1 /* Conversion loop frame work.
2 Copyright (C) 1998-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 /* This file provides a frame for the reader loop in all conversion modules.
20 The actual code must (of course) be provided in the actual module source
21 code but certain actions can be written down generically, with some
22 customization options which are these:
23
24 MIN_NEEDED_INPUT minimal number of input bytes needed for the next
25 conversion.
26 MIN_NEEDED_OUTPUT minimal number of bytes produced by the next round
27 of conversion.
28
29 MAX_NEEDED_INPUT you guess it, this is the maximal number of input
30 bytes needed. It defaults to MIN_NEEDED_INPUT
31 MAX_NEEDED_OUTPUT likewise for output bytes.
32
33 LOOPFCT name of the function created. If not specified
34 the name is `loop' but this prevents the use
35 of multiple functions in the same file.
36
37 BODY this is supposed to expand to the body of the loop.
38 The user must provide this.
39
40 EXTRA_LOOP_DECLS extra arguments passed from conversion loop call.
41
42 INIT_PARAMS code to define and initialize variables from params.
43 UPDATE_PARAMS code to store result in params.
44
45 ONEBYTE_BODY body of the specialized conversion function for a
46 single byte from the current character set to INTERNAL.
47 */
48
49 #include <assert.h>
50 #include <endian.h>
51 #include <iconv/gconv_int.h>
52 #include <stdint.h>
53 #include <string.h>
54 #include <wchar.h>
55 #include <sys/param.h> /* For MIN. */
56 #define __need_size_t
57 #include <stddef.h>
58 #include <libc-diag.h>
59
60 #undef FCTNAME2
61 #define FCTNAME(name) name
62
63
64 /* We need at least one byte for the next round. */
65 #ifndef MIN_NEEDED_INPUT
66 # error "MIN_NEEDED_INPUT definition missing"
67 #elif MIN_NEEDED_INPUT < 1
68 # error "MIN_NEEDED_INPUT must be >= 1"
69 #endif
70
71 /* Let's see how many bytes we produce. */
72 #ifndef MAX_NEEDED_INPUT
73 # define MAX_NEEDED_INPUT MIN_NEEDED_INPUT
74 #endif
75
76 /* We produce at least one byte in the next round. */
77 #ifndef MIN_NEEDED_OUTPUT
78 # error "MIN_NEEDED_OUTPUT definition missing"
79 #elif MIN_NEEDED_OUTPUT < 1
80 # error "MIN_NEEDED_OUTPUT must be >= 1"
81 #endif
82
83 /* Let's see how many bytes we produce. */
84 #ifndef MAX_NEEDED_OUTPUT
85 # define MAX_NEEDED_OUTPUT MIN_NEEDED_OUTPUT
86 #endif
87
88 /* Default name for the function. */
89 #ifndef LOOPFCT
90 # define LOOPFCT loop
91 #endif
92
93 /* Make sure we have a loop body. */
94 #ifndef BODY
95 # error "Definition of BODY missing for function" LOOPFCT
96 #endif
97
98
99 /* If no arguments have to passed to the loop function define the macro
100 as empty. */
101 #ifndef EXTRA_LOOP_DECLS
102 # define EXTRA_LOOP_DECLS
103 #endif
104
105 /* Allow using UPDATE_PARAMS in macros where #ifdef UPDATE_PARAMS test
106 isn't possible. */
107 #ifndef UPDATE_PARAMS
108 # define UPDATE_PARAMS do { } while (0)
109 #endif
110 #ifndef REINIT_PARAMS
111 # define REINIT_PARAMS do { } while (0)
112 #endif
113
114
115 /* To make it easier for the writers of the modules, we define a macro
116 to test whether we have to ignore errors. */
117 #define ignore_errors_p() \
118 (irreversible != NULL && (flags & __GCONV_IGNORE_ERRORS))
119
120
121 /* Error handling for the FROM_LOOP direction, with ignoring of errors.
