sh: Optimize variable code by storing the length of the name.

Obtained from:	NetBSD

2 files changed, 125 insertions, 124 deletions

diff --git a/bin/sh/var.c b/bin/sh/var.c
index 5c87a1f..33890db 100644
--- a/bin/sh/var.c
+++ b/bin/sh/var.c
@@ -136,8 +136,8 @@ static const int locale_categories[7] = {
 	LC_COLLATE, LC_CTYPE, LC_MONETARY, LC_NUMERIC, LC_TIME, LC_MESSAGES, 0
 };
 
-static struct var **hashvar(const char *);
 static int varequal(const char *, const char *);
+static struct var *find_var(const char *, struct var ***, int *);
 static int localevar(const char *);
 
 /*
@@ -174,20 +174,18 @@ initvar(void)
 	struct var **vpp;
 
 	for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
-		if ((vp->flags & VEXPORT) == 0) {
-			vpp = hashvar(ip->text);
-			vp->next = *vpp;
-			*vpp = vp;
-			vp->text = __DECONST(char *, ip->text);
-			vp->flags = ip->flags | VSTRFIXED | VTEXTFIXED;
-			vp->func = ip->func;
-		}
+		if (find_var(ip->text, &vpp, &vp->name_len) != NULL)
+			continue;
+		vp->next = *vpp;
+		*vpp = vp;
+		vp->text = __DECONST(char *, ip->text);
+		vp->flags = ip->flags | VSTRFIXED | VTEXTFIXED;
+		vp->func = ip->func;
 	}
 	/*
 	 * PS1 depends on uid
 	 */
-	if ((vps1.flags & VEXPORT) == 0) {
-		vpp = hashvar("PS1=");
+	if (find_var("PS1", &vpp, &vps1.name_len) == NULL) {
 		vps1.next = *vpp;
 		*vpp = &vps1;
 		vps1.text = __DECONST(char *, geteuid() ? "PS1=$ " : "PS1=# ");
@@ -323,50 +321,46 @@ void
 setvareq(char *s, int flags)
 {
 	struct var *vp, **vpp;
-	int len;
+	int nlen;
 
 	if (aflag)
 		flags |= VEXPORT;
-	vpp = hashvar(s);
-	for (vp = *vpp ; vp ; vp = vp->next) {
-		if (varequal(s, vp->text)) {
-			if (vp->flags & VREADONLY) {
-				len = strchr(s, '=') - s;
-				error("%.*s: is read only", len, s);
-			}
-			if (flags & VNOSET)
-				return;
-			INTOFF;
-
-			if (vp->func && (flags & VNOFUNC) == 0)
-				(*vp->func)(strchr(s, '=') + 1);
-
-			if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
-				ckfree(vp->text);
-
-			vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
-			vp->flags |= flags;
-			vp->text = s;
-
-			/*
-			 * We could roll this to a function, to handle it as
-			 * a regular variable function callback, but why bother?
-			 *
-			 * Note: this assumes iflag is not set to 1 initially.
-			 * As part of init(), this is called before arguments
-			 * are looked at.
-			 */
-			if ((vp == &vmpath || (vp == &vmail && ! mpathset())) &&
-			    iflag == 1)
-				chkmail(1);
-			if ((vp->flags & VEXPORT) && localevar(s)) {
-				change_env(s, 1);
-				(void) setlocale(LC_ALL, "");
-				updatecharset();
-			}
-			INTON;
+	vp = find_var(s, &vpp, &nlen);
+	if (vp != NULL) {
+		if (vp->flags & VREADONLY)
+			error("%.*s: is read only", vp->name_len, s);
+		if (flags & VNOSET)
 			return;
+		INTOFF;
+
+		if (vp->func && (flags & VNOFUNC) == 0)
+			(*vp->func)(s + vp->name_len + 1);
+
+		if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
+			ckfree(vp->text);
+
+		vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
+		vp->flags |= flags;
+		vp->text = s;
+
+		/*
+		 * We could roll this to a function, to handle it as
+		 * a regular variable function callback, but why bother?
+		 *
+		 * Note: this assumes iflag is not set to 1 initially.
+		 * As part of init(), this is called before arguments
+		 * are looked at.
+		 */
+		if ((vp == &vmpath || (vp == &vmail && ! mpathset())) &&
+		    iflag == 1)
+			chkmail(1);
+		if ((vp->flags & VEXPORT) && localevar(s)) {
+			change_env(s, 1);
+			(void) setlocale(LC_ALL, "");
+			updatecharset();
 		}
+		INTON;
+		return;
 	}
 	/* not found */
 	if (flags & VNOSET)
@@ -374,6 +368,7 @@ setvareq(char *s, int flags)
 	vp = ckmalloc(sizeof (*vp));
 	vp->flags = flags;
 	vp->text = s;
+	vp->name_len = nlen;
 	vp->next = *vpp;
 	vp->func = NULL;
 	INTOFF;
@@ -415,14 +410,10 @@ lookupvar(const char *name)
 {
 	struct var *v;
 
