shell: fix SIGWINCH and SIGCHLD (in hush) interrupting line input, closes 15256

function                                             old     new   delta
record_pending_signo                                  32      63     +31
lineedit_read_key                                    231     224      -7
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 31/-7)              Total: 24 bytes

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

2 files changed, 10 insertions, 3 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 18ccc1329..5f8c8ea19 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -10821,7 +10821,8 @@ preadfd(void)
  again:
                 /* For shell, LI_INTERRUPTIBLE is set:
                  * read_line_input will abort on either
-                 * getting EINTR in poll(), or if it sees bb_got_signal != 0
+                 * getting EINTR in poll() and bb_got_signal became != 0,
+                 * or if it sees bb_got_signal != 0
                  * (IOW: if signal arrives before poll() is reached).
                  * Interactive testcases:
                  * (while kill -INT $$; do sleep 1; done) &
diff --git a/shell/hush.c b/shell/hush.c
index d111f0cc5..f064b8fd2 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -1946,7 +1946,12 @@ static void record_pending_signo(int sig)
 {
         sigaddset(&G.pending_set, sig);
 #if ENABLE_FEATURE_EDITING
-        bb_got_signal = sig; /* for read_line_input: "we got a signal" */
+        if (sig != SIGCHLD
+         || (G_traps && G_traps[SIGCHLD] && G_traps[SIGCHLD][0])
+         /* ^^^ if SIGCHLD, interrupt line reading only if it has a trap */
+        ) {
+                bb_got_signal = sig; /* for read_line_input: "we got a signal" */
+        }
 #endif
 #if ENABLE_HUSH_FAST
         if (sig == SIGCHLD) {
@@ -2669,7 +2674,8 @@ static int get_user_input(struct in_str *i)
                 } else {
                         /* For shell, LI_INTERRUPTIBLE is set:
                          * read_line_input will abort on either
-                         * getting EINTR in poll(), or if it sees bb_got_signal != 0
+                         * getting EINTR in poll() and bb_got_signal became != 0,
+                         * or if it sees bb_got_signal != 0
                          * (IOW: if signal arrives before poll() is reached).
                          * Interactive testcases:
                          * (while kill -INT $$; do sleep 1; done) &