syslogd: do not segfault on parse error when using default config. Closes 5762

[oweals/busybox.git] / sysklogd / logread.c

diff --git a/sysklogd/logread.c b/sysklogd/logread.c
index 69a084ff68156872bbb54cfd9c611b3d4c1bb91c..9939569040d3640e5d46181fa9c05fb3e2d27f1d 100644 (file)
--- a/sysklogd/logread.c
+++ b/sysklogd/logread.c
@@ -6,9 +6,15 @@
  *
  * Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
  *
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 
+//usage:#define logread_trivial_usage
+//usage:       "[-f]"
+//usage:#define logread_full_usage "\n\n"
+//usage:       "Show messages in syslogd's circular buffer\n"
+//usage:     "\n       -f      Output data as log grows"
+
 #include "libbb.h"
 #include <sys/ipc.h>
 #include <sys/sem.h>
@@ -16,20 +22,34 @@
 
 #define DEBUG 0
 
+/* our shared key (syslogd.c and logread.c must be in sync) */
 enum { KEY_ID = 0x414e4547 }; /* "GENA" */
 
-static struct shbuf_ds {
+struct shbuf_ds {
        int32_t size;           // size of data - 1
        int32_t tail;           // end of message list
        char data[1];           // messages
-} *shbuf;
-
-// Semaphore operation structures
-static struct sembuf SMrup[1] = {{0, -1, IPC_NOWAIT | SEM_UNDO}}; // set SMrup
-static struct sembuf SMrdn[2] = {{1, 0}, {0, +1, SEM_UNDO}}; // set SMrdn
-
-
-static void error_exit(const char *str) ATTRIBUTE_NORETURN;
+};
+
+static const struct sembuf init_sem[3] = {
+       {0, -1, IPC_NOWAIT | SEM_UNDO},
+       {1, 0}, {0, +1, SEM_UNDO}
+};
+
+struct globals {
+       struct sembuf SMrup[1]; // {0, -1, IPC_NOWAIT | SEM_UNDO},
+       struct sembuf SMrdn[2]; // {1, 0}, {0, +1, SEM_UNDO}
+       struct shbuf_ds *shbuf;
+} FIX_ALIASING;
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define SMrup (G.SMrup)
+#define SMrdn (G.SMrdn)
+#define shbuf (G.shbuf)
+#define INIT_G() do { \
+       memcpy(SMrup, init_sem, sizeof(init_sem)); \
+} while (0)
+
+static void error_exit(const char *str) NORETURN;
 static void error_exit(const char *str)
 {
        //release all acquired resources
@@ -46,21 +66,23 @@ static void sem_up(int semid)
                error_exit("semop[SMrup]");
 }
 
-static void interrupted(int sig ATTRIBUTE_UNUSED)
+static void interrupted(int sig UNUSED_PARAM)
 {
        signal(SIGINT, SIG_IGN);
        shmdt(shbuf);
-       exit(0);
+       exit(EXIT_SUCCESS);
 }
 
-int logread_main(int argc, char **argv);
-int logread_main(int argc, char **argv)
+int logread_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int logread_main(int argc UNUSED_PARAM, char **argv)
 {
-       int cur;
+       unsigned cur;
        int log_semid; /* ipc semaphore id */
        int log_shmid; /* ipc shared memory id */
        smallint follow = getopt32(argv, "f");
 
+       INIT_G();
+
        log_shmid = shmget(KEY_ID, 0, 0);
        if (log_shmid == -1)
                bb_perror_msg_and_die("can't find syslogd buffer");
@@ -119,7 +141,7 @@ int logread_main(int argc, char **argv)
                } else { /* logread -f */
                        if (cur == shbuf_tail) {
                                sem_up(log_semid);
-                               fflush(stdout);
+                               fflush_all();
                                sleep(1); /* TODO: replace me with a sleep_on */
                                continue;
                        }