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1 /*
2 ** $Id: lzio.c,v 1.37.1.1 2017/04/19 17:20:42 roberto Exp $
3 ** Buffered streams
4 ** See Copyright Notice in lua.h
5 */
6 
7 #define lzio_c
8 #define LUA_CORE
9 
10 #include "lprefix.h"
11 
12 
13 #include <string.h>
14 
15 #include "lua.h"
16 
17 #include "llimits.h"
18 #include "lmem.h"
19 #include "lstate.h"
20 #include "lzio.h"
21 
22 
luaZ_fill(ZIO * z)23 int luaZ_fill (ZIO *z) {
24   size_t size;
25   lua_State *L = z->L;
26   const char *buff;
27   lua_unlock(L);
28   buff = z->reader(L, z->data, &size);
29   lua_lock(L);
30   if (buff == NULL || size == 0)
31     return EOZ;
32   z->n = size - 1;  /* discount char being returned */
33   z->p = buff;
34   return cast_uchar(*(z->p++));
35 }
36 
37 
luaZ_init(lua_State * L,ZIO * z,lua_Reader reader,void * data)38 void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
39   z->L = L;
40   z->reader = reader;
41   z->data = data;
42   z->n = 0;
43   z->p = NULL;
44 }
45 
46 
47 /* --------------------------------------------------------------- read --- */
luaZ_read(ZIO * z,void * b,size_t n)48 size_t luaZ_read (ZIO *z, void *b, size_t n) {
49   while (n) {
50     size_t m;
51     if (z->n == 0) {  /* no bytes in buffer? */
52       if (luaZ_fill(z) == EOZ)  /* try to read more */
53         return n;  /* no more input; return number of missing bytes */
54       else {
55         z->n++;  /* luaZ_fill consumed first byte; put it back */
56         z->p--;
57       }
58     }
59     m = (n <= z->n) ? n : z->n;  /* min. between n and z->n */
60     memcpy(b, z->p, m);
61     z->n -= m;
62     z->p += m;
63     b = (char *)b + m;
64     n -= m;
65   }
66   return 0;
67 }
68 
69