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cosmopolitan/third_party/duktape/duk_regexp_executor.c

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Initial import
2020-06-15 14:18:57 +00:00
/*
* Regexp executor.
*
* Safety: the ECMAScript executor should prevent user from reading and
* replacing regexp bytecode. Even so, the executor must validate all
* memory accesses etc. When an invalid access is detected (e.g. a 'save'
* opcode to invalid, unallocated index) it should fail with an internal
* error but not cause a segmentation fault.
*
* Notes:
*
* - Backtrack counts are limited to unsigned 32 bits but should
* technically be duk_size_t for strings longer than 4G chars.
* This also requires a regexp bytecode change.
*/
#include "third_party/duktape/duk_internal.h"
#if defined(DUK_USE_REGEXP_SUPPORT)
/*
* Helpers for UTF-8 handling
*
* For bytecode readers the duk_uint32_t and duk_int32_t types are correct
* because they're used for more than just codepoints.
*/
DUK_LOCAL duk_uint32_t duk__bc_get_u32(duk_re_matcher_ctx *re_ctx, const duk_uint8_t **pc) {
return (duk_uint32_t) duk_unicode_decode_xutf8_checked(re_ctx->thr, pc, re_ctx->bytecode, re_ctx->bytecode_end);
}
DUK_LOCAL duk_int32_t duk__bc_get_i32(duk_re_matcher_ctx *re_ctx, const duk_uint8_t **pc) {
duk_uint32_t t;
/* signed integer encoding needed to work with UTF-8 */
t = (duk_uint32_t) duk_unicode_decode_xutf8_checked(re_ctx->thr, pc, re_ctx->bytecode, re_ctx->bytecode_end);
if (t & 1) {
return -((duk_int32_t) (t >> 1));
} else {
return (duk_int32_t) (t >> 1);
}
}
DUK_LOCAL const duk_uint8_t *duk__utf8_backtrack(duk_hthread *thr, const duk_uint8_t **ptr, const duk_uint8_t *ptr_start, const duk_uint8_t *ptr_end, duk_uint_fast32_t count) {
const duk_uint8_t *p;
/* Note: allow backtracking from p == ptr_end */
p = *ptr;
if (p < ptr_start || p > ptr_end) {
goto fail;
}
while (count > 0) {
for (;;) {
p--;
if (p < ptr_start) {
goto fail;
}
if ((*p & 0xc0) != 0x80) {
/* utf-8 continuation bytes have the form 10xx xxxx */
break;
}
}
count--;
}
*ptr = p;
return p;
fail:
DUK_ERROR_INTERNAL(thr);
DUK_WO_NORETURN(return NULL;);
}
DUK_LOCAL const duk_uint8_t *duk__utf8_advance(duk_hthread *thr, const duk_uint8_t **ptr, const duk_uint8_t *ptr_start, const duk_uint8_t *ptr_end, duk_uint_fast32_t count) {
const duk_uint8_t *p;
p = *ptr;
if (p < ptr_start || p >= ptr_end) {
goto fail;
}
while (count > 0) {
for (;;) {
p++;
/* Note: if encoding ends by hitting end of input, we don't check that
* the encoding is valid, we just assume it is.
*/
if (p >= ptr_end || ((*p & 0xc0) != 0x80)) {
/* utf-8 continuation bytes have the form 10xx xxxx */
break;
}
}
count--;
}
*ptr = p;
return p;
fail:
DUK_ERROR_INTERNAL(thr);
DUK_WO_NORETURN(return NULL;);
}
/*
* Helpers for dealing with the input string
*/
/* Get a (possibly canonicalized) input character from current sp. The input
* itself is never modified, and captures always record non-canonicalized
* characters even in case-insensitive matching. Return <0 if out of input.
*/
DUK_LOCAL duk_codepoint_t duk__inp_get_cp(duk_re_matcher_ctx *re_ctx, const duk_uint8_t **sp) {
duk_codepoint_t res;
if (*sp >= re_ctx->input_end) {
return -1;
}
res = (duk_codepoint_t) duk_unicode_decode_xutf8_checked(re_ctx->thr, sp, re_ctx->input, re_ctx->input_end);
if (re_ctx->re_flags & DUK_RE_FLAG_IGNORE_CASE) {
res = duk_unicode_re_canonicalize_char(re_ctx->thr, res);
}
return res;
}
DUK_LOCAL const duk_uint8_t *duk__inp_backtrack(duk_re_matcher_ctx *re_ctx, const duk_uint8_t **sp, duk_uint_fast32_t count) {
return duk__utf8_backtrack(re_ctx->thr, sp, re_ctx->input, re_ctx->input_end, count);
}
/* Backtrack utf-8 input and return a (possibly canonicalized) input character. */
DUK_LOCAL duk_codepoint_t duk__inp_get_prev_cp(duk_re_matcher_ctx *re_ctx, const duk_uint8_t *sp) {
/* note: caller 'sp' is intentionally not updated here */
(void) duk__inp_backtrack(re_ctx, &sp, (duk_uint_fast32_t) 1);
return duk__inp_get_cp(re_ctx, &sp);
}
/*
* Regexp recursive matching function.
