From c48348233c467f7dc96728a31710abbb12cbe1f1 Mon Sep 17 00:00:00 2001 From: Filipe David Manana Date: Tue, 28 Dec 2010 10:57:04 +0000 Subject: Add file:allocate/3 operation This operation allows pre-allocation of space for files. It succeeds only on systems that support such operation. The POSIX standard defines the optional system call posix_fallocate() to implement this feature. However, some systems implement more specific functions to accomplish the same operation. On Linux, if the more specific function fallocate() is implemented, it is used instead of posix_fallocate(), falling back to posix_fallocate() if the fallocate() call failed (it's only supported for the ext4, ocfs2, xfs and btrfs file systems at the moment). On Mac OS X it uses the specific fcntl() operation F_PREALLOCATE, falling back to posix_fallocate() if it's available (at the moment Mac OS X doesn't provide posix_fallocate()). On any other UNIX system, it uses posix_fallocate() if it's available. Any other system not providing this system call or any function to pre-allocate space for files, this operation always fails with the ENOTSUP POSIX error. --- lib/kernel/src/file.erl | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'lib/kernel/src/file.erl') diff --git a/lib/kernel/src/file.erl b/lib/kernel/src/file.erl index de3eaad5a1..16f2dde464 100644 --- a/lib/kernel/src/file.erl +++ b/lib/kernel/src/file.erl @@ -38,7 +38,7 @@ %% Specialized -export([ipread_s32bu_p32bu/3]). %% Generic file contents. --export([open/2, close/1, advise/4, +-export([open/2, close/1, advise/4, allocate/3, read/2, write/2, pread/2, pread/3, pwrite/2, pwrite/3, read_line/1, @@ -490,6 +490,18 @@ advise(#file_descriptor{module = Module} = Handle, Offset, Length, Advise) -> advise(_, _, _, _) -> {error, badarg}. +-spec allocate(File, Offset, Length) -> + 'ok' | {'error', posix()} when + File :: io_device(), + Offset :: non_neg_integer(), + Length :: non_neg_integer(). + +allocate(File, Offset, Length) when is_pid(File) -> + R = file_request(File, {allocate, Offset, Length}), + wait_file_reply(File, R); +allocate(#file_descriptor{module = Module} = Handle, Offset, Length) -> + Module:allocate(Handle, Offset, Length). + -spec read(IoDevice, Number) -> {ok, Data} | eof | {error, Reason} when IoDevice :: io_device() | atom(), Number :: non_neg_integer(), -- cgit v1.2.3