/*
** $Id: liolib.c,v 2.73.1.4 2010/05/14 15:33:51 roberto Exp $
** Standard I/O (and system) library
** See Copyright Notice in lua.h
*/

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define liolib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"

#define IO_INPUT 1
#define IO_OUTPUT 2

static const char *const fnames[] = {"input", "output"};

static int pushresult(lua_State *L, int i, const char *filename)
{
    int en = errno; /* calls to Lua API may change this value */
    if (i) {
        lua_pushboolean(L, 1);
        return 1;
    }
    else {
        lua_pushnil(L);
        if (filename)
            lua_pushfstring(L, "%s: %s", filename, strerror(en));
        else
            lua_pushfstring(L, "%s", strerror(en));
        lua_pushinteger(L, en);
        return 3;
    }
}

static void fileerror(lua_State *L, int arg, const char *filename)
{
    lua_pushfstring(L, "%s: %s", filename, strerror(errno));
    luaL_argerror(L, arg, lua_tostring(L, -1));
}

#define tofilep(L) ((FILE **)luaL_checkudata(L, 1, LUA_FILEHANDLE))

static int io_type(lua_State *L)
{
    void *ud;
    luaL_checkany(L, 1);
    ud = lua_touserdata(L, 1);
    lua_getfield(L, LUA_REGISTRYINDEX, LUA_FILEHANDLE);
    if (ud == NULL || !lua_getmetatable(L, 1) || !lua_rawequal(L, -2, -1))
        lua_pushnil(L); /* not a file */
    else if (*((FILE **)ud) == NULL)
        lua_pushliteral(L, "closed file");
    else
        lua_pushliteral(L, "file");
    return 1;
}

static FILE *tofile(lua_State *L)
{
    FILE **f = tofilep(L);
    if (*f == NULL)
        luaL_error(L, "attempt to use a closed file");
    return *f;
}

/*
** When creating file handles, always creates a `closed' file handle
** before opening the actual file; so, if there is a memory error, the
** file is not left opened.
*/
static FILE **newfile(lua_State *L)
{
    FILE **pf = (FILE **)lua_newuserdata(L, sizeof(FILE *));
    *pf = NULL; /* file handle is currently `closed' */
    luaL_getmetatable(L, LUA_FILEHANDLE);
    lua_setmetatable(L, -2);
    return pf;
}

/*
** function to (not) close the standard files stdin, stdout, and stderr
*/
static int io_noclose(lua_State *L)
{
    lua_pushnil(L);
    lua_pushliteral(L, "cannot close standard file");
    return 2;
}

/*
** function to close 'popen' files
*/
static int io_pclose(lua_State *L)
{
    FILE **p = tofilep(L);
    int ok = lua_pclose(L, *p);
    *p = NULL;
    return pushresult(L, ok, NULL);
}

/*
** function to close regular files
*/
static int io_fclose(lua_State *L)
{
    FILE **p = tofilep(L);
    int ok = (fclose(*p) == 0);
    *p = NULL;
    return pushresult(L, ok, NULL);
}

static int aux_close(lua_State *L)
{
    lua_getfenv(L, 1);
    lua_getfield(L, -1, "__close");
    return (lua_tocfunction(L, -1))(L);
}

static int io_close(lua_State *L)
{
    if (lua_isnone(L, 1))
        lua_rawgeti(L, LUA_ENVIRONINDEX, IO_OUTPUT);
    tofile(L); /* make sure argument is a file */
    return aux_close(L);
}

static int io_gc(lua_State *L)
{
    FILE *f = *tofilep(L);
    /* ignore closed files */
    if (f != NULL)
        aux_close(L);
    return 0;
}

static int io_tostring(lua_State *L)
{
    FILE *f = *tofilep(L);
    if (f == NULL)
        lua_pushliteral(L, "file (closed)");
    else
        lua_pushfstring(L, "file (%p)", f);
    return 1;
}

static int io_open(lua_State *L)
{
    const char *filename = luaL_checkstring(L, 1);
    const char *mode = luaL_optstring(L, 2, "r");
    FILE **pf = newfile(L);
    *pf = fopen(filename, mode);
    return (*pf == NULL) ? pushresult(L, 0, filename) : 1;
}

