libc/inet/resolv.c: reread resolv.conf if its mtime was changed

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
index 6611466..ee06b44 100644 (file)
--- a/libc/inet/resolv.c
+++ b/libc/inet/resolv.c
@@ -312,6 +312,7 @@ Domain name in a message can be represented as either:
 #include <arpa/nameser.h>
 #include <sys/utsname.h>
 #include <sys/un.h>
+#include <sys/stat.h>
 #include <bits/uClibc_mutex.h>
 
 /* poll() is not supported in kernel <= 2.0, therefore if __NR_poll is
@@ -948,7 +949,7 @@ static char *skip_and_NUL_space(char *p)
 /* Must be called under __resolv_lock. */
 void attribute_hidden __open_nameservers(void)
 {
-       static uint8_t last_time;
+       static uint32_t resolv_conf_mtime;
 
        char szBuffer[MAXLEN_searchdomain];
        FILE *fp;
@@ -956,11 +957,11 @@ void attribute_hidden __open_nameservers(void)
        sockaddr46_t sa;
 
        if (!__res_sync) {
-               /* Provide for periodic reread of /etc/resolv.conf */
-               /* cur_time "ticks" every 256 seconds */
-               uint8_t cur_time = ((unsigned)time(NULL)) >> 8;
-               if (last_time != cur_time) {
-                       last_time = cur_time;
+               /* Reread /etc/resolv.conf if it was modified.  */
+               struct stat sb;
+               stat("/etc/resolv.conf", &sb);
+               if (resolv_conf_mtime != (uint32_t)sb.st_mtime) {
+                       resolv_conf_mtime = sb.st_mtime;
                        __close_nameservers(); /* force config reread */
                }
        }
@@ -969,6 +970,7 @@ void attribute_hidden __open_nameservers(void)
                goto sync;
 
        fp = fopen("/etc/resolv.conf", "r");
+#ifdef FALLBACK_TO_CONFIG_RESOLVCONF
        if (!fp) {
                /* If we do not have a pre-populated /etc/resolv.conf then
                   try to use the one from /etc/config which exists on numerous
@@ -976,6 +978,7 @@ void attribute_hidden __open_nameservers(void)
                   may be the only /etc dir that was mounted rw.  */
                fp = fopen("/etc/config/resolv.conf", "r");
        }
+#endif
 
        if (fp) {
                while (fgets(szBuffer, sizeof(szBuffer), fp) != NULL) {