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  1. /*
  2. ** $Id: liolib.c $
  3. ** Standard I/O (and system) library
  4. ** See Copyright Notice in lua.h
  5. */
  6.  
  7. #define liolib_c
  8. #define LUA_LIB
  9.  
  10. #include "lprefix.h"
  11.  
  12.  
  13. #include <ctype.h>
  14. #include <errno.h>
  15. #include <locale.h>
  16. #include <stdio.h>
  17. #include <stdlib.h>
  18. #include <string.h>
  19.  
  20. #include "lua.h"
  21.  
  22. #include "lauxlib.h"
  23. #include "lualib.h"
  24.  
  25.  
  26.  
  27.  
  28. /*
  29. ** Change this macro to accept other modes for 'fopen' besides
  30. ** the standard ones.
  31. */
  32. #if !defined(l_checkmode)
  33.  
  34. /* accepted extensions to 'mode' in 'fopen' */
  35. #if !defined(L_MODEEXT)
  36. #define L_MODEEXT       "b"
  37. #endif
  38.  
  39. /* Check whether 'mode' matches '[rwa]%+?[L_MODEEXT]*' */
  40. static int l_checkmode (const char *mode) {
  41.   return (*mode != '\0' && strchr("rwa", *(mode++)) != NULL &&
  42.          (*mode != '+' || ((void)(++mode), 1)) &&  /* skip if char is '+' */
  43.          (strspn(mode, L_MODEEXT) == strlen(mode)));  /* check extensions */
  44. }
  45.  
  46. #endif
  47.  
  48. /*
  49. ** {======================================================
  50. ** l_popen spawns a new process connected to the current
  51. ** one through the file streams.
  52. ** =======================================================
  53. */
  54.  
  55. #if !defined(l_popen)           /* { */
  56.  
  57. #if defined(LUA_USE_POSIX)      /* { */
  58.  
  59. #define l_popen(L,c,m)          (fflush(NULL), popen(c,m))
  60. #define l_pclose(L,file)        (pclose(file))
  61.  
  62. #elif defined(LUA_USE_WINDOWS)  /* }{ */
  63.  
  64. #define l_popen(L,c,m)          (_popen(c,m))
  65. #define l_pclose(L,file)        (_pclose(file))
  66.  
  67. #if !defined(l_checkmodep)
  68. /* Windows accepts "[rw][bt]?" as valid modes */
  69. #define l_checkmodep(m) ((m[0] == 'r' || m[0] == 'w') && \
  70.   (m[1] == '\0' || ((m[1] == 'b' || m[1] == 't') && m[2] == '\0')))
  71. #endif
  72.  
  73. #else                           /* }{ */
  74.  
  75. /* ISO C definitions */
  76. #define l_popen(L,c,m)  \
  77.           ((void)c, (void)m, \
  78.           luaL_error(L, "'popen' not supported"), \
  79.           (FILE*)0)
  80. #define l_pclose(L,file)                ((void)L, (void)file, -1)
  81.  
  82. #endif                          /* } */
  83.  
  84. #endif                          /* } */
  85.  
  86.  
  87. #if !defined(l_checkmodep)
  88. /* By default, Lua accepts only "r" or "w" as valid modes */
  89. #define l_checkmodep(m)        ((m[0] == 'r' || m[0] == 'w') && m[1] == '\0')
  90. #endif
  91.  
  92. /* }====================================================== */
  93.  
  94.  
  95. #if !defined(l_getc)            /* { */
  96.  
  97. #if defined(LUA_USE_POSIX)
  98. #define l_getc(f)               getc_unlocked(f)
  99. #define l_lockfile(f)           flockfile(f)
  100. #define l_unlockfile(f)         funlockfile(f)
  101. #else
  102. #define l_getc(f)               getc(f)
  103. #define l_lockfile(f)           ((void)0)
  104. #define l_unlockfile(f)         ((void)0)
  105. #endif
  106.  
  107. #endif                          /* } */
  108.  
  109.  
  110. /*
  111. ** {======================================================
  112. ** l_fseek: configuration for longer offsets
  113. ** =======================================================
  114. */
  115.  
  116. #if !defined(l_fseek)           /* { */
  117.  
