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/*
* Oracle Linux DTrace.
* Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
#include <errno.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <dt_impl.h>
#include <time.h>
/*
* These things do not go into the dtrace_hdl both because dt_dprintf doesn't
* take a dtrace_hdl, and because debugging output from different dtrace_hdls is
* mixed together when not using the ring buffer, and should appear identical
* when using it, too.
*/
int _dtrace_debug = 0; /* debug messages enabled (off) */
int _dtrace_debug_assert = 0; /* expensive debug assertions enabled (off) */
static char *ring; /* ring buffer, if non-NULL */
static size_t ring_size; /* ring size */
static size_t ring_start; /* start of ring (last printed position, if not
wrapped) */
static size_t ring_end; /* end of ring (last inserted position) */
static int dump_sig = SIGUSR1; /* ring-dump signal, 0 means 'none' */
static FILE *ring_fd;
_dt_constructor_(_dtrace_debug_init)
static void
_dtrace_debug_init(void)
{
char *debug_env;
debug_env = getenv("DTRACE_DEBUG");
if ((debug_env != NULL) && (debug_env[0] != '\0'))
_dtrace_debug = 1;
if (_dtrace_debug && (strcmp(debug_env, "signal") == 0)) {
char *size_str = getenv("DTRACE_DEBUG_BUF_SIZE");
char *err;
size_t size_mb = 128;
if (size_str) {
size_mb = strtoul(size_str, &err, 10);
if (err[0] != '\0') {
dt_dprintf("Debug buffer size %s invalid. "
"Signal-dump debugging disabled.\n",
size_str);
return;
}
}
ring_size = size_mb * 1024 * 1024;
ring = malloc(ring_size + 1);
if (!ring) {
dt_dprintf("Out of memory allocating debug buffer of "
"size %lu MiB. Signal-dump debugging disabled.\n",
size_mb);
}
ring[0] = '\0';
ring_fd = fmemopen(ring, size_mb * 1024 * 1024, "w");
setvbuf(ring_fd, NULL, _IONBF, 0);
}
dtrace_debug_set_dump_sig(dump_sig);
}
void
dtrace_debug_set_dump_sig(int signal)
{
struct sigaction sa;
if (!ring)
return;
sa.sa_handler = SIG_DFL;
sigaction(dump_sig, &sa, NULL);
if (signal == 0) {
if (ring) {
fclose(ring_fd);
free(ring);
ring = NULL;
}
} else {
sa.sa_handler = dt_debug_dump;
sa.sa_flags = SA_RESTART;
sigaction(signal, &sa, NULL);
}
dump_sig = signal;
}
/*PRINTFLIKE1*/
_dt_printflike_(1,2)
void
dt_dprintf(const char *format, ...)
{
va_list alist;
if (!_dtrace_debug)
return;
va_start(alist, format);
dt_debug_printf("libdtrace", format, alist);
va_end(alist);
}
void
dt_debug_printf(const char *subsys, const char *format, va_list alist)
{
if (!_dtrace_debug)
return;
if (!ring) {
flockfile(stderr);
fprintf(stderr, "%s DEBUG %li: ", subsys, time(NULL));
vfprintf(stderr, format, alist);
funlockfile(stderr);
} else {
va_list on_err;
size_t new_ring_end;
flockfile(ring_fd);
errno = 0;
fprintf(ring_fd, "%s DEBUG: %li: ", subsys, time(NULL));
if (errno == ENOSPC) {
rewind(ring_fd);
fprintf(ring_fd, "%s DEBUG: %li: ", subsys, time(NULL));
}
va_copy(on_err, alist);
errno = 0;
vfprintf(ring_fd, format, alist);
if (errno == ENOSPC) {
rewind(ring_fd);
vfprintf(ring_fd, format, on_err);
}
va_end(on_err);
new_ring_end = ftell(ring_fd);
/*
* Detect wraparound.
*/
if ((new_ring_end > ring_start && ring_end < ring_start) ||
(new_ring_end > ring_start && new_ring_end < ring_end))
ring_start = ring_end + 2; /* not +1, as that is '\0' */
ring_end = new_ring_end;
funlockfile(ring_fd);
}
}
void dt_debug_dump(int unused)
{
if (!ring)
return;
if (ring_start < ring_size)
fprintf(stderr, "%s", &ring[ring_start]);
if (ring_end < ring_start)
fprintf(stderr, "%s", ring);
ring_start = ring_end + 1;
}
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