Backout the contributed patch memaccounting from Postgres since it changes

the protections incompatibly and causes established tests to crash.

6 files changed, 80 insertions, 28 deletions

diff --git a/generic/regc_nfa.c b/generic/regc_nfa.c
index 6280e5e..d155b23 100644
--- a/generic/regc_nfa.c
+++ b/generic/regc_nfa.c
@@ -62,6 +62,7 @@ newnfa(
     nfa->nstates = 0;
     nfa->cm = cm;
     nfa->v = v;
+    nfa->size = 0;
     nfa->bos[0] = nfa->bos[1] = COLORLESS;
     nfa->eos[0] = nfa->eos[1] = COLORLESS;
     nfa->parent = parent;	/* Precedes newfstate so parent is valid. */
@@ -89,6 +90,61 @@ newnfa(
 }
 
 /*
+ - TooManyStates - checks if the max states exceeds the compile-time value
+ ^ static int TooManyStates(struct nfa *);
+ */
+static int
+TooManyStates(
+    struct nfa *nfa)
+{
+    struct nfa *parent = nfa->parent;
+    size_t sz = nfa->size;
+
+    while (parent != NULL) {
+	sz = parent->size;
+	parent = parent->parent;
+    }
+    if (sz > REG_MAX_STATES) {
+	return 1;
+    }
+    return 0;
+}
+
+/*
+ - IncrementSize - increases the tracked size of the NFA and its parents.
+ ^ static void IncrementSize(struct nfa *);
+ */
+static void
+IncrementSize(
+    struct nfa *nfa)
+{
+    struct nfa *parent = nfa->parent;
+
+    nfa->size++;
+    while (parent != NULL) {
+	parent->size++;
+	parent = parent->parent;
+    }
+}
+
+/*
+ - DecrementSize - increases the tracked size of the NFA and its parents.
+ ^ static void DecrementSize(struct nfa *);
+ */
+static void
+DecrementSize(
+    struct nfa *nfa)
+{
+    struct nfa *parent = nfa->parent;
+
+    nfa->size--;
+    while (parent != NULL) {
+	parent->size--;
+	parent = parent->parent;
+    }
+}
+
+/*
  - freenfa - free an entire NFA
  ^ static VOID freenfa(struct nfa *);
  */
@@ -124,20 +180,20 @@ newstate(
 {
     struct state *s;
 
+    if (TooManyStates(nfa)) {
+	/* XXX: add specific error for this */
+	NERR(REG_ETOOBIG);
+	return NULL;
+    }
     if (nfa->free != NULL) {
 	s = nfa->free;
 	nfa->free = s->next;
     } else {
-	if (nfa->v->spaceused >= REG_MAX_COMPILE_SPACE) {
-	    NERR(REG_ETOOBIG);
-	    return NULL;
-	}
 	s = (struct state *) MALLOC(sizeof(struct state));
 	if (s == NULL) {
 	    NERR(REG_ESPACE);
 	    return NULL;
 	}
-	nfa->v->spaceused += sizeof(struct state);
 	s->oas.next = NULL;
 	s->free = NULL;
 	s->noas = 0;
@@ -161,6 +217,12 @@ newstate(
     }
     s->prev = nfa->slast;
     nfa->slast = s;
+
+    /*
+     * Track the current size and the parent size.
+     */
+
+    IncrementSize(nfa);
     return s;
 }
 
@@ -231,6 +293,7 @@ freestate(
     s->prev = NULL;
     s->next = nfa->free;	/* don't delete it, put it on the free list */
     nfa->free = s;
+    DecrementSize(nfa);
 }
 
 /*
@@ -249,13 +312,11 @@ destroystate(
     for (ab=s->oas.next ; ab!=NULL ; ab=abnext) {
 	abnext = ab->next;
 	FREE(ab);
-	nfa->v->spaceused -= sizeof(struct arcbatch);
     }
     s->ins = NULL;
     s->outs = NULL;
     s->next = NULL;
     FREE(s);
-    nfa->v->spaceused -= sizeof(struct state);
 }
 
 /*
@@ -378,19 +439,14 @@ allocarc(
      */
 
     if (s->free == NULL) {
-	struct arcbatch *newAb;
+	struct arcbatch *newAb = (struct arcbatch *)
+		MALLOC(sizeof(struct arcbatch));
 	int i;
 