/*
** this function has a separated environment, which defines the
** correct __close for 'popen' files
*/
static int io_popen(lua_State *L)
{
    const char *filename = luaL_checkstring(L, 1);
    const char *mode = luaL_optstring(L, 2, "r");
    FILE **pf = newfile(L);
    *pf = lua_popen(L, filename, mode);
    return (*pf == NULL) ? pushresult(L, 0, filename) : 1;
}

static int io_tmpfile(lua_State *L)
{
    FILE **pf = newfile(L);
    *pf = tmpfile();
    return (*pf == NULL) ? pushresult(L, 0, NULL) : 1;
}

static FILE *getiofile(lua_State *L, int findex)
{
    FILE *f;
    lua_rawgeti(L, LUA_ENVIRONINDEX, findex);
    f = *(FILE **)lua_touserdata(L, -1);
    if (f == NULL)
        luaL_error(L, "standard %s file is closed", fnames[findex - 1]);
    return f;
}

static int g_iofile(lua_State *L, int f, const char *mode)
{
    if (!lua_isnoneornil(L, 1)) {
        const char *filename = lua_tostring(L, 1);
        if (filename) {
            FILE **pf = newfile(L);
            *pf = fopen(filename, mode);
            if (*pf == NULL)
                fileerror(L, 1, filename);
        }
        else {
            tofile(L); /* check that it's a valid file handle */
            lua_pushvalue(L, 1);
        }
        lua_rawseti(L, LUA_ENVIRONINDEX, f);
    }
    /* return current value */
    lua_rawgeti(L, LUA_ENVIRONINDEX, f);
    return 1;
}

static int io_input(lua_State *L) { return g_iofile(L, IO_INPUT, "r"); }

static int io_output(lua_State *L) { return g_iofile(L, IO_OUTPUT, "w"); }

static int io_readline(lua_State *L);

static void aux_lines(lua_State *L, int idx, int toclose)
{
    lua_pushvalue(L, idx);
    lua_pushboolean(L, toclose); /* close/not close file when finished */
    lua_pushcclosure(L, io_readline, 2);
}

static int f_lines(lua_State *L)
{
    tofile(L); /* check that it's a valid file handle */
    aux_lines(L, 1, 0);
    return 1;
}

static int io_lines(lua_State *L)
{
    if (lua_isnoneornil(L, 1)) { /* no arguments? */
        /* will iterate over default input */
        lua_rawgeti(L, LUA_ENVIRONINDEX, IO_INPUT);
        return f_lines(L);
    }
    else {
        const char *filename = luaL_checkstring(L, 1);
        FILE **pf = newfile(L);
        *pf = fopen(filename, "r");
        if (*pf == NULL)
            fileerror(L, 1, filename);
        aux_lines(L, lua_gettop(L), 1);
        return 1;
    }
}

/*
** {======================================================
** READ
** =======================================================
*/

static int read_number(lua_State *L, FILE *f)
{
    lua_Number d;
    if (fscanf(f, LUA_NUMBER_SCAN, &d) == 1) {
        lua_pushnumber(L, d);
        return 1;
    }
    else {
        lua_pushnil(L); /* "result" to be removed */
        return 0;       /* read fails */
    }
}

static int test_eof(lua_State *L, FILE *f)
{
    int c = getc(f);
    ungetc(c, f);
    lua_pushlstring(L, NULL, 0);
    return (c != EOF);
}

static int read_line(lua_State *L, FILE *f)
{
    luaL_Buffer b;
    luaL_buffinit(L, &b);
    for (;;) {
        size_t l;
        char *p = luaL_prepbuffer(&b);
        if (fgets(p, LUAL_BUFFERSIZE, f) == NULL) { /* eof? */
            luaL_pushresult(&b);                    /* close buffer */
            return (lua_objlen(L, -1) > 0); /* check whether read something */
        }
        l = strlen(p);
        if (l == 0 || p[l - 1] != '\n')
            luaL_addsize(&b, l);
        else {
            luaL_addsize(&b, l - 1); /* do not include `eol' */
            luaL_pushresult(&b);     /* close buffer */
            return 1;                /* read at least an `eol' */
        }
    }
}

