12561: Completion/Builtins/_zmodload, Doc/Zsh/builtins.yo,

Src/builtin.c, Src/module.c, Src/zsh.h: aliases for modules
done internally via `zmodload -[AR]'

Completion/Builtins/_zmodload

@@ -1,11 +1,18 @@
 #compdef zmodload
 
-local fl="$words[2]" expl
+local fl="$words[2]" expl ret=1
 
 if [[ "$fl" = -*(a*u|u*a)* || "$fl" = -*a* && CURRENT -ge 4 ]]; then
   _wanted builtins expl 'builtin command' compadd "$@" -k builtins
 elif [[ "$fl" = -*u* ]]; then
   _wanted modules expl module compadd -k modules
 else
-  _wanted files expl 'module file' _files -W module_path -/g '*.s[ol](:r)'
+  _tags files aliases
+  while _tags; do
+    _requested files expl 'module file' \
+      _files -W module_path -/g '*.s[ol](:r)' && ret=0
+    _requested aliases expl 'module alias' \
+      compadd -- ${${(f)"$(zmodload -A)"}%% *} && ret=0
+    (( ret )) || break
+  done
 fi

Doc/Zsh/builtins.yo

@@ -1479,9 +1479,11 @@ findex(zmodload)
 cindex(modules, loading)
 cindex(loading modules)
 xitem(tt(zmodload) [ tt(-dL) ] [ ... ])
-xitem(tt(zmodload -e) [ ... ])
+xitem(tt(zmodload -e) [ tt(-A) ] [ ... ])
 xitem(tt(zmodload) [ tt(-a) [ tt(-bcpf) [ tt(-I) ] ] ] [ tt(-iL) ] ...)
-item(tt(zmodload) tt(-u) [ tt(-abcdpf) [ tt(-I) ] ] [ tt(-iL) ] ...)(
+xitem(tt(zmodload) tt(-u) [ tt(-abcdpf) [ tt(-I) ] ] [ tt(-iL) ] ...)
+xitem(tt(zmodload) tt(-A) [ tt(-L) ] [ var(modalias)[tt(=)var(module)] ... ])
+item(tt(zmodload) tt(-R) var(modalias) ... )(
 Performs operations relating to zsh's loadable modules.
 Loading of modules while the shell is running (`dynamical loading') is not
 available on all operating systems, or on all installations on a particular
@@ -1583,13 +1585,53 @@ xitem(tt(zmodload) tt(-a) [ tt(-i) ] var(name) [ var(builtin) ... ])
 item(tt(zmodload) tt(-ua) [ tt(-i) ] var(builtin) ...)(
 Equivalent to tt(-ab) and tt(-ub).
 )
-item(tt(zmodload -e) [ var(string) ... ])(
+item(tt(zmodload -e) [ tt(-A) ] [ var(string) ... ])(
-The tt(-e) option without arguments lists all loaded modules.
+The tt(-e) option without arguments lists all loaded modules; if the tt(-A)
-With arguments only the return status is set to zero
+option is also given, module aliases corresponding to loaded modules are
+also shown.  With arguments only the return status is set to zero
 if all var(string)s given as arguments are names of loaded modules
 and to one if at least on var(string) is not the name of a
-loaded module. This can be used to test for the availability 
+loaded module.  This can be used to test for the availability 
-of things implemented by modules.
+of things implemented by modules.  In this case, any aliases are
+automatically resolved and the tt(-A) flag is not used.
+)
+item(tt(zmodload) tt(-A) [ tt(-L) ] [ var(modalias)[tt(=)var(module)] ... ])(
+For each argument, if both var(modlias) and var(module) are given,
+define var(modalias) to be an alias for the module var(module).
+If the module var(modalias) is ever subsequently requested, either via a
+call to tt(zmodload) or implicitly, the shell will attempt to load
+var(module) instead.  If var(module) is not given, show the definition of
+var(modalias).  If no arguments are given, list all defined module aliases.
+When listing, if the tt(-L) flag was also given, list the definition as a
+tt(zmodload) command to recreate the alias.
+
+The existence of aliases for modules is completely independent of whether
+the name resolved is actually loaded as a module: while the alias exists,
+loading and unloading the module under any alias has exactly the same
+effect as using the resolved name, and does not affect the connection
+between the alias and the resolved name which can be removed either by
+tt(zmodload -R) or by redefining the alias.  Chains of aliases (i.e. where
+the first resolved name is itself an alias) are valid so long as these are
+not circular.  As the aliases take the same format as module names, they
+may include path separators:  in this case, there is no requirement for any
+part of the path named to exist as the alias will be resolved first.  For
+example, `tt(any/old/alias)' is always a valid alias.
+
+Dependencies added to aliased modules are actually added to the resolved
+module; these remain if the alias is removed.  It is valid to create an
+alias whose name is one of the standard shell modules and which resolves to
+a different module.  However, if a module has dependencies, it
+will not be possible to use the module name as an alias as the module will
+already be marked as a loadable module in its own right.
+
+Apart from the above, aliases can be used in the tt(zmodload) command
+anywhere module names are required.  However, aliases will not be
+shown in lists of loaded modules with a bare `tt(zmodload)'.
+)
+item(tt(zmodload) tt(-R) var(modalias) ... )(
+For each var(modalias) argument that was previously defined as a module
+alias via tt(zmodload -A), delete the alias.  If any was not defined, an
+error is caused and the remainder of the line is ignored.
 )
 enditem()
 

