From 3194a475deb5e3e9e7aef680d9bf5fb0a63d551a Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Sun, 8 May 2022 11:05:30 +0100
Subject: ash: export certain variables to the environment immediately

The environment variables BB_OVERRIDE_APPLETS, BB_SKIP_ANSI_EMULATION
and BB_SYSTEMROOT affect of the behaviour of the shell itself.
Setting them as shell variables is insufficient for them to affect
the current shell.

When these three variables are exported from the shell they are
now placed in the environment immediately.  Conversely, when
they're unset or unexported they're removed from the environment.
---
 shell/ash.c | 42 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

(limited to 'shell')

diff --git a/shell/ash.c b/shell/ash.c
index c2c1f2098..ddac42895 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -2371,7 +2371,7 @@ static const struct {
 	{ VSTRFIXED|VTEXTFIXED|VUNSET, "HISTFILE"  , NULL            },
 #endif
 #if ENABLE_PLATFORM_MINGW32
-	{ VSTRFIXED|VTEXTFIXED|VUNSET, bb_skip_ansi_emulation, change_skip_ansi },
+	{ VSTRFIXED|VTEXTFIXED|VUNSET, BB_SKIP_ANSI_EMULATION, change_skip_ansi },
 #endif
 };
 
@@ -2652,6 +2652,29 @@ fix_pathvar(const char *path, int len)
 	}
 	return newpath;
 }
+
+#define BB_VAR_EXACT	1	/* exact match for name */
+#define BB_VAR_ASSIGN	2	/* matches name followed by '=' */
+
+/* Match variables that should be placed in the environment immediately
+ * they're exported and removed immediately they're no longer exported */
+static int
+is_bb_var(const char *s)
+{
+	const char *p;
+	int len;
+
+	for (p = bbvar; *p; p += len + 1) {
+		len = strlen(p);
+		if (strncmp(s, p, len) == 0) {
+			if (s[len] == '\0')
+				return BB_VAR_EXACT;
+			else if (s[len] == '=')
+				return BB_VAR_ASSIGN;
+		}
+	}
+	return FALSE;
+}
 #endif
 
 /*
@@ -2711,6 +2734,11 @@ setvareq(char *s, int flags)
 		if (!(vp->flags & (VTEXTFIXED|VSTACK)))
 			free((char*)vp->var_text);
 
+#if ENABLE_PLATFORM_MINGW32
+		if ((flags & VUNSET) && (vp->flags & VEXPORT) &&
+				is_bb_var(s) == BB_VAR_EXACT)
+			unsetenv(s);
+#endif
 		if (((flags & (VEXPORT|VREADONLY|VSTRFIXED|VUNSET)) | (vp->flags & VSTRFIXED)) == VUNSET) {
 			*vpp = vp->next;
 			free(vp);
@@ -2740,6 +2768,10 @@ setvareq(char *s, int flags)
 		s = ckstrdup(s);
 	vp->var_text = s;
 	vp->flags = flags;
+#if ENABLE_PLATFORM_MINGW32
+	if ((flags & VEXPORT) && is_bb_var(s) == BB_VAR_ASSIGN)
+		putenv(s);
+#endif
 
  out:
 	return vp;
@@ -15028,6 +15060,14 @@ exportcmd(int argc UNUSED_PARAM, char **argv)
 				} else {
 					vp = *findvar(hashvar(name), name);
 					if (vp) {
+#if ENABLE_PLATFORM_MINGW32
+						if (is_bb_var(name) == BB_VAR_EXACT) {
+							if (flag_off == ~VEXPORT)
+								unsetenv(name);
+							else if (flag == VEXPORT && !(vp->flags & VUNSET))
+								putenv(vp->var_text);
+						}
+#endif
 						vp->flags = ((vp->flags | flag) & flag_off);
 						continue;
 					}
-- 
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