static int read_chars(lua_State *L, FILE *f, size_t n)
{
    size_t rlen; /* how much to read */
    size_t nr;   /* number of chars actually read */
    luaL_Buffer b;
    luaL_buffinit(L, &b);
    rlen = LUAL_BUFFERSIZE; /* try to read that much each time */
    do {
        char *p = luaL_prepbuffer(&b);
        if (rlen > n)
            rlen = n; /* cannot read more than asked */
        nr = fread(p, sizeof(char), rlen, f);
        luaL_addsize(&b, nr);
        n -= nr;                   /* still have to read `n' chars */
    } while (n > 0 && nr == rlen); /* until end of count or eof */
    luaL_pushresult(&b);           /* close buffer */
    return (n == 0 || lua_objlen(L, -1) > 0);
}

static int g_read(lua_State *L, FILE *f, int first)
{
    int nargs = lua_gettop(L) - 1;
    int success;
    int n;
    clearerr(f);
    if (nargs == 0) { /* no arguments? */
        success = read_line(L, f);
        n = first + 1; /* to return 1 result */
    }
    else { /* ensure stack space for all results and for auxlib's buffer */
        luaL_checkstack(L, nargs + LUA_MINSTACK, "too many arguments");
        success = 1;
        for (n = first; nargs-- && success; n++) {
            if (lua_type(L, n) == LUA_TNUMBER) {
                size_t l = (size_t)lua_tointeger(L, n);
                success = (l == 0) ? test_eof(L, f) : read_chars(L, f, l);
            }
            else {
                const char *p = lua_tostring(L, n);
                luaL_argcheck(L, p && p[0] == '*', n, "invalid option");
                switch (p[1]) {
                case 'n': /* number */
                    success = read_number(L, f);
                    break;
                case 'l': /* line */
                    success = read_line(L, f);
                    break;
                case 'a':                           /* file */
                    read_chars(L, f, ~((size_t)0)); /* read MAX_SIZE_T chars */
                    success = 1;                    /* always success */
                    break;
                default:
                    return luaL_argerror(L, n, "invalid format");
                }
            }
        }
    }
    if (ferror(f))
        return pushresult(L, 0, NULL);
    if (!success) {
        lua_pop(L, 1);  /* remove last result */
        lua_pushnil(L); /* push nil instead */
    }
    return n - first;
}

static int io_read(lua_State *L)
{
    return g_read(L, getiofile(L, IO_INPUT), 1);
}

static int f_read(lua_State *L) { return g_read(L, tofile(L), 2); }

static int io_readline(lua_State *L)
{
    FILE *f = *(FILE **)lua_touserdata(L, lua_upvalueindex(1));
    int sucess;
    if (f == NULL) /* file is already closed? */
        luaL_error(L, "file is already closed");
    sucess = read_line(L, f);
    if (ferror(f))
        return luaL_error(L, "%s", strerror(errno));
    if (sucess)
        return 1;
    else { /* EOF */
        if (lua_toboolean(L,
                          lua_upvalueindex(2))) { /* generator created file? */
            lua_settop(L, 0);
            lua_pushvalue(L, lua_upvalueindex(1));
            aux_close(L); /* close it */
        }
        return 0;
    }
}

/* }====================================================== */

static int g_write(lua_State *L, FILE *f, int arg)
{
    int nargs = lua_gettop(L) - 1;
    int status = 1;
    for (; nargs--; arg++) {
        if (lua_type(L, arg) == LUA_TNUMBER) {
            /* optimization: could be done exactly as for strings */
            status =
                status && fprintf(f, LUA_NUMBER_FMT, lua_tonumber(L, arg)) > 0;
        }
        else {
            size_t l;
            const char *s = luaL_checklstring(L, arg, &l);
            status = status && (fwrite(s, sizeof(char), l, f) == l);
        }
    }
    return pushresult(L, status, NULL);
}

static int io_write(lua_State *L)
{
    return g_write(L, getiofile(L, IO_OUTPUT), 1);
}

