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