Fixes for environment variable handling on GNO:

* Push/pop environment to make sure it is isolated from our parents and children.
* Make all environment vars (and shell vars) case-insensitive, consistent with GNO's internal handling of environment vars.
* Wrap putenv and unsetenv to make sure they are called with lower-case variable names, which is necessary to maintain consistency between the environ array and the kernel's internal representation of variables.

include/libbb.h

@@ -481,6 +481,13 @@ off_t xlseek(int fd, off_t offset, int whence) FAST_FUNC;
 int xmkstemp(char *template) FAST_FUNC;
 off_t fdlength(int fd) FAST_FUNC;
 
+#ifdef __GNO__
+void unsetenv_wrapper(const char *var);
+int putenv_wrapper(char *string);
+# define unsetenv unsetenv_wrapper
+# define putenv putenv_wrapper
+#endif
+
 uoff_t FAST_FUNC get_volume_size_in_bytes(int fd,
 		const char *override,
 		unsigned override_units,

libbb/vfork.and.run.c

@@ -63,6 +63,7 @@ pid_t vfork_and_run(void (*fn)(void*) NORETURN, void *arg) {
 	 */
 	
 	long oldmask;
+	bool environPushed;
 	sig_t prev_alarm_sig;
 	pid_t pid;
 	kvmt *kvm_context;
@@ -72,6 +73,9 @@ pid_t vfork_and_run(void (*fn)(void*) NORETURN, void *arg) {
 	/* Block all signals for now */
 	oldmask = sigblock(-1);
 	
+	/* Isolate child process's environment from parent */
+	environPushed = !environPush();
+	
 	pid = fork2(fork_thunk, 1024, 0, forked_child_name, 
 				(sizeof(fn) + sizeof(arg) + sizeof(oldmask) + 1) / 2, 
 				fn, arg, oldmask);
@@ -106,6 +110,8 @@ pid_t vfork_and_run(void (*fn)(void*) NORETURN, void *arg) {
 	
 ret:
 	sigsetmask(oldmask);
+	if (environPushed)
+		environPop();
 	return pid;
 }
 

libbb/xfuncs.printf.c

@@ -335,12 +335,6 @@ char* FAST_FUNC xasprintf(const char *format, ...)
 	return string_ptr;
 }
 
-void FAST_FUNC xsetenv(const char *key, const char *value)
-{
-	if (setenv(key, value, 1))
-		bb_error_msg_and_die(bb_msg_memory_exhausted);
-}
-
 /* Handles "VAR=VAL" strings, even those which are part of environ
  * _right now_
  */
@@ -363,12 +357,50 @@ void FAST_FUNC bb_unsetenv(const char *var)
 	free(tp);
 }
 
-void FAST_FUNC bb_unsetenv_and_free(char *var)
+#ifdef __GNO__
+/* We wrap putenv and unsetenv functions to make them fully case-insensitive.
+ * The libc versions are case-insensitive with respect to the internal
+ * variable representation maintained by the kernel, but case-sensitive with
+ * respect to the environ array, with the result that the two representations
+ * may get out of sync.  We avoid this by always converting variable names to 
+ * lower case ourselves.  We'd also need to wrap setenv if it were used.
+ */
+# undef putenv
+int putenv_wrapper(char *string)
 {
-	bb_unsetenv(var);
+	int name_len, i;
-	free(var);
+	int retval;
+	char *string_lowercase = xstrdup(string);
+	
+	name_len = strcspn(string, "=");
+	for (i = 0; i < name_len; i++) {
+		string_lowercase[i] = tolower(string_lowercase[i]);
 	}
 	
+	/* We rely on putenv to copy its input string and not store the original,
+	 * which GNO does but POSIX-standard systems don't. */
+	retval = putenv(string_lowercase);
+	free(string_lowercase);
+	return retval;
+}
+# define putenv putenv_wrapper
+
+# undef unsetenv
+void unsetenv_wrapper(const char *var)
+{
+	char *c;
+	char *var_lowercase = xstrdup(var);
+	
+	for (c = var_lowercase; *c != 0; c++) {
+		*c = tolower(*c);
+	}
+	
+	unsetenv(var_lowercase);
+	free(var_lowercase);
+}
+# define unsetenv unsetenv_wrapper
+#endif
+
 // Die with an error message if we can't set gid.  (Because resource limits may
 // limit this user to a given number of processes, and if that fills up the
 // setgid() will fail and we'll _still_be_root_, which is bad.)

