prosody
3ce3633527af
util-src/struct.c

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util-src/struct.c @ 12354:3ce3633527af

util.struct: Import Roberto 'struct' library v0.3 Downloaded from http://www.inf.puc-rio.br/~roberto/struct/ This is for compatibility with Lua 5.2 (and 5.1). Eventually we can replace this with string.pack/string.unpack which are available in 5.3+.
author Matthew Wild <mwild1@gmail.com>
date Fri, 04 Mar 2022 15:03:02 +0000
child 12387:05c250fa335a
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equal deleted inserted replaced
12353:5ace23519e71 12354:3ce3633527af
1 /*
2 ** {======================================================
3 ** Library for packing/unpacking structures.
4 ** $Id: struct.c,v 1.8 2018/05/16 11:00:23 roberto Exp $
5 ** See Copyright Notice at the end of this file
6 ** =======================================================
7 */
8 /*
9 ** Valid formats:
10 ** > - big endian
11 ** < - little endian
12 ** ![num] - alignment
13 ** x - pading
14 ** b/B - signed/unsigned byte
15 ** h/H - signed/unsigned short
16 ** l/L - signed/unsigned long
17 ** T - size_t
18 ** i/In - signed/unsigned integer with size 'n' (default is size of int)
19 ** cn - sequence of 'n' chars (from/to a string); when packing, n==0 means
20 the whole string; when unpacking, n==0 means use the previous
21 read number as the string length
22 ** s - zero-terminated string
23 ** f - float
24 ** d - double
25 ** ' ' - ignored
26 */
27
28
29 #include <ctype.h>
30 #include <limits.h>
31 #include <stddef.h>
32 #include <string.h>
33
34
35 #include "lua.h"
36 #include "lauxlib.h"
37
38
39 #if (LUA_VERSION_NUM >= 502)
40
41 #define luaL_register(L,n,f) luaL_newlib(L,f)
42
43 #endif
44
45
46 /* basic integer type */
47 #if !defined(STRUCT_INT)
48 #define STRUCT_INT long
49 #endif
50
51 typedef STRUCT_INT Inttype;
52
53 /* corresponding unsigned version */
54 typedef unsigned STRUCT_INT Uinttype;
55
56
57 /* maximum size (in bytes) for integral types */
58 #define MAXINTSIZE 32
59
60 /* is 'x' a power of 2? */
61 #define isp2(x) ((x) > 0 && ((x) & ((x) - 1)) == 0)
62
63 /* dummy structure to get alignment requirements */
64 struct cD {
65 char c;
66 double d;
67 };
68
69
70 #define PADDING (sizeof(struct cD) - sizeof(double))
71 #define MAXALIGN (PADDING > sizeof(int) ? PADDING : sizeof(int))
72
73
74 /* endian options */
75 #define BIG 0
76 #define LITTLE 1
77
78
79 static union {
80 int dummy;
81 char endian;
82 } const native = {1};
83
84
85 typedef struct Header {
86 int endian;
87 int align;
88 } Header;
89
90
91 static int getnum (const char **fmt, int df) {
92 if (!isdigit(**fmt)) /* no number? */
93 return df; /* return default value */
94 else {
95 int a = 0;
96 do {
97 a = a*10 + *((*fmt)++) - '0';
98 } while (isdigit(**fmt));
99 return a;
100 }
101 }
102
103
104 #define defaultoptions(h) ((h)->endian = native.endian, (h)->align = 1)
105
106
107
108 static size_t optsize (lua_State *L, char opt, const char **fmt) {
109 switch (opt) {
110 case 'B': case 'b': return sizeof(char);
111 case 'H': case 'h': return sizeof(short);
112 case 'L': case 'l': return sizeof(long);
113 case 'T': return sizeof(size_t);
114 case 'f': return sizeof(float);
115 case 'd': return sizeof(double);
116 case 'x': return 1;
117 case 'c': return getnum(fmt, 1);
118 case 'i': case 'I': {
119 int sz = getnum(fmt, sizeof(int));
120 if (sz > MAXINTSIZE)
121 luaL_error(L, "integral size %d is larger than limit of %d",
122 sz, MAXINTSIZE);
123 return sz;
124 }
125 default: return 0; /* other cases do not need alignment */
126 }
127 }
128
129
130 /*
131 ** return number of bytes needed to align an element of size 'size'
132 ** at current position 'len'
133 */
134 static int gettoalign (size_t len, Header *h, int opt, size_t size) {
135 if (size == 0 || opt == 'c') return 0;
136 if (size > (size_t)h->align)
137 size = h->align; /* respect max. alignment */
138 return (size - (len & (size - 1))) & (size - 1);