  118. #if defined(LUA_USE_POSIX)      /* { */
  119.  
  120. #include <sys/types.h>
  121.  
  122. #define l_fseek(f,o,w)          fseeko(f,o,w)
  123. #define l_ftell(f)              ftello(f)
  124. #define l_seeknum               off_t
  125.  
  126. #elif defined(LUA_USE_WINDOWS) && !defined(_CRTIMP_TYPEINFO) \
  127.    && defined(_MSC_VER) && (_MSC_VER >= 1400)   /* }{ */
  128.  
  129. /* Windows (but not DDK) and Visual C++ 2005 or higher */
  130. #define l_fseek(f,o,w)          _fseeki64(f,o,w)
  131. #define l_ftell(f)              _ftelli64(f)
  132. #define l_seeknum               __int64
  133.  
  134. #else                           /* }{ */
  135.  
  136. /* ISO C definitions */
  137. #define l_fseek(f,o,w)          fseek(f,o,w)
  138. #define l_ftell(f)              ftell(f)
  139. #define l_seeknum               long
  140.  
  141. #endif                          /* } */
  142.  
  143. #endif                          /* } */
  144.  
  145. /* }====================================================== */
  146.  
  147.  
  148.  
  149. #define IO_PREFIX       "_IO_"
  150. #define IOPREF_LEN      (sizeof(IO_PREFIX)/sizeof(char) - 1)
  151. #define IO_INPUT        (IO_PREFIX "input")
  152. #define IO_OUTPUT       (IO_PREFIX "output")
  153.  
  154.  
  155. typedef luaL_Stream LStream;
  156.  
  157.  
  158. #define tolstream(L)    ((LStream *)luaL_checkudata(L, 1, LUA_FILEHANDLE))
  159.  
  160. #define isclosed(p)     ((p)->closef == NULL)
  161.  
  162.  
  163. static int io_type (lua_State *L) {
  164.   LStream *p;
  165.   luaL_checkany(L, 1);
  166.   p = (LStream *)luaL_testudata(L, 1, LUA_FILEHANDLE);
  167.   if (p == NULL)
  168.     luaL_pushfail(L);  /* not a file */
  169.   else if (isclosed(p))
  170.     lua_pushliteral(L, "closed file");
  171.   else
  172.     lua_pushliteral(L, "file");
  173.   return 1;
  174. }
  175.  
  176.  
  177. static int f_tostring (lua_State *L) {
  178.   LStream *p = tolstream(L);
  179.   if (isclosed(p))
  180.     lua_pushliteral(L, "file (closed)");
  181.   else
  182.     lua_pushfstring(L, "file (%p)", p->f);
  183.   return 1;
  184. }
  185.  
  186.  
  187. static FILE *tofile (lua_State *L) {
  188.   LStream *p = tolstream(L);
  189.   if (l_unlikely(isclosed(p)))
  190.     luaL_error(L, "attempt to use a closed file");
  191.   lua_assert(p->f);
  192.   return p->f;
  193. }
  194.  
  195.  
  196. /*
  197. ** When creating file handles, always creates a 'closed' file handle
  198. ** before opening the actual file; so, if there is a memory error, the
  199. ** handle is in a consistent state.
  200. */
  201. static LStream *newprefile (lua_State *L) {
  202.   LStream *p = (LStream *)lua_newuserdatauv(L, sizeof(LStream), 0);
  203.   p->closef = NULL;  /* mark file handle as 'closed' */
  204.   luaL_setmetatable(L, LUA_FILEHANDLE);
  205.   return p;
  206. }
  207.  
  208.  
  209. /*
  210. ** Calls the 'close' function from a file handle. The 'volatile' avoids
  211. ** a bug in some versions of the Clang compiler (e.g., clang 3.0 for
  212. ** 32 bits).
  213. */
  214. static int aux_close (lua_State *L) {
  215.   LStream *p = tolstream(L);
  216.   volatile lua_CFunction cf = p->closef;
  217.   p->closef = NULL;  /* mark stream as closed */
  218.   return (*cf)(L);  /* close it */
  219. }
  220.  
  221.  
  222. static int f_close (lua_State *L) {
  223.   tofile(L);  /* make sure argument is an open stream */
  224.   return aux_close(L);
  225. }
  226.  
