implement `unset` semantics as required by POSIX

3 files changed, 92 insertions, 7 deletions

diff --git a/shell/hush.c b/shell/hush.c
index a7aa32abe..cd6e12b11 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -1000,21 +1000,21 @@ static int set_local_var(char *str, int flg_export)
         return 0;
 }
 
-static void unset_local_var(const char *name)
+static int unset_local_var(const char *name)
 {
         struct variable *cur;
         struct variable *prev = prev; /* for gcc */
         int name_len;
 
         if (!name)
-                return;
+                return EXIT_SUCCESS;
         name_len = strlen(name);
         cur = G.top_var;
         while (cur) {
                 if (strncmp(cur->varstr, name, name_len) == 0 && cur->varstr[name_len] == '=') {
                         if (cur->flg_read_only) {
                                 bb_error_msg("%s: readonly variable", name);
-                                return;
+                                return EXIT_FAILURE;
                         }
                         /* prev is ok to use here because 1st variable, HUSH_VERSION,
                          * is ro, and we cannot reach this code on the 1st pass */
@@ -1024,11 +1024,12 @@ static void unset_local_var(const char *name)
                         if (!cur->max_len)
                                 free(cur->varstr);
                         free(cur);
-                        return;
+                        return EXIT_SUCCESS;
                 }
                 prev = cur;
                 cur = cur->next;
         }
+        return EXIT_SUCCESS;
 }
 
 
@@ -5025,11 +5026,40 @@ static int builtin_umask(char **argv)
         return EXIT_SUCCESS;
 }
 
+/* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#unset */
 static int builtin_unset(char **argv)
 {
-        /* bash always returns true */
-        unset_local_var(argv[1]);
-        return EXIT_SUCCESS;
+        size_t i;
+        int ret;
+        bool var = true;
+
+        if (!argv[1])
+                return EXIT_SUCCESS;
+
+        i = 0;
+        if (argv[1][0] == '-') {
+                switch (argv[1][1]) {
+                case 'v': break;
+                case 'f': if (ENABLE_HUSH_FUNCTIONS) { var = false; break; }
+                default:
+                        bb_error_msg("unset: %s: invalid option", argv[1]);
+                        return EXIT_FAILURE;
+                }
+                ++i;
+        }
+
+        ret = EXIT_SUCCESS;
+        while (argv[++i]) {
+                if (var) {
+                        if (unset_local_var(argv[i]))
+                                ret = EXIT_FAILURE;
+                }
+#if ENABLE_HUSH_FUNCTIONS
+                else
+                        unset_local_func(argv[i]);
+#endif
+        }
+        return ret;
 }
 
 /* http://www.opengroup.org/onlinepubs/9699919799/utilities/wait.html */
diff --git a/shell/hush_test/hush-vars/unset.right b/shell/hush_test/hush-vars/unset.right
new file mode 100644
index 000000000..8dea7c40d
--- /dev/null
+++ b/shell/hush_test/hush-vars/unset.right
@@ -0,0 +1,19 @@
+hush: unset: -: invalid option
+1
+hush: unset: -m: invalid option
+1
+0
+___
+0 f g
+0 g
+0
+___
+0 f g
+0
+0 f g
+0
+___
+hush: HUSH_VERSION: readonly variable
+1 f g
+hush: HUSH_VERSION: readonly variable
+1
diff --git a/shell/hush_test/hush-vars/unset.tests b/shell/hush_test/hush-vars/unset.tests
new file mode 100755
index 000000000..f59ce5923
--- /dev/null
+++ b/shell/hush_test/hush-vars/unset.tests
@@ -0,0 +1,36 @@
+# check invalid options are rejected
+unset -
+echo $?
+unset -m a b c
+echo $?
+
+# check funky usage
+unset
+echo $?
+
+# check normal usage
+echo ___
+f=f g=g
+echo $? $f $g
+unset f
+echo $? $f $g
+unset g
+echo $? $f $g
+
+echo ___
+f=f g=g
+echo $? $f $g
+unset f g
+echo $? $f $g
+f=f g=g
+echo $? $f $g
+unset -v f g
+echo $? $f $g
+
+# check read only vars
+echo ___
+f=f g=g
+unset HUSH_VERSION
+echo $? $f $g
+unset f HUSH_VERSION g
+echo $? $f $g