bb_info_msg: make it do atomic, unbuffered writes

udhcpc: fix a problem where we don't open listening socket fast enough

function                                             old     new   delta
bb_info_msg                                           70     126     +56
change_listen_mode                                    37      78     +41
udhcp_listen_socket                                  151     124     -27
udhcpc_main                                         2344    2285     -59

1 files changed, 26 insertions, 0 deletions

diff --git a/libbb/info_msg.c b/libbb/info_msg.c
index ffef05e54..8b8a1fcca 100644
--- a/libbb/info_msg.c
+++ b/libbb/info_msg.c
@@ -12,6 +12,7 @@
 
 void FAST_FUNC bb_info_msg(const char *s, ...)
 {
+#ifdef THIS_ONE_DOESNT_DO_SINGLE_WRITE
         va_list p;
         /* va_copy is used because it is not portable
          * to use va_list p twice */
@@ -27,4 +28,29 @@ void FAST_FUNC bb_info_msg(const char *s, ...)
                 vsyslog(LOG_INFO, s, p2);
         va_end(p2);
         va_end(p);
+#else
+        int used;
+        char *msg;
+        va_list p;
+
+        if (logmode == 0)
+                return;
+
+        va_start(p, s);
+        used = vasprintf(&msg, s, p);
+        if (used < 0)
+                return;
+
+        if (ENABLE_FEATURE_SYSLOG && (logmode & LOGMODE_SYSLOG))
+                syslog(LOG_INFO, "%s", msg);
+        if (logmode & LOGMODE_STDIO) {
+                fflush(stdout);
+                /* used = strlen(msg); - must be true already */
+                msg[used++] = '\n';
+                full_write(STDOUT_FILENO, msg, used);
+        }
+
+        free(msg);
+        va_end(p);
+#endif
 }