hush: export -n support

function                                             old     new   delta
builtin_export                                       206     256     +50
set_local_var                                        248     265     +17
expand_variables                                    2204    2203      -1

4 files changed, 95 insertions, 12 deletions

diff --git a/shell/Config.in b/shell/Config.in
index 6cc11ce80..57969f02c 100644
--- a/shell/Config.in
+++ b/shell/Config.in
@@ -232,6 +232,13 @@ config HUSH_FUNCTIONS
         help
           Enable support for shell functions in hush. +800 bytes.
 
+config HUSH_EXPORT_N
+        bool "Support export '-n' option"
+        default n
+        depends on HUSH
+        help
+          Enable support for export '-n' option in hush. It is a bash extension.
+
 config LASH
         bool "lash (deprecated: aliased to hush)"
         default n
diff --git a/shell/hush.c b/shell/hush.c
index d08652656..d59a5de82 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -1253,10 +1253,10 @@ static const char *get_local_var_value(const char *src)
 /* str holds "NAME=VAL" and is expected to be malloced.
  * We take ownership of it.
  * flg_export:
- *  0: do not export
- *  1: export
- * -1: if NAME is set, leave export status alone
- *     if NAME is not set, do not export
+ *  0: do not change export flag
+ *     (if creating new variable, flag will be 0)
+ *  1: set export flag and putenv the variable
+ * -1: clear export flag and unsetenv the variable
  * flg_read_only is set only when we handle -R var=val
  */
 #if BB_MMU
@@ -1297,6 +1297,7 @@ static int set_local_var(char *str, int flg_export, int flg_read_only)
                         free(str);
                         return -1;
                 }
+//TODO: optimize out redundant unsetenv/putenv's?
                 debug_printf_env("%s: unsetenv '%s'\n", __func__, str);
                 unsetenv(str); /* just in case */
                 *value = '=';
@@ -1331,8 +1332,13 @@ static int set_local_var(char *str, int flg_export, int flg_read_only)
         if (flg_export == 1)
                 cur->flg_export = 1;
         if (cur->flg_export) {
-                debug_printf_env("%s: putenv '%s'\n", __func__, cur->varstr);
-                return putenv(cur->varstr);
+                if (flg_export == -1) {
+                        cur->flg_export = 0;
+                        /* unsetenv was already done */
+                } else {
+                        debug_printf_env("%s: putenv '%s'\n", __func__, cur->varstr);
+                        return putenv(cur->varstr);
+                }
         }
         return 0;
 }
@@ -2214,7 +2220,7 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
                                                                 val = NULL;
                                                         } else {
                                                                 char *new_var = xasprintf("%s=%s", var, val);
-                                                                set_local_var(new_var, -1, 0);
+                                                                set_local_var(new_var, 0, 0);
                                                         }
                                                 }
                                         }
@@ -6400,7 +6406,9 @@ static void print_escaped(const char *s)
 
 static int builtin_export(char **argv)
 {
-        if (*++argv == NULL) {
+        unsigned opt_unexport;
+
+        if (argv[1] == NULL) {
                 char **e = environ;
                 if (e) {
                         while (*e) {
@@ -6426,15 +6434,33 @@ static int builtin_export(char **argv)
                 return EXIT_SUCCESS;
         }
 
+#if ENABLE_HUSH_EXPORT_N
+        opt_unexport = getopt32(argv, "+n"); /* "+": stop at 1st non-option */
+        argv += optind;
+#else
+        opt_unexport = 0;
+        argv++;
+#endif
+
         do {
                 char *name = *argv;
 
-                /* So far we do not check that name is valid */
+                /* So far we do not check that name is valid (TODO?) */
+
                 if (strchr(name, '=') == NULL) {
-                        /* Exporting a name without a =VALUE */
                         struct variable *var;
 
                         var = get_local_var(name);
+                        if (opt_unexport) {
+                                /* export -n NAME (without =VALUE) */
+                                if (var) {
+                                        var->flg_export = 0;
+                                        debug_printf_env("%s: unsetenv '%s'\n", __func__, name);
+                                        unsetenv(name);
+                                } /* else: export -n NOT_EXISTING_VAR: no-op */
+                                continue;
+                        }
+                        /* export NAME (without =VALUE) */
                         if (var) {
                                 var->flg_export = 1;
                                 debug_printf_env("%s: putenv '%s'\n", __func__, var->varstr);
@@ -6448,10 +6474,13 @@ static int builtin_export(char **argv)
                          * We just set it to "" and export. */
                         name = xasprintf("%s=", name);
                 } else {
-                        /* Exporting VAR=VALUE */
+                        /* (Un)exporting NAME=VALUE */
                         name = xstrdup(name);
                 }
-                set_local_var(name, 1, 0);
+                set_local_var(name,
+                        /*export:*/ (opt_unexport ? -1 : 1),
+                        /*readonly:*/ 0
+                );
         } while (*++argv);
 
         return EXIT_SUCCESS;
diff --git a/shell/hush_test/hush-misc/export-n.right b/shell/hush_test/hush-misc/export-n.right
new file mode 100644
index 000000000..3d55bf752
--- /dev/null
+++ b/shell/hush_test/hush-misc/export-n.right
@@ -0,0 +1,10 @@
+export aaa1="'''"
+export aaa2=''
+export aaa3="'''"'abc'
+export aaa8='8'
+aaa9=9
+aaa10=10
+Nothing:
+Nothing:
+Nothing:
+Done
diff --git a/shell/hush_test/hush-misc/export-n.tests b/shell/hush_test/hush-misc/export-n.tests
new file mode 100755
index 000000000..5252a1e14
--- /dev/null
+++ b/shell/hush_test/hush-misc/export-n.tests
@@ -0,0 +1,37 @@
+export aaa1="'''"
+export aaa2=""
+export aaa3="'''abc"
+export | grep aaa.=
+
+export -n aaa1
+unset aaa2; export -n aaa2="ghi"
+export -n aaa3="klm"
+export | grep aaa.=
+
+export aaa4=4 aaa5=5
+export -n aaa4=4n
+export -n aaa5
+export | grep aaa.=
+
+export aaa5=5 aaa6=6 aaa7=7 aaa8=8
+export -n aaa5 aaa6=6n aaa7
+export | grep aaa.=
+
+aaa9=9
+export -n aaa9
+set | grep ^aaa9=
+
+export aaa10=10
+export -n aaa10
+set | grep ^aaa10=
+
+
+export EXPORTED=qwe
+export -nnnnnn nnnnnn; echo "Nothing:"; env | grep nnnnnn
+
+export -n EXPORTED=123; echo "Nothing:"; env | grep ^EXPORTED
+
+export EXPORTED=qwe
+export -n EXPORTED; EXPORTED=123; echo "Nothing:"; env | grep ^EXPORTED
+
+echo Done