8 files changed, 57 insertions, 0 deletions
diff --git a/src/backend/regex/regc_nfa.c b/src/backend/regex/regc_nfa.c
index 05fe8b0808c..170da5954c7 100644
--- a/src/backend/regex/regc_nfa.c
+++ b/src/backend/regex/regc_nfa.c
@@ -174,11 +174,23 @@ newstate(struct nfa * nfa)
 {
 	struct state *s;
 
+	/*
+	 * This is a handy place to check for operation cancel during regex
+	 * compilation, since no code path will go very long without making a new
+	 * state.
+	 */
+	if (CANCEL_REQUESTED(nfa->v->re))
+	{
+		NERR(REG_CANCEL);
+		return NULL;
+	}
+
 	if (TooManyStates(nfa))
 	{
 		NERR(REG_ETOOBIG);
 		return NULL;
 	}
+
 	if (nfa->free != NULL)
 	{
 		s = nfa->free;
diff --git a/src/backend/regex/regcomp.c b/src/backend/regex/regcomp.c
index 9d92f9888bb..2ddcdff09a4 100644
--- a/src/backend/regex/regcomp.c
+++ b/src/backend/regex/regcomp.c
@@ -34,6 +34,8 @@
 
 #include "regex/regguts.h"
 
+#include "miscadmin.h"			/* needed by rcancelrequested() */
+
 /*
  * forward declarations, up here so forward datatypes etc. are defined early
  */
@@ -67,6 +69,7 @@ static long nfanode(struct vars *, struct subre *, FILE *);
 static int	newlacon(struct vars *, struct state *, struct state *, int);
 static void freelacons(struct subre *, int);
 static void rfree(regex_t *);
+static int	rcancelrequested(void);
 
 #ifdef REG_DEBUG
 static void dump(regex_t *, FILE *);
@@ -276,6 +279,7 @@ struct vars
 /* static function list */
 static struct fns functions = {
 	rfree,						/* regfree insides */
+	rcancelrequested			/* check for cancel request */
 };
 
 
@@ -1876,6 +1880,22 @@ rfree(regex_t *re)
 	}
 }
 
+/*
+ * rcancelrequested - check for external request to cancel regex operation
+ *
+ * Return nonzero to fail the operation with error code REG_CANCEL,
+ * zero to keep going
+ *
+ * The current implementation is Postgres-specific.  If we ever get around
+ * to splitting the regex code out as a standalone library, there will need
+ * to be some API to let applications define a callback function for this.
+ */
+static int
+rcancelrequested(void)
+{
+	return InterruptPending && (QueryCancelPending || ProcDiePending);
+}
+
 #ifdef REG_DEBUG
 
 /*
diff --git a/src/backend/regex/regexec.c b/src/backend/regex/regexec.c
index abcb5e7439f..7cd6679eded 100644
--- a/src/backend/regex/regexec.c
+++ b/src/backend/regex/regexec.c
@@ -713,6 +713,10 @@ cdissect(struct vars * v,
 	assert(t != NULL);
 	MDEBUG(("cdissect %ld-%ld %c\n", LOFF(begin), LOFF(end), t->op));
 
+	/* handy place to check for operation cancel */
+	if (CANCEL_REQUESTED(v->re))
+		return REG_CANCEL;
+
 	switch (t->op)
 	{
 		case '=':				/* terminal node */
diff --git a/src/backend/utils/adt/regexp.c b/src/backend/utils/adt/regexp.c
index b15b0905b74..7e05a53810e 100644
--- a/src/backend/utils/adt/regexp.c
+++ b/src/backend/utils/adt/regexp.c
@@ -31,6 +31,7 @@
 
 #include "catalog/pg_type.h"
 #include "funcapi.h"
+#include "miscadmin.h"
 #include "regex/regex.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -188,6 +189,15 @@ RE_compile_and_cache(text *text_re, int cflags, Oid collation)
 	if (regcomp_result != REG_OKAY)
 	{
 		/* re didn't compile (no need for pg_regfree, if so) */
+
+		/*
+		 * Here and in other places in this file, do CHECK_FOR_INTERRUPTS
+		 * before reporting a regex error.	This is so that if the regex
+		 * library aborts and returns REG_CANCEL, we don't print an error
+		 * message that implies the regex was invalid.
+		 */
+		CHECK_FOR_INTERRUPTS();
+
 		pg_regerror(regcomp_result, &re_temp.cre_re, errMsg, sizeof(errMsg));
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
@@ -268,6 +278,7 @@ RE_wchar_execute(regex_t *re, pg_wchar *data, int data_len,
 	if (regexec_result != REG_OKAY && regexec_result != REG_NOMATCH)
 	{
 		/* re failed??? */
+		CHECK_FOR_INTERRUPTS();
 		pg_regerror(regexec_result, re, errMsg, sizeof(errMsg));
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
@@ -1216,6 +1227,7 @@ regexp_fixed_prefix(text *text_re, bool case_insensitive, Oid collation,
 
 		default:
 			/* re failed??? */
+			CHECK_FOR_INTERRUPTS();
 			pg_regerror(re_result, re, errMsg, sizeof(errMsg));
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index fe06f1b5527..e9ea6288048 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -2854,6 +2854,7 @@ replace_text_regexp(text *src_text, void *regexp,
 		{
 			char		errMsg[100];
 
+			CHECK_FOR_INTERRUPTS();
 			pg_regerror(regexec_result, re, errMsg, sizeof(errMsg));
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
diff --git a/src/include/regex/regerrs.h b/src/include/regex/regerrs.h
index f02711ee176..809b5112660 100644
--- a/src/include/regex/regerrs.h
+++ b/src/include/regex/regerrs.h
@@ -81,3 +81,7 @@
 {
 	REG_ECOLORS, "REG_ECOLORS", "too many colors"
 },
+
+{
+	REG_CANCEL, "REG_CANCEL", "operation cancelled"
+},
diff --git a/src/include/regex/regex.h b/src/include/regex/regex.h
index 3e87dff17b2..2c7fa4df46f 100644
--- a/src/include/regex/regex.h
+++ b/src/include/regex/regex.h
@@ -154,6 +154,7 @@ typedef struct
 #define REG_BADOPT	18			/* invalid embedded option */
 #define REG_ETOOBIG 19			/* nfa has too many states */
 #define REG_ECOLORS 20			/* too many colors */
+#define REG_CANCEL	21			/* operation cancelled */
 /* two specials for debugging and testing */
 #define REG_ATOI	101			/* convert error-code name to number */
 #define REG_ITOA	102			/* convert error-code number to name */
diff --git a/src/include/regex/regguts.h b/src/include/regex/regguts.h
index 968a04edd99..55e1696fe8c 100644
--- a/src/include/regex/regguts.h
+++ b/src/include/regex/regguts.h
@@ -403,8 +403,11 @@ struct subre
 struct fns
 {
 	void		FUNCPTR(free, (regex_t *));
+	int			FUNCPTR(cancel_requested, (void));
 };
 
+#define CANCEL_REQUESTED(re)  \
+	((*((struct fns *) (re)->re_fns)->cancel_requested) ())
 
 
 /*