liblttng-ust-fd/lttng-ust-fd.c

   1 /*
   2  * Copyright (C) 2016  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; version 2.1 of
   7  * the License.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  17  */
  18
  19 #define _GNU_SOURCE
  20 #define _LGPL_SOURCE
  21 #include <limits.h>
  22 #include <stdio.h>
  23 #include <sys/types.h>
  24 #include <unistd.h>
  25 #include <ust-fd.h>
  26 #include <dlfcn.h>
  27
  28 #include <helper.h>
  29 #include "usterr-signal-safe.h"
  30
  31 volatile enum ust_loglevel ust_loglevel;
  32
  33 static int (*__lttng_ust_fd_plibc_close)(int fd);
  34 static int (*__lttng_ust_fd_plibc_fclose)(FILE *stream);
  35
  36 static
  37 int _lttng_ust_fd_libc_close(int fd)
  38 {
  39         if (!__lttng_ust_fd_plibc_close) {
  40                 __lttng_ust_fd_plibc_close = dlsym(RTLD_NEXT, "close");
  41                 if (!__lttng_ust_fd_plibc_close) {
  42                         fprintf(stderr, "%s\n", dlerror());
  43                         return -1;
  44                 }
  45         }
  46         return lttng_ust_safe_close_fd(fd, __lttng_ust_fd_plibc_close);
  47 }
  48
  49 static
  50 int _lttng_ust_fd_libc_fclose(FILE *stream)
  51 {
  52         if (!__lttng_ust_fd_plibc_fclose) {
  53                 __lttng_ust_fd_plibc_fclose = dlsym(RTLD_NEXT, "fclose");
  54                 if (!__lttng_ust_fd_plibc_fclose) {
  55                         fprintf(stderr, "%s\n", dlerror());
  56                         return -1;
  57                 }
  58         }
  59         return lttng_ust_safe_fclose_stream(stream,
  60                         __lttng_ust_fd_plibc_fclose);
  61 }
  62
  63 int close(int fd)
  64 {
  65         return _lttng_ust_fd_libc_close(fd);
  66 }
  67
  68 /*
  69  * Note: fcloseall() is not an issue because it fcloses only the
  70  * streams it knows about, which differs from the problems caused by
  71  * gnulib close_stdout(), which does an explicit fclose(stdout).
  72  */
  73 int fclose(FILE *stream)
  74 {
  75         return _lttng_ust_fd_libc_fclose(stream);
  76 }
  77
  78 #if defined(__sun__) || defined(__FreeBSD__)
  79 /* Solaris and FreeBSD. */
  80 void closefrom(int lowfd)
  81 {
  82         (void) lttng_ust_safe_closefrom(lowfd, __lttng_ust_fd_plibc_close);
  83 }
  84 #elif defined(__NetBSD__) || defined(__OpenBSD__)
  85 /* NetBSD and OpenBSD. */
  86 int closefrom(int lowfd)
  87 {
  88         return lttng_ust_safe_closefrom(lowfd, __lttng_ust_fd_plibc_close);
  89 }
  90 #else
  91 /* As far as we know, this OS does not implement closefrom. */
  92 #endif