-	for (v = *hashvar(name) ; v ; v = v->next) {
-		if (varequal(v->text, name)) {
-			if (v->flags & VUNSET)
-				return NULL;
-			return strchr(v->text, '=') + 1;
-		}
-	}
-	return NULL;
+	v = find_var(name, NULL, NULL);
+	if (v == NULL || v->flags & VUNSET)
+		return NULL;
+	return v->text + v->name_len + 1;
 }
 
 
@@ -447,15 +438,12 @@ bltinlookup(const char *name, int doall)
 	}
 	if (result != NULL)
 		return result;
-	for (v = *hashvar(name) ; v ; v = v->next) {
-		if (varequal(v->text, name)) {
-			if ((v->flags & VUNSET)
-			 || (!doall && (v->flags & VEXPORT) == 0))
-				return NULL;
-			return strchr(v->text, '=') + 1;
-		}
-	}
-	return NULL;
+
+	v = find_var(name, NULL, NULL);
+	if (v == NULL || v->flags & VUNSET ||
+	    (!doall && (v->flags & VEXPORT) == 0))
+		return NULL;
+	return v->text + v->name_len + 1;
 }
 
 
@@ -665,22 +653,18 @@ exportcmd(int argc, char **argv)
 			if ((p = strchr(name, '=')) != NULL) {
 				p++;
 			} else {
-				vpp = hashvar(name);
-				for (vp = *vpp ; vp ; vp = vp->next) {
-					if (varequal(vp->text, name)) {
-
-						vp->flags |= flag;
-						if ((vp->flags & VEXPORT) && localevar(vp->text)) {
-							change_env(vp->text, 1);
-							(void) setlocale(LC_ALL, "");
-							updatecharset();
-						}
-						goto found;
+				vp = find_var(name, NULL, NULL);
+				if (vp != NULL) {
+					vp->flags |= flag;
+					if ((vp->flags & VEXPORT) && localevar(vp->text)) {
+						change_env(vp->text, 1);
+						(void) setlocale(LC_ALL, "");
+						updatecharset();
 					}
+					continue;
 				}
 			}
 			setvar(name, p, flag);
-found:;
 		}
 	} else {
 		for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
@@ -747,8 +731,7 @@ mklocal(char *name)
 		memcpy(lvp->text, optlist, sizeof optlist);
 		vp = NULL;
 	} else {
-		vpp = hashvar(name);
-		for (vp = *vpp ; vp && ! varequal(vp->text, name) ; vp = vp->next);
+		vp = find_var(name, &vpp, NULL);
 		if (vp == NULL) {
 			if (strchr(name, '='))
 				setvareq(savestr(name), VSTRFIXED);
@@ -761,7 +744,7 @@ mklocal(char *name)
 			lvp->text = vp->text;
 			lvp->flags = vp->flags;
 			vp->flags |= VSTRFIXED|VTEXTFIXED;
-			if (strchr(name, '='))
+			if (name[vp->name_len] == '=')
 				setvareq(savestr(name), 0);
 		}
 	}
@@ -857,55 +840,34 @@ unsetvar(const char *s)
 	struct var **vpp;
 	struct var *vp;
 
