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os.getenvW: Fix case-insensitivity for Unicode env var names

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Windows does Unicode-aware case-insensitivity comparisons for environment variable names. Before, os.getenvW was only doing ASCII case-insensitivity. We can take advantage of RtlEqualUnicodeString in NtDll to get the proper Unicode case insensitivity.
This commit is contained in:
Ryan Liptak 2022-01-15 04:56:32 -08:00
parent 8841a71aa6
commit c87f79c957
2 changed files with 22 additions and 15 deletions
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31
lib/std/os.zig
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@ -1715,15 +1715,13 @@ pub fn getenvZ(key: [*:0]const u8) ?[]const u8 {
/// Windows-only. Get an environment variable with a null-terminated, WTF-16 encoded name.
/// See also `getenv`.
/// This function first attempts a case-sensitive lookup. If no match is found, and `key`
/// is ASCII, then it attempts a second case-insensitive lookup.
/// This function performs a Unicode-aware case-insensitive lookup using RtlEqualUnicodeString.
pub fn getenvW(key: [*:0]const u16) ?[:0]const u16 {
if (builtin.os.tag != .windows) {
@compileError("std.os.getenvW is a Windows-only API");
}
const key_slice = mem.sliceTo(key, 0);
const ptr = windows.peb().ProcessParameters.Environment;
var ascii_match: ?[:0]const u16 = null;
var i: usize = 0;
while (ptr[i] != 0) {
const key_start = i;
@ -1737,22 +1735,25 @@ pub fn getenvW(key: [*:0]const u16) ?[:0]const u16 {
while (ptr[i] != 0) : (i += 1) {}
const this_value = ptr[value_start..i :0];
if (mem.eql(u16, key_slice, this_key)) return this_value;
ascii_check: {
if (ascii_match != null) break :ascii_check;
if (key_slice.len != this_key.len) break :ascii_check;
for (key_slice) |a_c, key_index| {
const a = math.cast(u8, a_c) catch break :ascii_check;
const b = math.cast(u8, this_key[key_index]) catch break :ascii_check;
if (std.ascii.toLower(a) != std.ascii.toLower(b)) break :ascii_check;
}
ascii_match = this_value;
const key_string_bytes = @intCast(u16, key_slice.len * 2);
const key_string = windows.UNICODE_STRING{
.Length = key_string_bytes,
.MaximumLength = key_string_bytes,
.Buffer = @intToPtr([*]u16, @ptrToInt(key)),
};
const this_key_string_bytes = @intCast(u16, this_key.len * 2);
const this_key_string = windows.UNICODE_STRING{
.Length = this_key_string_bytes,
.MaximumLength = this_key_string_bytes,
.Buffer = this_key.ptr,
};
if (windows.ntdll.RtlEqualUnicodeString(&key_string, &this_key_string, windows.TRUE) == windows.TRUE) {
return this_value;
}
i += 1; // skip over null byte
}
return ascii_match;
return null;
}
pub const GetCwdError = error{

6
lib/std/os/windows/ntdll.zig
View File

@ -223,6 +223,12 @@ pub extern "ntdll" fn RtlWaitOnAddress(
Timeout: ?*const LARGE_INTEGER,
) callconv(WINAPI) NTSTATUS;
pub extern "ntdll" fn RtlEqualUnicodeString(
String1: *const UNICODE_STRING,
String2: *const UNICODE_STRING,
CaseInSensitive: BOOLEAN,
) callconv(WINAPI) BOOLEAN;
pub extern "ntdll" fn NtLockFile(
FileHandle: HANDLE,
Event: ?HANDLE,