1posix_fallocate(3C) Standard C Library Functions posix_fallocate(3C)
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6 posix_fallocate - file space control
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9 #include <fcntl.h>
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11 int posix_fallocate(int fd, off_t offset, off_t len);
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15 The posix_fallocate() function ensures that any required storage for
16 regular file data starting at offset and continuing for len bytes is
17 allocated on the file system storage media. If posix_fallocate()
18 returns successfully, subsequent writes to the specified file data will
19 not fail due to the lack of free space on the file system storage
20 media.
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23 If the offset+len is beyond the current file size, then posix_fallo‐
24 cate() adjusts the file size to offset+len. Otherwise, the file size is
25 not changed.
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28 Space allocated with posix_fallocate() is freed by a successful call to
29 creat(2) or open(2) that truncates the size of the file. Space allo‐
30 cated with posix_fallocate() may be freed by a successful call to
31 ftruncate(3C) that reduces the file size to a size smaller than off‐
32 set+len.
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35 Upon successful completion, posix_fallocate() returns zero. Otherwise,
36 an error number is returned to indicate the error.
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39 The posix_fallocate() function will fail if:
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41 EBADF The fd argument is not a valid file descriptor or references
42 a file that was opened without write permission.
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45 EFBIG The value of offset+len is greater than the maximum file
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49 EINTR A signal was caught during execution.
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52 EINVAL The len argument is less than or equal to zero, or the offset
53 argument is less than zero, or the underlying file system
54 does not support this operation.
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57 EIO An I/O error occurred while reading from or writing to a file
58 system.
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61 ENODEV The fd argument does not refer to a regular file.
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64 ENOSPC There is insufficient free space remaining on the file system
65 storage media.
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68 ESPIPE The fd argument is associated with a pipe or FIFO.
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72 The posix_fallocate() function has a transitional interface for 64-bit
73 file offsets. See lf64(5).
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76 See attributes(5) for descriptions of the following attributes:
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81 ┌─────────────────────────────┬─────────────────────────────┐
82 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
83 ├─────────────────────────────┼─────────────────────────────┤
84 │Interface Stability │Committed │
85 ├─────────────────────────────┼─────────────────────────────┤
86 │MT-Level │MT-Safe │
87 ├─────────────────────────────┼─────────────────────────────┤
88 │Standard │See standards(5). │
89 └─────────────────────────────┴─────────────────────────────┘
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92 creat(2), open(2), unlink(2), ftruncate(3C), attributes(5), stan‐
93 dards(5)
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97SunOS 5.11 14 Jul 2008 posix_fallocate(3C)