regex: copy back from Gnulib

Copy regex-related files back from Gnulib, to fix a problem with
static checking of regex calls noted by Martin Sebor.  This merges the
following changes:

* New macro __attribute_nonnull__ in misc/sys/cdefs.h, for use later
when copying other files back from Gnulib.

* Use __GNULIB_CDEFS instead of __GLIBC__ when deciding
whether to include bits/wordsize.h etc.

* Avoid duplicate entries in epsilon closure table.

* New regex.h macro _REGEX_NELTS to let regexec say that its pmatch
arg should contain nmatch elts.  Use that for regexec, instead of
__attr_access (which is incorrect).

* New regex.h macro _Attr_access_ which is like __attr_access except
portable to non-glibc platforms.

* Add some DEBUG_ASSERTs to pacify gcc -fanalyzer and to catch
recently-fixed performance bugs if they recur.

* Add Gnulib-specific stuff to port the dynarray- and lock-using parts
of regex code to non-glibc platforms.

* Fix glibc bug 11053.

* Avoid some undefined behavior when popping an empty fail stack.

1 files changed, 38 insertions, 11 deletions

diff --git a/posix/regex.h b/posix/regex.h
index 14fb1d8364..adb69768ee 100644
--- a/posix/regex.h
+++ b/posix/regex.h
@@ -522,6 +522,30 @@ typedef struct
 
 /* Declarations for routines.  */
 
+#ifndef _REGEX_NELTS
+# if (defined __STDC_VERSION__ && 199901L <= __STDC_VERSION__ \
+	&& !defined __STDC_NO_VLA__)
+#  define _REGEX_NELTS(n) n
+# else
+#  define _REGEX_NELTS(n)
+# endif
+#endif
+
+#if defined __GNUC__ && 4 < __GNUC__ + (6 <= __GNUC_MINOR__)
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wvla"
+#endif
+
+#ifndef _Attr_access_
+# ifdef __attr_access
+#  define _Attr_access_(arg) __attr_access (arg)
+# elif defined __GNUC__ && 10 <= __GNUC__
+#  define _Attr_access_(x) __attribute__ ((__access__ x))
+# else
+#  define _Attr_access_(x)
+# endif
+#endif
+
 #ifdef __USE_GNU
 /* Sets the current default syntax to SYNTAX, and return the old syntax.
    You can also simply assign to the 're_syntax_options' variable.  */
@@ -537,7 +561,7 @@ extern reg_syntax_t re_set_syntax (reg_syntax_t __syntax);
    'regfree'.  */
 extern const char *re_compile_pattern (const char *__pattern, size_t __length,
 				       struct re_pattern_buffer *__buffer)
-    __attr_access ((__read_only__, 1, 2));
+    _Attr_access_ ((__read_only__, 1, 2));
 
 
 /* Compile a fastmap for the compiled pattern in BUFFER; used to
@@ -555,7 +579,7 @@ extern regoff_t re_search (struct re_pattern_buffer *__buffer,
 			   const char *__String, regoff_t __length,
 			   regoff_t __start, regoff_t __range,
 			   struct re_registers *__regs)
-    __attr_access ((__read_only__, 2, 3));
+    _Attr_access_ ((__read_only__, 2, 3));
 
 
 /* Like 're_search', but search in the concatenation of STRING1 and
@@ -566,8 +590,8 @@ extern regoff_t re_search_2 (struct re_pattern_buffer *__buffer,
 			     regoff_t __start, regoff_t __range,
 			     struct re_registers *__regs,
 			     regoff_t __stop)
-    __attr_access ((__read_only__, 2, 3))
-    __attr_access ((__read_only__, 4, 5));
+    _Attr_access_ ((__read_only__, 2, 3))
+    _Attr_access_ ((__read_only__, 4, 5));
 
 
 /* Like 're_search', but return how many characters in STRING the regexp
@@ -575,7 +599,7 @@ extern regoff_t re_search_2 (struct re_pattern_buffer *__buffer,
 extern regoff_t re_match (struct re_pattern_buffer *__buffer,
 			  const char *__String, regoff_t __length,
 			  regoff_t __start, struct re_registers *__regs)
-    __attr_access ((__read_only__, 2, 3));
+    _Attr_access_ ((__read_only__, 2, 3));
 
 
 /* Relates to 're_match' as 're_search_2' relates to 're_search'.  */
@@ -584,8 +608,8 @@ extern regoff_t re_match_2 (struct re_pattern_buffer *__buffer,
 			    const char *__string2, regoff_t __length2,
 			    regoff_t __start, struct re_registers *__regs,
 			    regoff_t __stop)
-    __attr_access ((__read_only__, 2, 3))
-    __attr_access ((__read_only__, 4, 5));
+    _Attr_access_ ((__read_only__, 2, 3))
+    _Attr_access_ ((__read_only__, 4, 5));
 
 
 /* Set REGS to hold NUM_REGS registers, storing them in STARTS and
@@ -654,16 +678,19 @@ extern int regcomp (regex_t *_Restrict_ __preg,
 
 extern int regexec (const regex_t *_Restrict_ __preg,
 		    const char *_Restrict_ __String, size_t __nmatch,
-		    regmatch_t __pmatch[_Restrict_arr_],
-		    int __eflags)
-    __attr_access ((__write_only__, 4, 3));
+		    regmatch_t __pmatch[_Restrict_arr_
+					_REGEX_NELTS (__nmatch)],
+		    int __eflags);
 
 extern size_t regerror (int __errcode, const regex_t *_Restrict_ __preg,
 			char *_Restrict_ __errbuf, size_t __errbuf_size)
-    __attr_access ((__write_only__, 3, 4));
+    _Attr_access_ ((__write_only__, 3, 4));
 
 extern void regfree (regex_t *__preg);
 
+#if defined __GNUC__ && 4 < __GNUC__ + (6 <= __GNUC_MINOR__)
+# pragma GCC diagnostic pop
+#endif
 
 #ifdef __cplusplus
 }