-	if (nfa->v->spaceused >= REG_MAX_COMPILE_SPACE) {
-	    NERR(REG_ETOOBIG);
-	    return NULL;
-	}
-	newAb = (struct arcbatch *) MALLOC(sizeof(struct arcbatch));
 	if (newAb == NULL) {
 	    NERR(REG_ESPACE);
 	    return NULL;
 	}
-	nfa->v->spaceused += sizeof(struct arcbatch);
 	newAb->next = s->oas.next;
 	s->oas.next = newAb;
 
diff --git a/generic/regcomp.c b/generic/regcomp.c
index 8287b7e..fda40e0 100644
--- a/generic/regcomp.c
+++ b/generic/regcomp.c
@@ -227,7 +227,6 @@ struct vars {
     struct cvec *cv2;		/* utility cvec */
     struct subre *lacons;	/* lookahead-constraint vector */
     int nlacons;		/* size of lacons */
-    size_t spaceused;		/* approx. space used for compilation */
 };
 
 /* parsing macros; most know that `v' is the struct vars pointer */
@@ -337,7 +336,6 @@ compile(
     v->cv2 = NULL;
     v->lacons = NULL;
     v->nlacons = 0;
-    v->spaceused = 0;
     re->re_magic = REMAGIC;
     re->re_info = 0;		/* bits get set during parse */
     re->re_csize = sizeof(chr);
diff --git a/generic/regerrs.h b/generic/regerrs.h
index ee203d5..72548ff 100644
--- a/generic/regerrs.h
+++ b/generic/regerrs.h
@@ -16,5 +16,5 @@
 { REG_INVARG,	"REG_INVARG",	"invalid argument to regex function" },
 { REG_MIXED,	"REG_MIXED",	"character widths of regex and string differ" },
 { REG_BADOPT,	"REG_BADOPT",	"invalid embedded option" },
-{ REG_ETOOBIG,	"REG_ETOOBIG",	"regular expression is too complex" },
+{ REG_ETOOBIG,	"REG_ETOOBIG",	"nfa has too many states" },
 { REG_ECOLORS,	"REG_ECOLORS",	"too many colors" },
diff --git a/generic/regex.h b/generic/regex.h
index b5b11bd..b5dce50 100644
--- a/generic/regex.h
+++ b/generic/regex.h
@@ -277,7 +277,7 @@ typedef struct {
 #define	REG_INVARG	16	/* invalid argument to regex function */
 #define	REG_MIXED	17	/* character widths of regex and string differ */
 #define	REG_BADOPT	18	/* invalid embedded option */
-#define	REG_ETOOBIG	19	/* regular expression is too complex */
+#define	REG_ETOOBIG	19	/* nfa has too many states */
 #define	REG_ECOLORS	20	/* too many colors */
 /* two specials for debugging and testing */
 #define	REG_ATOI	101	/* convert error-code name to number */
diff --git a/generic/regguts.h b/generic/regguts.h
index 72bdcb3..7ed8ec1 100644
--- a/generic/regguts.h
+++ b/generic/regguts.h
@@ -307,6 +307,9 @@ struct nfa {
     struct colormap *cm;	/* the color map */
     color bos[2];		/* colors, if any, assigned to BOS and BOL */
     color eos[2];		/* colors, if any, assigned to EOS and EOL */
+    size_t size;		/* Current NFA size; differs from nstates as
+				 * it also counts the number of states created
+				 * by children of this state. */
     struct vars *v;		/* simplifies compile error reporting */
     struct nfa *parent;		/* parent NFA, if any */
 };
@@ -336,16 +339,11 @@ struct cnfa {
 #define	NULLCNFA(cnfa)	((cnfa).nstates == 0)
 
 /*
- * This symbol limits the transient heap space used by the regex compiler,
- * and thereby also the maximum complexity of NFAs that we'll deal with.
- * Currently we only count NFA states and arcs against this; the other
- * transient data is generally not large enough to notice compared to those.
- * Note that we do not charge anything for the final output data structures
- * (the compacted NFA and the colormap).
+ * Used to limit the maximum NFA size to something sane. [Bug 1810264]
  */
-#ifndef REG_MAX_COMPILE_SPACE
-#define REG_MAX_COMPILE_SPACE  \
-	(100000 * sizeof(struct state) + 100000 * sizeof(struct arcbatch))
+
+#ifndef REG_MAX_STATES
+#   define REG_MAX_STATES	100000
 #endif
 
 /*
diff --git a/tests/regexp.test b/tests/regexp.test
index 7878d41..362f425 100644
--- a/tests/regexp.test
+++ b/tests/regexp.test
@@ -716,7 +716,7 @@ test regexp-22.4 {Bug 3606139} -setup {
 	[a 668]([a 55])[a 668]([a 55])[a 668]([a 55])[a 511]] {}] a
 } -cleanup {
     rename a {}
-} -returnCodes 1 -match glob -result {couldn't compile regular expression pattern: *}
+} -returnCodes 1 -result {couldn't compile regular expression pattern: nfa has too many states}
 test regexp-22.5 {Bug 3610026} -setup {
     set e {}
     set cp 99