hush: fix var_leaks.tests and var_preserved.tests on NOMMU

function                                             old     new   delta
remove_nested_vars                                     -      77     +77
run_pipe                                            1756    1786     +30
pseudo_exec_argv                                     376     379      +3
leave_var_nest_level                                  98      32     -66
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/1 up/down: 110/-66)            Total: 44 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 59 insertions, 49 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 3a4b5d894..885561389 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -2266,6 +2266,7 @@ static int set_local_var(char *str, unsigned flags)
         }
 
         /* Not found or shadowed - create new variable struct */
+        debug_printf_env("%s: alloc new var '%s'/%u\n", __func__, str, local_lvl);
         cur = xzalloc(sizeof(*cur));
         cur->var_nest_level = local_lvl;
         cur->next = *cur_pp;
@@ -2420,7 +2421,7 @@ static void set_vars_and_save_old(char **strings)
                                  * global linked list.
                                  */
                         }
-                        //bb_error_msg("G.var_nest_level:%d", G.var_nest_level);
+                        debug_printf_env("%s: env override '%s'/%u\n", __func__, *s, G.var_nest_level);
                         set_local_var(*s, (G.var_nest_level << SETFLAG_VARLVL_SHIFT) | SETFLAG_EXPORT);
                 } else if (HUSH_DEBUG) {
                         bb_error_msg_and_die("BUG in varexp4");
@@ -7358,6 +7359,58 @@ static void unset_func(const char *name)
 }
 # endif
 
+static void remove_nested_vars(void)
+{
+        struct variable *cur;
+        struct variable **cur_pp;
+
+        cur_pp = &G.top_var;
+        while ((cur = *cur_pp) != NULL) {
+                if (cur->var_nest_level <= G.var_nest_level) {
+                        cur_pp = &cur->next;
+                        continue;
+                }
+                /* Unexport */
+                if (cur->flg_export) {
+                        debug_printf_env("unexporting nested '%s'/%u\n", cur->varstr, cur->var_nest_level);
+                        bb_unsetenv(cur->varstr);
+                }
+                /* Remove from global list */
+                *cur_pp = cur->next;
+                /* Free */
+                if (!cur->max_len) {
+                        debug_printf_env("freeing nested '%s'/%u\n", cur->varstr, cur->var_nest_level);
+                        free(cur->varstr);
+                }
+                free(cur);
+        }
+}
+
+static void enter_var_nest_level(void)
+{
+        G.var_nest_level++;
+        debug_printf_env("var_nest_level++ %u\n", G.var_nest_level);
+
+        /* Try: f() { echo -n .; f; }; f
+         * struct variable::var_nest_level is uint16_t,
+         * thus limiting recursion to < 2^16.
+         * In any case, with 8 Mbyte stack SEGV happens
+         * not too long after 2^16 recursions anyway.
+         */
+        if (G.var_nest_level > 0xff00)
+                bb_error_msg_and_die("fatal recursion (depth %u)", G.var_nest_level);
+}
+
+static void leave_var_nest_level(void)
+{
+        G.var_nest_level--;
+        debug_printf_env("var_nest_level-- %u\n", G.var_nest_level);
+        if (HUSH_DEBUG && (int)G.var_nest_level < 0)
+                bb_error_msg_and_die("BUG: nesting underflow");
+
+        remove_nested_vars();
+}
+
 # if BB_MMU
 #define exec_function(to_free, funcp, argv) \
         exec_function(funcp, argv)
@@ -7392,7 +7445,7 @@ static void exec_function(char ***to_free,
 
         /* "we are in a function, ok to use return" */
         G_flag_return_in_progress = -1;
-        G.var_nest_level++;
+        enter_var_nest_level();
         IF_HUSH_LOCAL(G.func_nest_level++;)
 
         /* On MMU, funcp->body is always non-NULL */
@@ -7412,53 +7465,6 @@ static void exec_function(char ***to_free,
 # endif
 }
 
-static void enter_var_nest_level(void)
-{
-        G.var_nest_level++;
-        debug_printf_env("var_nest_level++ %u\n", G.var_nest_level);
-
-        /* Try: f() { echo -n .; f; }; f
-         * struct variable::var_nest_level is uint16_t,
-         * thus limiting recursion to < 2^16.
-         * In any case, with 8 Mbyte stack SEGV happens
-         * not too long after 2^16 recursions anyway.
-         */
-        if (G.var_nest_level > 0xff00)
-                bb_error_msg_and_die("fatal recursion (depth %u)", G.var_nest_level);
-}
-
-static void leave_var_nest_level(void)
-{
-        struct variable *cur;
-        struct variable **cur_pp;
-
-        cur_pp = &G.top_var;
-        while ((cur = *cur_pp) != NULL) {
-                if (cur->var_nest_level < G.var_nest_level) {
-                        cur_pp = &cur->next;
-                        continue;
-                }
-                /* Unexport */
-                if (cur->flg_export) {
-                        debug_printf_env("unexporting nested '%s'/%u\n", cur->varstr, cur->var_nest_level);
-                        bb_unsetenv(cur->varstr);
-                }
-                /* Remove from global list */
-                *cur_pp = cur->next;
-                /* Free */
-                if (!cur->max_len) {
-                        debug_printf_env("freeing nested '%s'/%u\n", cur->varstr, cur->var_nest_level);
-                        free(cur->varstr);
-                }
-                free(cur);
-        }
-
-        G.var_nest_level--;
-        debug_printf_env("var_nest_level-- %u\n", G.var_nest_level);
-        if (HUSH_DEBUG && (int)G.var_nest_level < 0)
-                bb_error_msg_and_die("BUG: nesting underflow");
-}
-
 static int run_function(const struct function *funcp, char **argv)
 {
         int rc;
@@ -7648,6 +7654,7 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
         G.shadowed_vars_pp = NULL; /* "don't save, free them instead" */
 #else
         G.shadowed_vars_pp = &nommu_save->old_vars;
+        G.var_nest_level++;
 #endif
         set_vars_and_save_old(new_env);
         G.shadowed_vars_pp = sv_shadowed;
@@ -8522,6 +8529,7 @@ static NOINLINE int run_pipe(struct pipe *pi)
         while (cmd_no < pi->num_cmds) {
                 struct fd_pair pipefds;
 #if !BB_MMU
+                int sv_var_nest_level = G.var_nest_level;
                 volatile nommu_save_t nommu_save;
                 nommu_save.old_vars = NULL;
                 nommu_save.argv = NULL;
@@ -8615,6 +8623,8 @@ static NOINLINE int run_pipe(struct pipe *pi)
                 /* Clean up after vforked child */
                 free(nommu_save.argv);
                 free(nommu_save.argv_from_re_execing);
+                G.var_nest_level = sv_var_nest_level;
+                remove_nested_vars();
                 add_vars(nommu_save.old_vars);
 #endif
                 free(argv_expanded);