win32: adjust handling of executable extensions

Mixing Windows and Unix-style filename extensions was causing
problems.  Tweak how extensions are handled to try and improve
matters:

- Consistently check whether the unaltered filename is an
  executable before trying adding extensions.

- Check .exe and .com before .sh.

Saves up to 16 bytes.

(GitHub issue #405)

2 files changed, 13 insertions, 9 deletions

diff --git a/shell/ash.c b/shell/ash.c
index dc2115414..e32731d41 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -15059,7 +15059,7 @@ find_command(char *name, struct cmdentry *entry, int act, const char *path)
                 entry->u.index = -1;
                 entry->cmdtype = CMDNORMAL;
                 fullname = stack_add_ext_space(name);
-                if (add_win32_extension(fullname) || file_is_executable(fullname)) {
+                if (add_win32_extension(fullname)) {
                         return;
                 } else if (unix_path(name)) {
                         name = (char *)bb_basename(name);
diff --git a/win32/mingw.c b/win32/mingw.c
index b1225665c..8669cc137 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -2041,7 +2041,7 @@ void mingw_sync(void)
 }
 
 #define NUMEXT 5
-static const char win_suffix[NUMEXT][4] = { "sh", "com", "exe", "bat", "cmd" };
+static const char win_suffix[NUMEXT][4] = { "com", "exe", "sh", "bat", "cmd" };
 
 static int has_win_suffix(const char *name, int start)
 {
@@ -2082,21 +2082,25 @@ char *alloc_ext_space(const char *path)
         return s;
 }
 
-/* Check if path can be made into an executable by adding a suffix.
- * The suffix is added to the end of the argument which must be
- * long enough to allow this.
+/* Check if path is an executable or can be made into one by adding
+ * a suffix.  The suffix is added to the end of the argument which
+ * must be long enough to allow this.
  *
  * If the return value is TRUE the argument contains the new path,
  * if FALSE the argument is unchanged.
  */
-int add_win32_extension(char *p)
+int
+add_win32_extension(char *p)
 {
+        if (file_is_executable(p))
+                return TRUE;
+
         if (!has_exe_suffix_or_dot(p)) {
                 int i, len = strlen(p);
 
                 p[len] = '.';
-                for (i=0; i<NUMEXT; ++i) {
-                        strcpy(p+len+1, win_suffix[i]);
+                for (i = 0; i < NUMEXT; ++i) {
+                        strcpy(p + len + 1, win_suffix[i]);
                         if (file_is_executable(p))
                                 return TRUE;
                 }
@@ -2114,7 +2118,7 @@ file_is_win32_exe(const char *name)
 {
         char *path = alloc_ext_space(name);
 
-        if ((add_win32_extension(path) || file_is_executable(path)))
+        if (add_win32_extension(path))
                 return path;
 
         free(path);