misc/lua/lzlib/lzlib.c

   1 /*
   2  * --- T2-COPYRIGHT-NOTE-BEGIN ---
   3  * This copyright note is auto-generated by ./scripts/Create-CopyPatch.
   4  *
   5  * T2 SDE: misc/lua/lzlib/lzlib.c
   6  * Copyright (C) 2004 - 2006 The T2 SDE Project
   7  *
   8  * More information can be found in the files COPYING and README.
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; version 2 of the License. A copy of the
  13  * GNU General Public License can be found in the file COPYING.
  14  * --- T2-COPYRIGHT-NOTE-END ---
  15  */
  16 // compilation: gcc --shared lzlib.c -o lzlib.so -lz
  17 // contains some slightly addapted code pieces from lua's liolib.c
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <errno.h>
  23 #include <zlib.h>
  24 #include <lua.h>
  25 #include <lauxlib.h>
  26
  27 #define ZLIB_HANDLE "gzFile"
  28
  29 // ------------------- helper functions ------------------------
  30
  31 // pushes gzFile operation result string on lua stack
  32
  33 // first value is either true or nil (== operation failed),
  34 // in the latter case a string containing the error message and
  35 // the nummerical error codes (gzerror / errno) are returned
  36 // as additional values
  37
  38 static int pushresult (lua_State *L, gzFile* zf, const char *filename)
  39 {
  40   int zlib_result;
  41   const char* zmessage;
  42   if ((zf) == NULL)
  43     zlib_result = Z_ERRNO;
  44   else
  45     zmessage = gzerror (*zf, &zlib_result);
  46
  47   if (zlib_result == Z_OK) {
  48     lua_pushboolean(L, 1);
  49     return 1;
  50   } else {
  51
  52     if (zlib_result == Z_ERRNO) // error is a file io error
  53       zmessage = strerror(errno);
  54
  55     lua_pushnil(L);
  56
  57     if (filename)
  58       lua_pushfstring(L, "%s: %s", filename, zmessage);
  59     else
  60       lua_pushfstring(L, "%s", zmessage);
  61
  62     lua_pushinteger(L, zlib_result);
  63     lua_pushinteger(L, errno);
  64
  65     return 4;
  66   }
  67 }
  68
  69 // ensures first argument is an open zlib handle and returns it
  70 static gzFile *tozfile (lua_State *L)
  71 {
  72   gzFile *zf = ((gzFile *) luaL_checkudata(L, 1, ZLIB_HANDLE));
  73
  74   if (*zf == NULL)
  75     luaL_error(L, "attempt to use a closed gz file");
  76   return zf;
  77 }
  78
  79 // ----------------- poor man buffer in C ---------------------
  80
  81 char* content_buffer = NULL;
  82 size_t content_buffer_length = 0;
  83 size_t content_length = 0;
  84
  85 static inline void ResetBuffer ()
  86 {
  87   content_length = 0;
  88 }
  89
  90 static inline void ExtendBufferBySize (size_t min_size)
  91 {
  92   if (min_size > content_buffer_length) {
  93     if (content_buffer_length == 0)
  94       content_buffer = malloc (min_size);
  95     else
  96       content_buffer = realloc (content_buffer, min_size);
  97     content_buffer_length = min_size;
  98   }
  99 }
 100
 101 static inline void ExtendBuffer ()
 102 {
 103   ExtendBufferBySize ((content_buffer_length < 256) ? 256 : 2 * content_buffer_length);
 104   // for testing:  ExtendBufferBySize ((content_buffer_length < 10) ? 10 : 2 + content_buffer_length);
 105 }
 106
 107 static inline void AddToBuffer (char c)
 108 {
 109   if (content_buffer_length == content_length)
 110     ExtendBuffer ();
 111   content_buffer [content_length++] = c;
 112 }
 113
 114 static inline const char* FinishBuffer ()
 115 {
 116   AddToBuffer ('\0');
 117   return content_buffer;
 118 }
 119
 120 static inline int BufferFill ()
 121 {
 122   return content_length;
 123 }
 124
 125 static inline int BufferFree ()
 126 {
 127   return (content_buffer_length - content_length);
 128 }
 129
 130 // -------------------------- API ------------------------------
 131
 132 static int gz_open (lua_State *L)
 133 {
 134   const char *filename = luaL_checkstring(L, 1);
 135   const char *mode = luaL_optstring(L, 2, "r");
 136
