From b21899038683bd646446d3db9e84f64ea669d2ed Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Sat, 17 Aug 2024 11:38:30 +0100
Subject: which,ash: code shrink detection of standalone shell

Commit 6d87be4d7 (which,ash: changes to which/command/type) let
'which' detect when it's run from a standalone shell by having
the shell pass the undocumented '-s' option.

A better solution is to alter argv[0] when 'which' is run from a
standalone shell.  This is possible because the code path through
run_noexec_applet_and_exit() and which_main() doesn't actually
use argv[0].

- No special treatment is required in ash when 'which' has no
  arguments or the '--help' option.

- tryexec() no longer needs an extra element before the start of
  argv.  The commit 027fb22e2 can be reverted and the allocation
  of argv in evalcommand() simplified.

- 'which' no longer needs to handle the '-s' option.

Saves 96-104 bytes.
---
 debianutils/which.c | 17 ++---------------
 shell/ash.c         | 22 +++++++++-------------
 2 files changed, 11 insertions(+), 28 deletions(-)

diff --git a/debianutils/which.c b/debianutils/which.c
index 6815768ab..fd3f53d3e 100644
--- a/debianutils/which.c
+++ b/debianutils/which.c
@@ -32,13 +32,6 @@
 
 #include "libbb.h"
 
-#if ENABLE_PLATFORM_MINGW32 && ENABLE_FEATURE_SH_STANDALONE
-enum {
-	OPT_a = (1 << 0),
-	OPT_s = (1 << 1)
-};
-#endif
-
 int which_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int which_main(int argc UNUSED_PARAM, char **argv)
 {
@@ -47,7 +40,8 @@ int which_main(int argc UNUSED_PARAM, char **argv)
 	/* This sizeof(): bb_default_root_path is shorter than BB_PATH_ROOT_PATH */
 	char buf[sizeof(BB_PATH_ROOT_PATH)];
 #if ENABLE_PLATFORM_MINGW32 && ENABLE_FEATURE_SH_STANDALONE
-	int sh_standalone;
+	/* 'Which' in argv[0] indicates we were run from a standalone shell */
+	int sh_standalone = argv[0][0] == 'W';
 #endif
 
 	env_path = getenv("PATH");
@@ -55,14 +49,7 @@ int which_main(int argc UNUSED_PARAM, char **argv)
 		/* env_path must be writable, and must not alloc, so... */
 		env_path = strcpy(buf, bb_default_root_path);
 
-#if ENABLE_PLATFORM_MINGW32 && ENABLE_FEATURE_SH_STANDALONE
-	/* '-s' option indicates we were run from a standalone shell */
-	getopt32(argv, "^" "as" "\0" "-1"/*at least one arg*/);
-	sh_standalone = option_mask32 & OPT_s;
-	option_mask32 &= ~OPT_s;
-#else
 	getopt32(argv, "^" "a" "\0" "-1"/*at least one arg*/);
-#endif
 	argv += optind;
 
 	do {
diff --git a/shell/ash.c b/shell/ash.c
index 94aabbc4c..aa291b99d 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -9104,14 +9104,9 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, c
 			/* mingw-w64's getopt() uses __argv[0] as the program name */
 			__argv[0] = (char *)cmd;
 			/* 'which' wants to know if it was invoked from a standalone
-			 * shell.  Use the spare element of argv to add a flag, but
-			 * not if the first argument is '--help', that's a special
-			 * case. */
-			if (strcmp(argv[0], "which") == 0 &&
-					(argv[1] == NULL || strcmp(argv[1], "--help") != 0)) {
-				--argv;
-				argv[0] = argv[1];
-				argv[1] = (char *)"-s";
+			 * shell.  'Which' in argv[0] indicates this. */
+			if (strcmp(argv[0], "which") == 0) {
+				argv[0] = (char *)"Which";
 			}
 # else
 		if (APPLET_IS_NOEXEC(applet_no)) {
@@ -11585,9 +11580,13 @@ evalcommand(union node *cmd, int flags)
 
 	localvar_stop = pushlocalvars(vlocal);
 
+#if ENABLE_PLATFORM_MINGW32
+	argv = nargv = stalloc(sizeof(char *) * (argc + 1));
+#else
 	/* Reserve one extra spot at the front for shellexec. */
 	nargv = stalloc(sizeof(char *) * (argc + 2));
 	argv = ++nargv;
+#endif
 	for (sp = arglist.list; sp; sp = sp->next) {
 		TRACE(("evalcommand arg: %s\n", sp->text));
 		*nargv++ = sp->text;
@@ -16791,8 +16790,7 @@ argv_size(struct datasize ds, char **p)
 			ds.funcstringsize += align_len(*p);
 			p++;
 		}
-		// Allow for argv[-1] used by tryexec().
-		ds.funcblocksize += 2 * sizeof(char *);
+		ds.funcblocksize += sizeof(char *);
 	}
 	return ds;
 }
@@ -16806,8 +16804,6 @@ argv_copy(char **p)
 #endif
 
 	if (p) {
-		// argv[-1] for tryexec()
-		funcblock = (char *) funcblock + sizeof(char *);
 		while (*p) {
 			new = funcblock;
 			funcblock = (char *) funcblock + sizeof(char *);
@@ -16818,7 +16814,7 @@ argv_copy(char **p)
 		new = funcblock;
 		funcblock = (char *) funcblock + sizeof(char *);
 		*new = NULL;
-		return start + 1;
+		return start;
 	}
 	return NULL;
 }
-- 
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