122 Note that we cannot use the do while (0) trick since `break' and
123 `continue' must reach certain points. */
124 #define STANDARD_FROM_LOOP_ERR_HANDLER(Incr) \
125 { \
126 result = __GCONV_ILLEGAL_INPUT; \
127 \
128 if (! ignore_errors_p ()) \
129 break; \
130 \
131 /* We ignore the invalid input byte sequence. */ \
132 inptr += (Incr); \
133 ++*irreversible; \
134 /* But we keep result == __GCONV_ILLEGAL_INPUT, because of the constraint \
135 that "iconv -c" must give the same exitcode as "iconv". */ \
136 continue; \
137 }
138
139 /* Error handling for the TO_LOOP direction, with use of transliteration/
140 transcription functions and ignoring of errors. Note that we cannot use
141 the do while (0) trick since `break' and `continue' must reach certain
142 points. */
143 #define STANDARD_TO_LOOP_ERR_HANDLER(Incr) \
144 { \
145 result = __GCONV_ILLEGAL_INPUT; \
146 \
147 if (irreversible == NULL) \
148 /* This means we are in call from __gconv_transliterate. In this \
149 case we are not doing any error recovery outself. */ \
150 break; \
151 \
152 /* If needed, flush any conversion state, so that __gconv_transliterate \
153 starts with current shift state. */ \
154 UPDATE_PARAMS; \
155 \
156 /* First try the transliteration methods. */ \
157 if ((step_data->__flags & __GCONV_TRANSLIT) != 0) \
158 result = __gconv_transliterate \
159 (step, step_data, *inptrp, \
160 &inptr, inend, &outptr, irreversible); \
161 \
162 REINIT_PARAMS; \
163 \
164 /* If any of them recognized the input continue with the loop. */ \
165 if (result != __GCONV_ILLEGAL_INPUT) \
166 { \
167 if (__glibc_unlikely (result == __GCONV_FULL_OUTPUT)) \
168 break; \
169 \
170 continue; \
171 } \
172 \
173 /* Next see whether we have to ignore the error. If not, stop. */ \
174 if (! ignore_errors_p ()) \
175 break; \
176 \
177 /* When we come here it means we ignore the character. */ \
178 ++*irreversible; \
179 inptr += Incr; \
180 /* But we keep result == __GCONV_ILLEGAL_INPUT, because of the constraint \
181 that "iconv -c" must give the same exitcode as "iconv". */ \
182 continue; \
183 }
184
185
186 /* With GCC 7 when compiling with -Os for 32-bit s390 the compiler
187 warns that the variable 'ch', in the definition of BODY in
188 sysdeps/s390/multiarch/8bit-generic.c, may be used uninitialized in
189 the call to UNICODE_TAG_HANDLER in that macro. This variable is
190 actually always initialized before use, in the prior loop if INDEX
191 is nonzero and in the following 'if' if INDEX is zero. That code
192 has a comment referencing this diagnostic disabling; updates in one
193 place may require updates in the other. */
194 DIAG_PUSH_NEEDS_COMMENT;
195 DIAG_IGNORE_Os_NEEDS_COMMENT (7, "-Wmaybe-uninitialized");
196 /* Handling of Unicode 3.1 TAG characters. Unicode recommends
197 "If language codes are not relevant to the particular processing
198 operation, then they should be ignored." This macro is usually
199 called right before STANDARD_TO_LOOP_ERR_HANDLER (Incr). */
200 #define UNICODE_TAG_HANDLER(Character, Incr) \
201 { \
202 /* TAG characters are those in the range U+E0000..U+E007F. */ \
203 if (((Character) >> 7) == (0xe0000 >> 7)) \
204 { \
205 inptr += Incr; \
206 continue; \
207 } \
208 }
209 DIAG_POP_NEEDS_COMMENT;
210
211
212 /* The function returns the status, as defined in gconv.h. */
213 static inline int
214 __attribute ((always_inline))
215 FCTNAME (LOOPFCT) (struct __gconv_step *step,
216 struct __gconv_step_data *step_data,
217 const unsigned char **inptrp, const unsigned char *inend,
218 unsigned char **outptrp, const unsigned char *outend,
219 size_t *irreversible EXTRA_LOOP_DECLS)
220 {
221 #ifdef LOOP_NEED_STATE
222 mbstate_t *state = step_data->__statep;
223 #endif
224 #ifdef LOOP_NEED_FLAGS
225 int flags = step_data->__flags;
226 #endif
227 #ifdef LOOP_NEED_DATA
228 void *data = step->__data;
229 #endif
230 int result = __GCONV_EMPTY_INPUT;
231 const unsigned char *inptr = *inptrp;