139 }
140
141
142 /*
143 ** options to control endianess and alignment
144 */
145 static void controloptions (lua_State *L, int opt, const char **fmt,
146 Header *h) {
147 switch (opt) {
148 case ' ': return; /* ignore white spaces */
149 case '>': h->endian = BIG; return;
150 case '<': h->endian = LITTLE; return;
151 case '!': {
152 int a = getnum(fmt, MAXALIGN);
153 if (!isp2(a))
154 luaL_error(L, "alignment %d is not a power of 2", a);
155 h->align = a;
156 return;
157 }
158 default: {
159 const char *msg = lua_pushfstring(L, "invalid format option '%c'", opt);
160 luaL_argerror(L, 1, msg);
161 }
162 }
163 }
164
165
166 static void putinteger (lua_State *L, luaL_Buffer *b, int arg, int endian,
167 int size) {
168 lua_Number n = luaL_checknumber(L, arg);
169 Uinttype value;
170 char buff[MAXINTSIZE];
171 if (n < 0)
172 value = (Uinttype)(Inttype)n;
173 else
174 value = (Uinttype)n;
175 if (endian == LITTLE) {
176 int i;
177 for (i = 0; i < size; i++) {
178 buff[i] = (value & 0xff);
179 value >>= 8;
180 }
181 }
182 else {
183 int i;
184 for (i = size - 1; i >= 0; i--) {
185 buff[i] = (value & 0xff);
186 value >>= 8;
187 }
188 }
189 luaL_addlstring(b, buff, size);
190 }
191
192
193 static void correctbytes (char *b, int size, int endian) {
194 if (endian != native.endian) {
195 int i = 0;
196 while (i < --size) {
197 char temp = b[i];
198 b[i++] = b[size];
199 b[size] = temp;
200 }
201 }
202 }
203
204
205 static int b_pack (lua_State *L) {
206 luaL_Buffer b;
207 const char *fmt = luaL_checkstring(L, 1);
208 Header h;
209 int arg = 2;
210 size_t totalsize = 0;
211 defaultoptions(&h);
212 lua_pushnil(L); /* mark to separate arguments from string buffer */
213 luaL_buffinit(L, &b);
214 while (*fmt != '\0') {
215 int opt = *fmt++;
216 size_t size = optsize(L, opt, &fmt);
217 int toalign = gettoalign(totalsize, &h, opt, size);
218 totalsize += toalign;
219 while (toalign-- > 0) luaL_addchar(&b, '\0');
220 switch (opt) {
221 case 'b': case 'B': case 'h': case 'H':
222 case 'l': case 'L': case 'T': case 'i': case 'I': { /* integer types */
223 putinteger(L, &b, arg++, h.endian, size);
224 break;
225 }
226 case 'x': {
227 luaL_addchar(&b, '\0');
228 break;
229 }
230 case 'f': {
231 float f = (float)luaL_checknumber(L, arg++);
232 correctbytes((char *)&f, size, h.endian);
233 luaL_addlstring(&b, (char *)&f, size);
234 break;
235 }
236 case 'd': {
237 double d = luaL_checknumber(L, arg++);
238 correctbytes((char *)&d, size, h.endian);
239 luaL_addlstring(&b, (char *)&d, size);
240 break;
241 }
242 case 'c': case 's': {
243 size_t l;
244 const char *s = luaL_checklstring(L, arg++, &l);
245 if (size == 0) size = l;
246 luaL_argcheck(L, l >= (size_t)size, arg, "string too short");
247 luaL_addlstring(&b, s, size);
248 if (opt == 's') {
249 luaL_addchar(&b, '\0'); /* add zero at the end */
250 size++;
251 }
252 break;
253 }
254 default: controloptions(L, opt, &fmt, &h);
255 }
256 totalsize += size;
257 }
258 luaL_pushresult(&b);
259 return 1;
260 }
261
262
263 static lua_Number getinteger (const char *buff, int endian,
264 int issigned, int size) {
265 Uinttype l = 0;
266 int i;
267 if (endian == BIG) {
268 for (i = 0; i < size; i++) {
269 l <<= 8;
270 l |= (Uinttype)(unsigned char)buff[i];
271 }
272 }
273 else {
274 for (i = size - 1; i >= 0; i--) {
275 l <<= 8;
276 l |= (Uinttype)(unsigned char)buff[i];
277 }
278 }
279 if (!issigned)
280 return (lua_Number)l;
281 else { /* signed format */
282 Uinttype mask = (Uinttype)(~((Uinttype)0)) << (size*8 - 1);
283 if (l & mask) /* negative value? */
284 l |= mask; /* signal extension */
285 return (lua_Number)(Inttype)l;
286 }
287 }
288
289
290 static int b_unpack (lua_State *L) {
291 Header h;
292 const char *fmt = luaL_checkstring(L, 1);
293 size_t ld;
294 const char *data = luaL_checklstring(L, 2, &ld);
295 size_t pos = (size_t)luaL_optinteger(L, 3, 1) - 1;
296 int n = 0; /* number of results */
297 luaL_argcheck(L, pos <= ld, 3, "initial position out of string");