  227.  
  228. static int io_close (lua_State *L) {
  229.   if (lua_isnone(L, 1))  /* no argument? */
  230.     lua_getfield(L, LUA_REGISTRYINDEX, IO_OUTPUT);  /* use default output */
  231.   return f_close(L);
  232. }
  233.  
  234.  
  235. static int f_gc (lua_State *L) {
  236.   LStream *p = tolstream(L);
  237.   if (!isclosed(p) && p->f != NULL)
  238.     aux_close(L);  /* ignore closed and incompletely open files */
  239.   return 0;
  240. }
  241.  
  242.  
  243. /*
  244. ** function to close regular files
  245. */
  246. static int io_fclose (lua_State *L) {
  247.   LStream *p = tolstream(L);
  248.   int res = fclose(p->f);
  249.   return luaL_fileresult(L, (res == 0), NULL);
  250. }
  251.  
  252.  
  253. static LStream *newfile (lua_State *L) {
  254.   LStream *p = newprefile(L);
  255.   p->f = NULL;
  256.   p->closef = &io_fclose;
  257.   return p;
  258. }
  259.  
  260.  
  261. static void opencheck (lua_State *L, const char *fname, const char *mode) {
  262.   LStream *p = newfile(L);
  263.   p->f = fopen(fname, mode);
  264.   if (l_unlikely(p->f == NULL))
  265.     luaL_error(L, "cannot open file '%s' (%s)", fname, strerror(errno));
  266. }
  267.  
  268.  
  269. static int io_open (lua_State *L) {
  270.   const char *filename = luaL_checkstring(L, 1);
  271.   const char *mode = luaL_optstring(L, 2, "r");
  272.   LStream *p = newfile(L);
  273.   const char *md = mode;  /* to traverse/check mode */
  274.   luaL_argcheck(L, l_checkmode(md), 2, "invalid mode");
  275.   p->f = fopen(filename, mode);
  276.   return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1;
  277. }
  278.  
  279.  
  280. /*
  281. ** function to close 'popen' files
  282. */
  283. static int io_pclose (lua_State *L) {
  284.   LStream *p = tolstream(L);
  285.   errno = 0;
  286.   return luaL_execresult(L, l_pclose(L, p->f));
  287. }
  288.  
  289.  
  290. static int io_popen (lua_State *L) {
  291.   const char *filename = luaL_checkstring(L, 1);
  292.   const char *mode = luaL_optstring(L, 2, "r");
  293.   LStream *p = newprefile(L);
  294.   luaL_argcheck(L, l_checkmodep(mode), 2, "invalid mode");
  295.   p->f = l_popen(L, filename, mode);
  296.   p->closef = &io_pclose;
  297.   return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1;
  298. }
  299.  
  300.  
  301. static int io_tmpfile (lua_State *L) {
  302.   LStream *p = newfile(L);
  303.   p->f = tmpfile();
  304.   return (p->f == NULL) ? luaL_fileresult(L, 0, NULL) : 1;
  305. }
  306.  
  307.  
  308. static FILE *getiofile (lua_State *L, const char *findex) {
  309.   LStream *p;
  310.   lua_getfield(L, LUA_REGISTRYINDEX, findex);
  311.   p = (LStream *)lua_touserdata(L, -1);
  312.   if (l_unlikely(isclosed(p)))
  313.     luaL_error(L, "default %s file is closed", findex + IOPREF_LEN);
  314.   return p->f;
  315. }
  316.  
  317.  
  318. static int g_iofile (lua_State *L, const char *f, const char *mode) {
  319.   if (!lua_isnoneornil(L, 1)) {
  320.     const char *filename = lua_tostring(L, 1);
  321.     if (filename)
  322.       opencheck(L, filename, mode);
  323.     else {
  324.       tofile(L);  /* check that it's a valid file handle */
  325.       lua_pushvalue(L, 1);
  326.     }
  327.     lua_setfield(L, LUA_REGISTRYINDEX, f);
  328.   }
  329.   /* return current value */
  330.   lua_getfield(L, LUA_REGISTRYINDEX, f);
  331.   return 1;
  332. }
  333.  
