUALIB_API int (luaopen_string) (lua_State *L);