Src/builtin.c

@@ -123,7 +123,7 @@ static struct builtin builtins[] =
     BUILTIN("whence", 0, bin_whence, 0, -1, 0, "acmpvfsw", NULL),
     BUILTIN("where", 0, bin_whence, 0, -1, 0, "pmsw", "ca"),
     BUILTIN("which", 0, bin_whence, 0, -1, 0, "ampsw", "c"),
-    BUILTIN("zmodload", 0, bin_zmodload, 0, -1, 0, "ILabcfdipue", NULL),
+    BUILTIN("zmodload", 0, bin_zmodload, 0, -1, 0, "ARILabcfdipue", NULL),
     BUILTIN("zcompile", 0, bin_zcompile, 0, -1, 0, "tUMRcmzka", NULL),
 };
 

Src/module.c

@@ -88,6 +88,27 @@ register_module(char *n, Module_func setup, Module_func boot,
     zaddlinknode(linkedmodules, m);
 }
 
+/* Print an alias. */
+
+/**/
+static void
+printmodalias(Module m, char *ops)
+{
+    if (ops['L']) {
+	printf("zmodload -A ");
+	if (m->nam[0] == '-')
+	    fputs("-- ", stdout);
+	quotedzputs(m->nam, stdout);
+	putchar('=');
+	quotedzputs(m->u.alias, stdout);
+    } else {
+	nicezputs(m->nam, stdout);
+	fputs(" -> ", stdout);
+	nicezputs(m->u.alias, stdout);
+    }
+    putchar('\n');
+}
+
 /* Check if a module is linked in. */
 
 /**/
@@ -164,6 +185,15 @@ addwrapper(Module m, FuncWrap w)
 {
     FuncWrap p, q;
 
+    /*
+     * We can't add a wrapper to an alias, since it's supposed
+     * to behave identically to the resolved module.  This shouldn't
+     * happen since we usually add wrappers when a real module is
+     * loaded.
+     */
+    if (m->flags & MOD_ALIAS)
+	return 1;
+
     if (w->flags & WRAPF_ADDED)
 	return 1;
     for (p = wrappers, q = NULL; p; q = p, p = p->next);
@@ -256,6 +286,9 @@ deletewrapper(Module m, FuncWrap w)
 {
     FuncWrap p, q;
 
+    if (m->flags & MOD_ALIAS)
+	return 1;
+
     if (w->flags & WRAPF_ADDED) {
 	for (p = wrappers, q = NULL; p && p != w; q = p, p = p->next);
 
