Add SPDX license identifiers to source files under the LGPL

[thirdparty/systemd.git] / src / basic / io-util.c

diff --git a/src/basic/io-util.c b/src/basic/io-util.c
index 0037a37f2a458151bb62d1ec77202ac64bb76c92..98bb1857d97f766f2c6b7553aa803c18247c6112 100644 (file)
--- a/src/basic/io-util.c
+++ b/src/basic/io-util.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
 /***
   This file is part of systemd.
 
@@ -33,6 +34,11 @@ int flush_fd(int fd) {
                 .events = POLLIN,
         };
 
+        /* Read from the specified file descriptor, until POLLIN is not set anymore, throwing away everything
+         * read. Note that some file descriptors (notable IP sockets) will trigger POLLIN even when no data can be read
+         * (due to IP packet checksum mismatches), hence this function is only safe to be non-blocking if the fd used
+         * was set to non-blocking too. */
+
         for (;;) {
                 char buf[LINE_MAX];
                 ssize_t l;