1 /* Invoke tmpfile, but avoid some glitches. 2 Copyright (C) 2006, 2009-2021 Free Software Foundation, Inc. 3 4 This program is free software: you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 3 of the License, or 7 (at your option) any later version. 8 9 This program 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 General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 16 17 /* Written by Eric Blake, based on ideas from Paul Eggert. */ 18 19 #include <config.h> 20 21 #include "stdio-safer.h" 22 23 #include <errno.h> 24 #include <unistd.h> 25 #include "unistd-safer.h" 26 27 #include "binary-io.h" 28 29 /* Like tmpfile, but do not return stdin, stdout, or stderr. 30 31 Remember that tmpfile can leave files behind if your program calls _exit, 32 so this function should not be mixed with the close_stdout module. */ 33 34 FILE * 35 tmpfile_safer (void) /* */ 36 { 37 FILE *fp = tmpfile (); 38 39 if (fp) 40 { 41 int fd = fileno (fp); 42 43 if (0 <= fd && fd <= STDERR_FILENO) 44 { 45 int f = dup_safer (fd); 46 47 if (f < 0) 48 { 49 int e = errno; 50 fclose (fp); 51 errno = e; 52 return NULL; 53 } 54 55 /* Keep the temporary file in binary mode, on platforms 56 where that matters. */ 57 if (fclose (fp) != 0 58 || ! (fp = fdopen (f, O_BINARY ? "wb+" : "w+"))) 59 { 60 int e = errno; 61 close (f); 62 errno = e; 63 return NULL; 64 } 65 } 66 } 67 68 return fp; 69 }