(nuttx) branch releases/13.0 updated: syslog: avoid an infinite loop if one channel fails

[xiaoxiang]

This is an automated email from the ASF dual-hosted git repository.

xiaoxiang781216 pushed a commit to branch releases/13.0
in repository https://gitbox.apache.org/repos/asf/nuttx.git


The following commit(s) were added to refs/heads/releases/13.0 by this push:
     new eb21f59f2ff syslog: avoid an infinite loop if one channel fails
eb21f59f2ff is described below

commit eb21f59f2ff6a1bb53eed118b1717578c72f3295
Author: Michal Lenc <michall...@seznam.cz>
AuthorDate: Tue Jun 23 09:28:41 2026 +0200

    syslog: avoid an infinite loop if one channel fails
    
    The current implementation exits syslog_write_foreach function
    if write to one channel fails, causing other channels not being written
    and returning negated errno. libc syslog functions then stay in
    an infinite loop, because error is returned and the same bytes
    are still passed to syslograwstream_flush and syslog_write_foreach.
    
    The channel write may fail for many reasons - disconnected USB if
    CDC ACM syslog is enabled, lost networking if telnet syslog is enabled,
    error on NOR flash etc. This shouldn't lead to an ininite loop in the
    code though.
    
    The solution ensures all channels in syslog_write_foreach are tried,
    therefore the user get the output to the working channels even if
    the first one is broken. It also updates syslograwstream_addchar and
    syslograwstream_addstring to skip the bytes if all channels fails. This
    ensures syslog call won't result in an infinite loop, but the user may
    lost the debugging output.
    
    Co-authored-by: Martin Krasula <mkras...@elektroline.cz>
    Signed-off-by: Michal Lenc <michall...@seznam.cz>
---
 drivers/syslog/syslog_write.c          |  6 +++---
 libs/libc/stream/lib_syslograwstream.c | 16 +++++++++++++---
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/syslog/syslog_write.c b/drivers/syslog/syslog_write.c
index 8b3fefda709..94e6c0d330e 100644
--- a/drivers/syslog/syslog_write.c
+++ b/drivers/syslog/syslog_write.c
@@ -107,7 +107,7 @@ ssize_t syslog_write_foreach(FAR const char *buffer,
   syslog_write_t write;
   syslog_putc_t  putc;
   size_t nwritten = 0;
-  size_t nwritten_max = 0;
+  ssize_t nwritten_max = -EIO;
   ssize_t ret;
   int i;
 
@@ -153,7 +153,7 @@ ssize_t syslog_write_foreach(FAR const char *buffer,
 
                   if (ret < 0)
                     {
-                      return ret;
+                      continue;
                     }
 
                   nwritten = head + 1;
@@ -166,7 +166,7 @@ ssize_t syslog_write_foreach(FAR const char *buffer,
               ret = write(channel, buffer + nwritten, buflen - nwritten);
               if (ret < 0)
                 {
-                  return ret;
+                  continue;
                 }
               else
                 {
diff --git a/libs/libc/stream/lib_syslograwstream.c 
b/libs/libc/stream/lib_syslograwstream.c
index 76b149f1d3a..270205f83a4 100644
--- a/libs/libc/stream/lib_syslograwstream.c
+++ b/libs/libc/stream/lib_syslograwstream.c
@@ -123,7 +123,12 @@ static void syslograwstream_addchar(FAR struct 
lib_syslograwstream_s *stream,
 
       /* Yes.. then flush the buffer */
 
-      syslograwstream_flush(&stream->common);
+      int ret = syslograwstream_flush(&stream->common);
+      if (ret < 0)
+        {
+          stream->offset = 0;
+          stream->common.nput = 0;
+        }
     }
 }
 
@@ -136,7 +141,6 @@ syslograwstream_addstring(FAR struct lib_syslograwstream_s 
*stream,
                           FAR const char *buff, size_t len)
 {
   ssize_t ret = 0;
-
   do
     {
       size_t remain = CONFIG_SYSLOG_BUFSIZE - stream->offset;
@@ -155,7 +159,13 @@ syslograwstream_addstring(FAR struct lib_syslograwstream_s 
*stream,
 
           /* Yes.. then flush the buffer */
 
-          syslograwstream_flush(&stream->common);
+          int ret_flush = syslograwstream_flush(&stream->common);
+          if (ret_flush < 0)
+            {
+               stream->offset = 0;
+               stream->common.nput = 0;
+               break;
+            }
         }
     }
   while (ret < len);