sh: don't overwrite login environment variables if already set

Certain environment variables (HOME, LOGNAME, USER, SHELL) are set
during early shell startup to emulate what login/su would do on
UNIX.  If any of these are already set don't overwrite them.

1 files changed, 11 insertions, 0 deletions

diff --git a/libbb/setup_environment.c b/libbb/setup_environment.c
index 4258656fe..944ac5538 100644
--- a/libbb/setup_environment.c
+++ b/libbb/setup_environment.c
@@ -30,6 +30,14 @@
 
 #include "libbb.h"
 
+#if ENABLE_PLATFORM_MINGW32
+static void xsetenv_if_unset(const char *key, const char *value)
+{
+        if (!getenv(key))
+                xsetenv(key, value);
+}
+#endif
+
 void FAST_FUNC setup_environment(const char *shell, int flags, const struct passwd *pw)
 {
         if (!shell || !shell[0])
@@ -61,6 +69,9 @@ void FAST_FUNC setup_environment(const char *shell, int flags, const struct pass
                 //xsetenv("HOME",    pw->pw_dir);
                 //xsetenv("SHELL",   shell);
         } else if (flags & SETUP_ENV_CHANGEENV) {
+#if ENABLE_PLATFORM_MINGW32
+#define xsetenv(k, v) xsetenv_if_unset(k, v)
+#endif
                 /* Set HOME, SHELL, and if not becoming a super-user,
                  * USER and LOGNAME.  */
                 if (pw->pw_uid) {