  334.  
  335. static int io_input (lua_State *L) {
  336.   return g_iofile(L, IO_INPUT, "r");
  337. }
  338.  
  339.  
  340. static int io_output (lua_State *L) {
  341.   return g_iofile(L, IO_OUTPUT, "w");
  342. }
  343.  
  344.  
  345. static int io_readline (lua_State *L);
  346.  
  347.  
  348. /*
  349. ** maximum number of arguments to 'f:lines'/'io.lines' (it + 3 must fit
  350. ** in the limit for upvalues of a closure)
  351. */
  352. #define MAXARGLINE      250
  353.  
  354. /*
  355. ** Auxiliary function to create the iteration function for 'lines'.
  356. ** The iteration function is a closure over 'io_readline', with
  357. ** the following upvalues:
  358. ** 1) The file being read (first value in the stack)
  359. ** 2) the number of arguments to read
  360. ** 3) a boolean, true iff file has to be closed when finished ('toclose')
  361. ** *) a variable number of format arguments (rest of the stack)
  362. */
  363. static void aux_lines (lua_State *L, int toclose) {
  364.   int n = lua_gettop(L) - 1;  /* number of arguments to read */
  365.   luaL_argcheck(L, n <= MAXARGLINE, MAXARGLINE + 2, "too many arguments");
  366.   lua_pushvalue(L, 1);  /* file */
  367.   lua_pushinteger(L, n);  /* number of arguments to read */
  368.   lua_pushboolean(L, toclose);  /* close/not close file when finished */
  369.   lua_rotate(L, 2, 3);  /* move the three values to their positions */
  370.   lua_pushcclosure(L, io_readline, 3 + n);
  371. }
  372.  
  373.  
  374. static int f_lines (lua_State *L) {
  375.   tofile(L);  /* check that it's a valid file handle */
  376.   aux_lines(L, 0);
  377.   return 1;
  378. }
  379.  
  380.  
  381. /*
  382. ** Return an iteration function for 'io.lines'. If file has to be
  383. ** closed, also returns the file itself as a second result (to be
  384. ** closed as the state at the exit of a generic for).
  385. */
  386. static int io_lines (lua_State *L) {
  387.   int toclose;
  388.   if (lua_isnone(L, 1)) lua_pushnil(L);  /* at least one argument */
  389.   if (lua_isnil(L, 1)) {  /* no file name? */
  390.     lua_getfield(L, LUA_REGISTRYINDEX, IO_INPUT);  /* get default input */
  391.     lua_replace(L, 1);  /* put it at index 1 */
  392.     tofile(L);  /* check that it's a valid file handle */
  393.     toclose = 0;  /* do not close it after iteration */
  394.   }
  395.   else {  /* open a new file */
  396.     const char *filename = luaL_checkstring(L, 1);
  397.     opencheck(L, filename, "r");
  398.     lua_replace(L, 1);  /* put file at index 1 */
  399.     toclose = 1;  /* close it after iteration */
  400.   }
  401.   aux_lines(L, toclose);  /* push iteration function */
  402.   if (toclose) {
  403.     lua_pushnil(L);  /* state */
  404.     lua_pushnil(L);  /* control */
  405.     lua_pushvalue(L, 1);  /* file is the to-be-closed variable (4th result) */
  406.     return 4;
  407.   }
  408.   else
  409.     return 1;
  410. }
  411.  
  412.  
  413. /*
  414. ** {======================================================
  415. ** READ
  416. ** =======================================================
  417. */
  418.  
  419.  
  420. /* maximum length of a numeral */
  421. #if !defined (L_MAXLENNUM)
  422. #define L_MAXLENNUM     200
  423. #endif
  424.  
  425.  
  426. /* auxiliary structure used by 'read_number' */
  427. typedef struct {
  428.   FILE *f;  /* file being read */
  429.   int c;  /* current character (look ahead) */
  430.   int n;  /* number of elements in buffer 'buff' */
  431.   char buff[L_MAXLENNUM + 1];  /* +1 for ending '\0' */
  432. } RN;
  433.  
  434.  
