Adaptation of re-memaccounting.patch from Tom Lane @postgres.

5 files changed, 27 insertions, 79 deletions

diff --git a/generic/regc_nfa.c b/generic/regc_nfa.c
index bbc4dd6..5568bff 100644
--- a/generic/regc_nfa.c
+++ b/generic/regc_nfa.c
@@ -62,7 +62,6 @@ 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. */
@@ -90,61 +89,6 @@ 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 *);
  */
@@ -180,20 +124,20 @@ 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;
@@ -217,12 +161,6 @@ newstate(
     }
     s->prev = nfa->slast;
     nfa->slast = s;
-
-    /*
-     * Track the current size and the parent size.
-     */
-
-    IncrementSize(nfa);
     return s;
 }
 
@@ -293,7 +231,6 @@ freestate(
     s->prev = NULL;
     s->next = nfa->free;	/* don't delete it, put it on the free list */
     nfa->free = s;
-    DecrementSize(nfa);
 }
 
 /*
@@ -312,11 +249,13 @@ 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);
 }
 
 /*
@@ -439,14 +378,19 @@ allocarc(
      */
 
     if (s->free == NULL) {
-	struct arcbatch *newAb = (struct arcbatch *)
-		MALLOC(sizeof(struct arcbatch));
+	struct arcbatch *newAb;
 	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 6b40100..3c91962 100644
--- a/generic/regcomp.c
+++ b/generic/regcomp.c
@@ -228,6 +228,7 @@ 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 */
@@ -337,6 +338,7 @@ 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 72548ff..ee203d5 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",	"nfa has too many states" },
+{ REG_ETOOBIG,	"REG_ETOOBIG",	"regular expression is too complex" },
 { REG_ECOLORS,	"REG_ECOLORS",	"too many colors" },
diff --git a/generic/regex.h b/generic/regex.h
index b5dce50..b5b11bd 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	/* nfa has too many states */
+#define	REG_ETOOBIG	19	/* regular expression is too complex */
 #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 7ed8ec1..72bdcb3 100644
--- a/generic/regguts.h
+++ b/generic/regguts.h
@@ -307,9 +307,6 @@ 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 */
 };
@@ -339,11 +336,16 @@ struct cnfa {
 #define	NULLCNFA(cnfa)	((cnfa).nstates == 0)
 
 /*
- * Used to limit the maximum NFA size to something sane. [Bug 1810264]
+ * 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).
  */
-
-#ifndef REG_MAX_STATES
-#   define REG_MAX_STATES	100000
+#ifndef REG_MAX_COMPILE_SPACE
+#define REG_MAX_COMPILE_SPACE  \
+	(100000 * sizeof(struct state) + 100000 * sizeof(struct arcbatch))
 #endif
 
 /*