*
* Returns 'sp' on successful match (points to character after last matched one),
* NULL otherwise.
*
* The C recursion depth limit check is only performed in this function, this
* suffices because the function is present in all true recursion required by
* regexp execution.
*/
DUK_LOCAL const duk_uint8_t *duk__match_regexp(duk_re_matcher_ctx *re_ctx, const duk_uint8_t *pc, const duk_uint8_t *sp) {
duk_native_stack_check(re_ctx->thr);
if (re_ctx->recursion_depth >= re_ctx->recursion_limit) {
DUK_ERROR_RANGE(re_ctx->thr, DUK_STR_REGEXP_EXECUTOR_RECURSION_LIMIT);
DUK_WO_NORETURN(return NULL;);
}
re_ctx->recursion_depth++;
for (;;) {
duk_small_int_t op;
if (re_ctx->steps_count >= re_ctx->steps_limit) {
DUK_ERROR_RANGE(re_ctx->thr, DUK_STR_REGEXP_EXECUTOR_STEP_LIMIT);
DUK_WO_NORETURN(return NULL;);
}
re_ctx->steps_count++;
/* Opcodes are at most 7 bits now so they encode to one byte. If this
* were not the case or 'pc' is invalid here (due to a bug etc) we'll
* still fail safely through the switch default case.
*/
DUK_ASSERT(pc[0] <= 0x7fU);
#if 0
op = (duk_small_int_t) duk__bc_get_u32(re_ctx, &pc);
#endif
op = *pc++;
DUK_DDD(DUK_DDDPRINT("match: rec=%ld, steps=%ld, pc (after op)=%ld, sp=%ld, op=%ld",
(long) re_ctx->recursion_depth,
(long) re_ctx->steps_count,
(long) (pc - re_ctx->bytecode),
(long) (sp - re_ctx->input),
(long) op));
switch (op) {
case DUK_REOP_MATCH: {
goto match;
}
case DUK_REOP_CHAR: {
/*
* Byte-based matching would be possible for case-sensitive
* matching but not for case-insensitive matching. So, we
* match by decoding the input and bytecode character normally.
*
* Bytecode characters are assumed to be already canonicalized.
* Input characters are canonicalized automatically by
* duk__inp_get_cp() if necessary.
*
* There is no opcode for matching multiple characters. The
* regexp compiler has trouble joining strings efficiently
* during compilation. See doc/regexp.rst for more discussion.
*/
duk_codepoint_t c1, c2;
c1 = (duk_codepoint_t) duk__bc_get_u32(re_ctx, &pc);
DUK_ASSERT(!(re_ctx->re_flags & DUK_RE_FLAG_IGNORE_CASE) ||
c1 == duk_unicode_re_canonicalize_char(re_ctx->thr, c1)); /* canonicalized by compiler */
c2 = duk__inp_get_cp(re_ctx, &sp);
/* No need to check for c2 < 0 (end of input): because c1 >= 0, it
* will fail the match below automatically and cause goto fail.
*/
#if 0
if (c2 < 0) {
goto fail;
}
#endif
DUK_ASSERT(c1 >= 0);
DUK_DDD(DUK_DDDPRINT("char match, c1=%ld, c2=%ld", (long) c1, (long) c2));
if (c1 != c2) {
goto fail;
}
break;
}
case DUK_REOP_PERIOD: {
duk_codepoint_t c;
c = duk__inp_get_cp(re_ctx, &sp);
if (c < 0 || duk_unicode_is_line_terminator(c)) {
/* E5 Sections 15.10.2.8, 7.3 */
goto fail;
}
break;
}
case DUK_REOP_RANGES:
case DUK_REOP_INVRANGES: {
duk_uint32_t n;
duk_codepoint_t c;
duk_small_int_t match;
n = duk__bc_get_u32(re_ctx, &pc);
c = duk__inp_get_cp(re_ctx, &sp);
if (c < 0) {
goto fail;
}
match = 0;
while (n) {
duk_codepoint_t r1, r2;
r1 = (duk_codepoint_t) duk__bc_get_u32(re_ctx, &pc);
r2 = (duk_codepoint_t) duk__bc_get_u32(re_ctx, &pc);
DUK_DDD(DUK_DDDPRINT("matching ranges/invranges, n=%ld, r1=%ld, r2=%ld, c=%ld",
(long) n, (long) r1, (long) r2, (long) c));
if (c >= r1 && c <= r2) {
/* Note: don't bail out early, we must read all the ranges from
* bytecode. Another option is to skip them efficiently after
* breaking out of here. Prefer smallest code.
