hush: fix corner cases with exec in empty expansions

Cases like these:

var=val exec >redir

var=val `` >redir

function                                             old     new   delta
run_pipe                                            1701    1723     +22
redirect_and_varexp_helper                            56      55      -1
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 22/-1)              Total: 21 bytes

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

diff --git a/shell/ash_test/ash-redir/redir_exec1.right b/shell/ash_test/ash-redir/redir_exec1.right
new file mode 100644 (file)
index 0000000..d4393d1
--- /dev/null
+++ b/shell/ash_test/ash-redir/redir_exec1.right
@@ -0,0 +1,2 @@
+redir_exec1.tests: line 1: can't create /cant/be/created: nonexistent directory
+First

diff --git a/shell/ash_test/ash-redir/redir_exec1.tests b/shell/ash_test/ash-redir/redir_exec1.tests
new file mode 100755 (executable)
index 0000000..290e1cb
--- /dev/null
+++ b/shell/ash_test/ash-redir/redir_exec1.tests
@@ -0,0 +1,2 @@
+v=`echo First >&2` exec >/cant/be/created
+echo One:$?

diff --git a/shell/hush.c b/shell/hush.c
index 24ae237d7d2a32212104b90c066ac9e7e0f5cc2d..43702360aeebd0137fbeae80066501f7dc038903 100644 (file)
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -8200,19 +8200,21 @@ static int redirect_and_varexp_helper(
                struct squirrel **sqp,
                char **argv_expanded)
 {
+       /* Assignments occur before redirects. Try:
+        * a=`sleep 1` sleep 2 3>/qwe/rty
+        */
+
+       char **new_env = expand_assignments(command->argv, command->assignment_cnt);
+       dump_cmd_in_x_mode(new_env);
+       dump_cmd_in_x_mode(argv_expanded);
+       /* this takes ownership of new_env[i] elements, and frees new_env: */
+       set_vars_and_save_old(new_env);
+
        /* setup_redirects acts on file descriptors, not FILEs.
         * This is perfect for work that comes after exec().
         * Is it really safe for inline use?  Experimentally,
         * things seem to work. */
-       int rcode = setup_redirects(command, sqp);
-       if (rcode == 0) {
-               char **new_env = expand_assignments(command->argv, command->assignment_cnt);
-               dump_cmd_in_x_mode(new_env);
-               dump_cmd_in_x_mode(argv_expanded);
-               /* this takes ownership of new_env[i] elements, and frees new_env: */
-               set_vars_and_save_old(new_env);
-       }
-       return rcode;
+       return setup_redirects(command, sqp);
 }
 static NOINLINE int run_pipe(struct pipe *pi)
 {
@@ -8315,6 +8317,7 @@ static NOINLINE int run_pipe(struct pipe *pi)
                         * Ensure redirects take effect (that is, create files).
                         * Try "a=t >file"
                         */
+ only_assignments:
                        G.expand_exitcode = 0;
 
                        rcode = setup_redirects(command, &squirrel);
@@ -8359,12 +8362,10 @@ static NOINLINE int run_pipe(struct pipe *pi)
 #endif
                        argv_expanded = expand_strvec_to_strvec(argv + command->assignment_cnt);
 
-               /* if someone gives us an empty string: `cmd with empty output` */
-//TODO: what about: var=EXPR `` >FILE ? will var be set? Will FILE be created?
+               /* If someone gives us an empty string: `cmd with empty output` */
                if (!argv_expanded[0]) {
                        free(argv_expanded);
-                       debug_leave();
-                       return G.last_exitcode;
+                       goto only_assignments;
                }
 
                old_vars = NULL;
@@ -8378,9 +8379,17 @@ static NOINLINE int run_pipe(struct pipe *pi)
                if (x || funcp) {
                        if (x && x->b_function == builtin_exec && argv_expanded[1] == NULL) {
                                debug_printf("exec with redirects only\n");
-                               rcode = setup_redirects(command, NULL);
-//TODO: what about: var=EXPR exec >FILE ? will var be set?
+                               /*
+                                * Variable assignments are executed, but then "forgotten":
+                                *  a=`sleep 1;echo A` exec 3>&-; echo $a
+                                * sleeps, but prints nothing.
+                                */
+                               enter_var_nest_level();
+                               G.shadowed_vars_pp = &old_vars;
+                               rcode = redirect_and_varexp_helper(command, /*squirrel:*/ NULL, argv_expanded);
+                               G.shadowed_vars_pp = sv_shadowed;
                                /* rcode=1 can be if redir file can't be opened */
+
                                goto clean_up_and_ret1;
                        }
 
@@ -8452,9 +8461,10 @@ static NOINLINE int run_pipe(struct pipe *pi)
                } else
                        goto must_fork;
 
+               restore_redirects(squirrel);
+ clean_up_and_ret1:
                leave_var_nest_level();
                add_vars(old_vars);
-               restore_redirects(squirrel);
 
                /*
                 * Try "usleep 99999999" + ^C + "echo $?"
@@ -8474,7 +8484,6 @@ static NOINLINE int run_pipe(struct pipe *pi)
                        if (sigismember(&G.pending_set, SIGINT))
                                rcode = 128 + SIGINT;
                }
- clean_up_and_ret1:
                free(argv_expanded);
                IF_HAS_KEYWORDS(if (pi->pi_inverted) rcode = !rcode;)
                debug_leave();

diff --git a/shell/hush_test/hush-redir/redir_exec1.right b/shell/hush_test/hush-redir/redir_exec1.right
new file mode 100644 (file)
index 0000000..6ff8fc8
--- /dev/null
+++ b/shell/hush_test/hush-redir/redir_exec1.right
@@ -0,0 +1,3 @@
+First
+hush: can't open '/cant/be/created': No such file or directory
+One:1

diff --git a/shell/hush_test/hush-redir/redir_exec1.tests b/shell/hush_test/hush-redir/redir_exec1.tests
new file mode 100755 (executable)
index 0000000..290e1cb
--- /dev/null
+++ b/shell/hush_test/hush-redir/redir_exec1.tests
@@ -0,0 +1,2 @@
+v=`echo First >&2` exec >/cant/be/created
+echo One:$?