Re: Redirecting stdin/stdout/stderr in embedded environment
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- Subject: Re: Redirecting stdin/stdout/stderr in embedded environment
- From: Paul Moore <pf_moore@...>
- Date: 2007年4月19日 21:54:55 +0100
Paul Moore wrote:
Maybe the simplest way would be a small tweak to liolib.c to expose a C API
for resetting the FILE* handles that io.stdin/out/err point to. I can do this
locally, but would such a change be considered for inclusion in the next
release of Lua?
With a bit more reading, the following *seems* to work, and doesn't
require modifying liolib.c. Can anyone confirm if it's correct? It's a
really ugly hack, but I can live with that :-)
/* IO hack. This replaces the io library's idea of stdin/out/err
* with 3 new FILE* handles, without altering the C stdin/out/err
* values.
*
* It's a hugely ugly hack, fiddling with the internals of the io
* library. Tested with 5.1.2, may or may not work with other
* versions...
*/
void hackio(lua_State *L, FILE *in, FILE *out, FILE *err) {
FILE **pf;
lua_getglobal(L, "io"); /* Get the IO library */
lua_pushstring(L, "open");
lua_gettable(L, -2); /* io, io.open */
lua_getfenv(L, -1); /* io, io.open, io.open's env */
lua_getglobal(L, "io"); /* io, open, env, io */
lua_pushstring(L, "stdin");
lua_gettable(L, -2); /* io, open, env, io, io.stdin */
pf = (FILE **)lua_touserdata(L, -1);
*pf = in;
lua_rawseti(L, -3, 1); /* IO_INPUT = 1 */
lua_pushstring(L, "stdout");
lua_gettable(L, -2); /* io, open, env, io, io.stdout */
pf = (FILE **)lua_touserdata(L, -1);
*pf = out;
lua_rawseti(L, -3, 2); /* IO_OUTPUT = 2 */
lua_pushstring(L, "stderr");
lua_gettable(L, -2); /* io, open, env, io, io.stderr */
pf = (FILE **)lua_touserdata(L, -1);
*pf = err;
lua_pop(L, 5);
}
Paul.