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