ash: prevent mintty from setting HOME

The Cygwin terminal program mintty sets the HOME environment
variable.  Attempt to detect this and unset HOME so the usual
busybox-w32 initialisation of HOME is used instead.

Adds 80 bytes.

(GitHub issue #420)

1 files changed, 13 insertions, 1 deletions

diff --git a/shell/ash.c b/shell/ash.c
index b753678c0..4fdc6f1c6 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -15886,9 +15886,16 @@ static void setvar_if_unset(const char *key, const char *value)
 #endif
 
 #if ENABLE_PLATFORM_MINGW32
+/*
+ * Detect if the environment contains certain mixed-case names:
+ *
+ *   Home          is present in a standard Windows environment
+ *   ComSpec       is present in WINE
+ *   ProgramData   is present in Cygwin/MSYS2
+ */
 static int mixed_case_special_name(const char *envp)
 {
-        const char *names = "PATH=\0""COMSPEC=\0";
+        const char *names = "PATH=\0""COMSPEC=\0""PROGRAMDATA=\0";
         const char *n;
 
         for (n = names; *n; ) {
@@ -15936,6 +15943,11 @@ init(void)
                  */
                 for (envp = environ; envp && *envp; envp++) {
                         if (mixed_case_special_name(*envp)) {
+                                /* mintty sets HOME:  unset it */
+                                const char *tty = getenv("TERM_PROGRAM");
+                                if (tty && strcmp(tty, "mintty") == 0) {
+                                        unsetenv("HOME");
+                                }
                                 break;
                         }
                 }