*/
match = 1;
}
n--;
}
if (op == DUK_REOP_RANGES) {
if (!match) {
goto fail;
}
} else {
DUK_ASSERT(op == DUK_REOP_INVRANGES);
if (match) {
goto fail;
}
}
break;
}
case DUK_REOP_ASSERT_START: {
duk_codepoint_t c;
if (sp <= re_ctx->input) {
break;
}
if (!(re_ctx->re_flags & DUK_RE_FLAG_MULTILINE)) {
goto fail;
}
c = duk__inp_get_prev_cp(re_ctx, sp);
if (duk_unicode_is_line_terminator(c)) {
/* E5 Sections 15.10.2.8, 7.3 */
break;
}
goto fail;
}
case DUK_REOP_ASSERT_END: {
duk_codepoint_t c;
const duk_uint8_t *tmp_sp;
tmp_sp = sp;
c = duk__inp_get_cp(re_ctx, &tmp_sp);
if (c < 0) {
break;
}
if (!(re_ctx->re_flags & DUK_RE_FLAG_MULTILINE)) {
goto fail;
}
if (duk_unicode_is_line_terminator(c)) {
/* E5 Sections 15.10.2.8, 7.3 */
break;
}
goto fail;
}
case DUK_REOP_ASSERT_WORD_BOUNDARY:
case DUK_REOP_ASSERT_NOT_WORD_BOUNDARY: {
/*
* E5 Section 15.10.2.6. The previous and current character
* should -not- be canonicalized as they are now. However,
* canonicalization does not affect the result of IsWordChar()
* (which depends on Unicode characters never canonicalizing
* into ASCII characters) so this does not matter.
*/
duk_small_int_t w1, w2;
if (sp <= re_ctx->input) {
w1 = 0; /* not a wordchar */
} else {
duk_codepoint_t c;
c = duk__inp_get_prev_cp(re_ctx, sp);
w1 = duk_unicode_re_is_wordchar(c);
}
if (sp >= re_ctx->input_end) {
w2 = 0; /* not a wordchar */
} else {
const duk_uint8_t *tmp_sp = sp; /* dummy so sp won't get updated */
duk_codepoint_t c;
c = duk__inp_get_cp(re_ctx, &tmp_sp);
w2 = duk_unicode_re_is_wordchar(c);
}
if (op == DUK_REOP_ASSERT_WORD_BOUNDARY) {
if (w1 == w2) {
goto fail;
}
} else {
DUK_ASSERT(op == DUK_REOP_ASSERT_NOT_WORD_BOUNDARY);
if (w1 != w2) {
goto fail;
}
}
break;
}
case DUK_REOP_JUMP: {
duk_int32_t skip;
skip = duk__bc_get_i32(re_ctx, &pc);
pc += skip;
break;
}
case DUK_REOP_SPLIT1: {
/* split1: prefer direct execution (no jump) */
const duk_uint8_t *sub_sp;
duk_int32_t skip;
skip = duk__bc_get_i32(re_ctx, &pc);
sub_sp = duk__match_regexp(re_ctx, pc, sp);
if (sub_sp) {
sp = sub_sp;
goto match;
}
pc += skip;
break;
}
case DUK_REOP_SPLIT2: {
/* split2: prefer jump execution (not direct) */
const duk_uint8_t *sub_sp;
duk_int32_t skip;
skip = duk__bc_get_i32(re_ctx, &pc);
sub_sp = duk__match_regexp(re_ctx, pc + skip, sp);
if (sub_sp) {
sp = sub_sp;
goto match;
}
break;
}
case DUK_REOP_SQMINIMAL: {
duk_uint32_t q, qmin, qmax;
duk_int32_t skip;
const duk_uint8_t *sub_sp;
qmin = duk__bc_get_u32(re_ctx, &pc);
qmax = duk__bc_get_u32(re_ctx, &pc);
skip = duk__bc_get_i32(re_ctx, &pc);
DUK_DDD(DUK_DDDPRINT("minimal quantifier, qmin=%lu, qmax=%lu, skip=%ld",
(unsigned long) qmin, (unsigned long) qmax, (long) skip));
q = 0;
while (q <= qmax) {
if (q >= qmin) {
sub_sp = duk__match_regexp(re_ctx, pc + skip, sp);
if (sub_sp) {
sp = sub_sp;
goto match;
}
}
sub_sp = duk__match_regexp(re_ctx, pc, sp);
if (!sub_sp) {
break;
}
sp = sub_sp;
q++;
}
goto fail;
}
case DUK_REOP_SQGREEDY: {
duk_uint32_t q, qmin, qmax, atomlen;
duk_int32_t skip;
const duk_uint8_t *sub_sp;
qmin = duk__bc_get_u32(re_ctx, &pc);
qmax = duk__bc_get_u32(re_ctx, &pc);
atomlen = duk__bc_get_u32(re_ctx, &pc);
skip = duk__bc_get_i32(re_ctx, &pc);
DUK_DDD(DUK_DDDPRINT("greedy quantifier, qmin=%lu, qmax=%lu, atomlen=%lu, skip=%ld",
(unsigned long) qmin, (unsigned long) qmax, (unsigned long) atomlen, (long) skip));
q = 0;
while (q < qmax) {
sub_sp = duk__match_regexp(re_ctx, pc, sp);
if (!sub_sp) {
break;
}
sp = sub_sp;
q++;
}
while (q >= qmin) {
sub_sp = duk__match_regexp(re_ctx, pc + skip, sp);
if (sub_sp) {
sp = sub_sp;
goto match;
}
if (q == qmin) {
break;
}
/* Note: if atom were to contain e.g. captures, we would need to
* re-match the atom to get correct captures. Simply quantifiers
* do not allow captures in their atom now, so this is not an issue.
