klogctl: fix a problem where we don't terminate read data with '\0'

 and then misinterpret it. Code shrink while at it.

function                                             old     new   delta
klogd_main                                           404     362     -42

diff --git a/sysklogd/klogd.c b/sysklogd/klogd.c
index 723ca80677358de428ac7f166367fa7bae454414..a0e0bf7248e272675c07949c5531985cb1cd3e78 100644 (file)
--- a/sysklogd/klogd.c
+++ b/sysklogd/klogd.c
@@ -42,14 +42,14 @@ int klogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int klogd_main(int argc UNUSED_PARAM, char **argv)
 {
        int i = 0;
-       char *start;
+       char *opt_c;
        int opt;
        int used = 0;
 
-       opt = getopt32(argv, "c:n", &start);
+       opt = getopt32(argv, "c:n", &opt_c);
        if (opt & OPT_LEVEL) {
                /* Valid levels are between 1 and 8 */
-               i = xatou_range(start, 1, 8);
+               i = xatou_range(opt_c, 1, 8);
        }
        if (!(opt & OPT_FOREGROUND)) {
                bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
@@ -57,10 +57,7 @@ int klogd_main(int argc UNUSED_PARAM, char **argv)
 
        openlog("kernel", 0, LOG_KERN);
 
-       bb_signals(0
-               + (1 << SIGINT)
-               + (1 << SIGTERM)
-               , klogd_signal);
+       bb_signals(BB_FATAL_SIGS, klogd_signal);
        signal(SIGHUP, SIG_IGN);
 
        /* "Open the log. Currently a NOP" */
@@ -73,15 +70,14 @@ int klogd_main(int argc UNUSED_PARAM, char **argv)
 
        syslog(LOG_NOTICE, "klogd started: %s", bb_banner);
 
-       /* Initially null terminate the buffer in case of a very long line */
-       log_buffer[KLOGD_LOGBUF_SIZE - 1] = '\0';
-
        while (1) {
                int n;
                int priority;
+               char *start;
 
                /* "2 -- Read from the log." */
-               n = klogctl(2, log_buffer + used, KLOGD_LOGBUF_SIZE-1 - used);
+               start = log_buffer + used;
+               n = klogctl(2, start, KLOGD_LOGBUF_SIZE-1 - used);
                if (n < 0) {
                        if (errno == EINTR)
                                continue;
@@ -89,25 +85,25 @@ int klogd_main(int argc UNUSED_PARAM, char **argv)
                                        errno);
                        break;
                }
+               start[n] = '\0';
 
                /* klogctl buffer parsing modelled after code in dmesg.c */
-               start = &log_buffer[0];
-
                /* Process each newline-terminated line in the buffer */
                while (1) {
-                       char *newline = strchr(start, '\n');
+                       char *newline = strchrnul(start, '\n');
 
-                       if (!newline) {
+                       if (*newline == '\0') {
                                /* This line is incomplete... */
                                if (start != log_buffer) {
                                        /* move it to the front of the buffer */
-                                       strcpy(log_buffer, start);
+                                       overlapping_strcpy(log_buffer, start);
+                                       used = newline - start;
                                        /* don't log it yet */
-                                       used = strlen(log_buffer);
                                        break;
                                }
-                               /* ...but buffer is full, so log it anyway */
+                               /* ...but if buffer is full, log it anyway */
                                used = 0;
+                               newline = NULL;
                        } else {
                                *newline++ = '\0';
                        }
@@ -121,12 +117,13 @@ int klogd_main(int argc UNUSED_PARAM, char **argv)
                                        priority = (*start - '0');
                                        start++;
                                }
-                               if (*start == '>') {
+                               if (*start == '>')
                                        start++;
-                               }
                        }
+                       /* Log (only non-empty lines) */
                        if (*start)
                                syslog(priority, "%s", start);
+
                        if (!newline)
                                break;
                        start = newline;