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 _LGPL_SOURCE
  20 #include <limits.h>
  21 #include <stdio.h>
  22 #include <sys/types.h>
  23 #include <unistd.h>
  24 #include <ust-fd.h>
  25 #include <dlfcn.h>
  26
  27 #include <helper.h>
  28 #include "usterr-signal-safe.h"
  29
  30 static int (*__lttng_ust_fd_plibc_close)(int fd);
  31 static int (*__lttng_ust_fd_plibc_fclose)(FILE *stream);
  32
  33 static
  34 int _lttng_ust_fd_libc_close(int fd)
  35 {
  36         if (!__lttng_ust_fd_plibc_close) {
  37                 __lttng_ust_fd_plibc_close = dlsym(RTLD_NEXT, "close");
  38                 if (!__lttng_ust_fd_plibc_close) {
  39                         fprintf(stderr, "%s\n", dlerror());
  40                         return -1;
  41                 }
  42         }
  43         return lttng_ust_safe_close_fd(fd, __lttng_ust_fd_plibc_close);
  44 }
  45
  46 static
  47 int _lttng_ust_fd_libc_fclose(FILE *stream)
  48 {
  49         if (!__lttng_ust_fd_plibc_fclose) {
  50                 __lttng_ust_fd_plibc_fclose = dlsym(RTLD_NEXT, "fclose");
  51                 if (!__lttng_ust_fd_plibc_fclose) {
  52                         fprintf(stderr, "%s\n", dlerror());
  53                         return -1;
  54                 }
  55         }
  56         return lttng_ust_safe_fclose_stream(stream,
  57                         __lttng_ust_fd_plibc_fclose);
  58 }
  59
  60 int close(int fd)
  61 {
  62         return _lttng_ust_fd_libc_close(fd);
  63 }
  64
  65 /*
  66  * Note: fcloseall() is not an issue because it fcloses only the
  67  * streams it knows about, which differs from the problems caused by
  68  * gnulib close_stdout(), which does an explicit fclose(stdout).
  69  */
  70 int fclose(FILE *stream)
  71 {
  72         return _lttng_ust_fd_libc_fclose(stream);
  73 }
  74
  75 #if defined(__sun__) || defined(__FreeBSD__)
  76 /* Solaris and FreeBSD. */
  77 void closefrom(int lowfd)
  78 {
  79         (void) lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close);
  80 }
  81 #elif defined(__NetBSD__) || defined(__OpenBSD__)
  82 /* NetBSD and OpenBSD. */
  83 int closefrom(int lowfd)
  84 {
  85         return lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close);
  86 }
  87 #else
  88 /* As far as we know, this OS does not implement closefrom. */
  89 #endif