*/
DUK_DDD(DUK_DDDPRINT("greedy quantifier, backtrack %ld characters (atomlen)",
(long) atomlen));
sp = duk__inp_backtrack(re_ctx, &sp, (duk_uint_fast32_t) atomlen);
q--;
}
goto fail;
}
case DUK_REOP_SAVE: {
duk_uint32_t idx;
const duk_uint8_t *old;
const duk_uint8_t *sub_sp;
idx = duk__bc_get_u32(re_ctx, &pc);
if (idx >= re_ctx->nsaved) {
/* idx is unsigned, < 0 check is not necessary */
DUK_D(DUK_DPRINT("internal error, regexp save index insane: idx=%ld", (long) idx));
goto internal_error;
}
old = re_ctx->saved[idx];
re_ctx->saved[idx] = sp;
sub_sp = duk__match_regexp(re_ctx, pc, sp);
if (sub_sp) {
sp = sub_sp;
goto match;
}
re_ctx->saved[idx] = old;
goto fail;
}
case DUK_REOP_WIPERANGE: {
/* Wipe capture range and save old values for backtracking.
*
* XXX: this typically happens with a relatively small idx_count.
* It might be useful to handle cases where the count is small
* (say <= 8) by saving the values in stack instead. This would
* reduce memory churn and improve performance, at the cost of a
* slightly higher code footprint.
*/
duk_uint32_t idx_start, idx_count;
#if defined(DUK_USE_EXPLICIT_NULL_INIT)
duk_uint32_t idx_end, idx;
#endif
duk_uint8_t **range_save;
const duk_uint8_t *sub_sp;
idx_start = duk__bc_get_u32(re_ctx, &pc);
idx_count = duk__bc_get_u32(re_ctx, &pc);
DUK_DDD(DUK_DDDPRINT("wipe saved range: start=%ld, count=%ld -> [%ld,%ld] (captures [%ld,%ld])",
(long) idx_start, (long) idx_count,
(long) idx_start, (long) (idx_start + idx_count - 1),
(long) (idx_start / 2), (long) ((idx_start + idx_count - 1) / 2)));
if (idx_start + idx_count > re_ctx->nsaved || idx_count == 0) {
/* idx is unsigned, < 0 check is not necessary */
DUK_D(DUK_DPRINT("internal error, regexp wipe indices insane: idx_start=%ld, idx_count=%ld",
(long) idx_start, (long) idx_count));
goto internal_error;
}
DUK_ASSERT(idx_count > 0);
duk_require_stack(re_ctx->thr, 1);
range_save = (duk_uint8_t **) duk_push_fixed_buffer_nozero(re_ctx->thr,
sizeof(duk_uint8_t *) * idx_count);
DUK_ASSERT(range_save != NULL);
duk_memcpy(range_save, re_ctx->saved + idx_start, sizeof(duk_uint8_t *) * idx_count);
#if defined(DUK_USE_EXPLICIT_NULL_INIT)
idx_end = idx_start + idx_count;
for (idx = idx_start; idx < idx_end; idx++) {
re_ctx->saved[idx] = NULL;
}
#else
duk_memzero((void *) (re_ctx->saved + idx_start), sizeof(duk_uint8_t *) * idx_count);
#endif
sub_sp = duk__match_regexp(re_ctx, pc, sp);
if (sub_sp) {
/* match: keep wiped/resaved values */
DUK_DDD(DUK_DDDPRINT("match: keep wiped/resaved values [%ld,%ld] (captures [%ld,%ld])",
(long) idx_start, (long) (idx_start + idx_count - 1),
(long) (idx_start / 2), (long) ((idx_start + idx_count - 1) / 2)));
duk_pop_unsafe(re_ctx->thr);
sp = sub_sp;
goto match;
}
/* fail: restore saves */
DUK_DDD(DUK_DDDPRINT("fail: restore wiped/resaved values [%ld,%ld] (captures [%ld,%ld])",
(long) idx_start, (long) (idx_start + idx_count - 1),
(long) (idx_start / 2), (long) ((idx_start + idx_count - 1) / 2)));
duk_memcpy((void *) (re_ctx->saved + idx_start),
(const void *) range_save,
sizeof(duk_uint8_t *) * idx_count);
duk_pop_unsafe(re_ctx->thr);
goto fail;
}
case DUK_REOP_LOOKPOS:
case DUK_REOP_LOOKNEG: {
/*
* Needs a save of multiple saved[] entries depending on what range
* may be overwritten. Because the regexp parser does no such analysis,
* we currently save the entire saved array here. Lookaheads are thus
* a bit expensive. Note that the saved array is not needed for just
* the lookahead sub-match, but for the matching of the entire sequel.
