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>

1 files changed, 26 insertions, 16 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 31ca22a2e..8a467be80 100644
--- 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