232 unsigned char *outptr = *outptrp;
233
234 #ifdef INIT_PARAMS
235 INIT_PARAMS;
236 #endif
237
238 while (inptr != inend)
239 {
240 /* `if' cases for MIN_NEEDED_OUTPUT ==/!= 1 is made to help the
241 compiler generating better code. They will be optimized away
242 since MIN_NEEDED_OUTPUT is always a constant. */
243 if (MIN_NEEDED_INPUT > 1
244 && __builtin_expect (inptr + MIN_NEEDED_INPUT > inend, 0))
245 {
246 /* We don't have enough input for another complete input
247 character. */
248 result = __GCONV_INCOMPLETE_INPUT;
249 break;
250 }
251 if ((MIN_NEEDED_OUTPUT != 1
252 && __builtin_expect (outptr + MIN_NEEDED_OUTPUT > outend, 0))
253 || (MIN_NEEDED_OUTPUT == 1
254 && __builtin_expect (outptr >= outend, 0)))
255 {
256 /* Overflow in the output buffer. */
257 result = __GCONV_FULL_OUTPUT;
258 break;
259 }
260
261 /* Here comes the body the user provides. It can stop with
262 RESULT set to GCONV_INCOMPLETE_INPUT (if the size of the
263 input characters vary in size), GCONV_ILLEGAL_INPUT, or
264 GCONV_FULL_OUTPUT (if the output characters vary in size). */
265 BODY
266 }
267
268 /* Update the pointers pointed to by the parameters. */
269 *inptrp = inptr;
270 *outptrp = outptr;
271 UPDATE_PARAMS;
272
273 return result;
274 }
275
276
277 #if MAX_NEEDED_INPUT > 1
278 # define SINGLE(fct) SINGLE2 (fct)
279 # define SINGLE2(fct) fct##_single
280 static inline int
281 __attribute ((always_inline))
282 SINGLE(LOOPFCT) (struct __gconv_step *step,
283 struct __gconv_step_data *step_data,
284 const unsigned char **inptrp, const unsigned char *inend,
285 unsigned char **outptrp, unsigned char *outend,
286 size_t *irreversible EXTRA_LOOP_DECLS)
287 {
288 mbstate_t *state = step_data->__statep;
289 # ifdef LOOP_NEED_FLAGS
290 int flags = step_data->__flags;
291 # endif
292 # ifdef LOOP_NEED_DATA
293 void *data = step->__data;
294 # endif
295 int result = __GCONV_OK;
296 unsigned char bytebuf[MAX_NEEDED_INPUT];
297 const unsigned char *inptr = *inptrp;
298 unsigned char *outptr = *outptrp;
299 size_t inlen;
300
301 # ifdef INIT_PARAMS
302 INIT_PARAMS;
303 # endif
304
305 # ifdef UNPACK_BYTES
306 UNPACK_BYTES
307 # else
308 /* Add the bytes from the state to the input buffer. */
309 assert ((state->__count & 7) <= sizeof (state->__value));
310 for (inlen = 0; inlen < (size_t) (state->__count & 7); ++inlen)
311 bytebuf[inlen] = state->__value.__wchb[inlen];
312 # endif
313
314 /* Are there enough bytes in the input buffer? */
315 if (MIN_NEEDED_INPUT > 1
316 && __builtin_expect (inptr + (MIN_NEEDED_INPUT - inlen) > inend, 0))
317 {
318 *inptrp = inend;
319 # ifdef STORE_REST
320
321 /* Building with -O3 GCC emits a `array subscript is above array
322 bounds' warning. GCC BZ #64739 has been opened for this. */
323 DIAG_PUSH_NEEDS_COMMENT;
324 DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Warray-bounds");
325 while (inptr < inend)
326 bytebuf[inlen++] = *inptr++;
327 DIAG_POP_NEEDS_COMMENT;
328
329 inptr = bytebuf;
330 inptrp = &inptr;
331 inend = &bytebuf[inlen];
332
333 STORE_REST
334 # else
335 /* We don't have enough input for another complete input
336 character. */
337 size_t inlen_after = inlen + (inend - inptr);
338 assert (inlen_after <= sizeof (state->__value.__wchb));
339 for (; inlen < inlen_after; inlen++)
340 state->__value.__wchb[inlen] = *inptr++;
341 # endif
342
343 return __GCONV_INCOMPLETE_INPUT;
344 }
345
346 /* Enough space in output buffer. */
347 if ((MIN_NEEDED_OUTPUT != 1 && outptr + MIN_NEEDED_OUTPUT > outend)
348 || (MIN_NEEDED_OUTPUT == 1 && outptr >= outend))
349 /* Overflow in the output buffer. */
350 return __GCONV_FULL_OUTPUT;
351
352 /* Now add characters from the normal input buffer. */
353 if (inlen >= MAX_NEEDED_INPUT || inptr >= inend)
354 /* Avoid a -Wstringop-overflow= warning when this loop is
355 unrolled. The compiler cannot otherwise see that this is
356 unreachable because it depends on (state->__count & 7) not
357 being too large after a previous conversion step.
