hush: make pun_pipe loop clearer; fix "cmd | var=`cmd` | cmd" handling

function                                             old     new   delta
free_strings                                           -      38     +38
pseudo_exec_argv                                     161     171     +10
free_pipe                                            227     205     -22
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/1 up/down: 48/-22)             Total: 26 bytes

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

diff --git a/shell/hush.c b/shell/hush.c
index 31ca22a..8a467be 100644 (file)
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -3713,11 +3713,17 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
 {
        char **new_env;
 
-       /* Case when we are here: ... | var=val | ... */
-       if (!argv[assignment_cnt])
+       new_env = expand_assignments(argv, assignment_cnt);
+
+       if (!argv[assignment_cnt]) {
+               /* Case when we are here: ... | var=val | ...
+                * (note that we do not exit early, i.e., do not optimize out
+                * expand_assignments(): think about ... | var=`sleep 1` | ...
+                */
+               free_strings(new_env);
                _exit(EXIT_SUCCESS);
+       }
 
-       new_env = expand_assignments(argv, assignment_cnt);
 #if BB_MMU
        set_vars_and_save_old(new_env);
        free(new_env); /* optional */
@@ -3727,6 +3733,7 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
        nommu_save->new_env = new_env;
        nommu_save->old_vars = set_vars_and_save_old(new_env);
 #endif
+
        if (argv_expanded) {
                argv = argv_expanded;
        } else {
@@ -4145,8 +4152,9 @@ static int checkjobs_and_fg_shell(struct pipe* fg_pipe)
 static NOINLINE int run_pipe(struct pipe *pi)
 {
        static const char *const null_ptr = NULL;
-       int i;
-       int nextin;
+
+       int cmd_no;
+       int next_infd;
        struct command *command;
        char **argv_expanded;
        char **argv;
@@ -4160,7 +4168,7 @@ static NOINLINE int run_pipe(struct pipe *pi)
 
        IF_HUSH_JOB(pi->pgrp = -1;)
        pi->stopped_cmds = 0;
-       command = &(pi->cmds[0]);
+       command = &pi->cmds[0];
        argv_expanded = NULL;
 
        if (pi->num_cmds != 1
@@ -4358,9 +4366,10 @@ static NOINLINE int run_pipe(struct pipe *pi)
 
        /* Going to fork a child per each pipe member */
        pi->alive_cmds = 0;
-       nextin = 0;
+       next_infd = 0;
 
-       for (i = 0; i < pi->num_cmds; i++) {
+       cmd_no = 0;
+       while (cmd_no < pi->num_cmds) {
                struct fd_pair pipefds;
 #if !BB_MMU
                volatile nommu_save_t nommu_save;
@@ -4369,7 +4378,8 @@ static NOINLINE int run_pipe(struct pipe *pi)
                nommu_save.argv = NULL;
                nommu_save.argv_from_re_execing = NULL;
 #endif
-               command = &(pi->cmds[i]);
+               command = &pi->cmds[cmd_no];
+               cmd_no++;
                if (command->argv) {
                        debug_printf_exec(": pipe member '%s' '%s'...\n",
                                        command->argv[0], command->argv[1]);
@@ -4380,7 +4390,7 @@ static NOINLINE int run_pipe(struct pipe *pi)
                /* pipes are inserted between pairs of commands */
                pipefds.rd = 0;
                pipefds.wr = 1;
-               if ((i + 1) < pi->num_cmds)
+               if (cmd_no < pi->num_cmds)
                        xpiped_pair(pipefds);
 
                command->pid = BB_MMU ? fork() : vfork();
@@ -4413,7 +4423,7 @@ static NOINLINE int run_pipe(struct pipe *pi)
                                if (open(bb_dev_null, O_RDONLY))
                                        xopen("/", O_RDONLY);
                        } else {
-                               xmove_fd(nextin, 0);
+                               xmove_fd(next_infd, 0);
                        }
                        xmove_fd(pipefds.wr, 1);
                        if (pipefds.rd > 1)
@@ -4460,12 +4470,12 @@ static NOINLINE int run_pipe(struct pipe *pi)
 #endif
                }
 
-               if (i)
-                       close(nextin);
-               if ((i + 1) < pi->num_cmds)
+               if (cmd_no > 1)
+                       close(next_infd);
+               if (cmd_no < pi->num_cmds)
                        close(pipefds.wr);
                /* Pass read (output) pipe end to next iteration */
-               nextin = pipefds.rd;
+               next_infd = pipefds.rd;
        }
 
        if (!pi->alive_cmds) {
@@ -7153,7 +7163,7 @@ int hush_main(int argc, char **argv)
 #endif
                case 'n':
                case 'x':
-                       if (!set_mode('-', opt))
+                       if (set_mode('-', opt) == 0) /* no error */
                                break;
                default:
 #ifndef BB_VER