 137   gzFile* zf = (gzFile *) lua_newuserdata(L, sizeof(gzFile));
 138   luaL_getmetatable(L, ZLIB_HANDLE);
 139   lua_setmetatable(L, -2);
 140
 141   *zf = gzopen(filename, mode);
 142
 143   return (*zf == NULL) ? pushresult(L, NULL, filename) : 1;
 144 }
 145
 146 static int gz_close (lua_State *L)
 147 {
 148   gzFile *zf = tozfile(L);
 149   int result = gzclose(*zf);
 150   *zf = NULL;
 151
 152   // need to emulate pushresult behavior, because gzerror
 153   // does not work anymore after closing stream *grrrr*
 154
 155   if (result == Z_OK) {
 156     lua_pushboolean (L, 1);
 157     return 1;
 158   } else {
 159     const char* zmessage;
 160     if (result == Z_ERRNO) // error is a file io error
 161       zmessage = strerror(errno);
 162     else
 163       zmessage = zError(result);
 164
 165     lua_pushnil(L);
 166     lua_pushfstring(L, zmessage);
 167     lua_pushinteger(L, result);
 168     lua_pushinteger(L, errno);
 169     return 4;
 170   }
 171 }
 172
 173
 174 static int __gz_lines_iterator (lua_State *L)
 175 {
 176   gzFile zf = (gzFile) lua_topointer (L, lua_upvalueindex(1));
 177   int ch = '\0';
 178   char* ret;
 179
 180   if (content_buffer_length == 0)
 181     ExtendBuffer ();
 182   else
 183     ResetBuffer ();
 184
 185   #ifdef READ_LINE_ONE_BY_ONE
 186
 187   while ( (ch = gzgetc(zf)) != -1 && ch != '\n') {
 188     AddToBuffer ((char) ch);
 189   }
 190
 191   #else
 192
 193   do {
 194     ret = gzgets (zf, content_buffer + BufferFill (), BufferFree ());
 195     if (ret == Z_NULL)
 196       break;
 197     int l = strlen (content_buffer);
 198     content_length = l;
 199     if (l > 0) {
 200       ch = content_buffer[l - 1];
 201       if (ch != '\n')
 202         ExtendBuffer ();
 203       else
 204         content_buffer[l-1] = '\0';
 205     }
 206   } while (ret && ch != '\n');
 207
 208   #endif
 209
 210   if (ch == '\n' || BufferFill () > 0) {
 211     if (ch == '\n')
 212
 213     lua_pushstring (L, FinishBuffer ());
 214     return 1;
 215   } else {
 216     return pushresult(L, &zf, NULL);
 217   }
 218 }
 219
 220
 221 static int gz_lines (lua_State *L)
 222 {
 223   gzFile *zf = tozfile(L);
 224   lua_pushlightuserdata (L, *zf);
 225   lua_pushcclosure (L, __gz_lines_iterator, 1);
 226   return 1;
 227 }
 228
 229 static int gz_status (lua_State *L)
 230 {
 231   gzFile *zf = tozfile(L);
 232   return pushresult (L, zf, NULL);
 233 }
 234
 235 static int gz_eof (lua_State *L)
 236 {
 237   gzFile *zf = tozfile(L);
 238   int eof = gzeof (*zf);
 239   lua_pushboolean(L, eof);
 240   if (eof == 1) {
 241     const char* eof_reason;
 242     int eof_reason_code;
 243     eof_reason = gzerror (*zf, &eof_reason_code);
 244     lua_pushboolean (L, eof_reason_code == Z_STREAM_END);
 245     lua_pushstring (L, eof_reason);
 246     return 3;
 247   }
 248   return 0;
 249 }
 250
 251 // ------------------- init and registering --------------------
 252
 253 static const luaL_reg R[] = {
 254   {"open", gz_open},
 255   {"close", gz_close},
 256   {"lines", gz_lines},
 257   {"status", gz_status},
 258   {"eof", gz_eof},
 259   {NULL, NULL}
 260 };
 261
 262 static const luaL_Reg zlib[] = {
 263   {"close", gz_close},
 264   {"lines", gz_lines},
 265   {"status", gz_status},
 266   {"eof", gz_eof},
 267   {"__gc", gz_close},
 268   {NULL, NULL}
 269 };
 270
 271 static void createmeta (lua_State *L) {
 272   luaL_newmetatable(L, ZLIB_HANDLE);  /* create metatable for zlib handles */
 273   lua_pushvalue(L, -1);  /* push metatable */
 274   lua_setfield(L, -2, "__index");  /* metatable.__index = metatable */
 275   luaL_register(L, NULL, zlib);  /* gz file methods */
 276 }
 277
 278 LUALIB_API int luaopen_lzlib (lua_State *L)
 279 {
 280   createmeta(L);
 281   luaL_openlib(L, "lzlib", R, 0);
 282   lua_pushliteral(L,"version");           /** version */
 283   lua_pushliteral(L,"pre-alpha");
 284   lua_settable(L,-3);
 285   return 1;
 286 }