@@ -292,7 +325,8 @@ load_and_bind(const char *fn)
 	int err = loadbind(0, (void *) addbuiltin, ret);
 	for (node = firstnode(modules); !err && node; incnode(node)) {
 	    Module m = (Module) getdata(node);
-	    if (m->u.handle && !(m->flags & MOD_LINKED))
+	    if (!(m->flags & MOD_ALIAS) &&
+		m->u.handle && !(m->flags & MOD_LINKED))
 		err |= loadbind(0, m->u.handle, ret);
 	}
 
@@ -431,21 +465,60 @@ do_load_module(char const *name)
 /**/
 #endif /* !DYNAMIC */
 
+/*
+ * Find a module in the list.
+ * If aliasp is non-zero, resolve any aliases to the underlying module.
+ * If namep is set, this is set to point to the last alias value resolved,
+ *   even if that module was not loaded. or the module name if no aliases.
+ *   Hence this is always the physical module to load in a chain of aliases.
+ * Return NULL if the module named is not stored as a structure, or if we were
+ * resolving aliases and the final module named is not stored as a
+ * structure.
+ *
+ * TODO: now we have aliases, there may be some merit in using a hash
+ * table instead of a linked list.
+ */
 /**/
 static LinkNode
-find_module(const char *name)
+find_module(const char *name, int aliasp, const char **namep)
 {
     Module m;
     LinkNode node;
 
     for (node = firstnode(modules); node; incnode(node)) {
 	m = (Module) getdata(node);
-	if (!strcmp(m->nam, name))
+	if (!strcmp(m->nam, name)) {
+	    if (aliasp && (m->flags & MOD_ALIAS)) {
+		if (namep)
+		    *namep = m->u.alias;
+		return find_module(m->u.alias, 1, namep);
+	    }
+	    if (namep)
+		*namep = m->nam;
 	    return node;
+	}
     }
     return NULL;
 }
 
+/*
+ * Unlink and free a module node from the linked list.
+ */
+
+/**/
+static void
+delete_module(LinkNode node)
+{
+    Module m = (Module) remnode(modules, node);
+
+    if (m->flags & MOD_ALIAS)
+	zsfree(m->u.alias);
+    zsfree(m->nam);
+    if (m->deps)
+	freelinklist(m->deps, freestr);
+    zfree(m, sizeof(*m));
+}
+
 /**/
 mod_export int
 module_loaded(const char *name)
@@ -453,11 +526,17 @@ module_loaded(const char *name)
     LinkNode node;
     Module m;
 
-    return ((node = find_module(name)) &&
+    return ((node = find_module(name, 1, NULL)) &&
 	    (m = ((Module) getdata(node)))->u.handle &&
 	    !(m->flags & MOD_UNLOAD));
 }
 
+/*
+ * Setup and cleanup functions:  we don't search for aliases here,
+ * since they should have been resolved before we try to load or unload
+ * the module.
+ */
+
 /**/
 #ifdef DYNAMIC
 
@@ -679,7 +758,12 @@ load_module(char const *name)
 	zerr("invalid module name `%s'", name, 0);
 	return 0;
     }
-    if (!(node = find_module(name))) {
+    /*
+     * The following function call may alter name to the final name in a
+     * chain of aliases.  This makes sure the actual module loaded
+     * is the right one.
+     */
+    if (!(node = find_module(name, 1, &name))) {
 	if (!(linked = module_linked(name)) &&
 	    !(handle = do_load_module(name)))
 	    return 0;
@@ -697,10 +781,7 @@ load_module(char const *name)
 	if ((set = setup_module(m)) || boot_module(m)) {
 	    if (!set)
 		finish_module(m);
-	    remnode(modules, node);
+	    delete_module(node);
-	    zsfree(m->nam);
-	    zfree(m, sizeof(*m));
-	    m->flags &= ~MOD_SETUP;
 	    return 0;
 	}
 	m->flags |= MOD_INIT_S | MOD_INIT_B;
@@ -773,12 +854,13 @@ load_module(char const *name)
 
 /**/
 mod_export int
-require_module(char *nam, char *module, int res, int test)
+require_module(char *nam, const char *module, int res, int test)
 {
     Module m = NULL;
     LinkNode node;
 