  435. /*
  436. ** Add current char to buffer (if not out of space) and read next one
  437. */
  438. static int nextc (RN *rn) {
  439.   if (l_unlikely(rn->n >= L_MAXLENNUM)) {  /* buffer overflow? */
  440.     rn->buff[0] = '\0';  /* invalidate result */
  441.     return 0;  /* fail */
  442.   }
  443.   else {
  444.     rn->buff[rn->n++] = rn->c;  /* save current char */
  445.     rn->c = l_getc(rn->f);  /* read next one */
  446.     return 1;
  447.   }
  448. }
  449.  
  450.  
  451. /*
  452. ** Accept current char if it is in 'set' (of size 2)
  453. */
  454. static int test2 (RN *rn, const char *set) {
  455.   if (rn->c == set[0] || rn->c == set[1])
  456.     return nextc(rn);
  457.   else return 0;
  458. }
  459.  
  460.  
  461. /*
  462. ** Read a sequence of (hex)digits
  463. */
  464. static int readdigits (RN *rn, int hex) {
  465.   int count = 0;
  466.   while ((hex ? isxdigit(rn->c) : isdigit(rn->c)) && nextc(rn))
  467.     count++;
  468.   return count;
  469. }
  470.  
  471.  
  472. /*
  473. ** Read a number: first reads a valid prefix of a numeral into a buffer.
  474. ** Then it calls 'lua_stringtonumber' to check whether the format is
  475. ** correct and to convert it to a Lua number.
  476. */
  477. static int read_number (lua_State *L, FILE *f) {
  478.   RN rn;
  479.   int count = 0;
  480.   int hex = 0;
  481.   char decp[2];
  482.   rn.f = f; rn.n = 0;
  483.   decp[0] = lua_getlocaledecpoint();  /* get decimal point from locale */
  484.   decp[1] = '.';  /* always accept a dot */
  485.   l_lockfile(rn.f);
  486.   do { rn.c = l_getc(rn.f); } while (isspace(rn.c));  /* skip spaces */
  487.   test2(&rn, "-+");  /* optional sign */
  488.   if (test2(&rn, "00")) {
  489.     if (test2(&rn, "xX")) hex = 1;  /* numeral is hexadecimal */
  490.     else count = 1;  /* count initial '0' as a valid digit */
  491.   }
  492.   count += readdigits(&rn, hex);  /* integral part */
  493.   if (test2(&rn, decp))  /* decimal point? */
  494.     count += readdigits(&rn, hex);  /* fractional part */
  495.   if (count > 0 && test2(&rn, (hex ? "pP" : "eE"))) {  /* exponent mark? */
  496.     test2(&rn, "-+");  /* exponent sign */
  497.     readdigits(&rn, 0);  /* exponent digits */
  498.   }
  499.   ungetc(rn.c, rn.f);  /* unread look-ahead char */
  500.   l_unlockfile(rn.f);
  501.   rn.buff[rn.n] = '\0';  /* finish string */
  502.   if (l_likely(lua_stringtonumber(L, rn.buff)))
  503.     return 1;  /* ok, it is a valid number */
  504.   else {  /* invalid format */
  505.    lua_pushnil(L);  /* "result" to be removed */
  506.    return 0;  /* read fails */
  507.   }
  508. }
  509.  
  510.  
  511. static int test_eof (lua_State *L, FILE *f) {
  512.   int c = getc(f);
  513.   ungetc(c, f);  /* no-op when c == EOF */
  514.   lua_pushliteral(L, "");
  515.   return (c != EOF);
  516. }
  517.  
  518.  
  519. static int read_line (lua_State *L, FILE *f, int chop) {
  520.   luaL_Buffer b;
  521.   int c;
  522.   luaL_buffinit(L, &b);
  523.   do {  /* may need to read several chunks to get whole line */
  524.     char *buff = luaL_prepbuffer(&b);  /* preallocate buffer space */
  525.     int i = 0;
  526.     l_lockfile(f);  /* no memory errors can happen inside the lock */
  527.     while (i < LUAL_BUFFERSIZE && (c = l_getc(f)) != EOF && c != '\n')
  528.       buff[i++] = c;  /* read up to end of line or buffer limit */
  529.     l_unlockfile(f);
  530.     luaL_addsize(&b, i);
  531.   } while (c != EOF && c != '\n');  /* repeat until end of line */
  532.   if (!chop && c == '\n')  /* want a newline and have one? */
  533.     luaL_addchar(&b, c);  /* add ending newline to result */
  534.   luaL_pushresult(&b);  /* close buffer */
  535.   /* return ok if read something (either a newline or something else) */
  536.   return (c == '\n' || lua_rawlen(L, -1) > 0);
  537. }
  538.  
