win32: allow for trailing separator in PATH

In recent versions of Windows the PATH environment variable has
a trailing semicolon.  This is insignificant to Windows because
it's ignored.  busybox-w32 conforms to the POSIX interpretation
of PATH which treats an empty path element as denoting the current
directory.  As result, on these versions of Windows executables
may by default be run from the current directory, contrary to
usual Unix practice.

Attempt to detect and remove the trailing semicolon on applet
start up.  If the user insists, they can add a trailing semicolon
to the shell variable PATH and it will be respected in the
conventional manner.

Adds 88-112 bytes.

(GitHub issue #422)

1 files changed, 12 insertions, 0 deletions

diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index 1232d97c9..1f9968f10 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -1410,6 +1410,18 @@ int main(int argc UNUSED_PARAM, char **argv)
                 if (s)
                         *s = '\0';
         }
+
+        if (windows_env()) {
+                /* remove single trailing separator from PATH */
+                for (char **envp = environ; envp && *envp; envp++) {
+                        if (is_prefixed_with_case(*envp, "PATH=")) {
+                                char *end = last_char_is(*envp, ';');
+                                if (end && end[-1] != ';')
+                                        *end = '\0';
+                                break;
+                        }
+                }
+        }
 # endif
         applet_name = bb_basename(applet_name);