-    node = find_module(module);
+    /* Resolve aliases and actual loadable module as for load_module */
+    node = find_module(module, 1, &module);
     if (node && (m = ((Module) getdata(node)))->u.handle &&
 	!(m->flags & MOD_UNLOAD)) {
 	if (test) {
@@ -793,12 +875,24 @@ require_module(char *nam, char *module, int res, int test)
 
 /**/
 void
-add_dep(char *name, char *from)
+add_dep(const char *name, char *from)
 {
     LinkNode node;
     Module m;
 
-    if (!(node = find_module(name))) {
+    /*
+     * If we were passed an alias, we must resolve it to a final
+     * module name (and maybe add the corresponding struct), since otherwise
+     * we would need to check all modules to see if they happen
+     * to be aliased to the same thing to implement depencies properly.
+     *
+     * This should mean that an attempt to add an alias which would
+     * have the same name as a module which has dependencies is correctly
+     * rejected, because then the module named already exists as a non-alias.
+     * Better make sure.  (There's no problem making a an alias which
+     * *points* to a module with dependencies, of course.)
+     */
+    if (!(node = find_module(name, 1, &name))) {
 	m = zcalloc(sizeof(*m));
 	m->nam = ztrdup(name);
 	zaddlinknode(modules, m);
@@ -845,12 +939,21 @@ autoloadscan(HashNode hn, int printflags)
 int
 bin_zmodload(char *nam, char **args, char *ops, int func)
 {
-    if ((ops['b'] || ops['c'] || ops['p'] || ops['f']) &&
+    int ops_bcpf = ops['b'] || ops['c'] || ops['p'] || ops['f'];
-	!(ops['a'] || ops['u'])) {
+    int ops_au = ops['a'] || ops['u'];
+    if (ops_bcpf && !ops_au) {
 	zwarnnam(nam, "-b, -c, -f, and -p must be combined with -a or -u",
 		 NULL, 0);
 	return 1;
     }
+    if (ops['A'] || ops['R']) {
+	if (ops_bcpf || ops_au || ops['d'] || (ops['R'] && ops['e'])) {
+	    zwarnnam(nam, "illegal flags combined with -A or -R", NULL, 0);
+	    return 1;
+	}
+	if (!ops['e'])
+	    return bin_zmodload_alias(nam, args, ops);
+    }
     if (ops['d'] && ops['a']) {
 	zwarnnam(nam, "-d cannot be combined with -a", NULL, 0);
 	return 1;
@@ -884,34 +987,150 @@ bin_zmodload(char *nam, char **args, char *ops, int func)
     return 1;
 }
 