  539.  
  540. static void read_all (lua_State *L, FILE *f) {
  541.   size_t nr;
  542.   luaL_Buffer b;
  543.   luaL_buffinit(L, &b);
  544.   do {  /* read file in chunks of LUAL_BUFFERSIZE bytes */
  545.     char *p = luaL_prepbuffer(&b);
  546.     nr = fread(p, sizeof(char), LUAL_BUFFERSIZE, f);
  547.     luaL_addsize(&b, nr);
  548.   } while (nr == LUAL_BUFFERSIZE);
  549.   luaL_pushresult(&b);  /* close buffer */
  550. }
  551.  
  552.  
  553. static int read_chars (lua_State *L, FILE *f, size_t n) {
  554.   size_t nr;  /* number of chars actually read */
  555.   char *p;
  556.   luaL_Buffer b;
  557.   luaL_buffinit(L, &b);
  558.   p = luaL_prepbuffsize(&b, n);  /* prepare buffer to read whole block */
  559.   nr = fread(p, sizeof(char), n, f);  /* try to read 'n' chars */
  560.   luaL_addsize(&b, nr);
  561.   luaL_pushresult(&b);  /* close buffer */
  562.   return (nr > 0);  /* true iff read something */
  563. }
  564.  
  565.  
  566. static int g_read (lua_State *L, FILE *f, int first) {
  567.   int nargs = lua_gettop(L) - 1;
  568.   int n, success;
  569.   clearerr(f);
  570.   if (nargs == 0) {  /* no arguments? */
  571.     success = read_line(L, f, 1);
  572.     n = first + 1;  /* to return 1 result */
  573.   }
  574.   else {
  575.     /* ensure stack space for all results and for auxlib's buffer */
  576.     luaL_checkstack(L, nargs+LUA_MINSTACK, "too many arguments");
  577.     success = 1;
  578.     for (n = first; nargs-- && success; n++) {
  579.       if (lua_type(L, n) == LUA_TNUMBER) {
  580.         size_t l = (size_t)luaL_checkinteger(L, n);
  581.         success = (l == 0) ? test_eof(L, f) : read_chars(L, f, l);
  582.       }
  583.       else {
  584.         const char *p = luaL_checkstring(L, n);
  585.         if (*p == '*') p++;  /* skip optional '*' (for compatibility) */
  586.         switch (*p) {
  587.           case 'n':  /* number */
  588.             success = read_number(L, f);
  589.             break;
  590.           case 'l':  /* line */
  591.             success = read_line(L, f, 1);
  592.             break;
  593.           case 'L':  /* line with end-of-line */
  594.             success = read_line(L, f, 0);
  595.             break;
  596.           case 'a':  /* file */
  597.             read_all(L, f);  /* read entire file */
  598.             success = 1; /* always success */
  599.             break;
  600.           default:
  601.             return luaL_argerror(L, n, "invalid format");
  602.         }
  603.       }
  604.     }
  605.   }
  606.   if (ferror(f))
  607.     return luaL_fileresult(L, 0, NULL);
  608.   if (!success) {
  609.     lua_pop(L, 1);  /* remove last result */
  610.     luaL_pushfail(L);  /* push nil instead */
  611.   }
  612.   return n - first;
  613. }
  614.  
  615.  
  616. static int io_read (lua_State *L) {
  617.   return g_read(L, getiofile(L, IO_INPUT), 1);
  618. }
  619.  
  620.  
  621. static int f_read (lua_State *L) {
  622.   return g_read(L, tofile(L), 2);
  623. }
  624.  
  625.  
  626. /*
  627. ** Iteration function for 'lines'.
