lib/backtrace.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2011, 2013 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #include <inttypes.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23
  24 #include "backtrace.h"
  25 #include "openvswitch/vlog.h"
  26 #include "util.h"
  27
  28 VLOG_DEFINE_THIS_MODULE(backtrace);
  29
  30 #ifdef HAVE_BACKTRACE
  31 #include <execinfo.h>
  32 void
  33 backtrace_capture(struct backtrace *b)
  34 {
  35     void *frames[BACKTRACE_MAX_FRAMES];
  36     int i;
  37
  38     b->n_frames = backtrace(frames, BACKTRACE_MAX_FRAMES);
  39     for (i = 0; i < b->n_frames; i++) {
  40         b->frames[i] = (uintptr_t) frames[i];
  41     }
  42 }
  43
  44 #else
  45 void
  46 backtrace_capture(struct backtrace *backtrace)
  47 {
  48     backtrace->n_frames = 0;
  49 }
  50 #endif
  51
  52 static char *
  53 backtrace_format(const struct backtrace *b, struct ds *ds)
  54 {
  55     if (b->n_frames) {
  56         int i;
  57
  58         ds_put_cstr(ds, " (backtrace:");
  59         for (i = 0; i < b->n_frames; i++) {
  60             ds_put_format(ds, " 0x%08"PRIxPTR, b->frames[i]);
  61         }
  62         ds_put_cstr(ds, ")");
  63     }
  64
  65     return ds_cstr(ds);
  66 }
  67
  68 void
  69 log_backtrace_at(const char *msg, const char *where)
  70 {
  71     struct backtrace b;
  72     struct ds ds = DS_EMPTY_INITIALIZER;
  73
  74     backtrace_capture(&b);
  75     if (msg) {
  76         ds_put_format(&ds, "%s ", msg);
  77     }
  78
  79     ds_put_cstr(&ds, where);
  80     VLOG_ERR("%s", backtrace_format(&b, &ds));
  81
  82     ds_destroy(&ds);
  83 }
  84
  85 #ifdef HAVE_UNWIND
  86 void
  87 log_received_backtrace(int fd) {
  88     int byte_read;
  89     struct unw_backtrace backtrace[UNW_MAX_DEPTH];
  90
  91     VLOG_WARN("%s fd %d", __func__, fd);
  92     fcntl(fd, F_SETFL, O_NONBLOCK);
  93     memset(backtrace, 0, UNW_MAX_BUF);
  94
  95     byte_read = read(fd, backtrace, UNW_MAX_BUF);
  96     if (byte_read < 0) {
  97         VLOG_ERR("Read fd %d failed: %s", fd,
  98                  ovs_strerror(errno));
  99     } else if (byte_read > 0) {
 100         VLOG_WARN("SIGSEGV detected, backtrace:");
 101         for (int i = 0; i < UNW_MAX_DEPTH; i++) {
 102             if (backtrace[i].func[0] == 0) {
 103                 break;
 104             }
 105             VLOG_WARN("0x%016"PRIxPTR" <%s+0x%"PRIxPTR">\n",
 106                       backtrace[i].ip,
 107                       backtrace[i].func,
 108                       backtrace[i].offset);
 109         }
 110     }
 111 }
 112 #else /* !HAVE_UNWIND */
 113 void
 114 log_received_backtrace(int daemonize_fd OVS_UNUSED) {
 115     VLOG_WARN("Backtrace using libunwind not supported.");
 116 }
 117 #endif /* HAVE_UNWIND */