+/**/
+static int
+bin_zmodload_alias(char *nam, char **args, char *ops)
+{
+    /*
+     * TODO: while it would be too nasty to have aliases, as opposed
+     * to real loadable modules, with dependencies --- just what would
+     * we need to load when, exactly? --- there is in principle no objection
+     * to making it possible to force an alias onto an existing unloaded
+     * module which has dependencies.  This would simply transfer
+     * the dependencies down the line to the aliased-to module name.
+     * This is actually useful, since then you can alias zsh/zle=mytestzle
+     * to load another version of zle.  But then what happens when the
+     * alias is removed?  Do you transfer the dependencies back? And
+     * suppose other names are aliased to the same file?  It might be
+     * kettle of fish best left unwormed.
+     */
+    LinkNode node;
+    Module m;
+    int ret = 0;
+
+    if (!*args) {
+	if (ops['R']) {
+	    zwarnnam(nam, "no module alias to remove", NULL, 0);
+	    return 1;
+	}
+	for (node = firstnode(modules); node; incnode(node)) {
+	    m = (Module) getdata(node);
+	    if (m->flags & MOD_ALIAS)
+		printmodalias(m, ops);
+	}
+	return 0;
+    }
+
+    for (; !ret && *args; args++) {
+	char *eqpos = strchr(*args, '=');
+	char *aliasname = eqpos ? eqpos+1 : NULL;
+	if (eqpos)
+	    *eqpos = '\0';
+	if (!modname_ok(*args)) {
+	    zwarnnam(nam, "invalid module name `%s'", *args, 0);
+	    return 1;
+	}
+	if (ops['R']) {
+	    if (aliasname) {
+		zwarnnam(nam, "bad syntax for removing module alias: %s",
+			 *args, 0);
+		return 1;
+	    }
+	    node = find_module(*args, 0, NULL);
+	    if (node) {
+		m = (Module) getdata(node);
+		if (!(m->flags & MOD_ALIAS)) {
+		    zwarnnam(nam, "module is not an alias: %s", *args, 0);
+		    ret = 1;
+		    break;
+		}
+		delete_module(node);
+	    } else {
+		zwarnnam(nam, "no such module alias: %s", *args, 0);
+		return 1;
+	    }
+	} else {
+	    if (aliasname) {
+		const char *mname = aliasname;
+		if (!modname_ok(aliasname)) {
+		    zwarnnam(nam, "invalid module name `%s'", aliasname, 0);
+		    return 1;
+		}
+		find_module(aliasname, 1, &mname);
+		if (!strcmp(mname, *args)) {
+		    zwarnnam(nam, "module alias would refer to itself: %s",
+			     *args, 0);
+		    return 1;
+		}
+		node = find_module(*args, 0, NULL);
+		if (node) {
+		    m = (Module) getdata(node);
+		    if (!(m->flags & MOD_ALIAS)) {
+			zwarnnam(nam, "module is not an alias: %s", *args, 0);
+			return 1;
+		    }
+		    zsfree(m->u.alias);
+		} else {
+		    m = (Module) zcalloc(sizeof(*m));
+		    m->nam = ztrdup(*args);
+		    m->flags = MOD_ALIAS;
+		    zaddlinknode(modules, m);
+		}
+		m->u.alias = ztrdup(aliasname);
+	    } else {
+		if ((node = find_module(*args, 0, NULL))) {
+		    m = (Module) getdata(node);
+		    if (m->flags & MOD_ALIAS)
+			printmodalias(m, ops);
+		    else {
+			zwarnnam(nam, "module is not an alias: %s",
+				 *args, 0);
+			return 1;
+		    }
+		} else {
+		    zwarnnam(nam, "no such module alias: %s", *args, 0);
+		    return 1;
+		}
+	    }
+	}
+    }
+
+    return 0;
+}
+
 /**/
 static int
 bin_zmodload_exist(char *nam, char **args, char *ops)
 {
     LinkNode node;
     Module m;
+    char *modname;
 
     if (!*args) {
 	for (node = firstnode(modules); node; incnode(node)) {
 	    m = (Module) getdata(node);
+	    modname = m->nam;
+	    if (m->flags & MOD_ALIAS) {
+		LinkNode node2;
+		if (ops['A'] && (node2 = find_module(m->u.alias, 1, NULL)))
+		    m = (Module) getdata(node2);
+		else
+		    continue;
+	    } 
 	    if (m->u.handle && !(m->flags & MOD_UNLOAD)) {
-		nicezputs(m->nam, stdout);
+		nicezputs(modname, stdout);
 		putchar('\n');
 	    }
 	}
 	return 0;
     } else {
-	int ret = 0, f;
+	int ret = 0;
 