-	vpp = hashvar(s);
-	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
-		if (varequal(vp->text, s)) {
-			if (vp->flags & VREADONLY)
-				return (1);
-			INTOFF;
-			if (*(strchr(vp->text, '=') + 1) != '\0')
-				setvar(s, nullstr, 0);
-			if ((vp->flags & VEXPORT) && localevar(vp->text)) {
-				change_env(s, 0);
-				setlocale(LC_ALL, "");
-				updatecharset();
-			}
-			vp->flags &= ~VEXPORT;
-			vp->flags |= VUNSET;
-			if ((vp->flags & VSTRFIXED) == 0) {
-				if ((vp->flags & VTEXTFIXED) == 0)
-					ckfree(vp->text);
-				*vpp = vp->next;
-				ckfree(vp);
-			}
-			INTON;
-			return (0);
-		}
+	vp = find_var(s, &vpp, NULL);
+	if (vp == NULL)
+		return (0);
+	if (vp->flags & VREADONLY)
+		return (1);
+	INTOFF;
+	if (vp->text[vp->name_len + 1] != '\0')
+		setvar(s, nullstr, 0);
+	if ((vp->flags & VEXPORT) && localevar(vp->text)) {
+		change_env(s, 0);
+		setlocale(LC_ALL, "");
+		updatecharset();
 	}
-
+	vp->flags &= ~VEXPORT;
+	vp->flags |= VUNSET;
+	if ((vp->flags & VSTRFIXED) == 0) {
+		if ((vp->flags & VTEXTFIXED) == 0)
+			ckfree(vp->text);
+		*vpp = vp->next;
+		ckfree(vp);
+	}
+	INTON;
 	return (0);
 }
 
 
 
 /*
- * Find the appropriate entry in the hash table from the name.
- */
-
-static struct var **
-hashvar(const char *p)
-{
-	unsigned int hashval;
-
-	hashval = ((unsigned char) *p) << 4;
-	while (*p && *p != '=')
-		hashval += (unsigned char) *p++;
-	return &vartab[hashval % VTABSIZE];
-}
-
-
-
-/*
  * Returns true if the two strings specify the same varable.  The first
  * variable name is terminated by '='; the second may be terminated by
  * either '=' or '\0'.
@@ -922,3 +884,41 @@ varequal(const char *p, const char *q)
 		return 1;
 	return 0;
 }
+
+/*
+ * Search for a variable.
+ * 'name' may be terminated by '=' or a NUL.
+ * vppp is set to the pointer to vp, or the list head if vp isn't found
+ * lenp is set to the number of charactets in 'name'
+ */
+
+static struct var *
+find_var(const char *name, struct var ***vppp, int *lenp)
+{
+	unsigned int hashval;
+	int len;
+	struct var *vp, **vpp;
+	const char *p = name;
+
+	hashval = 0;
+	while (*p && *p != '=')
+		hashval = 2 * hashval + (unsigned char)*p++;
+	len = p - name;
+
+	if (lenp)
+		*lenp = len;
+	vpp = &vartab[hashval % VTABSIZE];
+	if (vppp)
+		*vppp = vpp;
+
+	for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
+		if (vp->name_len != len)
+			continue;
+		if (memcmp(vp->text, name, len) != 0)
+			continue;
+		if (vppp)
+			*vppp = vpp;
+		return vp;
+	}
+	return NULL;
+}
diff --git a/bin/sh/var.h b/bin/sh/var.h
index 4336562..323ddc2 100644
--- a/bin/sh/var.h
+++ b/bin/sh/var.h
@@ -51,6 +51,7 @@
 struct var {
 	struct var *next;		/* next entry in hash list */
 	int flags;			/* flags are defined above */
+	int name_len;			/* length of name */
 	char *text;			/* name=value */
 	void (*func)(const char *);
 					/* function to be called when  */