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/************************************************************************
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* Author : Tiago Dionizio (tngd@mega.ist.utl.pt) *
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* Library : lgzip - a gzip file access binding for Lua 5 *
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* based on liolib.c from Lua 5.0 library *
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* Permission is hereby granted, free of charge, to any person obtaining *
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* a copy of this software and associated documentation files (the *
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* "Software"), to deal in the Software without restriction, including *
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* without limitation the rights to use, copy, modify, merge, publish, *
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* distribute, sublicense, and/or sell copies of the Software, and to *
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* permit persons to whom the Software is furnished to do so, subject to *
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* the following conditions: *
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* The above copyright notice and this permission notice shall be *
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* included in all copies or substantial portions of the Software. *
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, *
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY *
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, *
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE *
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
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************************************************************************/
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/************************************************************************
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$Id: lgzip.c,v 1.2 2003/12/28 01:26:16 tngd Exp $
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************************************************************************/
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** {======================================================
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** =======================================================
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#define FILEHANDLE "zlib:gzFile"
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static int pushresult (lua_State *L, int i, const char *filename) {
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lua_pushboolean(L, 1);
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lua_pushfstring(L, "%s: %s", filename, strerror(errno));
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lua_pushfstring(L, "%s", strerror(errno));
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lua_pushnumber(L, errno);
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static gzFile *topfile (lua_State *L, int findex) {
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gzFile*f = (gzFile*)luaL_checkudata(L, findex, FILEHANDLE);
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if (f == NULL) luaL_argerror(L, findex, "bad file");
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static gzFile tofile (lua_State *L, int findex) {
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gzFile*f = topfile(L, findex);
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luaL_error(L, "attempt to use a closed file");
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** When creating file handles, always creates a `closed' file handle
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** before opening the actual file; so, if there is a memory error, the
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** file is not left opened.
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static gzFile *newfile (lua_State *L) {
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gzFile *pf = (gzFile*)lua_newuserdata(L, sizeof(gzFile));
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*pf = NULL; /* file handle is currently `closed' */
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luaL_getmetatable(L, FILEHANDLE);
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lua_setmetatable(L, -2);
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static int aux_close (lua_State *L) {
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gzFile f = tofile(L, 1);
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int ok = (gzclose(f) == Z_OK);
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*(gzFile*)lua_touserdata(L, 1) = NULL; /* mark file as closed */
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static int io_close (lua_State *L) {
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return pushresult(L, aux_close(L), NULL);
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static int io_gc (lua_State *L) {
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gzFile *f = topfile(L, 1);
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if (*f != NULL) /* ignore closed files */
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static int io_tostring (lua_State *L) {
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gzFile *f = topfile(L, 1);
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strcpy(buff, "closed");
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sprintf(buff, "%p", lua_touserdata(L, 1));
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lua_pushfstring(L, "gzip file (%s)", buff);
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static int io_open (lua_State *L) {
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const char *filename = luaL_checkstring(L, 1);
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const char *mode = luaL_optstring(L, 2, "rb");
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gzFile *pf = newfile(L);
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*pf = gzopen(filename, mode);
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return (*pf == NULL) ? pushresult(L, 0, filename) : 1;
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static int io_readline (lua_State *L);
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static void aux_lines (lua_State *L, int idx, int close) {
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lua_pushliteral(L, FILEHANDLE);
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lua_rawget(L, LUA_REGISTRYINDEX);
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lua_pushvalue(L, idx);
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lua_pushboolean(L, close); /* close/not close file when finished */
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lua_pushcclosure(L, io_readline, 3);
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static int f_lines (lua_State *L) {
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tofile(L, 1); /* check that it's a valid file handle */
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static int io_lines (lua_State *L) {
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const char *filename = luaL_checkstring(L, 1);
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gzFile *pf = newfile(L);
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*pf = gzopen(filename, "rb");
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luaL_argcheck(L, *pf, 1, strerror(errno));
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aux_lines(L, lua_gettop(L), 1);
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** {======================================================
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** =======================================================
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static int test_eof (lua_State *L, gzFile f) {
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lua_pushlstring(L, NULL, 0);
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return (gzeof(f) != 1);
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static int read_line (lua_State *L, gzFile f) {
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luaL_buffinit(L, &b);
