Changeset 3621 in MondoRescue for branches/3.3/mindi-busybox/sysklogd/logread.c

Timestamp:

Dec 20, 2016, 4:07:32 PM (7 years ago)

Author:

Bruno Cornec

Message:

New 3?3 banch for incorporation of latest busybox 1.25. Changing minor version to handle potential incompatibilities.

Location:

branches/3.3

Files:

• . (copied) (copied from branches/3.2 )
• mindi-busybox/sysklogd/logread.c (modified) (10 diffs)

branches/3.3/mindi-busybox/sysklogd/logread.c

@@ -9 +9 @@
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
+//config:config LOGREAD
+//config:   bool "logread"
+//config:   default y
+//config:   depends on FEATURE_IPC_SYSLOG
+//config:   help
+//config:     If you enabled Circular Buffer support, you almost
+//config:     certainly want to enable this feature as well. This
+//config:     utility will allow you to read the messages that are
+//config:     stored in the syslogd circular buffer.
+//config:
+//config:config FEATURE_LOGREAD_REDUCED_LOCKING
+//config:   bool "Double buffering"
+//config:   default y
+//config:   depends on LOGREAD
+//config:   help
+//config:     'logread' ouput to slow serial terminals can have
+//config:     side effects on syslog because of the semaphore.
+//config:     This option make logread to double buffer copy
+//config:     from circular buffer, minimizing semaphore
+//config:     contention at some minor memory expense.
+//config:
+
+//applet:IF_LOGREAD(APPLET(logread, BB_DIR_SBIN, BB_SUID_DROP))
+
+//kbuild:lib-$(CONFIG_LOGREAD) += logread.o
 
 //usage:#define logread_trivial_usage
-//usage:       "[-f]"
+//usage:       "[-fF]"
 //usage:#define logread_full_usage "\n\n"
 //usage:       "Show messages in syslogd's circular buffer\n"
 //usage:     "\n    -f  Output data as log grows"
+//usage:     "\n    -F  Same as -f, but dump buffer first"
 
 #include "libbb.h"
+#include "common_bufsiz.h"
 #include <sys/ipc.h>
 #include <sys/sem.h>
@@ -42 +69 @@
     struct shbuf_ds *shbuf;
 } FIX_ALIASING;
-#define G (*(struct globals*)&bb_common_bufsiz1)
+#define G (*(struct globals*)bb_common_bufsiz1)
 #define SMrup (G.SMrup)
 #define SMrdn (G.SMrdn)
 #define shbuf (G.shbuf)
 #define INIT_G() do { \
+    setup_common_bufsiz(); \
     memcpy(SMrup, init_sem, sizeof(init_sem)); \
 } while (0)
 
+#if 0
 static void error_exit(const char *str) NORETURN;
 static void error_exit(const char *str)
 {
-    //release all acquired resources
+    /* Release all acquired resources */
     shmdt(shbuf);
     bb_perror_msg_and_die(str);
 }
+#else
+/* On Linux, shmdt is not mandatory on exit */
+# define error_exit(str) bb_perror_msg_and_die(str)
+#endif
 
 /*
@@ -67 +100 @@
 }
 
-static void interrupted(int sig UNUSED_PARAM)
-{
-    signal(SIGINT, SIG_IGN);
-    shmdt(shbuf);
-    exit(EXIT_SUCCESS);
+static void interrupted(int sig)
+{
+    /* shmdt(shbuf); - on Linux, shmdt is not mandatory on exit */
+    kill_myself_with_sig(sig);
 }
 
@@ -80 +112 @@
     int log_semid; /* ipc semaphore id */
     int log_shmid; /* ipc shared memory id */
-    smallint follow = getopt32(argv, "f");
+    int follow = getopt32(argv, "fF");
 
     INIT_G();
@@ -86 +118 @@
     log_shmid = shmget(KEY_ID, 0, 0);
     if (log_shmid == -1)
-        bb_perror_msg_and_die("can't find syslogd buffer");
+        bb_perror_msg_and_die("can't %s syslogd buffer", "find");
 
     /* Attach shared memory to our char* */
     shbuf = shmat(log_shmid, NULL, SHM_RDONLY);
     if (shbuf == NULL)
-        bb_perror_msg_and_die("can't access syslogd buffer");
+        bb_perror_msg_and_die("can't %s syslogd buffer", "access");
 
     log_semid = semget(KEY_ID, 0, 0);
@@ -97 +129 @@
         error_exit("can't get access to semaphores for syslogd buffer");
 
-    signal(SIGINT, interrupted);
+    bb_signals(BB_FATAL_SIGS, interrupted);
 
     /* Suppose atomic memory read */
@@ -103 +135 @@
     cur = shbuf->tail;
 
-    /* Loop for logread -f, one pass if there was no -f */
+    /* Loop for -f or -F, one pass otherwise */
     do {
         unsigned shbuf_size;
@@ -123 +155 @@
 
         if (DEBUG)
-            printf("cur:%d tail:%i size:%i\n",
+            printf("cur:%u tail:%u size:%u\n",
                     cur, shbuf_tail, shbuf_size);
 
-        if (!follow) {
+        if (!(follow & 1)) { /* not -f */
+            /* if -F, "convert" it to -f, so that we dont
+             * dump the entire buffer on each iteration
+             */
+            follow >>= 1;
+
             /* advance to oldest complete message */
             /* find NUL */
@@ -139 +176 @@
             if (cur >= shbuf_size) /* last byte in buffer? */
                 cur = 0;
-        } else { /* logread -f */
+        } else { /* -f */
             if (cur == shbuf_tail) {
                 sem_up(log_semid);
@@ -184 +221 @@
         free(copy);
 #endif
+        fflush_all();
     } while (follow);
 
-    shmdt(shbuf);
+    /* shmdt(shbuf); - on Linux, shmdt is not mandatory on exit */
 
     fflush_stdout_and_exit(EXIT_SUCCESS);