shell: for signal exitcode, use 128 | sig, not 128 + sig - MIPS has signal 128

function                                             old     new   delta
wait_for_child_or_signal                             213     214      +1
refill_HFILE_and_getc                                 89      88      -1
getstatus                                             97      96      -1
builtin_wait                                         339     337      -2
checkjobs                                            187     183      -4
process_wait_result                                  450     444      -6
waitcmd                                              290     281      -9
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/6 up/down: 1/-23)             Total: -22 bytes

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

2 files changed, 18 insertions, 16 deletions

diff --git a/shell/ash.c b/shell/ash.c
index f4d296289..aa2a93bca 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -4610,7 +4610,7 @@ getstatus(struct job *job)
                                 job->sigint = 1;
 #endif
                 }
-                retval += 128;
+                retval |= 128;
         }
         TRACE(("getstatus: job %d, nproc %d, status 0x%x, retval 0x%x\n",
                 jobno(job), job->nprocs, status, retval));
@@ -4676,7 +4676,7 @@ waitcmd(int argc UNUSED_PARAM, char **argv)
                                 if (status != -1 && !WIFSTOPPED(status)) {
                                         retval = WEXITSTATUS(status);
                                         if (WIFSIGNALED(status))
-                                                retval = WTERMSIG(status) + 128;
+                                                retval = 128 | WTERMSIG(status);
                                         goto ret;
                                 }
                         }
@@ -4711,7 +4711,7 @@ waitcmd(int argc UNUSED_PARAM, char **argv)
  ret:
         return retval;
  sigout:
-        retval = 128 + pending_sig;
+        retval = 128 | pending_sig;
         return retval;
 }
 
diff --git a/shell/hush.c b/shell/hush.c
index dec5d544b..6b8f1c88c 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -1656,12 +1656,12 @@ static int refill_HFILE_and_getc(HFILE *fp)
                 return EOF;
         }
         /* Try to buffer more input */
-        fp->cur = fp->buf;
         n = safe_read(fp->fd, fp->buf, sizeof(fp->buf));
         if (n < 0) {
                 bb_simple_perror_msg("read error");
                 n = 0;
         }
+        fp->cur = fp->buf;
         fp->end = fp->buf + n;
         if (n == 0) {
                 /* EOF/error */
@@ -2651,7 +2651,7 @@ static int get_user_input(struct in_str *i)
                 /* ^C or SIGINT: return EOF */
                 /* bash prints ^C even on real SIGINT (non-kbd generated) */
                 write(STDOUT_FILENO, "^C\n", 3);
-                G.last_exitcode = 128 + SIGINT;
+                G.last_exitcode = 128 | SIGINT;
                 i->p = NULL;
                 i->peek_buf[0] = r = EOF;
                 return r;
@@ -2685,7 +2685,7 @@ static int get_user_input(struct in_str *i)
                  */
                 check_and_run_traps();
                 if (G.flag_SIGINT)
-                        G.last_exitcode = 128 + SIGINT;
+                        G.last_exitcode = 128 | SIGINT;
                 if (r != '\0')
                         break;
         }
@@ -8756,9 +8756,10 @@ static int process_wait_result(struct pipe *fg_pipe, pid_t childpid, int status)
                                                 puts(sig == SIGINT || sig == SIGPIPE ? "" : strsignal(sig));
                                         }
                                         /* TODO: if (WCOREDUMP(status)) + " (core dumped)"; */
-                                        /* TODO: MIPS has 128 sigs (1..128), what if sig==128 here?
-                                         * Maybe we need to use sig | 128? */
-                                        ex = sig + 128;
+                                        /* MIPS has 128 sigs (1..128), if sig==128,
+                                         * 128 + sig would result in exitcode 256 -> 0!
+                                         */
+                                        ex = 128 | sig;
                                 }
                                 fg_pipe->cmds[i].cmd_exitcode = ex;
                         } else {
@@ -8805,7 +8806,8 @@ static int process_wait_result(struct pipe *fg_pipe, pid_t childpid, int status)
                 /* child exited */
                 int rcode = WEXITSTATUS(status);
                 if (WIFSIGNALED(status))
-                        rcode = 128 + WTERMSIG(status);
+                        /* NB: not 128 + sig, MIPS has sig 128 */
+                        rcode = 128 | WTERMSIG(status);
                 pi->cmds[i].cmd_exitcode = rcode;
                 if (G.last_bg_pid == pi->cmds[i].pid)
                         G.last_bg_pid_exitcode = rcode;
@@ -8925,10 +8927,10 @@ static int checkjobs(struct pipe *fg_pipe, pid_t waitfor_pid)
                         debug_printf_exec("childpid==waitfor_pid:%d status:0x%08x\n", childpid, status);
                         rcode = WEXITSTATUS(status);
                         if (WIFSIGNALED(status))
-                                rcode = 128 + WTERMSIG(status);
+                                rcode = 128 | WTERMSIG(status);
                         if (WIFSTOPPED(status))
-                                /* bash: "cmd & wait $!" and cmd stops: $? = 128 + stopsig */
-                                rcode = 128 + WSTOPSIG(status);
+                                /* bash: "cmd & wait $!" and cmd stops: $? = 128 | stopsig */
+                                rcode = 128 | WSTOPSIG(status);
                         rcode++;
                         break; /* "wait PID" called us, give it exitcode+1 */
                 }
@@ -9318,7 +9320,7 @@ static NOINLINE int run_pipe(struct pipe *pi)
                          * during builtin/nofork.
                          */
                         if (sigismember(&G.pending_set, SIGINT))
-                                rcode = 128 + SIGINT;
+                                rcode = 128 | SIGINT;
                 }
                 free(argv_expanded);
                 IF_HAS_KEYWORDS(if (pi->pi_inverted) rcode = !rcode;)
@@ -11718,7 +11720,7 @@ static int wait_for_child_or_signal(struct pipe *waitfor_pipe, pid_t waitfor_pid
                 sig = check_and_run_traps();
                 if (sig /*&& sig != SIGCHLD - always true */) {
                         /* Do this for any (non-ignored) signal, not only for ^C */
-                        ret = 128 + sig;
+                        ret = 128 | sig;
                         break;
                 }
                 /* SIGCHLD, or no signal, or ignored one, such as SIGQUIT. Repeat */
@@ -11818,7 +11820,7 @@ static int FAST_FUNC builtin_wait(char **argv)
                         process_wait_result(NULL, pid, status);
                         ret = WEXITSTATUS(status);
                         if (WIFSIGNALED(status))
-                                ret = 128 + WTERMSIG(status);
+                                ret = 128 | WTERMSIG(status);
                 }
         } while (*++argv);