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Diffstat (limited to 'i/pc104/initrd/conf/busybox/sysklogd/logread.c')
-rw-r--r--i/pc104/initrd/conf/busybox/sysklogd/logread.c144
1 files changed, 144 insertions, 0 deletions
diff --git a/i/pc104/initrd/conf/busybox/sysklogd/logread.c b/i/pc104/initrd/conf/busybox/sysklogd/logread.c
new file mode 100644
index 0000000..b1758a6
--- /dev/null
+++ b/i/pc104/initrd/conf/busybox/sysklogd/logread.c
@@ -0,0 +1,144 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * circular buffer syslog implementation for busybox
+ *
+ * Copyright (C) 2000 by Gennady Feldman <gfeldman@gena01.com>
+ *
+ * Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
+#include "busybox.h"
+#include <sys/ipc.h>
+#include <sys/sem.h>
+#include <sys/shm.h>
+
+#define DEBUG 0
+
+enum { KEY_ID = 0x414e4547 }; /* "GENA" */
+
+static struct shbuf_ds {
+ int32_t size; // size of data written
+ int32_t head; // start of message list
+ int32_t tail; // end of message list
+ char data[1]; // data/messages
+} *buf; // shared memory pointer
+
+// 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 void error_exit(const char *str)
+{
+ //release all acquired resources
+ shmdt(buf);
+ bb_perror_msg_and_die(str);
+}
+
+/*
+ * sem_up - up()'s a semaphore.
+ */
+static void sem_up(int semid)
+{
+ if (semop(semid, SMrup, 1) == -1)
+ error_exit("semop[SMrup]");
+}
+
+static void interrupted(int sig ATTRIBUTE_UNUSED)
+{
+ signal(SIGINT, SIG_IGN);
+ shmdt(buf);
+ exit(0);
+}
+
+int logread_main(int argc, char **argv);
+int logread_main(int argc, char **argv)
+{
+ int cur;
+ int log_semid; /* ipc semaphore id */
+ int log_shmid; /* ipc shared memory id */
+ smallint follow = getopt32(argc, argv, "f");
+
+ log_shmid = shmget(KEY_ID, 0, 0);
+ if (log_shmid == -1)
+ bb_perror_msg_and_die("can't find syslogd buffer");
+
+ // Attach shared memory to our char*
+ buf = shmat(log_shmid, NULL, SHM_RDONLY);
+ if (buf == NULL)
+ bb_perror_msg_and_die("can't access syslogd buffer");
+
+ log_semid = semget(KEY_ID, 0, 0);
+ if (log_semid == -1)
+ error_exit("can't get access to semaphores for syslogd buffer");
+
+ // attempt to redefine ^C signal
+ signal(SIGINT, interrupted);
+
+ // Suppose atomic memory move
+ cur = follow ? buf->tail : buf->head;
+
+ do {
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
+ char *buf_data;
+ int log_len, j;
+#endif
+ if (semop(log_semid, SMrdn, 2) == -1)
+ error_exit("semop[SMrdn]");
+
+ if (DEBUG)
+ printf("head:%i cur:%d tail:%i size:%i\n",
+ buf->head, cur, buf->tail, buf->size);
+
+ if (buf->head == buf->tail || cur == buf->tail) {
+ if (follow) {
+ sem_up(log_semid);
+ fflush(stdout);
+ sleep(1); /* TODO: replace me with a sleep_on */
+ continue;
+ }
+ puts("<empty syslog>");
+ }
+
+ // Read Memory
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
+ log_len = buf->tail - cur;
+ if (log_len < 0)
+ log_len += buf->size;
+ buf_data = xmalloc(log_len);
+
+ if (buf->tail >= cur)
+ j = log_len;
+ else
+ j = buf->size - cur;
+ memcpy(buf_data, buf->data + cur, j);
+
+ if (buf->tail < cur)
+ memcpy(buf_data + buf->size - cur, buf->data, buf->tail);
+ cur = buf->tail;
+#else
+ while (cur != buf->tail) {
+ fputs(buf->data + cur, stdout);
+ cur += strlen(buf->data + cur) + 1;
+ if (cur >= buf->size)
+ cur = 0;
+ }
+#endif
+ // release the lock on the log chain
+ sem_up(log_semid);
+
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
+ for (j = 0; j < log_len; j += strlen(buf_data+j) + 1) {
+ fputs(buf_data + j, stdout);
+ }
+ free(buf_data);
+#endif
+ } while (follow);
+
+ shmdt(buf);
+
+ fflush_stdout_and_exit(EXIT_SUCCESS);
+}