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POSIX_FALLOCATE(2) System Calls Manual POSIX_FALLOCATE(2) NAME posix_fallocate -- pre-allocate storage for a range in a file LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <fcntl.h> int posix_fallocate(int fd, off_t offset, off_t len); DESCRIPTION Required storage for the range offset to offset + len in the file refer- enced by fd is guaranteed to be allocated upon successful return. That is, if posix_fallocate() returns successfully, subsequent writes to the speci- fied file data will not fail due to lack of free space on the file system storage media. Any existing file data in the specified range is unmodi- fied. If offset + len is beyond the current file size, then posix_fallo- cate() will adjust the file size to offset + len. Otherwise, the file size will not be changed. Space allocated by posix_fallocate() will be freed by a successful call to creat(2) or open(2) that truncates the size of the file. Space allocated via posix_fallocate() may be freed by a successful call to ftruncate(2) that reduces the file size to a size smaller than offset + len. RETURN VALUES If successful, posix_fallocate() returns zero. It returns an error on failure, without setting errno. ERRORS Possible failure conditions: [EBADF] The fd argument is not a valid file descriptor. [EBADF] The fd argument references a file that was opened with- out write permission. [EFBIG] The value of offset + len is greater than the maximum file size. [EINTR] A signal was caught during execution. [EINVAL] The len argument was less than or equal to zero, the offset argument was less than zero, or the operation is not supported by the file system. [EIO] An I/O error occurred while reading from or writing to a file system. [EINTEGRITY] Corrupted data was detected while reading from the file system. [ENODEV] The fd argument does not refer to a file that supports posix_fallocate. [ENOSPC] There is insufficient free space remaining on the file system storage media. [ENOTCAPABLE] The file descriptor fd has insufficient rights. [ESPIPE] The fd argument is associated with a pipe or FIFO. SEE ALSO creat(2), ftruncate(2), open(2), unlink(2) STANDARDS The posix_fallocate() system call conforms to IEEE Std 1003.1-2004 ("POSIX.1"). HISTORY The posix_fallocate() function appeared in FreeBSD 9.0. AUTHORS posix_fallocate() and this manual page were initially written by Matthew Fleming <mdf@FreeBSD.org>. FreeBSD ports 15.quarterly March 30, 2020 POSIX_FALLOCATE(2)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY | AUTHORS
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