Code 87 when attempting to write files

[asevans48]

Issue

The program can read files but switching to a mutable map in memmap-rs or memmap2 on Windows breaks due to an inappropriate call to Windows. The resulting error is a code 87 incorrect parameter error. I would love some guidance on what the actual issue is or a patch as I am actively trying to build a cache system after all other options appear to have moved to a NoSQL database due to popularity. My goal is to achieve a near-real-time tracking system for streaming ETL. Memory mapping allows me to avoid constantly loading files from memory in a SQL-lite memory-mapped style approach to storage.

Action

Switch from an immutable memory map to a mutable map.

Code in memmap/memmap2/memmap-rs

let mut file2 = File::open("E:\testfiles\mmap\test.mmap").unwrap();
let map = unsafe{MmapOptions::new().map(&file2).unwrap()};
let mut mut_map = map.make_mut().unwrap();

Expected Result

The retrieval of a writable/mutable memory mapping.

Actual Result

The action on line 3 fails with an apparent winapi issue:

thread 'main' panicked at 'called Result::unwrap() on an Err value: Os { code: 87, kind: Other, message: "The parameter is incorrect." }', src\main.rs:35:23

Stack Trace

thread 'main' panicked at 'called Result::unwrap() on an Err value: Os { code: 87, kind: Other, message: "The parameter is incorrect." }', src\main.rs:35:23
stack backtrace:
0: backtrace::backtrace::trace_unsynchronized
at C:\Users\VssAdministrator.cargo\registry\src\github.com-1ecc6299db9ec823\backtrace-0.3.46\src\backtrace\mod.rs:66
1: std::sys_common::backtrace::_print_fmt
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\sys_common\backtrace.rs:78
2: std::sys_common::backtrace::_print::{{impl}}::fmt
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\sys_common\backtrace.rs:59
3: core::fmt::write
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libcore\fmt\mod.rs:1076
4: std::io::Write::write_fmtstd::sys::windows::stdio::Stderr
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\io\mod.rs:1537
5: std::sys_common::backtrace::_print
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\sys_common\backtrace.rs:62
6: std::sys_common::backtrace::print
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\sys_common\backtrace.rs:49
7: std::panicking::default_hook::{{closure}}
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\panicking.rs:198
8: std::panicking::default_hook
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\panicking.rs:218
9: std::panicking::rust_panic_with_hook
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\panicking.rs:486
10: std::panicking::begin_panic_handler
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\panicking.rs:388
11: core::panicking::panic_fmt
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libcore\panicking.rs:101
12: core::option::expect_none_failed
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libcore\option.rs:1272
13: core::result::Result<memmap::MmapMut, std::io::error::Error>::unwrapmemmap::MmapMut,std::io::error::Error
at C:\Users\aseva.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libcore\result.rs:1005
14: test_other_stuff::main
at .\src\main.rs:35
15: std::rt::lang_start::{{closure}}<()>
at C:\Users\aseva.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libstd\rt.rs:67
16: std::rt::lang_start_internal::{{closure}}
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\rt.rs:52
17: std::panicking::try::do_call
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\panicking.rs:297
18: std::panicking::try
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\panicking.rs:274
19: std::panic::catch_unwind
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\panic.rs:394
20: std::rt::lang_start_internal
at /rustc/fe10f1a49f5ca46e57261b95f46f519523f418fe/src\libstd\rt.rs:51
21: std::rt::lang_start<()>
at C:\Users\aseva.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libstd\rt.rs:67
22: main
23: invoke_main
at d:\agent_work\3\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:78
24: __scrt_common_main_seh
at d:\agent_work\3\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288
25: BaseThreadInitThunk
26: RtlUserThreadStart
note: Some details are omitted, run with RUST_BACKTRACE=full for a verbose backtrace.
error: process didn't exit successfully: target\debug\test-other-stuff.exe (exit code: 101)

[asevans48]

I found the problem. It was my firewall. Sorry guys. Had me hammering at file permissions and all kinds of things.