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