35067: Add (b) parameter flag for pattern char backslashing.

Doc tweak from Daniel in 35071.

Includes test.

4 files changed, 42 insertions, 6 deletions

diff --git a/Src/subst.c b/Src/subst.c
index f52bcdfc8..bf80495bd 100644
--- a/Src/subst.c
+++ b/Src/subst.c
@@ -1592,7 +1592,7 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int pf_flags)
     /* combination of (L), (U) and (C) flags. */
     int casmod = CASMOD_NONE;
     /*
-     * quotemod says we are doing either (q) (positive), (Q) (negative)
+     * quotemod says we are doing either (q/b) (positive), (Q) (negative)
      * or not (0).  quotetype counts the q's for the first case.
      * quoterr is simply (X) but gets passed around a lot because the
      * combination (eX) needs it.
@@ -1861,6 +1861,12 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int pf_flags)
 			quotemod++, quotetype++;
 		    }
 		    break;
+		case 'b':
+		    if (quotemod || quotetype != QT_NONE)
+			goto flagerr;
+		    quotemod = 1;
+		    quotetype = QT_BACKSLASH_PATTERN;
+		    break;
 		case 'Q':
 		    quotemod--;
 		    break;
@@ -3460,7 +3466,7 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int pf_flags)
     if (quotemod) {
 	int pre = 0, post = 0;
 
-	if (quotemod > 0 && quotetype > QT_BACKSLASH) {
+	if (quotemod > 0) {
 	    switch (quotetype)
 	    {
 	    case QT_DOLLARS:
@@ -3471,6 +3477,9 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int pf_flags)
 
 	    case QT_SINGLE_OPTIONAL:
 		/* quotes will be added for us */
+	    case QT_BACKSLASH:
+	    case QT_BACKSLASH_PATTERN:
+		/* no quotes */
 		break;
 
 	    default:
diff --git a/Src/utils.c b/Src/utils.c
index 13d4b83d4..271c800fd 100644
--- a/Src/utils.c
+++ b/Src/utils.c
@@ -3694,6 +3694,8 @@ inittyptab(void)
 	typtab[bangchar] |= ISPECIAL;
     } else
 	typtab_flags &= ~ZTF_BANGCHAR;
+    for (s = PATCHARS; *s; s++)
+	typtab[STOUC(*s)] |= IPATTERN;
 
     unqueue_signals();
 }
@@ -5075,6 +5077,10 @@ quotestring(const char *s, char **e, int instring)
 	alloclen = slen * 7 + 1;
 	break;
 
+    case QT_BACKSLASH_PATTERN:
+	alloclen = slen * 2  + 1;
+	break;
+
     case QT_SINGLE_OPTIONAL:
 	/*
 	 * Here, we may need to add single quotes.
@@ -5094,7 +5100,7 @@ quotestring(const char *s, char **e, int instring)
     quotestart = v = buf = zshcalloc(alloclen);
 
     DPUTS(instring < QT_BACKSLASH || instring == QT_BACKTICK ||
-	  instring > QT_SINGLE_OPTIONAL,
+	  instring > QT_BACKSLASH_PATTERN,
 	  "BUG: bad quote type in quotestring");
     u = s;
     if (instring == QT_DOLLARS) {
@@ -5134,9 +5140,18 @@ quotestring(const char *s, char **e, int instring)
 		u = uend;
 	    }
 	}
-    }
-    else
-    {
+    } else if (instring == QT_BACKSLASH_PATTERN) {
+	while (*u) {
+	    if (e && !sf && *e == u) {
+		*e = v;
+		sf = 1;
+	    }
+
+	    if (ipattern(*u))
+		*v++ = '\\';
+	    *v++ = *u++;
+	}
+    } else {
 	if (shownull) {
 	    /* We can't show an empty string with just backslash quoting. */
 	    if (!*u) {
diff --git a/Src/zsh.h b/Src/zsh.h
index bb52e106d..b2ab1dfae 100644
--- a/Src/zsh.h
+++ b/Src/zsh.h
@@ -215,6 +215,10 @@ struct mathfunc {
 
 #define SPECCHARS "#$^*()=|{}[]`<>?~;&\n\t \\\'\""
 
+/* chars that need to be quoted for pattern matching */
+
+#define PATCHARS "#^*()|[]<>?~"
+
 /*
  * Types of quote.  This is used in various places, so care needs
  * to be taken when changing them.  (Oooh, don't you look surprised.)
@@ -249,6 +253,12 @@ enum {
      */
     QT_SINGLE_OPTIONAL,
     /*
+     * Only quote pattern characters.
+     * ${(b)foo} guarantees that ${~foo} matches the string
+     * contained in foo.
+     */
+    QT_BACKSLASH_PATTERN,
+    /*
      * As QT_BACKSLASH, but a NULL string is shown as ''.
      */
     QT_BACKSLASH_SHOWNULL
diff --git a/Src/ztype.h b/Src/ztype.h
index b73e3f840..76589b152 100644
--- a/Src/ztype.h
+++ b/Src/ztype.h
@@ -42,6 +42,7 @@
 #define IMETA    (1 << 12)
 #define IWSEP    (1 << 13)
 #define INULL    (1 << 14)
+#define IPATTERN (1 << 15)
 #define zistype(X,Y) (typtab[STOUC(X)] & Y)
 #define idigit(X) zistype(X,IDIGIT)
 #define ialnum(X) zistype(X,IALNUM)
@@ -58,6 +59,7 @@
 #define imeta(X) zistype(X,IMETA)
 #define iwsep(X) zistype(X,IWSEP)
 #define inull(X) zistype(X,INULL)
+#define ipattern(X) zistype(X,IPATTERN)
 
 /*
  * Bit flags for typtab_flags --- preserved after