| 1 | /* ftruncate emulations that work on some System V's. |
| 2 | This file is in the public domain. */ |
| 3 | |
| 4 | /* Copyright (C) 2012-2017 Free Software Foundation, Inc. |
| 5 | |
| 6 | This file is part of gold. |
| 7 | |
| 8 | This program is free software; you can redistribute it and/or modify |
| 9 | it under the terms of the GNU General Public License as published by |
| 10 | the Free Software Foundation; either version 3 of the License, or |
| 11 | (at your option) any later version. |
| 12 | |
| 13 | This program is distributed in the hope that it will be useful, |
| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | GNU General Public License for more details. |
| 17 | |
| 18 | You should have received a copy of the GNU General Public License |
| 19 | along with this program; if not, write to the Free Software |
| 20 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 21 | MA 02110-1301, USA. */ |
| 22 | |
| 23 | #include <config.h> |
| 24 | |
| 25 | /* Specification. */ |
| 26 | #include <unistd.h> |
| 27 | |
| 28 | #include <sys/types.h> |
| 29 | #include <fcntl.h> |
| 30 | |
| 31 | extern int ftruncate (int, off_t); |
| 32 | |
| 33 | #ifdef F_CHSIZE |
| 34 | |
| 35 | int |
| 36 | ftruncate (int fd, off_t length) |
| 37 | { |
| 38 | return fcntl (fd, F_CHSIZE, length); |
| 39 | } |
| 40 | |
| 41 | #else /* not F_CHSIZE */ |
| 42 | # ifdef F_FREESP |
| 43 | |
| 44 | /* By William Kucharski <kucharsk@netcom.com>. */ |
| 45 | |
| 46 | # include <sys/stat.h> |
| 47 | # include <errno.h> |
| 48 | |
| 49 | int |
| 50 | ftruncate (int fd, off_t length) |
| 51 | { |
| 52 | struct flock fl; |
| 53 | struct stat filebuf; |
| 54 | |
| 55 | if (fstat (fd, &filebuf) < 0) |
| 56 | return -1; |
| 57 | |
| 58 | if (filebuf.st_size < length) |
| 59 | { |
| 60 | /* Extend file length. */ |
| 61 | if (lseek (fd, (length - 1), SEEK_SET) < 0) |
| 62 | return -1; |
| 63 | |
| 64 | /* Write a "0" byte. */ |
| 65 | if (write (fd, "", 1) != 1) |
| 66 | return -1; |
| 67 | } |
| 68 | else |
| 69 | { |
| 70 | |
| 71 | /* Truncate length. */ |
| 72 | |
| 73 | fl.l_whence = 0; |
| 74 | fl.l_len = 0; |
| 75 | fl.l_start = length; |
| 76 | fl.l_type = F_WRLCK; /* write lock on file space */ |
| 77 | |
| 78 | /* This relies on the *undocumented* F_FREESP argument to fcntl, |
| 79 | which truncates the file so that it ends at the position |
| 80 | indicated by fl.l_start. Will minor miracles never cease? */ |
| 81 | |
| 82 | if (fcntl (fd, F_FREESP, &fl) < 0) |
| 83 | return -1; |
| 84 | } |
| 85 | |
| 86 | return 0; |
| 87 | } |
| 88 | |
| 89 | # else /* not F_CHSIZE nor F_FREESP */ |
| 90 | # if HAVE_CHSIZE /* native Windows, e.g. mingw */ |
| 91 | |
| 92 | int |
| 93 | ftruncate (int fd, off_t length) |
| 94 | { |
| 95 | return chsize (fd, length); |
| 96 | } |
| 97 | |
| 98 | # else /* not F_CHSIZE nor F_FREESP nor HAVE_CHSIZE */ |
| 99 | |
| 100 | # include <errno.h> |
| 101 | |
| 102 | int |
| 103 | ftruncate (int fd, off_t length) |
| 104 | { |
| 105 | errno = EIO; |
| 106 | return -1; |
| 107 | } |
| 108 | |
| 109 | # endif /* not HAVE_CHSIZE */ |
| 110 | # endif /* not F_FREESP */ |
| 111 | #endif /* not F_CHSIZE */ |