Implement posix_fallocate with set_len() functionality
#4664
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| // only macos doesn't support `posix_fallocate` | ||
| "posix_fallocate" if &*this.tcx.sess.target.os != "macos" => { |
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Not sure if this is the correct way, from what I could find online, only macos doesn't implement posix_fallocate.
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If that is the case then the test should also be for all OSes except macos.
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Also, please check pipe2 for how we make a shim available only on some OSes. Please do not use a match guard.
| let ebadf = Scalar::from_i32(this.eval_libc_i32("EBADF")); | ||
| let einval = Scalar::from_i32(this.eval_libc_i32("EINVAL")); | ||
| let enodev = Scalar::from_i32(this.eval_libc_i32("ENODEV")); |
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I think it's better to just inline these where they are needed; the error path shouldn't take so much space on the happy path.
Also, you can use eval_libc instead of Scalar::from_i32(eval_libc_i32).
| return interp_ok(einval); | ||
| } | ||
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| if file.writable { |
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Please make this more like
if !file.writable { return error; }to avoid rightwards drift
| Err(err) => return this.io_error_to_errnum(err), | ||
| }; | ||
| let new_size = match offset.checked_add(len) { | ||
| Some(size) => size.try_into().unwrap(), // We just checked negative `offset` and `len`. |
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Please change this code so it is clear what type we are converting this into.
Also the comment does not explain why the size would fit into the target type.
| // `posix_fallocate` only specifies increasing the file size. | ||
| if current_size < new_size { | ||
| let result = file.file.set_len(new_size); | ||
| let result = this.try_unwrap_io_result(result.map(|_| 0i32))?; |
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This can set the errno. Didn't you say the function does not do that?
| Ok(metadata) => metadata.len(), | ||
| Err(err) => return this.io_error_to_errnum(err), | ||
| }; | ||
| let new_size = match offset.checked_add(len) { |
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IIUC, if this operation overflows we should return EFBIG.
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should close #4464.
I used this man page for the implementation.
Changes included in this pr:
posix_fallocateandposix_fallocate64(same as truncate versions because of libc::off_t)unix/foreign_items.pass-dep/libc/libc-fs.rs.