shell/hush.c

@@ -375,6 +375,17 @@
 
 #define SPECIAL_VAR_SYMBOL   3
 
+/* Use case-insensitive variable name comparisons on GNO, consistent with
+ * GNO's internal handling of environment variables.
+ */
+#ifdef __GNO__
+# define varnamecmp strcasecmp
+# define varnamencmp strncasecmp
+#else
+# define varnamecmp strcmp
+# define varnamencmp strncmp
+#endif
+
 struct variable;
 
 static const char hush_version_str[] ALIGN1 = "HUSH_VERSION="BB_VER;
@@ -1860,7 +1871,7 @@ static struct variable **get_ptr_to_local_var(const char *name, unsigned len)
 
 	pp = &G.top_var;
 	while ((cur = *pp) != NULL) {
-		if (strncmp(cur->varstr, name, len) == 0 && cur->varstr[len] == '=')
+		if (varnamencmp(cur->varstr, name, len) == 0 && cur->varstr[len] == '=')
 			return pp;
 		pp = &cur->next;
 	}
@@ -1876,7 +1887,7 @@ static const char* FAST_FUNC get_local_var_value(const char *name)
 		char **cpp = G.expanded_assignments;
 		while (*cpp) {
 			char *cp = *cpp;
-			if (strncmp(cp, name, len) == 0 && cp[len] == '=')
+			if (varnamencmp(cp, name, len) == 0 && cp[len] == '=')
 				return cp + len + 1;
 			cpp++;
 		}
@@ -1886,11 +1897,11 @@ static const char* FAST_FUNC get_local_var_value(const char *name)
 	if (vpp)
 		return (*vpp)->varstr + len + 1;
 
-	if (strcmp(name, "PPID") == 0)
+	if (varnamecmp(name, "PPID") == 0)
 		return utoa(G.root_ppid);
 	// bash compat: UID? EUID?
 #if ENABLE_HUSH_RANDOM_SUPPORT
-	if (strcmp(name, "RANDOM") == 0)
+	if (varnamecmp(name, "RANDOM") == 0)
 		return utoa(next_random(&G.random_gen));
 #endif
 	return NULL;
@@ -1933,7 +1944,7 @@ static int set_local_var(char *str, int flg_export, int local_lvl, int flg_read_
 	name_len = eq_sign - str + 1; /* including '=' */
 	var_pp = &G.top_var;
 	while ((cur = *var_pp) != NULL) {
-		if (strncmp(cur->varstr, str, name_len) != 0) {
+		if (varnamencmp(cur->varstr, str, name_len) != 0) {
 			var_pp = &cur->next;
 			continue;
 		}
@@ -2010,7 +2021,7 @@ static int set_local_var(char *str, int flg_export, int local_lvl, int flg_read_
  exp:
 	if (flg_export == 1)
 		cur->flg_export = 1;
-	if (name_len == 4 && cur->varstr[0] == 'P' && cur->varstr[1] == 'S')
+	if (name_len == 4 && varnamencmp(cur->varstr, "PS", 2) == 0)
 		cmdedit_update_prompt();
 	if (cur->flg_export) {
 		if (flg_export == -1) {
@@ -2040,7 +2051,7 @@ static int unset_local_var_len(const char *name, int name_len)
 		return EXIT_SUCCESS;
 	var_pp = &G.top_var;
 	while ((cur = *var_pp) != NULL) {
-		if (strncmp(cur->varstr, name, name_len) == 0 && cur->varstr[name_len] == '=') {
+		if (varnamencmp(cur->varstr, name, name_len) == 0 && cur->varstr[name_len] == '=') {
 			if (cur->flg_read_only) {
 				bb_error_msg("%s: readonly variable", name);
 				return EXIT_FAILURE;
@@ -2048,7 +2059,7 @@ static int unset_local_var_len(const char *name, int name_len)
 			*var_pp = cur->next;
 			debug_printf_env(("%s: unsetenv '%s'\n", "unset_local_var_len", cur->varstr));
 			bb_unsetenv(cur->varstr);
-			if (name_len == 3 && cur->varstr[0] == 'P' && cur->varstr[1] == 'S')
+			if (name_len == 3 && varnamencmp(cur->varstr, "PS", 2) == 0)
 				cmdedit_update_prompt();
 			if (!cur->max_len)
 				free(cur->varstr);
@@ -5869,7 +5880,7 @@ static void re_execute_shell(char ***to_free, const char *s,
 	*pp++ = (char *) G.argv0_for_re_execing;
 	*pp++ = param_buf;
 	for (cur = G.top_var; cur; cur = cur->next) {
-		if (strcmp(cur->varstr, hush_version_str) == 0)
+		if (varnamecmp(cur->varstr, hush_version_str) == 0)
 			continue;
 		if (cur->flg_read_only) {
 			*pp++ = (char *) "-R";
@@ -8081,6 +8092,9 @@ int hush_main(int argc, char **argv)
 	INIT_G();
 	hush_exec_path = get_exec_path();
 #ifdef __GNO__
+	/* Make sure our environment is isolated from the parent process's */
+	if (environPush() == 0)
+		atexit(environPop);
 	environInit();
 #endif
 	if (EXIT_SUCCESS != 0) /* if EXIT_SUCCESS == 0, it is already done */