Mercurial > hg > octave-kai > gnulib-hg
annotate lib/ftruncate.c @ 2886:dc65428d47a6
*** empty log message ***
| author | Jim Meyering <jim@meyering.net> |
|---|---|
| date | Tue, 17 Oct 2000 06:45:57 +0000 |
| parents | 38fd8f5d359d |
| children | a535859efd14 |
| 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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9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
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parents:
316
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4 #if HAVE_CONFIG_H |
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9ad625a30b7d
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parents:
316
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5 # include <config.h> |
| 291 | 6 #endif |
| 5 | 7 |
| 8 #include <sys/types.h> | |
| 9 #include <fcntl.h> | |
| 10 | |
| 11 #ifdef F_CHSIZE | |
| 291 | 12 |
| 5 | 13 int |
| 1557 | 14 ftruncate (int fd, off_t length) |
| 5 | 15 { |
| 16 return fcntl (fd, F_CHSIZE, length); | |
| 17 } | |
| 291 | 18 |
| 19 #else /* not F_CHSIZE */ | |
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9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
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20 # ifdef F_FREESP |
| 291 | 21 |
| 22 /* By William Kucharski <kucharsk@netcom.com>. */ | |
| 5 | 23 |
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9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
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parents:
316
diff
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24 # include <sys/stat.h> |
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9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
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25 # include <errno.h> |
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9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
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26 # if HAVE_UNISTD_H |
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9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
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27 # include <unistd.h> |
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9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
28 # endif |
| 5 | 29 |
| 30 int | |
| 1557 | 31 ftruncate (int fd, off_t length) |
| 5 | 32 { |
| 33 struct flock fl; | |
| 34 struct stat filebuf; | |
| 35 | |
| 36 if (fstat (fd, &filebuf) < 0) | |
| 37 return -1; | |
| 38 | |
| 39 if (filebuf.st_size < length) | |
| 40 { | |
| 41 /* Extend file length. */ | |
| 42 if (lseek (fd, (length - 1), SEEK_SET) < 0) | |
| 43 return -1; | |
| 44 | |
| 45 /* Write a "0" byte. */ | |
| 46 if (write (fd, "", 1) != 1) | |
| 47 return -1; | |
| 48 } | |
| 49 else | |
| 50 { | |
| 291 | 51 |
| 5 | 52 /* Truncate length. */ |
| 291 | 53 |
| 5 | 54 fl.l_whence = 0; |
| 55 fl.l_len = 0; | |
| 56 fl.l_start = length; | |
| 291 | 57 fl.l_type = F_WRLCK; /* write lock on file space */ |
| 5 | 58 |
| 291 | 59 /* This relies on the *undocumented* F_FREESP argument to fcntl, |
| 60 which truncates the file so that it ends at the position | |
| 61 indicated by fl.l_start. Will minor miracles never cease? */ | |
| 62 | |
| 5 | 63 if (fcntl (fd, F_FREESP, &fl) < 0) |
| 64 return -1; | |
| 65 } | |
| 66 | |
| 67 return 0; | |
| 68 } | |
| 291 | 69 |
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1278
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
70 # else /* not F_CHSIZE nor F_FREESP */ |
|
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
71 # if HAVE_CHSIZE |
| 291 | 72 |
| 5 | 73 int |
| 1557 | 74 ftruncate (int fd, off_t length) |
| 5 | 75 { |
| 76 return chsize (fd, length); | |
| 77 } | |
| 291 | 78 |
|
1278
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
79 # else /* not F_CHSIZE nor F_FREESP nor HAVE_CHSIZE */ |
| 291 | 80 |
|
1278
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
81 # include <errno.h> |
|
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
82 # ifndef errno |
| 293 | 83 extern int errno; |
|
1278
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
84 # endif |
| 293 | 85 |
| 291 | 86 int |
| 1557 | 87 ftruncate (int fd, off_t length) |
| 291 | 88 { |
| 89 errno = EIO; | |
| 90 return -1; | |
| 91 } | |
| 92 | |
|
1278
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
93 # endif /* not HAVE_CHSIZE */ |
|
9ad625a30b7d
Use #if, not #ifdef with HAVE_ macros
Jim Meyering <jim@meyering.net>
parents:
316
diff
changeset
|
94 # endif /* not F_FREESP */ |
| 291 | 95 #endif /* not F_CHSIZE */ |