Mercurial > hg > octave-shane > gnulib-hg
annotate lib/ftruncate.c @ 8199:51d32a83a7df
Move more declarations into <unistd.h>.
| author | Bruno Haible <bruno@clisp.org> |
|---|---|
| date | Mon, 19 Feb 2007 02:23:32 +0000 |
| parents | 8a1a9361108c |
| children | 717accda417a |
| rev | line source |
|---|---|
| 5 | 1 /* ftruncate emulations that work on some System V's. |
| 291 | 2 This file is in the public domain. */ |
| 3 | |
|
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* _fpending.c: Include <config.h> unconditionally, since we no
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4 #include <config.h> |
| 5 | 5 |
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51d32a83a7df
Move more declarations into <unistd.h>.
Bruno Haible <bruno@clisp.org>
parents:
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6 /* Specification. */ |
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51d32a83a7df
Move more declarations into <unistd.h>.
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7 #include <unistd.h> |
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51d32a83a7df
Move more declarations into <unistd.h>.
Bruno Haible <bruno@clisp.org>
parents:
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diff
changeset
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8 |
| 5 | 9 #include <sys/types.h> |
| 10 #include <fcntl.h> | |
| 11 | |
| 12 #ifdef F_CHSIZE | |
| 291 | 13 |
| 5 | 14 int |
| 1557 | 15 ftruncate (int fd, off_t length) |
| 5 | 16 { |
| 17 return fcntl (fd, F_CHSIZE, length); | |
| 18 } | |
| 291 | 19 |
| 20 #else /* not F_CHSIZE */ | |
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Use #if, not #ifdef with HAVE_ macros
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21 # ifdef F_FREESP |
| 291 | 22 |
| 23 /* By William Kucharski <kucharsk@netcom.com>. */ | |
| 5 | 24 |
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Use #if, not #ifdef with HAVE_ macros
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25 # include <sys/stat.h> |
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26 # include <errno.h> |
| 5 | 27 |
| 28 int | |
| 1557 | 29 ftruncate (int fd, off_t length) |
| 5 | 30 { |
| 31 struct flock fl; | |
| 32 struct stat filebuf; | |
| 33 | |
| 34 if (fstat (fd, &filebuf) < 0) | |
| 35 return -1; | |
| 36 | |
| 37 if (filebuf.st_size < length) | |
| 38 { | |
| 39 /* Extend file length. */ | |
| 40 if (lseek (fd, (length - 1), SEEK_SET) < 0) | |
| 41 return -1; | |
| 42 | |
| 43 /* Write a "0" byte. */ | |
| 44 if (write (fd, "", 1) != 1) | |
| 45 return -1; | |
| 46 } | |
| 47 else | |
| 48 { | |
| 291 | 49 |
| 5 | 50 /* Truncate length. */ |
| 291 | 51 |
| 5 | 52 fl.l_whence = 0; |
| 53 fl.l_len = 0; | |
| 54 fl.l_start = length; | |
| 291 | 55 fl.l_type = F_WRLCK; /* write lock on file space */ |
| 5 | 56 |
| 291 | 57 /* This relies on the *undocumented* F_FREESP argument to fcntl, |
| 58 which truncates the file so that it ends at the position | |
| 59 indicated by fl.l_start. Will minor miracles never cease? */ | |
| 60 | |
| 5 | 61 if (fcntl (fd, F_FREESP, &fl) < 0) |
| 62 return -1; | |
| 63 } | |
| 64 | |
| 65 return 0; | |
| 66 } | |
| 291 | 67 |
|
1278
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
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68 # else /* not F_CHSIZE nor F_FREESP */ |
|
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
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69 # if HAVE_CHSIZE |
| 291 | 70 |
| 5 | 71 int |
| 1557 | 72 ftruncate (int fd, off_t length) |
| 5 | 73 { |
| 74 return chsize (fd, length); | |
| 75 } | |
| 291 | 76 |
|
1278
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
77 # else /* not F_CHSIZE nor F_FREESP nor HAVE_CHSIZE */ |
| 291 | 78 |
|
1278
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
79 # include <errno.h> |
| 293 | 80 |
| 291 | 81 int |
| 1557 | 82 ftruncate (int fd, off_t length) |
| 291 | 83 { |
| 84 errno = EIO; | |
| 85 return -1; | |
| 86 } | |
| 87 | |
|
1278
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
88 # endif /* not HAVE_CHSIZE */ |
|
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
89 # endif /* not F_FREESP */ |
| 291 | 90 #endif /* not F_CHSIZE */ |