From 26ba73098e714459e3294679228a1d54eed14799 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Fri, 6 May 2022 08:26:55 +0100
Subject: win32: search PATH for missing Unix-style executables

Commit 41ef232fc5 (win32: use built-in applets for non-existent
binaries with Unix-style paths) alters what happens when trying
to find an executable.  If all of the following apply:

- the pathname starts with one of the standard directories for Unix
  executables (/bin, /usr/bin, /sbin, /usr/sbin);

- the file isn't found relative to the system root;

- the basename matches an applet

then the applet is run.

Further extend the procedure so that if the first two conditions are
met and either:

- the PREFER_APPLETS and SH_STANDALONE features are enabled and the
  basename *doesn't* match an applet

or

- the PREFER_APPLETS and SH_STANDALONE features are disabled

then PATH is searched for the basename.

This affects:

- how interpreters and binaries are spawned by mingw_spawn_interpreter()
  and mingw_spawnvp();

- how 'which' and the shell search for binaries.

Special steps need to be taken in the shell to avoid treating shell
built-ins and functions as applets.

As a consequence of this change:

- An executable that isn't an applet, say curl.exe, can be run as
  /usr/bin/curl so long as it's in a directory in PATH.  It doesn't
  have to be in C:/usr/bin.

- If the PREFER_APPLETS and SH_STANDALONE features are disabled binaries
  can be run using paths referring to standard Unix directories even if
  they're installed elsewhere in PATH.
---
 shell/ash.c | 46 +++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

(limited to 'shell')

diff --git a/shell/ash.c b/shell/ash.c
index 97075ed5f..6c1e58d6f 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -8983,6 +8983,7 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, c
  * have to change the find_command routine as well.
  * argv[-1] must exist and be writable! See tryexec() for why.
  */
+static struct builtincmd *find_builtin(const char *name);
 static void shellexec(char *prog, char **argv, const char *path, int idx) NORETURN;
 static void shellexec(char *prog, char **argv, const char *path, int idx)
 {
@@ -9011,9 +9012,7 @@ static void shellexec(char *prog, char **argv, const char *path, int idx)
 #endif
 	) {
 #if ENABLE_PLATFORM_MINGW32
-# if ENABLE_FEATURE_SH_STANDALONE
 		char *oldprog = prog;
-# endif
 		prog = stack_add_system_drive(prog);
 #endif
 		tryexec(IF_FEATURE_SH_STANDALONE(applet_no,) prog, argv, envp);
@@ -9025,16 +9024,17 @@ static void shellexec(char *prog, char **argv, const char *path, int idx)
 			goto try_PATH;
 		}
 		e = errno;
-#if ENABLE_PLATFORM_MINGW32 && ENABLE_FEATURE_SH_STANDALONE
-		if (unix_path(oldprog)) {
+#if ENABLE_PLATFORM_MINGW32
+		if (unix_path(oldprog) && !find_builtin(bb_basename(oldprog))) {
+# if ENABLE_FEATURE_SH_STANDALONE
 			const char *name = bb_basename(oldprog);
 			if ((applet_no = find_applet_by_name(name)) >= 0) {
 				tryexec(applet_no, name, argv, envp);
 				e = errno;
 			}
-			else {
-				e = ENOENT;
-			}
+# endif
+			argv[0] = (char *)bb_basename(oldprog);
+			goto try_PATH;
 		}
 #endif
 	} else {
@@ -9481,6 +9481,10 @@ describe_command(char *command, const char *path, int describe_command_verbose)
 			p = command;
 #endif
 		} else {
+#if ENABLE_PLATFORM_MINGW32
+			if (unix_path(command))
+				command = (char *)bb_basename(command);
+#endif
 			do {
 				padvance(&path, command);
 			} while (--j >= 0);
@@ -14658,24 +14662,20 @@ find_command(char *name, struct cmdentry *entry, int act, const char *path)
 #else /* ENABLE_PLATFORM_MINGW32 */
 	/* If name contains a slash or drive prefix, don't use PATH or hash table */
 	if (has_path(name)) {
-		fullname = stack_add_system_drive(name);
 		entry->u.index = -1;
-		if (act & DO_ABS) {
-			if (!add_win32_extension(fullname) && stat(fullname, &statb) < 0) {
-# if ENABLE_FEATURE_SH_STANDALONE
-				if (unix_path(name) &&
-						find_applet_by_name(bb_basename(name)) >= 0) {
-					entry->cmdtype = CMDNORMAL;
-					entry->u.index = INT_MIN;
-					return;
-				}
-# endif
-				entry->cmdtype = CMDUNKNOWN;
-				return;
-			}
-		}
 		entry->cmdtype = CMDNORMAL;
-		return;
+		fullname = stack_add_system_drive(name);
+		if (add_win32_extension(fullname) || file_is_executable(fullname)) {
+			return;
+		} else if (unix_path(name) && !find_builtin(bb_basename(name))) {
+			name = (char *)bb_basename(name);
+			act |= DO_NOFUNC;
+		} else if (act & DO_ABS) {
+			entry->cmdtype = CMDUNKNOWN;
+			return;
+		} else {
+			return;
+		}
 	}
 #endif /* ENABLE_PLATFORM_MINGW32 */
 
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