libs/nixio/src/file.c

   1 /*
   2  * nixio - Linux I/O library for lua
   3  *
   4  *   Copyright (C) 2009 Steven Barth <steven@midlink.org>
   5  *
   6  *  Licensed under the Apache License, Version 2.0 (the "License");
   7  *  you may not use this file except in compliance with the License.
   8  *  You may obtain a copy of the License at
   9  *
  10  *      http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  *  Unless required by applicable law or agreed to in writing, software
  13  *  distributed under the License is distributed on an "AS IS" BASIS,
  14  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  *  See the License for the specific language governing permissions and
  16  *  limitations under the License.
  17  */
  18
  19 #include "nixio.h"
  20 #include <errno.h>
  21 #include <stdlib.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25
  26
  27 static int nixio_file(lua_State *L) {
  28         const char *filename = luaL_checklstring(L, 1, NULL);
  29         const char *mode = luaL_optlstring(L, 2, "r", NULL);
  30
  31         FILE *file = fopen(filename, mode);
  32         if (!file) {
  33                 return nixio__perror(L);
  34         }
  35
  36         FILE **udata = lua_newuserdata(L, sizeof(FILE**));
  37         *udata = file;
  38
  39         luaL_getmetatable(L, NIXIO_FILE_META);
  40         lua_setmetatable(L, -2);
  41
  42         return 1;
  43 }
  44
  45 static int nixio_pipe(lua_State *L) {
  46         int pipefd[2];
  47         FILE **udata;
  48         if (pipe(pipefd)) {
  49                 return nixio__perror(L);
  50         }
  51
  52         luaL_getmetatable(L, NIXIO_FILE_META);
  53         udata = lua_newuserdata(L, sizeof(FILE**));
  54         if (!(*udata = fdopen(pipefd[0], "r"))) {
  55                 return nixio__perror(L);
  56         }
  57         lua_pushvalue(L, -2);
  58         lua_setmetatable(L, -2);
  59
  60
  61         udata = lua_newuserdata(L, sizeof(FILE**));
  62         if (!(*udata = fdopen(pipefd[1], "w"))) {
  63                 return nixio__perror(L);
  64         }
  65         lua_pushvalue(L, -3);
  66         lua_setmetatable(L, -2);
  67
  68         return 2;
  69 }
  70
  71 static int nixio_file_write(lua_State *L) {
  72         FILE *fp = nixio__checkfile(L);
  73         size_t len, written;
  74         const char *data = luaL_checklstring(L, 2, &len);
  75         written = fwrite(data, sizeof(char), len, fp);
  76         if (written < 0) {
  77                 return nixio__perror(L);
  78         } else {
  79                 return written;
  80         }
  81 }
  82
  83
  84 /* Some code borrowed from Lua 5.1.4 liolib.c */
  85 static int nixio_file_read(lua_State *L) {
  86         FILE *f = nixio__checkfile(L);
  87         size_t n = (size_t)luaL_checkinteger(L, 2);
  88         luaL_argcheck(L, 2, n >= 0, "invalid length");
  89
  90         if (n == 0) {
  91                 if (feof(f)) {
  92                         return 0;
  93                 } else {
  94                         lua_pushliteral(L, "");
  95                         return 1;
  96                 }
  97         }
  98
  99         size_t rlen;  /* how much to read */
 100         size_t nr;  /* number of chars actually read */
 101         luaL_Buffer b;
 102         luaL_buffinit(L, &b);
 103         rlen = LUAL_BUFFERSIZE;  /* try to read that much each time */
 104
 105         do {
 106                 char *p = luaL_prepbuffer(&b);
 107                 if (rlen > n) rlen = n;  /* cannot read more than asked */
 108                         nr = fread(p, sizeof(char), rlen, f);
 109                         luaL_addsize(&b, nr);
 110                         n -= nr;  /* still have to read `n' chars */
 111         } while (n > 0 && nr == rlen);  /* until end of count or eof */
 112         luaL_pushresult(&b);  /* close buffer */
 113         return (n == 0 || lua_objlen(L, -1) > 0);
 114 }
 115
 116 static int nixio_file_seek(lua_State *L) {
 117         FILE *f = nixio__checkfile(L);
 118         off_t len = (off_t)luaL_checknumber(L, 2);
 119         int whence;
 120         const char *whstr = luaL_optlstring(L, 3, "set", NULL);
 121         if (!strcmp(whstr, "set")) {
 122                 whence = SEEK_SET;
 123         } else if (!strcmp(whstr, "cur")) {
 124                 whence = SEEK_CUR;
 125         } else if (!strcmp(whstr, "end")) {
 126                 whence = SEEK_END;
 127         } else {
 128                 return luaL_argerror(L, 3, "supported values: set, cur, end");
 129         }
 130         return nixio__pstatus(L, !fseeko(f, len, whence));
 131 }
 132
 133 static int nixio_file_tell(lua_State *L) {
 134         FILE *f = nixio__checkfile(L);
 135         off_t pos = ftello(f);
 136         if (pos < 0) {
 137                 return nixio__perror(L);
 138         } else {
 139                 lua_pushnumber(L, (lua_Number)pos);
 140                 return 1;
 141         }
 142 }
 143
 144 static int nixio_file_flush(lua_State *L) {
 145         FILE *f = nixio__checkfile(L);
 146         return nixio__pstatus(L, !fflush(f));
 147 }
 148
 149 static int nixio_file_close(lua_State *L) {
 150         FILE **fpp = (FILE**)luaL_checkudata(L, 1, NIXIO_FILE_META);
 151         luaL_argcheck(L, *fpp, 1, "invalid file object");
 152         int res = fclose(*fpp);
 153         *fpp = NULL;
 154         return nixio__pstatus(L, !res);
 155 }
 156
 157 static int nixio_file__gc(lua_State *L) {
 158         FILE **fpp = (FILE**)luaL_checkudata(L, 1, NIXIO_FILE_META);
 159         if (*fpp) {
 160                 fclose(*fpp);
 161                 *fpp = NULL;
 162         }
 163         return 0;
 164 }
 165
 166 /**
 167  * string representation
 168  */
 169 static int nixio_file__tostring(lua_State *L) {
 170         lua_pushfstring(L, "nixio file %d", nixio__tofd(L, 1));
 171         return 1;
 172 }
 173
 174 /* method table */
 175 static const luaL_reg M[] = {
 176         {"write",               nixio_file_write},
 177         {"read",                nixio_file_read},
 178         {"tell",                nixio_file_tell},
 179         {"seek",                nixio_file_seek},
 180         {"flush",               nixio_file_flush},
 181         {"close",               nixio_file_close},
 182         {"__gc",                nixio_file__gc},
 183         {"__tostring",  nixio_file__tostring},
 184         {NULL,                  NULL}
 185 };
 186
 187 /* module table */
 188 static const luaL_reg R[] = {
 189         {"open",                nixio_file},
 190         {"pipe",                nixio_pipe},
 191         {NULL,                  NULL}
 192 };
 193
 194 void nixio_open_file(lua_State *L) {
 195         luaL_register(L, NULL, R);
 196
 197         luaL_newmetatable(L, NIXIO_FILE_META);
 198         luaL_register(L, NULL, M);
 199         lua_pushvalue(L, -1);
 200         lua_setfield(L, -2, "__index");
 201         lua_pop(L, 1);
 202 }