win32: rework adding of extensions to filenames

Previously there was one function to handle adding extensions to
executable filenames, add_win32_extension().  Refactor this into
three functions:

add_win32_extension() appends the suffix to the argument string
in-place.  The argument must be long enough to cope with this,
as is the case in ash where path_advance() adds 4 bytes to each
filename for just this reason.

alloc_win32_extension() is equivalent to the old add_win32_extension().
It allocates a string to hold the new filename then calls the new
add_win32_extension() function.  The caller is responsible for
managing the returned string.

auto_win32_extension() calls alloc_win32_extension() and saves the
resulting string using auto_string().  It's used where the new
filename is consumed immediately or the actual value isn't needed.

Rewrite code to use the most appropriate function.  Also reorder
some code in find_executable() and find_command().

1 files changed, 1 insertions, 2 deletions

diff --git a/debianutils/which.c b/debianutils/which.c
index 0b0a6a645..9b10b62f9 100644
--- a/debianutils/which.c
+++ b/debianutils/which.c
@@ -67,10 +67,9 @@ int which_main(int argc UNUSED_PARAM, char **argv)
                 /* If file contains a slash don't use PATH */
                 if (strchr(*argv, '/') || (ENABLE_PLATFORM_MINGW32 && strchr(*argv, '\\'))) {
 #if ENABLE_PLATFORM_MINGW32
-                        if ((p=add_win32_extension(*argv)) != NULL) {
+                        if ((p=auto_win32_extension(*argv)) != NULL) {
                                 missing = 0;
                                 puts(p);
-                                free(p);
                         }
                         else
 #endif