static int f_write(lua_State *L) { return g_write(L, tofile(L), 2); }

static int f_seek(lua_State *L)
{
    static const int mode[] = {SEEK_SET, SEEK_CUR, SEEK_END};
    static const char *const modenames[] = {"set", "cur", "end", NULL};
    FILE *f = tofile(L);
    int op = luaL_checkoption(L, 2, "cur", modenames);
    long offset = luaL_optlong(L, 3, 0);
    op = fseek(f, offset, mode[op]);
    if (op)
        return pushresult(L, 0, NULL); /* error */
    else {
        lua_pushinteger(L, ftell(f));
        return 1;
    }
}

static int f_setvbuf(lua_State *L)
{
    static const int mode[] = {_IONBF, _IOFBF, _IOLBF};
    static const char *const modenames[] = {"no", "full", "line", NULL};
    FILE *f = tofile(L);
    int op = luaL_checkoption(L, 2, NULL, modenames);
    lua_Integer sz = luaL_optinteger(L, 3, LUAL_BUFFERSIZE);
    int res = setvbuf(f, NULL, mode[op], sz);
    return pushresult(L, res == 0, NULL);
}

static int io_flush(lua_State *L)
{
    return pushresult(L, fflush(getiofile(L, IO_OUTPUT)) == 0, NULL);
}

static int f_flush(lua_State *L)
{
    return pushresult(L, fflush(tofile(L)) == 0, NULL);
}

static const luaL_Reg iolib[] = {
    {"close", io_close}, {"flush", io_flush}, {"input", io_input},
    {"lines", io_lines}, {"open", io_open},   {"output", io_output},
    {"popen", io_popen}, {"read", io_read},   {"tmpfile", io_tmpfile},
    {"type", io_type},   {"write", io_write}, {NULL, NULL}};

static const luaL_Reg flib[] = {
    {"close", io_close}, {"flush", f_flush}, {"lines", f_lines},
    {"read", f_read},    {"seek", f_seek},   {"setvbuf", f_setvbuf},
    {"write", f_write},  {"__gc", io_gc},    {"__tostring", io_tostring},
    {NULL, NULL}};

static void createmeta(lua_State *L)
{
    luaL_newmetatable(L,
                      LUA_FILEHANDLE); /* create metatable for file handles */
    lua_pushvalue(L, -1);              /* push metatable */
    lua_setfield(L, -2, "__index");    /* metatable.__index = metatable */
    luaL_register(L, NULL, flib);      /* file methods */
}

static void createstdfile(lua_State *L, FILE *f, int k, const char *fname)
{
    *newfile(L) = f;
    if (k > 0) {
        lua_pushvalue(L, -1);
        lua_rawseti(L, LUA_ENVIRONINDEX, k);
    }
    lua_pushvalue(L, -2); /* copy environment */
    lua_setfenv(L, -2);   /* set it */
    lua_setfield(L, -3, fname);
}

static void newfenv(lua_State *L, lua_CFunction cls)
{
    lua_createtable(L, 0, 1);
    lua_pushcfunction(L, cls);
    lua_setfield(L, -2, "__close");
}

LUALIB_API int luaopen_io(lua_State *L)
{
    createmeta(L);
    /* create (private) environment (with fields IO_INPUT, IO_OUTPUT, __close) */
    newfenv(L, io_fclose);
    lua_replace(L, LUA_ENVIRONINDEX);
    /* open library */
    luaL_register(L, LUA_IOLIBNAME, iolib);
    /* create (and set) default files */
    newfenv(L, io_noclose); /* close function for default files */
    createstdfile(L, stdin, IO_INPUT, "stdin");
    createstdfile(L, stdout, IO_OUTPUT, "stdout");
    createstdfile(L, stderr, 0, "stderr");
    lua_pop(L, 1); /* pop environment for default files */
    lua_getfield(L, -1, "popen");
    newfenv(L, io_pclose); /* create environment for 'popen' */
    lua_setfenv(L, -2);    /* set fenv for 'popen' */
    lua_pop(L, 1);         /* pop 'popen' */
    return 1;
}
