From 3ea59e15db1edc319a56495021b3d1e58dd49f30 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Tue, 11 Apr 2023 11:35:44 +0100
Subject: ash,hush: improvements to tab completion

Cosmetic changes.

Avoid accessing beyond the end of the command and alias arrays in ash.

Code shrink.  Change since commit 3165054d2:

function                                             old     new   delta
ash_command_name                                       -     153    +153
hush_command_name                                      -     110    +110
complete_cmd_dir_file                                876     880      +4
ash_builtin_name                                      17       -     -17
hush_builtin_name                                     38       -     -38
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 1/0 up/down: 267/-55)           Total: 212 bytes

(GitHub issue #301)

Signed-off-by: Ron Yorston <rmy@pobox.com>
---
 shell/ash.c  | 54 +++++++++++++++++++++++++++++++++---------------------
 shell/hush.c | 26 ++++++++++++--------------
 2 files changed, 45 insertions(+), 35 deletions(-)

diff --git a/shell/ash.c b/shell/ash.c
index c77ee8620..9bb8fd805 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -10286,44 +10286,56 @@ find_builtin(const char *name)
 static const char * FAST_FUNC
 ash_command_name(struct exe_state *e)
 {
-	if (e->e_type == 0) {
-		if (/*e->e_index >= 0 &&*/ e->e_index < ARRAY_SIZE(builtintab)) {
+	int index;
+	struct tblentry *cmdp;
+# if ENABLE_ASH_ALIAS
+	struct alias *ap;
+# endif
+
+	index = e->e_index;
+	switch (e->e_type) {
+	case 0:
+		if (index < ARRAY_SIZE(builtintab))
 			return builtintab[e->e_index++].name + 1;
-		}
 		e->e_type++;
-		e->e_index = 0;
-		e->e_ptr = cmdtable[0];
-	}
-	if (e->e_type == 1) {
-		struct tblentry *cmdp = (struct tblentry *)e->e_ptr;
-		while (e->e_index < CMDTABLESIZE) {
+		index = 0;
+		/* e->e_ptr = NULL; */
+		/* fall through */
+	case 1:
+		cmdp = (struct tblentry *)e->e_ptr;
+		for (;;) {
 			while (cmdp) {
 				if (cmdp->cmdtype == CMDFUNCTION) {
+					e->e_index = index;
 					e->e_ptr = cmdp->next;
 					return cmdp->cmdname;
 				}
 				cmdp = cmdp->next;
 			}
-			cmdp = cmdtable[++e->e_index];
+			if (++index == CMDTABLESIZE)
+				break;
+			cmdp = cmdtable[index];
 		}
 # if ENABLE_ASH_ALIAS
 		e->e_type++;
-		e->e_index = 0;
-		e->e_ptr = atab[0];
-# endif
-	}
-# if ENABLE_ASH_ALIAS
-	if (e->e_type == 2) {
-		struct alias *ap = (struct alias *)e->e_ptr;
-		while (e->e_index < ATABSIZE) {
-			while (ap) {
+		index = 0;
+		e->e_ptr = NULL;
+		/* fall through */
+	case 2:
+		ap = (struct alias *)e->e_ptr;
+		for (;;) {
+			if (ap) {
+				e->e_index = index;
 				e->e_ptr = ap->next;
 				return ap->name;
 			}
-			ap = atab[++e->e_index];
+			if (++index == ATABSIZE)
+				break;
+			ap = atab[index];
 		}
-	}
 # endif
+		break;
+	}
 	return NULL;
 }
 #endif
diff --git a/shell/hush.c b/shell/hush.c
index 443bdeccf..04633ab2d 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -8222,33 +8222,31 @@ static const struct built_in_command *find_builtin(const char *name)
 #if ENABLE_HUSH_JOB && ENABLE_FEATURE_TAB_COMPLETION
 static const char * FAST_FUNC hush_command_name(exe_state *e)
 {
-	if (e->e_type == 0) {
-		if (/*e->e_index >= 0 && */ e->e_index < ARRAY_SIZE(bltins1)) {
+	switch (e->e_type) {
+	case 0:
+		if (e->e_index < ARRAY_SIZE(bltins1))
 			return bltins1[e->e_index++].b_cmd;
-		}
 		e->e_type++;
 		e->e_index = 0;
 		/* e->e_ptr = NULL; */
-	}
-	if (e->e_type == 1) {
-		if (e->e_index < ARRAY_SIZE(bltins2)) {
+		/* fall through */
+	case 1:
+		if (e->e_index < ARRAY_SIZE(bltins2))
 			return bltins2[e->e_index++].b_cmd;
-		}
 # if ENABLE_HUSH_FUNCTIONS
 		e->e_type++;
 		/* e->e_index = 0; */
 		e->e_ptr = G.top_func;
-# endif
-	}
-# if ENABLE_HUSH_FUNCTIONS
-	if (e->e_type == 2) {
-		struct function *funcp = (struct function *)e->e_ptr;
-		while (funcp) {
+		/* fall through */
+	case 2:
+		if (e->e_ptr) {
+			struct function *funcp = (struct function *)e->e_ptr;
 			e->e_ptr = funcp->next;
 			return funcp->name;
 		}
-	}
 # endif
+		break;
+	}
 	return NULL;
 }
 #endif
-- 
cgit v1.2.3-55-g6feb