*
* The temporary save buffer is pushed on to the valstack to handle
* errors correctly. Each lookahead causes a C recursion and pushes
* more stuff on the value stack. If the C recursion limit is less
* than the value stack slack, there is no need to check the stack.
* We do so regardless, just in case.
*/
duk_int32_t skip;
duk_uint8_t **full_save;
const duk_uint8_t *sub_sp;
DUK_ASSERT(re_ctx->nsaved > 0);
duk_require_stack(re_ctx->thr, 1);
full_save = (duk_uint8_t **) duk_push_fixed_buffer_nozero(re_ctx->thr,
sizeof(duk_uint8_t *) * re_ctx->nsaved);
DUK_ASSERT(full_save != NULL);
duk_memcpy(full_save, re_ctx->saved, sizeof(duk_uint8_t *) * re_ctx->nsaved);
skip = duk__bc_get_i32(re_ctx, &pc);
sub_sp = duk__match_regexp(re_ctx, pc, sp);
if (op == DUK_REOP_LOOKPOS) {
if (!sub_sp) {
goto lookahead_fail;
}
} else {
if (sub_sp) {
goto lookahead_fail;
}
}
sub_sp = duk__match_regexp(re_ctx, pc + skip, sp);
if (sub_sp) {
/* match: keep saves */
duk_pop_unsafe(re_ctx->thr);
sp = sub_sp;
goto match;
}
/* fall through */
lookahead_fail:
/* fail: restore saves */
duk_memcpy((void *) re_ctx->saved,
(const void *) full_save,
sizeof(duk_uint8_t *) * re_ctx->nsaved);
duk_pop_unsafe(re_ctx->thr);
goto fail;
}
case DUK_REOP_BACKREFERENCE: {
/*
* Byte matching for back-references would be OK in case-
* sensitive matching. In case-insensitive matching we need
* to canonicalize characters, so back-reference matching needs
* to be done with codepoints instead. So, we just decode
* everything normally here, too.
*
* Note: back-reference index which is 0 or higher than
* NCapturingParens (= number of capturing parens in the
* -entire- regexp) is a compile time error. However, a
* backreference referring to a valid capture which has
* not matched anything always succeeds! See E5 Section
* 15.10.2.9, step 5, sub-step 3.
*/
duk_uint32_t idx;
const duk_uint8_t *p;
idx = duk__bc_get_u32(re_ctx, &pc);
idx = idx << 1; /* backref n -> saved indices [n*2, n*2+1] */
if (idx < 2 || idx + 1 >= re_ctx->nsaved) {
/* regexp compiler should catch these */
DUK_D(DUK_DPRINT("internal error, backreference index insane"));
goto internal_error;
}
if (!re_ctx->saved[idx] || !re_ctx->saved[idx+1]) {
/* capture is 'undefined', always matches! */
DUK_DDD(DUK_DDDPRINT("backreference: saved[%ld,%ld] not complete, always match",
(long) idx, (long) (idx + 1)));
break;
}
DUK_DDD(DUK_DDDPRINT("backreference: match saved[%ld,%ld]", (long) idx, (long) (idx + 1)));
p = re_ctx->saved[idx];
while (p < re_ctx->saved[idx+1]) {
duk_codepoint_t c1, c2;
/* Note: not necessary to check p against re_ctx->input_end:
* the memory access is checked by duk__inp_get_cp(), while
* valid compiled regexps cannot write a saved[] entry
* which points to outside the string.
*/
c1 = duk__inp_get_cp(re_ctx, &p);
DUK_ASSERT(c1 >= 0);
c2 = duk__inp_get_cp(re_ctx, &sp);
/* No need for an explicit c2 < 0 check: because c1 >= 0,
* the comparison will always fail if c2 < 0.
*/
#if 0
if (c2 < 0) {
goto fail;
}
#endif
if (c1 != c2) {
goto fail;
}
}
break;
}
default: {
DUK_D(DUK_DPRINT("internal error, regexp opcode error: %ld", (long) op));
goto internal_error;
}
}
}
match:
re_ctx->recursion_depth--;
return sp;
fail:
re_ctx->recursion_depth--;
return NULL;
internal_error:
DUK_ERROR_INTERNAL(re_ctx->thr);
DUK_WO_NORETURN(return NULL;);
}
/*
* Exposed matcher function which provides the semantics of RegExp.prototype.exec().