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char *p = luaL_prepbuffer(&b);
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if (gzgets(f, p, LUAL_BUFFERSIZE) == NULL) { /* eof? */
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luaL_pushresult(&b); /* close buffer */
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return (lua_strlen(L, -1) > 0); /* check whether read something */
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luaL_addsize(&b, l - 1); /* do not include `eol' */
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luaL_pushresult(&b); /* close buffer */
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return 1; /* read at least an `eol' */
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static int read_chars (lua_State *L, gzFile f, size_t n) {
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size_t rlen; /* how much to read */
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size_t nr; /* number of chars actually read */
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luaL_buffinit(L, &b);
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rlen = LUAL_BUFFERSIZE; /* try to read that much each time */
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char *p = luaL_prepbuffer(&b);
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if (rlen > n) rlen = n; /* cannot read more than asked */
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nr = gzread(f, p, rlen);
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luaL_addsize(&b, nr);
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n -= nr; /* still have to read `n' chars */
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} while (n > 0 && nr == rlen); /* until end of count or eof */
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luaL_pushresult(&b); /* close buffer */
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return (n == 0 || lua_strlen(L, -1) > 0);
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static int g_read (lua_State *L, gzFile f, int first) {
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int nargs = lua_gettop(L) - 1;
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if (nargs == 0) { /* no arguments? */
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success = read_line(L, f);
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n = first+1; /* to return 1 result */
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else { /* ensure stack space for all results and for auxlib's buffer */
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luaL_checkstack(L, nargs+LUA_MINSTACK, "too many arguments");
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for (n = first; nargs-- && success; n++) {
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if (lua_type(L, n) == LUA_TNUMBER) {
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size_t l = (size_t)lua_tonumber(L, n);
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success = (l == 0) ? test_eof(L, f) : read_chars(L, f, l);
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const char *p = lua_tostring(L, n);
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luaL_argcheck(L, p && p[0] == '*', n, "invalid option");
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success = read_line(L, f);
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read_chars(L, f, ~((size_t)0)); /* read MAX_SIZE_T chars */
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success = 1; /* always success */
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return luaL_argerror(L, n, "invalid format");
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lua_pop(L, 1); /* remove last result */
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lua_pushnil(L); /* push nil instead */
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static int f_read (lua_State *L) {
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return g_read(L, tofile(L, 1), 2);
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static int io_readline (lua_State *L) {
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gzFile f = *(gzFile*)lua_touserdata(L, lua_upvalueindex(2));
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if (f == NULL) /* file is already closed? */
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luaL_error(L, "file is already closed");
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if (read_line(L, f)) return 1;
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if (lua_toboolean(L, lua_upvalueindex(3))) { /* generator created file? */
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lua_pushvalue(L, lua_upvalueindex(2));
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aux_close(L); /* close it */
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/* }====================================================== */
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static int g_write (lua_State *L, gzFile f, int arg) {
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int nargs = lua_gettop(L) - 1;
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for (; nargs--; arg++) {
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if (lua_type(L, arg) == LUA_TNUMBER) {
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/* optimization: could be done exactly as for strings */
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gzprintf(f, LUA_NUMBER_FMT, lua_tonumber(L, arg)) > 0;
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const char *s = luaL_checklstring(L, arg, &l);
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status = status && (gzwrite(f, (char*)s, l) == l);
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return pushresult(L, status, NULL);
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static int f_write (lua_State *L) {
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return g_write(L, tofile(L, 1), 2);
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static int f_seek (lua_State *L) {
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static const int mode[] = {SEEK_SET, SEEK_CUR};
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static const char *const modenames[] = {"set", "cur", NULL};
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gzFile f = tofile(L, 1);
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int op = luaL_checkoption(L, 2, "cur", modenames);
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long offset = luaL_optlong(L, 3, 0);
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luaL_argcheck(L, op != -1, 2, "invalid mode");
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op = gzseek(f, offset, mode[op]);
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return pushresult(L, 0, NULL); /* error */
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lua_pushnumber(L, op);
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static int f_flush (lua_State *L) {
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return pushresult(L, gzflush(tofile(L, 1), Z_FINISH) == Z_OK, NULL);
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static const luaL_reg iolib[] = {
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static const luaL_reg flib[] = {
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{"__tostring", io_tostring},
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static void createmeta (lua_State *L) {
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luaL_newmetatable(L, FILEHANDLE); /* create new metatable for file handles */
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lua_pushliteral(L, "__index");
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lua_pushvalue(L, -2); /* push metatable */
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lua_rawset(L, -3); /* metatable.__index = metatable */
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luaL_openlib(L, NULL, flib, 0);
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/* }====================================================== */
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LUALIB_API int luaopen_gzip (lua_State *L) {
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lua_pushvalue(L, -1);
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luaL_openlib(L, "gzip", iolib, 1);