1 /* fclose replacement. 2 Copyright (C) 2008-2021 Free Software Foundation, Inc. 3 4 This file is free software: you can redistribute it and/or modify 5 it under the terms of the GNU Lesser General Public License as 6 published by the Free Software Foundation; either version 2.1 of the 7 License, or (at your option) any later version. 8 9 This file 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 12 GNU Lesser General Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public License 15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 16 17 #include <config.h> 18 19 /* Specification. */ 20 #include <stdio.h> 21 22 #include <errno.h> 23 #include <unistd.h> 24 25 #include "freading.h" 26 #if HAVE_MSVC_INVALID_PARAMETER_HANDLER 27 # include "msvc-inval.h" 28 #endif 29 30 #undef fclose 31 32 #if HAVE_MSVC_INVALID_PARAMETER_HANDLER 33 static int 34 fclose_nothrow (FILE *fp) /* */ 35 { 36 int result; 37 38 TRY_MSVC_INVAL 39 { 40 result = fclose (fp); 41 } 42 CATCH_MSVC_INVAL 43 { 44 result = EOF; 45 errno = EBADF; 46 } 47 DONE_MSVC_INVAL; 48 49 return result; 50 } 51 #else 52 # define fclose_nothrow fclose 53 #endif 54 55 /* Override fclose() to call the overridden fflush() or close(). */ 56 57 int 58 rpl_fclose (FILE *fp) /* */ 59 { 60 int saved_errno = 0; 61 int fd; 62 int result = 0; 63 64 /* Don't change behavior on memstreams. */ 65 fd = fileno (fp); 66 if (fd < 0) 67 return fclose_nothrow (fp); 68 69 /* We only need to flush the file if it is not reading or if it is 70 seekable. This only guarantees the file position of input files 71 if the fflush module is also in use. */ 72 if ((!freading (fp) || lseek (fileno (fp), 0, SEEK_CUR) != -1) 73 && fflush (fp)) 74 saved_errno = errno; 75 76 /* fclose() calls close(), but we need to also invoke all hooks that our 77 overridden close() function invokes. See lib/close.c. */ 78 #if WINDOWS_SOCKETS 79 /* Call the overridden close(), then the original fclose(). 80 Note about multithread-safety: There is a race condition where some 81 other thread could open fd between our close and fclose. */ 82 if (close (fd) < 0 && saved_errno == 0) 83 saved_errno = errno; 84 85 fclose_nothrow (fp); /* will fail with errno = EBADF, 86 if we did not lose a race */ 87 88 #else /* !WINDOWS_SOCKETS */ 89 /* Call fclose() and invoke all hooks of the overridden close(). */ 90 91 # if REPLACE_FCHDIR 92 /* Note about multithread-safety: There is a race condition here as well. 93 Some other thread could open fd between our calls to fclose and 94 _gl_unregister_fd. */ 95 result = fclose_nothrow (fp); 96 if (result == 0) 97 _gl_unregister_fd (fd); 98 # else 99 /* No race condition here. */ 100 result = fclose_nothrow (fp); 101 # endif 102 103 #endif /* !WINDOWS_SOCKETS */ 104 105 if (saved_errno != 0) 106 { 107 errno = saved_errno; 108 result = EOF; 109 } 110 111 return result; 112 }