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 <helper.h>
  31 #include "usterr-signal-safe.h"
  32
  33 /* Include link.h last else it conflicts with ust-dlfcn. */
  34 #include <link.h>
  35
  36 #define TRACEPOINT_DEFINE
  37 #include "ust_dl.h"
  38
  39 static void *(*__lttng_ust_plibc_dlopen)(const char *filename, int flag);
  40 static int (*__lttng_ust_plibc_dlclose)(void *handle);
  41
  42 static
  43 void *_lttng_ust_dl_libc_dlopen(const char *filename, int flag)
  44 {
  45         if (!__lttng_ust_plibc_dlopen) {
  46                 __lttng_ust_plibc_dlopen = dlsym(RTLD_NEXT, "dlopen");
  47                 if (!__lttng_ust_plibc_dlopen) {
  48                         fprintf(stderr, "%s\n", dlerror());
  49                         return NULL;
  50                 }
  51         }
  52         return __lttng_ust_plibc_dlopen(filename, flag);
  53 }
  54
  55 static
  56 int _lttng_ust_dl_libc_dlclose(void *handle)
  57 {
  58         if (!__lttng_ust_plibc_dlclose) {
  59                 __lttng_ust_plibc_dlclose = dlsym(RTLD_NEXT, "dlclose");
  60                 if (!__lttng_ust_plibc_dlclose) {
  61                         fprintf(stderr, "%s\n", dlerror());
  62                         return -1;
  63                 }
  64         }
  65         return __lttng_ust_plibc_dlclose(handle);
  66 }
  67
  68 static
  69 void lttng_ust_dl_dlopen(void *so_base, const char *so_name, void *ip)
  70 {
  71         char resolved_path[PATH_MAX];
  72         struct lttng_ust_elf *elf;
  73         uint64_t memsz;
  74         uint8_t *build_id = NULL;
  75         size_t build_id_len;
  76         char *dbg_file = NULL;
  77         uint32_t crc;
  78         int has_build_id = 0, has_debug_link = 0;
  79         int ret;
  80
  81         if (!realpath(so_name, resolved_path)) {
  82                 ERR("could not resolve path '%s'", so_name);
  83                 return;
  84         }
  85
  86         elf = lttng_ust_elf_create(resolved_path);
  87         if (!elf) {
  88                 ERR("could not acces file %s", resolved_path);
  89                 return;
  90         }
  91
  92         ret = lttng_ust_elf_get_memsz(elf, &memsz);
  93         if (ret) {
  94                 goto end;
  95         }
  96         ret = lttng_ust_elf_get_build_id(
  97                 elf, &build_id, &build_id_len, &has_build_id);
  98         if (ret) {
  99                 goto end;
 100         }
 101         ret = lttng_ust_elf_get_debug_link(
 102                 elf, &dbg_file, &crc, &has_debug_link);
 103         if (ret) {
 104                 goto end;
 105         }
 106
 107         tracepoint(lttng_ust_dl, dlopen,
 108                 ip, so_base, resolved_path, memsz,
 109                 has_build_id, has_debug_link);
 110
 111         if (has_build_id) {
 112                 tracepoint(lttng_ust_dl, build_id,
 113                         ip, so_base, build_id, build_id_len);
 114         }
 115
 116         if (has_debug_link) {
 117                 tracepoint(lttng_ust_dl, debug_link,
 118                         ip, so_base, dbg_file, crc);
 119         }
 120
 121 end:
 122         free(dbg_file);
 123         free(build_id);
 124         lttng_ust_elf_destroy(elf);
 125         return;
 126 }
 127
 128 void *dlopen(const char *filename, int flag)
 129 {
 130         void *handle;
 131
 132         handle = _lttng_ust_dl_libc_dlopen(filename, flag);
 133         if (__tracepoint_ptrs_registered && handle) {
 134                 struct link_map *p = NULL;
 135                 int ret;
 136
 137                 ret = dlinfo(handle, RTLD_DI_LINKMAP, &p);
 138                 if (ret != -1 && p != NULL && p->l_addr != 0) {
 139                         lttng_ust_dl_dlopen((void *) p->l_addr, p->l_name,
 140                                 LTTNG_UST_CALLER_IP());
 141                 }
 142         }
 143
 144         return handle;
 145 }
 146
 147 int dlclose(void *handle)
 148 {
 149         if (__tracepoint_ptrs_registered) {
 150                 struct link_map *p = NULL;
 151                 int ret;
 152
 153                 ret = dlinfo(handle, RTLD_DI_LINKMAP, &p);
 154                 if (ret != -1 && p != NULL && p->l_addr != 0) {
 155                         tracepoint(lttng_ust_dl, dlclose,
 156                                 LTTNG_UST_CALLER_IP(),
 157                                 (void *) p->l_addr);
 158                 }
 159         }
 160
 161         return _lttng_ust_dl_libc_dlclose(handle);
 162 }