init: set stderr to NONBLOCK

*: s/setenv(a,b,1)/xsetenv(a,b)/

function                                             old     new   delta
init_main                                            856     895     +39
message                                              146     144      -2
crond_main                                          1418    1416      -2
run                                                  661     658      -3
zcip_main                                           1409    1403      -6
edit_file                                            910     901      -9
environment                                           20       -     -20

1 files changed, 14 insertions, 19 deletions

diff --git a/init/init.c b/init/init.c
index e02773cc0..e00a3b128 100644
--- a/init/init.c
+++ b/init/init.c
@@ -77,14 +77,6 @@ enum {
 #endif
 };
 
-static const char *const environment[] = {
-        "HOME=/",
-        bb_PATH_root_path,
-        "SHELL=/bin/sh",
-        "USER=root",
-        NULL
-};
-
 /* Function prototypes */
 static void halt_reboot_pwoff(int sig) NORETURN;
 
@@ -118,15 +110,16 @@ static void message(int where, const char *fmt, ...)
 {
         static int log_fd = -1;
         va_list arguments;
-        int l;
+        unsigned l;
         char msg[128];
 
         msg[0] = '\r';
         va_start(arguments, fmt);
-        vsnprintf(msg + 1, sizeof(msg) - 2, fmt, arguments);
+        l = vsnprintf(msg + 1, sizeof(msg) - 2, fmt, arguments);
+        if (l > sizeof(msg) - 2)
+                l = sizeof(msg) - 2;
+        msg[l] = '\0';
         va_end(arguments);
-        msg[sizeof(msg) - 2] = '\0';
-        l = strlen(msg);
 
         if (ENABLE_FEATURE_INIT_SYSLOG) {
                 /* Log the message to syslogd */
@@ -213,6 +206,8 @@ static void console_init(void)
                 /* Make sure fd 0,1,2 are not closed
                  * (so that they won't be used by future opens) */
                 bb_sanitize_stdio();
+                /* Make sure init can't be blocked by writing to stderr */
+                fcntl(STDERR_FILENO, F_SETFL, fcntl(STDERR_FILENO, F_GETFL) | O_NONBLOCK);
         }
 
         s = getenv("TERM");
@@ -825,15 +820,15 @@ int init_main(int argc UNUSED_PARAM, char **argv)
         set_sane_term();
         xchdir("/");
         setsid();
-        {
-                const char *const *e;
-                /* Make sure environs is set to something sane */
-                for (e = environment; *e; e++)
-                        putenv((char *) *e);
-        }
+
+        /* Make sure environs is set to something sane */
+        putenv((char *) "HOME=/");
+        putenv((char *) bb_PATH_root_path);
+        putenv((char *) "SHELL=/bin/sh");
+        putenv((char *) "USER=root"); /* needed? why? */
 
         if (argv[1])
-                setenv("RUNLEVEL", argv[1], 1);
+                xsetenv("RUNLEVEL", argv[1]);
 
         /* Hello world */
         message(MAYBE_CONSOLE | L_LOG, "init started: %s", bb_banner);