1 files changed, 30 insertions, 9 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 086773dd7..55df54bd0 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -3679,7 +3679,9 @@ signal_handler(int signo)
                 if (!trap[SIGCHLD])
                         return;
         }
-
+#if ENABLE_FEATURE_EDITING
+        bb_got_signal = signo; /* for read_line_input: "we got a signal" */
+#endif
         gotsig[signo - 1] = 1;
         pending_sig = signo;
 
@@ -10784,33 +10786,52 @@ preadfd(void)
 # endif
                 reinit_unicode_for_ash();
  again:
-//BUG: not in INT_OFF/INT_ON section - SIGINT et al would longjmp out of read_line_input()!
-//This would cause a memory leak in interactive shell
-//(repeated internal allocations in read_line_input):
-// (while kill -INT $$; do :; done) &
+                /* For shell, LI_INTERRUPTIBLE is set:
+                 * read_line_input will abort on either
+                 * getting EINTR in poll(), or if it sees bb_got_signal != 0
+                 * (IOW: if signal arrives before poll() is reached).
+                 * Interactive testcases:
+                 * (while kill -INT $$; do sleep 1; done) &
+                 * #^^^ prints ^C, prints prompt, repeats
+                 * trap 'echo I' int; (while kill -INT $$; do sleep 1; done) &
+                 * #^^^ prints ^C, prints "I", prints prompt, repeats
+                 * trap 'echo T' term; (while kill $$; do sleep 1; done) &
+                 * #^^^ prints "T", prints prompt, repeats
+                 * #(bash 5.0.17 exits after first "T", looks like a bug)
+                 */
+                bb_got_signal = 0;
+                INT_OFF; /* no longjmp'ing out of read_line_input please */
                 nr = read_line_input(line_input_state, cmdedit_prompt, buf, IBUFSIZ);
+                if (bb_got_signal == SIGINT)
+                        write(STDOUT_FILENO, "^C\n", 3);
+                INT_ON; /* here non-blocked SIGINT will longjmp */
                 if (nr == 0) {
                         /* ^C pressed, "convert" to SIGINT */
-                        write(STDOUT_FILENO, "^C", 2);
-                        raise(SIGINT);
+                        write(STDOUT_FILENO, "^C\n", 3);
+                        raise(SIGINT); /* here non-blocked SIGINT will longjmp */
                         /* raise(SIGINT) did not work! (e.g. if SIGINT
                          * is SIG_IGNed on startup, it stays SIG_IGNed)
                          */
                         if (trap[SIGINT]) {
+ empty_line_input:
                                 buf[0] = '\n';
                                 buf[1] = '\0';
                                 return 1;
                         }
                         exitstatus = 128 + SIGINT;
                         /* bash behavior on ^C + ignored SIGINT: */
-                        write(STDOUT_FILENO, "\n", 1);
                         goto again;
                 }
                 if (nr < 0) {
                         if (errno == 0) {
-                                /* Ctrl+D pressed */
+                                /* ^D pressed */
                                 nr = 0;
                         }
+                        else if (errno == EINTR) { /* got signal? */
+                                if (bb_got_signal != SIGINT)
+                                        write(STDOUT_FILENO, "\n", 1);
+                                goto empty_line_input;
+                        }
 # if ENABLE_ASH_IDLE_TIMEOUT
                         else if (errno == EAGAIN && timeout > 0) {
                                 puts("\007timed out waiting for input: auto-logout");