hush: fix "while...do f1() {a;}; f1; f1 {b;}; f1; done" bug

2 files changed, 59 insertions, 21 deletions

diff --git a/shell/hush.c b/shell/hush.c
index a055ec14f..a56b2e6ca 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -330,7 +330,7 @@ struct redir_struct {
         /* note: for heredocs, rd_filename contains heredoc delimiter,
          * and subsequently heredoc itself; and rd_dup is a bitmask:
          * 1: do we need to trim leading tabs?
-         * 2: is heredoc quoted (<<'dleim' syntax) ?
+         * 2: is heredoc quoted (<<'delim' syntax) ?
          */
 };
 typedef enum redir_type {
@@ -357,25 +357,42 @@ struct command {
         int assignment_cnt;         /* how many argv[i] are assignments? */
         smallint is_stopped;        /* is the command currently running? */
         smallint grp_type;          /* GRP_xxx */
+#define GRP_NORMAL   0
+#define GRP_SUBSHELL 1
+#if ENABLE_HUSH_FUNCTIONS
+# define GRP_FUNCTION 2
+#endif
         struct pipe *group;         /* if non-NULL, this "command" is { list },
                                      * ( list ), or a compound statement */
 #if !BB_MMU
         char *group_as_string;
 #endif
+#if ENABLE_HUSH_FUNCTIONS
+        struct function *child_func;
+/* This field is used to prevent a bug here:
+ * while...do f1() {a;}; f1; f1 {b;}; f1; done
+ * When we execute "f1() {a;}" cmd, we create new function and clear
+ * cmd->group, cmd->group_as_string, cmd->argv[0].
+ * when we execute "f1 {b;}", we notice that f1 exists,
+ * and that it's "parent cmd" struct is still "alive",
+ * we put those fields back into cmd->xxx
+ * (struct function has ->parent_cmd ptr to facilitate that).
+ * When we loop back, we can execute "f1() {a;}" again and set f1 correctly.
+ * Without this trick, loop would execute a;b;b;b;...
+ * instead of correct sequence a;b;a;b;...
+ * When command is freed, it severs the link
+ * (sets ->child_func->parent_cmd to NULL).
+ */
+#endif
         char **argv;                /* command name and arguments */
-        struct redir_struct *redirects; /* I/O redirections */
-};
 /* argv vector may contain variable references (^Cvar^C, ^C0^C etc)
  * and on execution these are substituted with their values.
  * Substitution can make _several_ words out of one argv[n]!
  * Example: argv[0]=='.^C*^C.' here: echo .$*.
  * References of the form ^C`cmd arg^C are `cmd arg` substitutions.
  */
-#define GRP_NORMAL   0
-#define GRP_SUBSHELL 1
-#if ENABLE_HUSH_FUNCTIONS
-# define GRP_FUNCTION 2
-#endif
+        struct redir_struct *redirects; /* I/O redirections */
+};
 
 struct pipe {
         struct pipe *next;
@@ -456,6 +473,7 @@ enum {
 struct function {
         struct function *next;
         char *name;
+        struct command *parent_cmd;
         struct pipe *body;
 #if !BB_MMU
         char *body_as_string;
@@ -743,7 +761,6 @@ static void syntax_error_unexpected_ch(unsigned lineno, char ch)
         msg[0] = ch;
         msg[1] = '\0';
         die_if_script(lineno, "syntax error: unexpected %s", msg);
-        xfunc_die();
 }
 
 #if HUSH_DEBUG < 2
@@ -2573,6 +2590,14 @@ static void free_pipe(struct pipe *pi, int indent)
                         debug_printf_clean("%s   end group\n", indenter(indent));
                         command->group = NULL;
                 }
+                /* else is crucial here.
+                 * If group != NULL, child_func is meaningless */
+#if ENABLE_HUSH_FUNCTIONS
+                else if (command->child_func) {
+                        debug_printf_exec("cmd %p releases child func at %p\n", command, command->child_func);
+                        command->child_func->parent_cmd = NULL;
+                }
+#endif
 #if !BB_MMU
                 free(command->group_as_string);
                 command->group_as_string = NULL;
@@ -3173,9 +3198,24 @@ static int run_pipe(struct pipe *pi)
 
                         while ((funcp = *funcpp) != NULL) {
                                 if (strcmp(funcp->name, command->argv[0]) == 0) {
-                                        debug_printf_exec("replacing function '%s'\n", funcp->name);
-                                        free(funcp->name);
-                                        free_pipe_list(funcp->body, /* indent: */ 0);
+                                        struct command *cmd = funcp->parent_cmd;
+
+                                        debug_printf_exec("func %p parent_cmd %p\n", funcp, cmd);
+                                        if (!cmd) {
+                                                debug_printf_exec("freeing & replacing function '%s'\n", funcp->name);
+                                                free(funcp->name);
+                                                free_pipe_list(funcp->body, /* indent: */ 0);
+#if !BB_MMU
+                                                free(funcp->body_as_string);
+#endif
+                                        } else {
+                                                debug_printf_exec("reinserting in tree & replacing function '%s'\n", funcp->name);
+                                                cmd->argv[0] = funcp->name;
+                                                cmd->group = funcp->body;
+#if !BB_MMU
+                                                cmd->group_as_string = funcp->body_as_string;
+#endif
+                                        }
                                         goto skip;
                                 }
                                 funcpp = &funcp->next;
@@ -3192,13 +3232,9 @@ static int run_pipe(struct pipe *pi)
 #endif
                         command->group = NULL;
                         command->argv[0] = NULL;
-                        free_strings(command->argv);
-                        command->argv = NULL;
-                        /* note: if we are in a loop, future "executions"
-                         * of func def will see it as null command since
-                         * command->group == NULL and command->argv == NULL */
-//this isn't exactly right: while...do f1() {a;}; f1; f1 {b;}; done
-//second loop will execute b!
+                        debug_printf_exec("cmd %p has child func at %p\n", command, funcp);
+                        funcp->parent_cmd = command;
+                        command->child_func = funcp;
 
                         return EXIT_SUCCESS;
                 }
diff --git a/shell/hush_test/hush-z_slow/leak_all1.tests b/shell/hush_test/hush-z_slow/leak_all1.tests
index 4c9d41afb..21fdb0d1e 100755
--- a/shell/hush_test/hush-z_slow/leak_all1.tests
+++ b/shell/hush_test/hush-z_slow/leak_all1.tests
@@ -62,7 +62,8 @@ HERE
     echo >/dev/null ${var%%*}
     set -- par1_$i par2_$i par3_$i par4_$i
     trap "echo trap$i" WINCH
-    f() { echo $1; }
+    f() { true; true; true; true; true; true; true; true; }
+    f() { true; true; true; true; true; true; true; true; echo $1; }
     f >/dev/null
     : $((i++))
 done
@@ -127,7 +128,8 @@ HERE
     echo >/dev/null ${var%%*}
     set -- par1_$i par2_$i par3_$i par4_$i
     trap "echo trap$i" WINCH
-    f() { echo $1; }
+    f() { true; true; true; true; true; true; true; true; }
+    f() { true; true; true; true; true; true; true; true; echo $1; }
     f >/dev/null
     : $((i++))
 done