 	for (; !ret && *args; args++) {
-	    f = 0;
+	    if (!(node = find_module(*args, 1, NULL))
-	    for (node = firstnode(modules);
+		|| !(m = (Module) getdata(node))->u.handle
-		 !f && node; incnode(node)) {
+		|| (m->flags & MOD_UNLOAD))
-		m = (Module) getdata(node);
+		ret = 1;
-		if (m->u.handle && !(m->flags & MOD_UNLOAD))
-		    f = !strcmp(*args, m->nam);
-	    }
-	    ret = !f;
 	}
 	return ret;
     }
@@ -924,9 +1143,9 @@ bin_zmodload_dep(char *nam, char **args, char *ops)
     LinkNode node;
     Module m;
     if(ops['u']) {
-	/* remove dependencies */
+	/* remove dependencies, which can't pertain to aliases */
-	char *tnam = *args++;
+	const char *tnam = *args++;
-	node = find_module(tnam);
+	node = find_module(tnam, 1, &tnam);
 	if (!node)
 	    return 0;
 	m = (Module) getdata(node);
@@ -949,11 +1168,8 @@ bin_zmodload_dep(char *nam, char **args, char *ops)
 		m->deps = NULL;
 	    }
 	}
-	if (!m->deps && !m->u.handle) {
+	if (!m->deps && !m->u.handle)
-	    remnode(modules, node);
+	    delete_module(node);
-	    zsfree(m->nam);
-	    zfree(m, sizeof(*m));
-	}
 	return 0;
     } else if(!args[0] || !args[1]) {
 	/* list dependencies */
@@ -1216,6 +1432,15 @@ bin_zmodload_param(char *nam, char **args, char *ops)
 int
 unload_module(Module m, LinkNode node)
 {
+    /*
+     * Only unload the real module, so resolve aliases.
+     */
+    if (m->flags & MOD_ALIAS) {
+	LinkNode node = find_module(m->u.alias, 1, NULL);
+	if (!node)
+	    return 1;
+	m = (Module) getdata(node);
+    }
     if ((m->flags & MOD_INIT_S) &&
 	!(m->flags & MOD_UNLOAD) &&
 	((m->flags & MOD_LINKED) ?
@@ -1249,7 +1474,7 @@ unload_module(Module m, LinkNode node)
 	    LinkNode n;
 
 	    for (n = firstnode(m->deps); n; incnode(n)) {
-		LinkNode dn = find_module((char *) getdata(n));
+		LinkNode dn = find_module((char *) getdata(n), 1, NULL);
 		Module dm;
 
 		if (dn && (dm = (Module) getdata(dn)) &&
@@ -1287,9 +1512,7 @@ unload_module(Module m, LinkNode node)
 		if (!node)
 		    return 1;
 	    }
-	    remnode(modules, node);
+	    delete_module(node);
-	    zsfree(m->nam);
-	    zfree(m, sizeof(*m));
 	}
     }
     return 0;
@@ -1304,8 +1527,9 @@ bin_zmodload_load(char *nam, char **args, char *ops)
     int ret = 0;
     if(ops['u']) {
 	/* unload modules */
+	const char *mname = *args;
 	for(; *args; args++) {
-	    node = find_module(*args);
+	    node = find_module(*args, 1, &mname);
 	    if (node) {
 		LinkNode mn, dn;
 		int del = 0;
@@ -1314,11 +1538,11 @@ bin_zmodload_load(char *nam, char **args, char *ops)
 		    m = (Module) getdata(mn);
 		    if (m->deps && m->u.handle)
 			for (dn = firstnode(m->deps); dn; incnode(dn))
-			    if (!strcmp((char *) getdata(dn), *args)) {
+			    if (!strcmp((char *) getdata(dn), mname)) {
 				if (m->flags & MOD_UNLOAD)
 				    del = 1;
 				else {
-				    zwarnnam(nam, "module %s is in use by another module and cannot be unloaded", *args, 0);
+				    zwarnnam(nam, "module %s is in use by another module and cannot be unloaded", mname, 0);
 				    ret = 1;
 				    goto cont;
 				}
@@ -1342,7 +1566,7 @@ bin_zmodload_load(char *nam, char **args, char *ops)
 	/* list modules */
 	for (node = firstnode(modules); node; incnode(node)) {
 	    m = (Module) getdata(node);
-	    if (m->u.handle && !(m->flags & MOD_UNLOAD)) {
+	    if (m->u.handle && !(m->flags & (MOD_UNLOAD|MOD_ALIAS))) {
 		if(ops['L']) {
 		    printf("zmodload ");
 		    if(m->nam[0] == '-')

Src/zsh.h

@@ -957,6 +957,7 @@ struct module {
     union {
 	void *handle;
 	Linkedmod linked;
+	char *alias;
     } u;
     LinkList deps;
     int wrapper;
@@ -968,6 +969,7 @@ struct module {
 #define MOD_LINKED  (1<<3)
 #define MOD_INIT_S  (1<<4)
 #define MOD_INIT_B  (1<<5)
+#define MOD_ALIAS   (1<<6)
 
 typedef int (*Module_func) _((Module));