udhcp: MAC_BCAST_ADDR and blank_chaddr are in fact constant, move to rodata.

a few global variables reduced to smallints
function                                             old     new   delta
add_lease                                             75     227    +152
static.blank_chaddr                                    -      16     +16
MAC_BCAST_ADDR                                         -       6      +6
sockfd                                                 4       8      +4
udhcp_run_script                                    1153    1155      +2
state                                                  8       5      -3
listen_mode                                            4       1      -3
perform_release                                      152     148      -4
fd                                                     8       4      -4
blank_chaddr                                          16       -     -16
udhcpc_main                                         2518    2497     -21
.rodata                                           131864  131832     -32
oldest_expired_lease                                  61       -     -61
clear_lease                                          127       -    -127
------------------------------------------------------------------------------
(add/remove: 2/3 grow/shrink: 3/6 up/down: 180/-271)          Total: -91 bytes

1 files changed, 21 insertions, 15 deletions

diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index e8cdd79df..362e70169 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -17,22 +17,23 @@
 #include "options.h"
 
 
-static int state;
 /* Something is definitely wrong here. IPv4 addresses
  * in variables of type long?? BTW, we use inet_ntoa()
  * in the code. Manpage says that struct in_addr has a member of type long (!)
  * which holds IPv4 address, and the struct is passed by value (!!)
  */
+static unsigned long timeout;
 static unsigned long requested_ip; /* = 0 */
 static uint32_t server_addr;
-static unsigned long timeout;
 static int packet_num; /* = 0 */
-static int fd = -1;
+static int sockfd = -1;
 
 #define LISTEN_NONE 0
 #define LISTEN_KERNEL 1
 #define LISTEN_RAW 2
-static int listen_mode;
+static smallint listen_mode;
+
+static smallint state;
 
 struct client_config_t client_config;
 
@@ -42,8 +43,10 @@ static void change_mode(int new_mode)
 {
         DEBUG("entering %s listen mode",
                 new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
-        if (fd >= 0) close(fd);
-        fd = -1;
+        if (sockfd >= 0) {
+                close(sockfd);
+                sockfd = -1;
+        }
         listen_mode = new_mode;
 }
 
@@ -111,6 +114,7 @@ static void client_background(void)
  * If that will be properly disabled for NOMMU, client_background()
  * will work on NOMMU too */
 #else
+// chdir(/) is problematic. Imagine that e.g. pidfile name is RELATIVE! what will unlink do then, eh?
         bb_daemonize(DAEMON_CHDIR_ROOT);
         logmode &= ~LOGMODE_STDIO;
 #endif
@@ -289,13 +293,13 @@ int udhcpc_main(int argc, char **argv)
                 tv.tv_sec = timeout - uptime();
                 tv.tv_usec = 0;
 
-                if (listen_mode != LISTEN_NONE && fd < 0) {
+                if (listen_mode != LISTEN_NONE && sockfd < 0) {
                         if (listen_mode == LISTEN_KERNEL)
-                                fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
+                                sockfd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
                         else
-                                fd = raw_socket(client_config.ifindex);
+                                sockfd = raw_socket(client_config.ifindex);
                 }
-                max_fd = udhcp_sp_fd_set(&rfds, fd);
+                max_fd = udhcp_sp_fd_set(&rfds, sockfd);
 
                 if (tv.tv_sec > 0) {
                         DEBUG("Waiting on select...");
@@ -342,7 +346,8 @@ int udhcpc_main(int argc, char **argv)
                                         packet_num++;
                                 } else {
                                         /* timed out, go back to init state */
-                                        if (state == RENEW_REQUESTED) udhcp_run_script(NULL, "deconfig");
+                                        if (state == RENEW_REQUESTED)
+                                                udhcp_run_script(NULL, "deconfig");
                                         state = INIT_SELECTING;
                                         timeout = now;
                                         packet_num = 0;
@@ -393,12 +398,12 @@ int udhcpc_main(int argc, char **argv)
                                 timeout = 0x7fffffff;
                                 break;
                         }
-                } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
+                } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) {
                         /* a packet is ready, read it */
 
                         if (listen_mode == LISTEN_KERNEL)
-                                len = udhcp_get_packet(&packet, fd);
-                        else len = get_raw_packet(&packet, fd);
+                                len = udhcp_get_packet(&packet, sockfd);
+                        else len = get_raw_packet(&packet, sockfd);
 
                         if (len == -1 && errno != EINTR) {
                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
@@ -418,7 +423,8 @@ int udhcpc_main(int argc, char **argv)
                                 continue;
                         }
 
-                        if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
+                        message = get_option(&packet, DHCP_MESSAGE_TYPE);
+                        if (message == NULL) {
                                 bb_error_msg("cannot get option from packet - ignoring");
                                 continue;
                         }