Re: zsh doesn't support standard "unalias -a"

[Peter Stephenson <p.stephenson@xxxxxxxxxxx>]

On Mon, 18 May 2015 14:28:17 +0100
Martijn Dekker <martijn@xxxxxxxx> wrote:
> In a cross-platform shell library I'm writing, I would like to start by
> removing all aliases from the current execution environment, to help
> assure a consistent command language. The standard command to remove all
> aliases is "unalias -a".

This, at least, is easy.  It's slightly annoying that we can't pass this
via "unhash -a", unlike the other options, but actually there's no
particular reason ever to use "unhash -a" in preference to unalias.

pws

diff --git a/Doc/Zsh/builtins.yo b/Doc/Zsh/builtins.yo
index 5327789..1b8729d 100644
--- a/Doc/Zsh/builtins.yo
+++ b/Doc/Zsh/builtins.yo
@@ -2056,7 +2056,14 @@ the symbolic form the permissions you specify are those which are to be
 allowed (not denied) to the users specified.
 )
 cindex(aliases, removing)
-alias(unalias)(unhash -a)
+item(tt(unalias) [ tt(-ams) ] var(name) ...)(
+Removes aliases.  This command works the same as tt(unhash -a), except that
+the tt(-a) option removes all regular or global aliases, or with tt(-s)
+all suffix aliases: in this case no var(name) arguments may appear.  The
+options tt(-m) (remove by pattern) and tt(-s) without tt(-a) (remove
+listed suffix aliases) behave as for tt(unhash -a).  Note that
+the meaning of tt(-a) is different between tt(unalias) and tt(unhash).
+)
 cindex(functions, removing)
 alias(unfunction)(unhash -f)
 findex(unhash)
diff --git a/Src/builtin.c b/Src/builtin.c
index dbcd022..a9afb45 100644
--- a/Src/builtin.c
+++ b/Src/builtin.c
@@ -122,9 +122,9 @@ static struct builtin builtins[] =
     BUILTIN("type", 0, bin_whence, 0, -1, 0, "ampfsSw", "v"),
     BUILTIN("typeset", BINF_PLUSOPTS | BINF_MAGICEQUALS | BINF_PSPECIAL, bin_typeset, 0, -1, 0, "AE:%F:%HL:%R:%TUZ:%afghi:%klprtuxmz", NULL),
     BUILTIN("umask", 0, bin_umask, 0, 1, 0, "S", NULL),
-    BUILTIN("unalias", 0, bin_unhash, 1, -1, 0, "ms", "a"),
-    BUILTIN("unfunction", 0, bin_unhash, 1, -1, 0, "m", "f"),
-    BUILTIN("unhash", 0, bin_unhash, 1, -1, 0, "adfms", NULL),
+    BUILTIN("unalias", 0, bin_unhash, 0, -1, BIN_UNALIAS, "ams", NULL),
+    BUILTIN("unfunction", 0, bin_unhash, 1, -1, BIN_UNFUNCTION, "m", "f"),
+    BUILTIN("unhash", 0, bin_unhash, 1, -1, BIN_UNHASH, "adfms", NULL),
     BUILTIN("unset", BINF_PSPECIAL, bin_unset, 1, -1, 0, "fmv", NULL),
     BUILTIN("unsetopt", 0, bin_setopt, 0, -1, BIN_UNSETOPT, NULL, NULL),
     BUILTIN("wait", 0, bin_fg, 0, -1, BIN_WAIT, NULL, NULL),
@@ -3557,26 +3557,54 @@ bin_hash(char *name, char **argv, Options ops, UNUSED(int func))
 
 /**/
 int
-bin_unhash(char *name, char **argv, Options ops, UNUSED(int func))
+bin_unhash(char *name, char **argv, Options ops, int func)
 {
     HashTable ht;
     HashNode hn, nhn;
     Patprog pprog;
-    int match = 0, returnval = 0;
+    int match = 0, returnval = 0, all = 0;
     int i;
 
     /* Check which hash table we are working with. */
-    if (OPT_ISSET(ops,'d'))
+    if (func == BIN_UNALIAS) {
+	if (OPT_ISSET(ops,'s'))
+	    ht = sufaliastab;	/* suffix aliases */
+	else
+	    ht = aliastab;	/* aliases           */
+	if (OPT_ISSET(ops, 'a')) {
+	    if (*argv) {
+		zwarnnam(name, "-a: too many arguments");
+		return 1;
+	    }
+	    all = 1;
+	} else if (!*argv) {
+	    zwarnnam(name, "not enough arguments");
+	    return 1;
+	}
+    } else if (OPT_ISSET(ops,'d'))
 	ht = nameddirtab;	/* named directories */
     else if (OPT_ISSET(ops,'f'))
 	ht = shfunctab;		/* shell functions   */
     else if (OPT_ISSET(ops,'s'))
 	ht = sufaliastab;	/* suffix aliases, must precede aliases */
-    else if (OPT_ISSET(ops,'a'))
+    else if (func == BIN_UNHASH && (OPT_ISSET(ops,'a')))
 	ht = aliastab;		/* aliases           */
     else
 	ht = cmdnamtab;		/* external commands */
 
+    if (all) {
+	queue_signals();
+	for (i = 0; i < ht->hsize; i++) {
+	    for (hn = ht->nodes[i]; hn; hn = nhn) {
+		/* record pointer to next, since we may free this one */
+		nhn = hn->next;
+		ht->freenode(ht->removenode(ht, hn->nam));
+	    }
+	}
+	unqueue_signals();
+	return 0;
+    }
+
     /* With -m option, treat arguments as glob patterns. *
      * "unhash -m '*'" is legal, but not recommended.    */
     if (OPT_ISSET(ops,'m')) {
diff --git a/Src/hashtable.h b/Src/hashtable.h
index 131c15c..b6346bb 100644
--- a/Src/hashtable.h
+++ b/Src/hashtable.h
@@ -59,6 +59,9 @@
 #define BIN_ENABLE   25
 #define BIN_PRINTF   26
 #define BIN_COMMAND  27
+#define BIN_UNHASH   28
+#define BIN_UNALIAS  29
+#define BIN_UNFUNCTION  30
 
 /* These currently depend on being 0 and 1. */
 #define BIN_SETOPT    0
diff --git a/Test/A02alias.ztst b/Test/A02alias.ztst
index cace2a4..b294e65 100644
--- a/Test/A02alias.ztst
+++ b/Test/A02alias.ztst
@@ -83,3 +83,13 @@
 > a string S 
 *>*5*echo S a string S "
 # Note there is a trailing space on the "> a string S " line
+
+  (
+  unalias -a
+  alias
+  )
+0:unalias -a
+
+  alias -s foo=print
+  unalias -as
+0:unalias -as