liblttng-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 <ust-fd.h>
  13 #include <dlfcn.h>
  14
  15 #include <ust-helper.h>
  16
  17 static int (*__lttng_ust_fd_plibc_close)(int fd);
  18 static int (*__lttng_ust_fd_plibc_fclose)(FILE *stream);
  19
  20 static
  21 int _lttng_ust_fd_libc_close(int fd)
  22 {
  23         if (!__lttng_ust_fd_plibc_close) {
  24                 __lttng_ust_fd_plibc_close = dlsym(RTLD_NEXT, "close");
  25                 if (!__lttng_ust_fd_plibc_close) {
  26                         fprintf(stderr, "%s\n", dlerror());
  27                         return -1;
  28                 }
  29         }
  30         return lttng_ust_safe_close_fd(fd, __lttng_ust_fd_plibc_close);
  31 }
  32
  33 static
  34 int _lttng_ust_fd_libc_fclose(FILE *stream)
  35 {
  36         if (!__lttng_ust_fd_plibc_fclose) {
  37                 __lttng_ust_fd_plibc_fclose = dlsym(RTLD_NEXT, "fclose");
  38                 if (!__lttng_ust_fd_plibc_fclose) {
  39                         fprintf(stderr, "%s\n", dlerror());
  40                         return -1;
  41                 }
  42         }
  43         return lttng_ust_safe_fclose_stream(stream,
  44                         __lttng_ust_fd_plibc_fclose);
  45 }
  46
  47 int close(int fd)
  48 {
  49         return _lttng_ust_fd_libc_close(fd);
  50 }
  51
  52 /*
  53  * Note: fcloseall() is not an issue because it fcloses only the
  54  * streams it knows about, which differs from the problems caused by
  55  * gnulib close_stdout(), which does an explicit fclose(stdout).
  56  */
  57 int fclose(FILE *stream)
  58 {
  59         return _lttng_ust_fd_libc_fclose(stream);
  60 }
  61
  62 #if defined(__sun__) || defined(__FreeBSD__)
  63 /* Solaris and FreeBSD. */
  64 void closefrom(int lowfd)
  65 {
  66         (void) lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close);
  67 }
  68 #elif defined(__NetBSD__) || defined(__OpenBSD__)
  69 /* NetBSD and OpenBSD. */
  70 int closefrom(int lowfd)
  71 {
  72         return lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close);
  73 }
  74 #else
  75 /* As far as we know, this OS does not implement closefrom. */
  76 #endif