fix playback of stdout/stderr without embedded carriage returns

diff --git a/plugins/sudoers/sudoreplay.c b/plugins/sudoers/sudoreplay.c
index 468f426cc856a7dbc2ffb2a7a93c644ab93b49f8..e1e69e68e01f3abff47d676f432611850f1e3394 100644 (file)
--- a/plugins/sudoers/sudoreplay.c
+++ b/plugins/sudoers/sudoreplay.c
@@ -118,6 +118,7 @@ struct replay_closure {
        unsigned int len; /* buffer length (how much produced) */
        unsigned int off; /* write position (how much already consumed) */
        unsigned int toread; /* how much remains to be read */
+       int lastc;        /* last char written */
        char buf[64 * 1024];
     } iobuf;
 };
@@ -785,6 +786,7 @@ read_timing_record(struct replay_closure *closure)
     if (closure->timing.idx != IOFD_TIMING) {
        closure->iobuf.len = 0;
        closure->iobuf.off = 0;
+       closure->iobuf.lastc = '\0';
        closure->iobuf.toread = closure->timing.u.nbytes;
     }
 
@@ -1054,10 +1056,11 @@ static void
 write_output(int fd, int what, void *v)
 {
     struct replay_closure *closure = v;
+    const struct timing_closure *timing = &closure->timing;
     struct io_buffer *iobuf = &closure->iobuf;
     unsigned iovcnt = 1;
     struct iovec iov[2];
-    bool need_nlcr = false;
+    bool added_cr = false;
     size_t nbytes, nwritten;
     debug_decl(write_output, SUDO_DEBUG_UTIL)
 
@@ -1067,24 +1070,30 @@ write_output(int fd, int what, void *v)
        debug_return;
     }
 
-    if (closure->interactive)
-       need_nlcr = (fd == IOFD_STDOUT || fd == IOFD_STDERR);
-
     nbytes = iobuf->len - iobuf->off;
     iov[0].iov_base = iobuf->buf + iobuf->off;
     iov[0].iov_len = nbytes;
 
-    if (need_nlcr) {
+    if (closure->interactive &&
+       (timing->idx == IOFD_STDOUT || timing->idx == IOFD_STDERR)) {
        char *nl;
 
-       /* We may need to add a carriage return after the newline. */
+       /*
+        * We may need to insert a carriage return before the newline.
+        * Note that the carriage return may have already been written.
+        */
        nl = memchr(iov[0].iov_base, '\n', iov[0].iov_len);
        if (nl != NULL) {
-           iov[0].iov_len--;   /* skip the existing newline */
-           iov[1].iov_base = "\r\n";
-           iov[1].iov_len = 2;
-           iovcnt = 2;
-           nbytes++;           /* account for the added carriage return */
+           size_t len = (size_t)(nl - (char *)iov[0].iov_base);
+           if ((nl == iov[0].iov_base && iobuf->lastc != '\r') ||
+               (nl != iov[0].iov_base && nl[-1] != '\r')) {
+               iov[0].iov_len = len;
+               iov[1].iov_base = "\r\n";
+               iov[1].iov_len = 2;
+               iovcnt = 2;
+               nbytes = iov[0].iov_len + iov[1].iov_len;
+               added_cr = true;
+           }
        }
     }
 
@@ -1094,10 +1103,20 @@ write_output(int fd, int what, void *v)
        if (errno != EINTR && errno != EAGAIN)
            sudo_fatal(U_("unable to write to %s"), "stdout");
        break;
+    case 0:
+       /* Should not happen. */
+       break;
     default:
-       if (iovcnt == 2 && nwritten == nbytes) {
-               /* subtract one for the carriage return we added above. */
-               nwritten--;
+       if (added_cr && nwritten >= nbytes - 1) {
+           /* The last char written was either '\r' or '\n'. */
+           iobuf->lastc = nwritten == nbytes ? '\n' : '\r';
+       } else {
+           /* Stash the last char written. */
+           iobuf->lastc = *((char *)iov[0].iov_base + nwritten);
+       }
+       if (added_cr) {
+           /* Subtract one for the carriage return we added above. */
+           nwritten--;
        }
        iobuf->off += nwritten;
        break;