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 #include "usterr-signal-safe.h"
  17
  18 static int (*__lttng_ust_fd_plibc_close)(int fd);
  19 static int (*__lttng_ust_fd_plibc_fclose)(FILE *stream);
  20
  21 static __attribute__((constructor))
  22 void _lttng_ust_fd_init(void)
  23 {
  24         ust_err_init();
  25 }
  26
  27 static
  28 int _lttng_ust_fd_libc_close(int fd)
  29 {
  30         if (!__lttng_ust_fd_plibc_close) {
  31                 __lttng_ust_fd_plibc_close = dlsym(RTLD_NEXT, "close");
  32                 if (!__lttng_ust_fd_plibc_close) {
  33                         fprintf(stderr, "%s\n", dlerror());
  34                         return -1;
  35                 }
  36         }
  37         return lttng_ust_safe_close_fd(fd, __lttng_ust_fd_plibc_close);
  38 }
  39
  40 static
  41 int _lttng_ust_fd_libc_fclose(FILE *stream)
  42 {
  43         if (!__lttng_ust_fd_plibc_fclose) {
  44                 __lttng_ust_fd_plibc_fclose = dlsym(RTLD_NEXT, "fclose");
  45                 if (!__lttng_ust_fd_plibc_fclose) {
  46                         fprintf(stderr, "%s\n", dlerror());
  47                         return -1;
  48                 }
  49         }
  50         return lttng_ust_safe_fclose_stream(stream,
  51                         __lttng_ust_fd_plibc_fclose);
  52 }
  53
  54 int close(int fd)
  55 {
  56         return _lttng_ust_fd_libc_close(fd);
  57 }
  58
  59 /*
  60  * Note: fcloseall() is not an issue because it fcloses only the
  61  * streams it knows about, which differs from the problems caused by
  62  * gnulib close_stdout(), which does an explicit fclose(stdout).
  63  */
  64 int fclose(FILE *stream)
  65 {
  66         return _lttng_ust_fd_libc_fclose(stream);
  67 }
  68
  69 #if defined(__sun__) || defined(__FreeBSD__)
  70 /* Solaris and FreeBSD. */
  71 void closefrom(int lowfd)
  72 {
  73         (void) lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close);
  74 }
  75 #elif defined(__NetBSD__) || defined(__OpenBSD__)
  76 /* NetBSD and OpenBSD. */
  77 int closefrom(int lowfd)
  78 {
  79         return lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close);
  80 }
  81 #else
  82 /* As far as we know, this OS does not implement closefrom. */
  83 #endif