From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Tue, 16 Jul 2019 16:35:34 +0000 (+0200)
Subject: firstboot: fix hang waiting for second Enter on input
X-Git-Tag: v243-rc1~96^2~1
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=ee41670ffbecb000db873f839a7381495bbe2bc6;p=thirdparty%2Fsystemd.git

firstboot: fix hang waiting for second Enter on input

The comment explains the reason: we'd wait for the second \n
and then ungetc() it. Then the buffered \n would cause a problem
when the next prompt was issued, so in effect it wasn't possible
to answer the second question.
---

diff --git a/src/basic/fileio.c b/src/basic/fileio.c
index bd4c964bec5..623e43e4cae 100644
--- a/src/basic/fileio.c
+++ b/src/basic/fileio.c
@@ -776,7 +776,7 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(FILE*, funlockfile);
 int read_line_full(FILE *f, size_t limit, ReadLineFlags flags, char **ret) {
         size_t n = 0, allocated = 0, count = 0;
         _cleanup_free_ char *buffer = NULL;
-        int r;
+        int r, tty = -1;
 
         assert(f);
 
@@ -850,6 +850,17 @@ int read_line_full(FILE *f, size_t limit, ReadLineFlags flags, char **ret) {
 
                         count++;
 
+                        if (eol != EOL_NONE) {
+                                /* If we are on a tty, we can't wait for more input. But we expect only
+                                 * \n as the single EOL marker, so there is no need to wait. We check
+                                 * this condition last to avoid isatty() check if not necessary. */
+
+                                if (tty < 0)
+                                        tty = isatty(fileno(f));
+                                if (tty > 0)
+                                        break;
+                        }
+
                         if (eol != EOL_NONE) {
                                 previous_eol |= eol;
                                 continue;