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

4 files changed, 22 insertions, 27 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);
diff --git a/miscutils/crond.c b/miscutils/crond.c
index 2f0bf6ea8..7d1908c63 100644
--- a/miscutils/crond.c
+++ b/miscutils/crond.c
@@ -187,7 +187,7 @@ int crond_main(int argc UNUSED_PARAM, char **argv)
 
         xchdir(CDir);
         //signal(SIGHUP, SIG_IGN); /* ? original crond dies on HUP... */
-        setenv("SHELL", DEFAULT_SHELL, 1); /* once, for all future children */
+        xsetenv("SHELL", DEFAULT_SHELL); /* once, for all future children */
         crondlog(LVL9 "crond (busybox "BB_VER") started, log level %d", LogLevel);
         SynchronizeDir();
 
@@ -275,8 +275,8 @@ static void SetEnv(struct passwd *pas)
         /* if we want to set user's shell instead: */
         /*safe_setenv(env_var_user, "SHELL", pas->pw_shell, 5);*/
 #else
-        setenv("USER", pas->pw_name, 1);
-        setenv("HOME", pas->pw_dir, 1);
+        xsetenv("USER", pas->pw_name);
+        xsetenv("HOME", pas->pw_dir);
 #endif
         /* currently, we use constant one: */
         /*setenv("SHELL", DEFAULT_SHELL, 1); - done earlier */
diff --git a/miscutils/crontab.c b/miscutils/crontab.c
index f8662babb..ef6d94375 100644
--- a/miscutils/crontab.c
+++ b/miscutils/crontab.c
@@ -21,9 +21,9 @@
 
 static void change_user(const struct passwd *pas)
 {
-        setenv("USER", pas->pw_name, 1);
-        setenv("HOME", pas->pw_dir, 1);
-        setenv("SHELL", DEFAULT_SHELL, 1);
+        xsetenv("USER", pas->pw_name);
+        xsetenv("HOME", pas->pw_dir);
+        xsetenv("SHELL", DEFAULT_SHELL);
 
         /* initgroups, setgid, setuid */
         change_identity(pas);
diff --git a/networking/zcip.c b/networking/zcip.c
index 221edd322..f406b6c16 100644
--- a/networking/zcip.c
+++ b/networking/zcip.c
@@ -144,7 +144,7 @@ static int run(char *argv[3], struct in_addr *ip)
 
         if (ip) {
                 addr = inet_ntoa(*ip);
-                setenv("ip", addr, 1);
+                xsetenv("ip", addr);
                 fmt -= 3;
         }
         bb_info_msg(fmt, argv[1], intf, addr);
@@ -238,7 +238,7 @@ int zcip_main(int argc, char **argv)
 
         intf = argv[0];
         script_av[0] = argv[1];
-        setenv("interface", intf, 1);
+        xsetenv("interface", intf);
 
         // initialize the interface (modprobe, ifup, etc)
         script_av[1] = (char*)"init";