298 defaultoptions(&h);
299 while (*fmt) {
300 int opt = *fmt++;
301 size_t size = optsize(L, opt, &fmt);
302 pos += gettoalign(pos, &h, opt, size);
303 luaL_argcheck(L, size <= ld - pos, 2, "data string too short");
304 /* stack space for item + next position */
305 luaL_checkstack(L, 2, "too many results");
306 switch (opt) {
307 case 'b': case 'B': case 'h': case 'H':
308 case 'l': case 'L': case 'T': case 'i': case 'I': { /* integer types */
309 int issigned = islower(opt);
310 lua_Number res = getinteger(data+pos, h.endian, issigned, size);
311 lua_pushnumber(L, res); n++;
312 break;
313 }
314 case 'x': {
315 break;
316 }
317 case 'f': {
318 float f;
319 memcpy(&f, data+pos, size);
320 correctbytes((char *)&f, sizeof(f), h.endian);
321 lua_pushnumber(L, f); n++;
322 break;
323 }
324 case 'd': {
325 double d;
326 memcpy(&d, data+pos, size);
327 correctbytes((char *)&d, sizeof(d), h.endian);
328 lua_pushnumber(L, d); n++;
329 break;
330 }
331 case 'c': {
332 if (size == 0) {
333 if (n == 0 || !lua_isnumber(L, -1))
334 luaL_error(L, "format 'c0' needs a previous size");
335 size = lua_tonumber(L, -1);
336 lua_pop(L, 1); n--;
337 luaL_argcheck(L, size <= ld - pos, 2, "data string too short");
338 }
339 lua_pushlstring(L, data+pos, size); n++;
340 break;
341 }
342 case 's': {
343 const char *e = (const char *)memchr(data+pos, '\0', ld - pos);
344 if (e == NULL)
345 luaL_error(L, "unfinished string in data");
346 size = (e - (data+pos)) + 1;
347 lua_pushlstring(L, data+pos, size - 1); n++;
348 break;
349 }
350 default: controloptions(L, opt, &fmt, &h);
351 }
352 pos += size;
353 }
354 lua_pushinteger(L, pos + 1); /* next position */
355 return n + 1;
356 }
357
358
359 static int b_size (lua_State *L) {
360 Header h;
361 const char *fmt = luaL_checkstring(L, 1);
362 size_t pos = 0;
363 defaultoptions(&h);
364 while (*fmt) {
365 int opt = *fmt++;
366 size_t size = optsize(L, opt, &fmt);
367 pos += gettoalign(pos, &h, opt, size);
368 if (opt == 's')
369 luaL_argerror(L, 1, "option 's' has no fixed size");
370 else if (opt == 'c' && size == 0)
371 luaL_argerror(L, 1, "option 'c0' has no fixed size");
372 if (!isalnum(opt))
373 controloptions(L, opt, &fmt, &h);
374 pos += size;
375 }
376 lua_pushinteger(L, pos);
377 return 1;
378 }
379
380 /* }====================================================== */
381
382
383
384 static const struct luaL_Reg thislib[] = {
385 {"pack", b_pack},
386 {"unpack", b_unpack},
387 {"size", b_size},
388 {NULL, NULL}
389 };
390
391
392 LUALIB_API int luaopen_util_struct (lua_State *L);
393
394 LUALIB_API int luaopen_util_struct (lua_State *L) {
395 luaL_register(L, "struct", thislib);
396 return 1;
397 }
398
399
400 /******************************************************************************
401 * Copyright (C) 2010-2018 Lua.org, PUC-Rio. All rights reserved.
402 *
403 * Permission is hereby granted, free of charge, to any person obtaining
404 * a copy of this software and associated documentation files (the
405 * "Software"), to deal in the Software without restriction, including
406 * without limitation the rights to use, copy, modify, merge, publish,
407 * distribute, sublicense, and/or sell copies of the Software, and to
408 * permit persons to whom the Software is furnished to do so, subject to
409 * the following conditions:
410 *
411 * The above copyright notice and this permission notice shall be
412 * included in all copies or substantial portions of the Software.
413 *
414 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
415 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
416 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
417 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
418 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
419 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
420 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
421 ******************************************************************************/
422