*
* RegExp.prototype.test() has the same semantics as exec() but does not return the
* result object (which contains the matching string and capture groups). Currently
* there is no separate test() helper, so a temporary result object is created and
* discarded if test() is needed. This is intentional, to save code space.
*
* Input stack: [ ... re_obj input ]
* Output stack: [ ... result ]
*/
DUK_LOCAL void duk__regexp_match_helper(duk_hthread *thr, duk_small_int_t force_global) {
duk_re_matcher_ctx re_ctx;
duk_hobject *h_regexp;
duk_hstring *h_bytecode;
duk_hstring *h_input;
duk_uint8_t *p_buf;
const duk_uint8_t *pc;
const duk_uint8_t *sp;
duk_small_int_t match = 0;
duk_small_int_t global;
duk_uint_fast32_t i;
double d;
duk_uint32_t char_offset;
DUK_ASSERT(thr != NULL);
DUK_DD(DUK_DDPRINT("regexp match: regexp=%!T, input=%!T",
(duk_tval *) duk_get_tval(thr, -2),
(duk_tval *) duk_get_tval(thr, -1)));
/*
* Regexp instance check, bytecode check, input coercion.
*
* See E5 Section 15.10.6.
*/
/* TypeError if wrong; class check, see E5 Section 15.10.6 */
h_regexp = duk_require_hobject_with_class(thr, -2, DUK_HOBJECT_CLASS_REGEXP);
DUK_ASSERT(h_regexp != NULL);
DUK_ASSERT(DUK_HOBJECT_GET_CLASS_NUMBER(h_regexp) == DUK_HOBJECT_CLASS_REGEXP);
DUK_UNREF(h_regexp);
h_input = duk_to_hstring(thr, -1);
DUK_ASSERT(h_input != NULL);
duk_xget_owndataprop_stridx_short(thr, -2, DUK_STRIDX_INT_BYTECODE); /* [ ... re_obj input ] -> [ ... re_obj input bc ] */
h_bytecode = duk_require_hstring(thr, -1); /* no regexp instance should exist without a non-configurable bytecode property */
DUK_ASSERT(h_bytecode != NULL);
/*
* Basic context initialization.
*
* Some init values are read from the bytecode header
* whose format is (UTF-8 codepoints):
*
* uint flags
* uint nsaved (even, 2n+2 where n = num captures)
*/
/* [ ... re_obj input bc ] */
duk_memzero(&re_ctx, sizeof(re_ctx));
re_ctx.thr = thr;
re_ctx.input = (const duk_uint8_t *) DUK_HSTRING_GET_DATA(h_input);
re_ctx.input_end = re_ctx.input + DUK_HSTRING_GET_BYTELEN(h_input);
re_ctx.bytecode = (const duk_uint8_t *) DUK_HSTRING_GET_DATA(h_bytecode);
re_ctx.bytecode_end = re_ctx.bytecode + DUK_HSTRING_GET_BYTELEN(h_bytecode);
re_ctx.saved = NULL;
re_ctx.recursion_limit = DUK_USE_REGEXP_EXECUTOR_RECLIMIT;
re_ctx.steps_limit = DUK_RE_EXECUTE_STEPS_LIMIT;
/* read header */
pc = re_ctx.bytecode;
re_ctx.re_flags = duk__bc_get_u32(&re_ctx, &pc);
re_ctx.nsaved = duk__bc_get_u32(&re_ctx, &pc);
re_ctx.bytecode = pc;
DUK_ASSERT(DUK_RE_FLAG_GLOBAL < 0x10000UL); /* must fit into duk_small_int_t */
global = (duk_small_int_t) (force_global | (duk_small_int_t) (re_ctx.re_flags & DUK_RE_FLAG_GLOBAL));
DUK_ASSERT(re_ctx.nsaved >= 2);
DUK_ASSERT((re_ctx.nsaved % 2) == 0);
p_buf = (duk_uint8_t *) duk_push_fixed_buffer(thr, sizeof(duk_uint8_t *) * re_ctx.nsaved); /* rely on zeroing */
DUK_UNREF(p_buf);
re_ctx.saved = (const duk_uint8_t **) duk_get_buffer(thr, -1, NULL);
DUK_ASSERT(re_ctx.saved != NULL);
/* [ ... re_obj input bc saved_buf ] */
#if defined(DUK_USE_EXPLICIT_NULL_INIT)
for (i = 0; i < re_ctx.nsaved; i++) {
re_ctx.saved[i] = (duk_uint8_t *) NULL;
}
#elif defined(DUK_USE_ZERO_BUFFER_DATA)
/* buffer is automatically zeroed */
#else
duk_memzero((void *) p_buf, sizeof(duk_uint8_t *) * re_ctx.nsaved);
#endif
DUK_DDD(DUK_DDDPRINT("regexp ctx initialized, flags=0x%08lx, nsaved=%ld, recursion_limit=%ld, steps_limit=%ld",
(unsigned long) re_ctx.re_flags, (long) re_ctx.nsaved, (long) re_ctx.recursion_limit,
(long) re_ctx.steps_limit));
/*
* Get starting character offset for match, and initialize 'sp' based on it.
