src/lib/lttng-ust-fd/lttng-ust-fd.c

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2016  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #define _LGPL_SOURCE
   8 #include <limits.h>
   9 #include <stdio.h>
  10 #include <sys/types.h>
  11 #include <unistd.h>
  12 #include <dlfcn.h>
  13
  14 #include <lttng/ust-common.h>
  15
  16 #include "common/macros.h"
  17 #include "common/ust-fd.h"
  18
  19 static int (*__lttng_ust_fd_plibc_close)(int fd);
  20 static int (*__lttng_ust_fd_plibc_fclose)(FILE *stream);
  21
  22 static
  23 void _lttng_ust_fd_ctor(void)
  24         __attribute__((constructor));
  25 static
  26 void _lttng_ust_fd_ctor(void)
  27 {
  28         lttng_ust_common_ctor();
  29 }
  30
  31 static
  32 int _lttng_ust_fd_libc_close(int fd)
  33 {
  34         if (!__lttng_ust_fd_plibc_close) {
  35                 __lttng_ust_fd_plibc_close = dlsym(RTLD_NEXT, "close");
  36                 if (!__lttng_ust_fd_plibc_close) {
  37                         fprintf(stderr, "%s\n", dlerror());
  38                         return -1;
  39                 }
  40         }
  41         return lttng_ust_safe_close_fd(fd, __lttng_ust_fd_plibc_close);
  42 }
  43
  44 static
  45 int _lttng_ust_fd_libc_fclose(FILE *stream)
  46 {
  47         if (!__lttng_ust_fd_plibc_fclose) {
  48                 __lttng_ust_fd_plibc_fclose = dlsym(RTLD_NEXT, "fclose");
  49                 if (!__lttng_ust_fd_plibc_fclose) {
  50                         fprintf(stderr, "%s\n", dlerror());
  51                         return -1;
  52                 }
  53         }
  54         return lttng_ust_safe_fclose_stream(stream,
  55                         __lttng_ust_fd_plibc_fclose);
  56 }
  57
  58 int close(int fd)
  59 {
  60         return _lttng_ust_fd_libc_close(fd);
  61 }
  62
  63 /*
  64  * Note: fcloseall() is not an issue because it fcloses only the
  65  * streams it knows about, which differs from the problems caused by
  66  * gnulib close_stdout(), which does an explicit fclose(stdout).
  67  */
  68 int fclose(FILE *stream)
  69 {
  70         return _lttng_ust_fd_libc_fclose(stream);
  71 }
  72
  73 #if defined(__sun__) || defined(__FreeBSD__)
  74 /* Solaris and FreeBSD. */
  75 void closefrom(int lowfd)
  76 {
  77         (void) lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close);
  78 }
  79 #elif defined(__NetBSD__) || defined(__OpenBSD__)
  80 /* NetBSD and OpenBSD. */
  81 int closefrom(int lowfd)
  82 {
  83         return lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close);
  84 }
  85 #else
  86 /* As far as we know, this OS does not implement closefrom. */
  87 #endif