358 Starting with GCC 12, we also have mark the inptr >= inend
359 case as unreachable to omit the warning. Note that this SINGLE
360 function is only used to implement the mb*towc*() or wc*tomb*()
361 functions. Those functions use inptr and inend pointing to a
362 variable on stack, compute the inend pointer or explicitly check
363 the arguments which always leads to inptr < inend. */
364 __builtin_unreachable ();
365 do
366 bytebuf[inlen++] = *inptr++;
367 while (inlen < MAX_NEEDED_INPUT && inptr < inend);
368
369 inptr = bytebuf;
370 inend = &bytebuf[inlen];
371
372 do
373 {
374 BODY
375 }
376 while (0);
377
378 /* Now we either have produced an output character and consumed all the
379 bytes from the state and at least one more, or the character is still
380 incomplete, or we have some other error (like illegal input character,
381 no space in output buffer). */
382 if (__glibc_likely (inptr != bytebuf))
383 {
384 /* We found a new character. */
385 assert (inptr - bytebuf > (state->__count & 7));
386
387 *inptrp += inptr - bytebuf - (state->__count & 7);
388 *outptrp = outptr;
389
390 result = __GCONV_OK;
391
392 /* Clear the state buffer. */
393 # ifdef CLEAR_STATE
394 CLEAR_STATE;
395 # else
396 state->__count &= ~7;
397 # endif
398 }
399 else if (result == __GCONV_INCOMPLETE_INPUT)
400 {
401 /* This can only happen if we have less than MAX_NEEDED_INPUT bytes
402 available. */
403 assert (inend != &bytebuf[MAX_NEEDED_INPUT]);
404
405 *inptrp += inend - bytebuf - (state->__count & 7);
406 # ifdef STORE_REST
407 inptrp = &inptr;
408
409 STORE_REST
410 # else
411 /* We don't have enough input for another complete input
412 character. */
413 assert (inend - inptr > (state->__count & ~7));
414 assert (inend - inptr <= sizeof (state->__value.__wchb));
415 state->__count = (state->__count & ~7) | (inend - inptr);
416 for (inlen = 0; inlen < inend - inptr; inlen++)
417 state->__value.__wchb[inlen] = inptr[inlen];
418 inptr = inend;
419 # endif
420 }
421
422 return result;
423 }
424 # undef SINGLE
425 # undef SINGLE2
426
427
428 # ifdef ONEBYTE_BODY
429 /* Define the shortcut function for btowc. */
430 static wint_t
431 gconv_btowc (struct __gconv_step *step, unsigned char c)
432 ONEBYTE_BODY
433 # define FROM_ONEBYTE gconv_btowc
434 # endif
435
436 #endif
437
438 /* We remove the macro definitions so that we can include this file again
439 for the definition of another function. */
440 #undef MIN_NEEDED_INPUT
441 #undef MAX_NEEDED_INPUT
442 #undef MIN_NEEDED_OUTPUT
443 #undef MAX_NEEDED_OUTPUT
444 #undef LOOPFCT
445 #undef BODY
446 #undef LOOPFCT
447 #undef EXTRA_LOOP_DECLS
448 #undef INIT_PARAMS
449 #undef UPDATE_PARAMS
450 #undef REINIT_PARAMS
451 #undef ONEBYTE_BODY
452 #undef UNPACK_BYTES
453 #undef CLEAR_STATE
454 #undef LOOP_NEED_STATE
455 #undef LOOP_NEED_FLAGS
456 #undef LOOP_NEED_DATA