liblttng-ust-dl/lttng-ust-dl.c

   1 /*
   2  * Copyright (C) 2013  Paul Woegerer <paul.woegerer@mentor.com>
   3  * Copyright (C) 2015  Antoine Busque <abusque@efficios.com>
   4  * Copyright (C) 2016  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; version 2.1 of
   9  * the License.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 #define _GNU_SOURCE
  22 #define _LGPL_SOURCE
  23 #include <limits.h>
  24 #include <stdio.h>
  25 #include <sys/types.h>
  26 #include <unistd.h>
  27
  28 #include <lttng/ust-dlfcn.h>
  29 #include <lttng/ust-elf.h>
  30 #include <lttng/ust-events.h>
  31 #include <helper.h>
  32 #include "usterr-signal-safe.h"
  33
  34 /* Include link.h last else it conflicts with ust-dlfcn. */
  35 #include <link.h>
  36
  37 #define TRACEPOINT_DEFINE
  38 #include "ust_dl.h"
  39
  40 static void *(*__lttng_ust_plibc_dlopen)(const char *filename, int flag);
  41 static int (*__lttng_ust_plibc_dlclose)(void *handle);
  42
  43 static
  44 void *_lttng_ust_dl_libc_dlopen(const char *filename, int flag)
  45 {
  46         if (!__lttng_ust_plibc_dlopen) {
  47                 __lttng_ust_plibc_dlopen = dlsym(RTLD_NEXT, "dlopen");
  48                 if (!__lttng_ust_plibc_dlopen) {
  49                         fprintf(stderr, "%s\n", dlerror());
  50                         return NULL;
  51                 }
  52         }
  53         return __lttng_ust_plibc_dlopen(filename, flag);
  54 }
  55
  56 static
  57 int _lttng_ust_dl_libc_dlclose(void *handle)
  58 {
  59         if (!__lttng_ust_plibc_dlclose) {
  60                 __lttng_ust_plibc_dlclose = dlsym(RTLD_NEXT, "dlclose");
  61                 if (!__lttng_ust_plibc_dlclose) {
  62                         fprintf(stderr, "%s\n", dlerror());
  63                         return -1;
  64                 }
  65         }
  66         return __lttng_ust_plibc_dlclose(handle);
  67 }
  68
  69 static
  70 void lttng_ust_dl_dlopen(void *so_base, const char *so_name, void *ip)
  71 {
  72         char resolved_path[PATH_MAX];
  73         struct lttng_ust_elf *elf;
  74         uint64_t memsz;
  75         uint8_t *build_id = NULL;
  76         size_t build_id_len;
  77         char *dbg_file = NULL;
  78         uint32_t crc;
  79         int has_build_id = 0, has_debug_link = 0;
  80         int ret;
  81
  82         if (!realpath(so_name, resolved_path)) {
  83                 ERR("could not resolve path '%s'", so_name);
  84                 return;
  85         }
  86
  87         elf = lttng_ust_elf_create(resolved_path);
  88         if (!elf) {
  89                 ERR("could not acces file %s", resolved_path);
  90                 return;
  91         }
  92
  93         ret = lttng_ust_elf_get_memsz(elf, &memsz);
  94         if (ret) {
  95                 goto end;
  96         }
  97         ret = lttng_ust_elf_get_build_id(
  98                 elf, &build_id, &build_id_len, &has_build_id);
  99         if (ret) {
 100                 goto end;
 101         }
 102         ret = lttng_ust_elf_get_debug_link(
 103                 elf, &dbg_file, &crc, &has_debug_link);
 104         if (ret) {
 105                 goto end;
 106         }
 107
 108         tracepoint(lttng_ust_dl, dlopen,
 109                 ip, so_base, resolved_path, memsz,
 110                 has_build_id, has_debug_link);
 111
 112         if (has_build_id) {
 113                 tracepoint(lttng_ust_dl, build_id,
 114                         ip, so_base, build_id, build_id_len);
 115         }
 116
 117         if (has_debug_link) {
 118                 tracepoint(lttng_ust_dl, debug_link,
 119                         ip, so_base, dbg_file, crc);
 120         }
 121
 122 end:
 123         free(dbg_file);
 124         free(build_id);
 125         lttng_ust_elf_destroy(elf);
 126         return;
 127 }
 128
 129 void *dlopen(const char *filename, int flag)
 130 {
 131         void *handle;
 132
 133         handle = _lttng_ust_dl_libc_dlopen(filename, flag);
 134         if (__tracepoint_ptrs_registered && handle) {
 135                 struct link_map *p = NULL;
 136                 int ret;
 137
 138                 ret = dlinfo(handle, RTLD_DI_LINKMAP, &p);
 139                 if (ret != -1 && p != NULL && p->l_addr != 0) {
 140                         lttng_ust_dl_dlopen((void *) p->l_addr,
 141                                 p->l_name,
 142                                 LTTNG_UST_CALLER_IP());
 143                 }
 144         }
 145         lttng_ust_dl_update(LTTNG_UST_CALLER_IP());
 146         return handle;
 147 }
 148
 149 int dlclose(void *handle)
 150 {
 151         int ret;
 152
 153         if (__tracepoint_ptrs_registered) {
 154                 struct link_map *p = NULL;
 155
 156                 ret = dlinfo(handle, RTLD_DI_LINKMAP, &p);
 157                 if (ret != -1 && p != NULL && p->l_addr != 0) {
 158                         tracepoint(lttng_ust_dl, dlclose,
 159                                 LTTNG_UST_CALLER_IP(),
 160                                 (void *) p->l_addr);
 161                 }
 162         }
 163         ret = _lttng_ust_dl_libc_dlclose(handle);
 164         lttng_ust_dl_update(LTTNG_UST_CALLER_IP());
 165         return ret;
 166 }