  628. */
  629. static int io_readline (lua_State *L) {
  630.   LStream *p = (LStream *)lua_touserdata(L, lua_upvalueindex(1));
  631.   int i;
  632.   int n = (int)lua_tointeger(L, lua_upvalueindex(2));
  633.   if (isclosed(p))  /* file is already closed? */
  634.     return luaL_error(L, "file is already closed");
  635.   lua_settop(L , 1);
  636.   luaL_checkstack(L, n, "too many arguments");
  637.   for (i = 1; i <= n; i++)  /* push arguments to 'g_read' */
  638.     lua_pushvalue(L, lua_upvalueindex(3 + i));
  639.   n = g_read(L, p->f, 2);  /* 'n' is number of results */
  640.   lua_assert(n > 0);  /* should return at least a nil */
  641.   if (lua_toboolean(L, -n))  /* read at least one value? */
  642.     return n;  /* return them */
  643.   else {  /* first result is false: EOF or error */
  644.     if (n > 1) {  /* is there error information? */
  645.       /* 2nd result is error message */
  646.       return luaL_error(L, "%s", lua_tostring(L, -n + 1));
  647.     }
  648.     if (lua_toboolean(L, lua_upvalueindex(3))) {  /* generator created file? */
  649.       lua_settop(L, 0);  /* clear stack */
  650.       lua_pushvalue(L, lua_upvalueindex(1));  /* push file at index 1 */
  651.       aux_close(L);  /* close it */
  652.     }
  653.     return 0;
  654.   }
  655. }
  656.  
  657. /* }====================================================== */
  658.  
  659.  
  660. static int g_write (lua_State *L, FILE *f, int arg) {
  661.   int nargs = lua_gettop(L) - arg;
  662.   int status = 1;
  663.   for (; nargs--; arg++) {
  664.     if (lua_type(L, arg) == LUA_TNUMBER) {
  665.       /* optimization: could be done exactly as for strings */
  666.       int len = lua_isinteger(L, arg)
  667.                 ? fprintf(f, LUA_INTEGER_FMT,
  668.                              (LUAI_UACINT)lua_tointeger(L, arg))
  669.                 : fprintf(f, LUA_NUMBER_FMT,
  670.                              (LUAI_UACNUMBER)lua_tonumber(L, arg));
  671.       status = status && (len > 0);
  672.     }
  673.     else {
  674.       size_t l;
  675.       const char *s = luaL_checklstring(L, arg, &l);
  676.       status = status && (fwrite(s, sizeof(char), l, f) == l);
  677.     }
  678.   }
  679.   if (l_likely(status))
  680.     return 1;  /* file handle already on stack top */
  681.   else return luaL_fileresult(L, status, NULL);
  682. }
  683.  
  684.  
  685. static int io_write (lua_State *L) {
  686.   return g_write(L, getiofile(L, IO_OUTPUT), 1);
  687. }
  688.  
  689.  
  690. static int f_write (lua_State *L) {
  691.   FILE *f = tofile(L);
  692.   lua_pushvalue(L, 1);  /* push file at the stack top (to be returned) */
  693.   return g_write(L, f, 2);
  694. }
  695.  
  696.  
  697. static int f_seek (lua_State *L) {
  698.   static const int mode[] = {SEEK_SET, SEEK_CUR, SEEK_END};
  699.   static const char *const modenames[] = {"set", "cur", "end", NULL};
  700.   FILE *f = tofile(L);
  701.   int op = luaL_checkoption(L, 2, "cur", modenames);
  702.   lua_Integer p3 = luaL_optinteger(L, 3, 0);
  703.   l_seeknum offset = (l_seeknum)p3;
  704.   luaL_argcheck(L, (lua_Integer)offset == p3, 3,
  705.                   "not an integer in proper range");
  706.   op = l_fseek(f, offset, mode[op]);
  707.   if (l_unlikely(op))
  708.     return luaL_fileresult(L, 0, NULL);  /* error */
  709.   else {
  710.     lua_pushinteger(L, (lua_Integer)l_ftell(f));
  711.     return 1;
  712.   }
  713. }
  714.  
  715.  