*
* Note: lastIndex is non-configurable so it must be present (we check the
* internal class of the object above, so we know it is). User code can set
* its value to an arbitrary (garbage) value though; E5 requires that lastIndex
* be coerced to a number before using. The code below works even if the
* property is missing: the value will then be coerced to zero.
*
* Note: lastIndex may be outside Uint32 range even after ToInteger() coercion.
* For instance, ToInteger(+Infinity) = +Infinity. We track the match offset
* as an integer, but pre-check it to be inside the 32-bit range before the loop.
* If not, the check in E5 Section 15.10.6.2, step 9.a applies.
*/
/* XXX: lastIndex handling produces a lot of asm */
/* [ ... re_obj input bc saved_buf ] */
duk_get_prop_stridx_short(thr, -4, DUK_STRIDX_LAST_INDEX); /* -> [ ... re_obj input bc saved_buf lastIndex ] */
(void) duk_to_int(thr, -1); /* ToInteger(lastIndex) */
d = duk_get_number(thr, -1); /* integer, but may be +/- Infinite, +/- zero (not NaN, though) */
duk_pop_nodecref_unsafe(thr);
if (global) {
if (d < 0.0 || d > (double) DUK_HSTRING_GET_CHARLEN(h_input)) {
/* match fail */
char_offset = 0; /* not really necessary */
DUK_ASSERT(match == 0);
goto match_over;
}
char_offset = (duk_uint32_t) d;
} else {
/* lastIndex must be ignored for non-global regexps, but get the
* value for (theoretical) side effects. No side effects can
* really occur, because lastIndex is a normal property and is
* always non-configurable for RegExp instances.
*/
char_offset = (duk_uint32_t) 0;
}
DUK_ASSERT(char_offset <= DUK_HSTRING_GET_CHARLEN(h_input));
sp = re_ctx.input + duk_heap_strcache_offset_char2byte(thr, h_input, char_offset);
/*
* Match loop.
*
* Try matching at different offsets until match found or input exhausted.
*/
/* [ ... re_obj input bc saved_buf ] */
DUK_ASSERT(match == 0);
for (;;) {
/* char offset in [0, h_input->clen] (both ends inclusive), checked before entry */
DUK_ASSERT_DISABLE(char_offset >= 0);
DUK_ASSERT(char_offset <= DUK_HSTRING_GET_CHARLEN(h_input));
/* Note: re_ctx.steps is intentionally not reset, it applies to the entire unanchored match */
DUK_ASSERT(re_ctx.recursion_depth == 0);
DUK_DDD(DUK_DDDPRINT("attempt match at char offset %ld; %p [%p,%p]",
(long) char_offset, (const void *) sp,
(const void *) re_ctx.input, (const void *) re_ctx.input_end));
/*
* Note:
*
* - duk__match_regexp() is required not to longjmp() in ordinary "non-match"
* conditions; a longjmp() will terminate the entire matching process.
*
* - Clearing saved[] is not necessary because backtracking does it
*
* - Backtracking also rewinds re_ctx.recursion back to zero, unless an
* internal/limit error occurs (which causes a longjmp())
*
* - If we supported anchored matches, we would break out here
* unconditionally; however, ECMAScript regexps don't have anchored
* matches. It might make sense to implement a fast bail-out if
* the regexp begins with '^' and sp is not 0: currently we'll just
* run through the entire input string, trivially failing the match
* at every non-zero offset.
*/
if (duk__match_regexp(&re_ctx, re_ctx.bytecode, sp) != NULL) {
DUK_DDD(DUK_DDDPRINT("match at offset %ld", (long) char_offset));
match = 1;
break;
}
/* advance by one character (code point) and one char_offset */
char_offset++;
if (char_offset > DUK_HSTRING_GET_CHARLEN(h_input)) {
/*
* Note:
*
* - Intentionally attempt (empty) match at char_offset == k_input->clen
*
* - Negative char_offsets have been eliminated and char_offset is duk_uint32_t
* -> no need or use for a negative check
*/
DUK_DDD(DUK_DDDPRINT("no match after trying all sp offsets"));
break;
}
/* avoid calling at end of input, will DUK_ERROR (above check suffices to avoid this) */
(void) duk__utf8_advance(thr, &sp, re_ctx.input, re_ctx.input_end, (duk_uint_fast32_t) 1);
}
match_over:
/*
* Matching complete, create result array or return a 'null'. Update lastIndex
* if necessary. See E5 Section 15.10.6.2.
