Function createWindowsEnvBlock [src]

Caller must free result.

Prototype

pub fn createWindowsEnvBlock(allocator: mem.Allocator, env_map: *const EnvMap) ![]u16

Parameters

allocator: mem.Allocatorenv_map: *const EnvMap

Source

  pub fn createWindowsEnvBlock(allocator: mem.Allocator, env_map: *const EnvMap) ![]u16 {
    // count bytes needed
    const max_chars_needed = x: {
        // Only need 2 trailing NUL code units for an empty environment
        var max_chars_needed: usize = if (env_map.count() == 0) 2 else 1;
        var it = env_map.iterator();
        while (it.next()) |pair| {
            // +1 for '='
            // +1 for null byte
            max_chars_needed += pair.key_ptr.len + pair.value_ptr.len + 2;
        }
        break :x max_chars_needed;
    };
    const result = try allocator.alloc(u16, max_chars_needed);
    errdefer allocator.free(result);

    var it = env_map.iterator();
    var i: usize = 0;
    while (it.next()) |pair| {
        i += try unicode.wtf8ToWtf16Le(result[i..], pair.key_ptr.*);
        result[i] = '=';
        i += 1;
        i += try unicode.wtf8ToWtf16Le(result[i..], pair.value_ptr.*);
        result[i] = 0;
        i += 1;
    }
    result[i] = 0;
    i += 1;
    // An empty environment is a special case that requires a redundant
    // NUL terminator. CreateProcess will read the second code unit even
    // though theoretically the first should be enough to recognize that the
    // environment is empty (see https://nullprogram.com/blog/2023/08/23/)
    if (env_map.count() == 0) {
        result[i] = 0;
        i += 1;
    }
    return try allocator.realloc(result, i);
}  