  716. static int f_setvbuf (lua_State *L) {
  717.   static const int mode[] = {_IONBF, _IOFBF, _IOLBF};
  718.   static const char *const modenames[] = {"no", "full", "line", NULL};
  719.   FILE *f = tofile(L);
  720.   int op = luaL_checkoption(L, 2, NULL, modenames);
  721.   lua_Integer sz = luaL_optinteger(L, 3, LUAL_BUFFERSIZE);
  722.   int res = setvbuf(f, NULL, mode[op], (size_t)sz);
  723.   return luaL_fileresult(L, res == 0, NULL);
  724. }
  725.  
  726.  
  727.  
  728. static int io_flush (lua_State *L) {
  729.   return luaL_fileresult(L, fflush(getiofile(L, IO_OUTPUT)) == 0, NULL);
  730. }
  731.  
  732.  
  733. static int f_flush (lua_State *L) {
  734.   return luaL_fileresult(L, fflush(tofile(L)) == 0, NULL);
  735. }
  736.  
  737.  
  738. /*
  739. ** functions for 'io' library
  740. */
  741. static const luaL_Reg iolib[] = {
  742.   {"close", io_close},
  743.   {"flush", io_flush},
  744.   {"input", io_input},
  745.   {"lines", io_lines},
  746.   {"open", io_open},
  747.   {"output", io_output},
  748.   {"popen", io_popen},
  749.   {"read", io_read},
  750.   {"tmpfile", io_tmpfile},
  751.   {"type", io_type},
  752.   {"write", io_write},
  753.   {NULL, NULL}
  754. };
  755.  
  756.  
  757. /*
  758. ** methods for file handles
  759. */
  760. static const luaL_Reg meth[] = {
  761.   {"read", f_read},
  762.   {"write", f_write},
  763.   {"lines", f_lines},
  764.   {"flush", f_flush},
  765.   {"seek", f_seek},
  766.   {"close", f_close},
  767.   {"setvbuf", f_setvbuf},
  768.   {NULL, NULL}
  769. };
  770.  
  771.  
  772. /*
  773. ** metamethods for file handles
  774. */
  775. static const luaL_Reg metameth[] = {
  776.   {"__index", NULL},  /* place holder */
  777.   {"__gc", f_gc},
  778.   {"__close", f_gc},
  779.   {"__tostring", f_tostring},
  780.   {NULL, NULL}
  781. };
  782.  
  783.  
  784. static void createmeta (lua_State *L) {
  785.   luaL_newmetatable(L, LUA_FILEHANDLE);  /* metatable for file handles */
  786.   luaL_setfuncs(L, metameth, 0);  /* add metamethods to new metatable */
  787.   luaL_newlibtable(L, meth);  /* create method table */
  788.   luaL_setfuncs(L, meth, 0);  /* add file methods to method table */
  789.   lua_setfield(L, -2, "__index");  /* metatable.__index = method table */
  790.   lua_pop(L, 1);  /* pop metatable */
  791. }
  792.  
  793.  
  794. /*
  795. ** function to (not) close the standard files stdin, stdout, and stderr
  796. */
  797. static int io_noclose (lua_State *L) {
  798.   LStream *p = tolstream(L);
  799.   p->closef = &io_noclose;  /* keep file opened */
  800.   luaL_pushfail(L);
  801.   lua_pushliteral(L, "cannot close standard file");
  802.   return 2;
  803. }
  804.  
  805.  
  806. static void createstdfile (lua_State *L, FILE *f, const char *k,
  807.                            const char *fname) {
  808.   LStream *p = newprefile(L);
  809.   p->f = f;
  810.   p->closef = &io_noclose;
  811.   if (k != NULL) {
  812.     lua_pushvalue(L, -1);
  813.     lua_setfield(L, LUA_REGISTRYINDEX, k);  /* add file to registry */
  814.   }
  815.   lua_setfield(L, -2, fname);  /* add file to module */
  816. }
  817.  
  818.  
  819. LUAMOD_API int luaopen_io (lua_State *L) {
  820.   luaL_newlib(L, iolib);  /* new module */
  821.   createmeta(L);
  822.   /* create (and set) default files */
  823.   createstdfile(L, stdin, IO_INPUT, "stdin");
  824.   createstdfile(L, stdout, IO_OUTPUT, "stdout");
  825.   createstdfile(L, stderr, NULL, "stderr");
  826.   return 1;
  827. }
  828.  
  829.