*
* Because lastIndex is a character (not byte) offset, we need the character
* length of the match which we conveniently get as a side effect of interning
* the matching substring (0th index of result array).
*
* saved[0] start pointer (~ byte offset) of current match
* saved[1] end pointer (~ byte offset) of current match (exclusive)
* char_offset start character offset of current match (-> .index of result)
* char_end_offset end character offset (computed below)
*/
/* [ ... re_obj input bc saved_buf ] */
if (match) {
#if defined(DUK_USE_ASSERTIONS)
duk_hobject *h_res;
#endif
duk_uint32_t char_end_offset = 0;
DUK_DDD(DUK_DDDPRINT("regexp matches at char_offset %ld", (long) char_offset));
DUK_ASSERT(re_ctx.nsaved >= 2); /* must have start and end */
DUK_ASSERT((re_ctx.nsaved % 2) == 0); /* and even number */
/* XXX: Array size is known before and (2 * re_ctx.nsaved) but not taken
* advantage of now. The array is not compacted either, as regexp match
* objects are usually short lived.
*/
duk_push_array(thr);
#if defined(DUK_USE_ASSERTIONS)
h_res = duk_require_hobject(thr, -1);
DUK_ASSERT(DUK_HOBJECT_HAS_EXTENSIBLE(h_res));
DUK_ASSERT(DUK_HOBJECT_HAS_EXOTIC_ARRAY(h_res));
DUK_ASSERT(DUK_HOBJECT_GET_CLASS_NUMBER(h_res) == DUK_HOBJECT_CLASS_ARRAY);
#endif
/* [ ... re_obj input bc saved_buf res_obj ] */
duk_push_u32(thr, char_offset);
duk_xdef_prop_stridx_short_wec(thr, -2, DUK_STRIDX_INDEX);
duk_dup_m4(thr);
duk_xdef_prop_stridx_short_wec(thr, -2, DUK_STRIDX_INPUT);
for (i = 0; i < re_ctx.nsaved; i += 2) {
/* Captures which are undefined have NULL pointers and are returned
* as 'undefined'. The same is done when saved[] pointers are insane
* (this should, of course, never happen in practice).
*/
if (re_ctx.saved[i] && re_ctx.saved[i + 1] && re_ctx.saved[i + 1] >= re_ctx.saved[i]) {
duk_push_lstring(thr,
(const char *) re_ctx.saved[i],
(duk_size_t) (re_ctx.saved[i+1] - re_ctx.saved[i]));
if (i == 0) {
/* Assumes that saved[0] and saved[1] are always
* set by regexp bytecode (if not, char_end_offset
* will be zero). Also assumes clen reflects the
* correct char length.
*/
char_end_offset = char_offset + (duk_uint32_t) duk_get_length(thr, -1); /* add charlen */
}
} else {
duk_push_undefined(thr);
}
/* [ ... re_obj input bc saved_buf res_obj val ] */
duk_put_prop_index(thr, -2, (duk_uarridx_t) (i / 2));
}
/* [ ... re_obj input bc saved_buf res_obj ] */
/* NB: 'length' property is automatically updated by the array setup loop */
if (global) {
/* global regexp: lastIndex updated on match */
duk_push_u32(thr, char_end_offset);
duk_put_prop_stridx_short(thr, -6, DUK_STRIDX_LAST_INDEX);
} else {
/* non-global regexp: lastIndex never updated on match */
;
}
} else {
/*
* No match, E5 Section 15.10.6.2, step 9.a.i - 9.a.ii apply, regardless
* of 'global' flag of the RegExp. In particular, if lastIndex is invalid
* initially, it is reset to zero.
*/
DUK_DDD(DUK_DDDPRINT("regexp does not match"));
duk_push_null(thr);
/* [ ... re_obj input bc saved_buf res_obj ] */
duk_push_int(thr, 0);
duk_put_prop_stridx_short(thr, -6, DUK_STRIDX_LAST_INDEX);
}
/* [ ... re_obj input bc saved_buf res_obj ] */
duk_insert(thr, -5);
/* [ ... res_obj re_obj input bc saved_buf ] */
duk_pop_n_unsafe(thr, 4);
/* [ ... res_obj ] */
/* XXX: these last tricks are unnecessary if the function is made
* a genuine native function.
*/
}
DUK_INTERNAL void duk_regexp_match(duk_hthread *thr) {
duk__regexp_match_helper(thr, 0 /*force_global*/);
}
/* This variant is needed by String.prototype.split(); it needs to perform
* global-style matching on a cloned RegExp which is potentially non-global.
*/
DUK_INTERNAL void duk_regexp_match_force_global(duk_hthread *thr) {
duk__regexp_match_helper(thr, 1 /*force_global*/);
}
#else /* DUK_USE_REGEXP_SUPPORT */
/* regexp support disabled */
#endif /* DUK_USE_REGEXP_SUPPORT */