std\backtrace\src\symbolize\gimli/
libs_windows.rs

1use super::super::super::windows_sys::*;
2use super::mystd::ffi::OsString;
3use super::mystd::os::windows::prelude::*;
4use super::{coff, mmap, Library, LibrarySegment};
5use alloc::vec;
6use alloc::vec::Vec;
7use core::mem;
8use core::mem::MaybeUninit;
9
10// For loading native libraries on Windows, see some discussion on
11// rust-lang/rust#71060 for the various strategies here.
12pub(super) fn native_libraries() -> Vec<Library> {
13    let mut ret = Vec::new();
14    unsafe {
15        add_loaded_images(&mut ret);
16    }
17    return ret;
18}
19
20unsafe fn add_loaded_images(ret: &mut Vec<Library>) {
21    unsafe {
22        let snap = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, 0);
23        if snap == INVALID_HANDLE_VALUE {
24            return;
25        }
26
27        // huge struct, probably should avoid manually initializing it even if we can
28        let mut me = MaybeUninit::<MODULEENTRY32W>::zeroed().assume_init();
29        me.dwSize = mem::size_of_val(&me) as u32;
30        if Module32FirstW(snap, &mut me) == TRUE {
31            loop {
32                if let Some(lib) = load_library(&me) {
33                    ret.push(lib);
34                }
35
36                if Module32NextW(snap, &mut me) != TRUE {
37                    break;
38                }
39            }
40        }
41
42        CloseHandle(snap);
43    }
44}
45
46unsafe fn load_library(me: &MODULEENTRY32W) -> Option<Library> {
47    let pos = me
48        .szExePath
49        .iter()
50        .position(|i| *i == 0)
51        .unwrap_or(me.szExePath.len());
52    let name = OsString::from_wide(&me.szExePath[..pos]);
53
54    // MinGW libraries currently don't support ASLR
55    // (rust-lang/rust#16514), but DLLs can still be relocated around in
56    // the address space. It appears that addresses in debug info are
57    // all as-if this library was loaded at its "image base", which is a
58    // field in its COFF file headers. Since this is what debuginfo
59    // seems to list we parse the symbol table and store addresses as if
60    // the library was loaded at "image base" as well.
61    //
62    // The library may not be loaded at "image base", however.
63    // (presumably something else may be loaded there?) This is where
64    // the `bias` field comes into play, and we need to figure out the
65    // value of `bias` here. Unfortunately though it's not clear how to
66    // acquire this from a loaded module. What we do have, however, is
67    // the actual load address (`modBaseAddr`).
68    //
69    // As a bit of a cop-out for now we mmap the file, read the file
70    // header information, then drop the mmap. This is wasteful because
71    // we'll probably reopen the mmap later, but this should work well
72    // enough for now.
73    //
74    // Once we have the `image_base` (desired load location) and the
75    // `base_addr` (actual load location) we can fill in the `bias`
76    // (difference between the actual and desired) and then the stated
77    // address of each segment is the `image_base` since that's what the
78    // file says.
79    //
80    // For now it appears that unlike ELF/MachO we can make do with one
81    // segment per library, using `modBaseSize` as the whole size.
82    let mmap = mmap(name.as_ref())?;
83    let image_base = coff::get_image_base(&mmap)?;
84    let base_addr = me.modBaseAddr as usize;
85    Some(Library {
86        name,
87        bias: base_addr.wrapping_sub(image_base),
88        segments: vec![LibrarySegment {
89            stated_virtual_memory_address: image_base,
90            len: me.modBaseSize as usize,
91        }],
92    })
93}
std\backtrace\src\symbolize\gimli/libs_windows.rs

std\backtrace\src\symbolize\gimli/
libs_windows.rs
