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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:02:58 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:02:58 +0000
commit698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch)
tree173a775858bd501c378080a10dca74132f05bc50 /library/backtrace/src/symbolize/gimli/libs_macos.rs
parentInitial commit. (diff)
downloadrustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz
rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'library/backtrace/src/symbolize/gimli/libs_macos.rs')
-rw-r--r--library/backtrace/src/symbolize/gimli/libs_macos.rs146
1 files changed, 146 insertions, 0 deletions
diff --git a/library/backtrace/src/symbolize/gimli/libs_macos.rs b/library/backtrace/src/symbolize/gimli/libs_macos.rs
new file mode 100644
index 000000000..17703b88a
--- /dev/null
+++ b/library/backtrace/src/symbolize/gimli/libs_macos.rs
@@ -0,0 +1,146 @@
+#![allow(deprecated)]
+
+use super::mystd::ffi::{CStr, OsStr};
+use super::mystd::os::unix::prelude::*;
+use super::mystd::prelude::v1::*;
+use super::{Library, LibrarySegment};
+use core::convert::TryInto;
+use core::mem;
+
+pub(super) fn native_libraries() -> Vec<Library> {
+ let mut ret = Vec::new();
+ let images = unsafe { libc::_dyld_image_count() };
+ for i in 0..images {
+ ret.extend(native_library(i));
+ }
+ return ret;
+}
+
+fn native_library(i: u32) -> Option<Library> {
+ use object::macho;
+ use object::read::macho::{MachHeader, Segment};
+ use object::NativeEndian;
+
+ // Fetch the name of this library which corresponds to the path of
+ // where to load it as well.
+ let name = unsafe {
+ let name = libc::_dyld_get_image_name(i);
+ if name.is_null() {
+ return None;
+ }
+ CStr::from_ptr(name)
+ };
+
+ // Load the image header of this library and delegate to `object` to
+ // parse all the load commands so we can figure out all the segments
+ // involved here.
+ let (mut load_commands, endian) = unsafe {
+ let header = libc::_dyld_get_image_header(i);
+ if header.is_null() {
+ return None;
+ }
+ match (*header).magic {
+ macho::MH_MAGIC => {
+ let endian = NativeEndian;
+ let header = &*(header as *const macho::MachHeader32<NativeEndian>);
+ let data = core::slice::from_raw_parts(
+ header as *const _ as *const u8,
+ mem::size_of_val(header) + header.sizeofcmds.get(endian) as usize,
+ );
+ (header.load_commands(endian, data, 0).ok()?, endian)
+ }
+ macho::MH_MAGIC_64 => {
+ let endian = NativeEndian;
+ let header = &*(header as *const macho::MachHeader64<NativeEndian>);
+ let data = core::slice::from_raw_parts(
+ header as *const _ as *const u8,
+ mem::size_of_val(header) + header.sizeofcmds.get(endian) as usize,
+ );
+ (header.load_commands(endian, data, 0).ok()?, endian)
+ }
+ _ => return None,
+ }
+ };
+
+ // Iterate over the segments and register known regions for segments
+ // that we find. Additionally record information bout text segments
+ // for processing later, see comments below.
+ let mut segments = Vec::new();
+ let mut first_text = 0;
+ let mut text_fileoff_zero = false;
+ while let Some(cmd) = load_commands.next().ok()? {
+ if let Some((seg, _)) = cmd.segment_32().ok()? {
+ if seg.name() == b"__TEXT" {
+ first_text = segments.len();
+ if seg.fileoff(endian) == 0 && seg.filesize(endian) > 0 {
+ text_fileoff_zero = true;
+ }
+ }
+ segments.push(LibrarySegment {
+ len: seg.vmsize(endian).try_into().ok()?,
+ stated_virtual_memory_address: seg.vmaddr(endian).try_into().ok()?,
+ });
+ }
+ if let Some((seg, _)) = cmd.segment_64().ok()? {
+ if seg.name() == b"__TEXT" {
+ first_text = segments.len();
+ if seg.fileoff(endian) == 0 && seg.filesize(endian) > 0 {
+ text_fileoff_zero = true;
+ }
+ }
+ segments.push(LibrarySegment {
+ len: seg.vmsize(endian).try_into().ok()?,
+ stated_virtual_memory_address: seg.vmaddr(endian).try_into().ok()?,
+ });
+ }
+ }
+
+ // Determine the "slide" for this library which ends up being the
+ // bias we use to figure out where in memory objects are loaded.
+ // This is a bit of a weird computation though and is the result of
+ // trying a few things in the wild and seeing what sticks.
+ //
+ // The general idea is that the `bias` plus a segment's
+ // `stated_virtual_memory_address` is going to be where in the
+ // actual address space the segment resides. The other thing we rely
+ // on though is that a real address minus the `bias` is the index to
+ // look up in the symbol table and debuginfo.
+ //
+ // It turns out, though, that for system loaded libraries these
+ // calculations are incorrect. For native executables, however, it
+ // appears correct. Lifting some logic from LLDB's source it has
+ // some special-casing for the first `__TEXT` section loaded from
+ // file offset 0 with a nonzero size. For whatever reason when this
+ // is present it appears to mean that the symbol table is relative
+ // to just the vmaddr slide for the library. If it's *not* present
+ // then the symbol table is relative to the the vmaddr slide plus
+ // the segment's stated address.
+ //
+ // To handle this situation if we *don't* find a text section at
+ // file offset zero then we increase the bias by the first text
+ // sections's stated address and decrease all stated addresses by
+ // that amount as well. That way the symbol table is always appears
+ // relative to the library's bias amount. This appears to have the
+ // right results for symbolizing via the symbol table.
+ //
+ // Honestly I'm not entirely sure whether this is right or if
+ // there's something else that should indicate how to do this. For
+ // now though this seems to work well enough (?) and we should
+ // always be able to tweak this over time if necessary.
+ //
+ // For some more information see #318
+ let mut slide = unsafe { libc::_dyld_get_image_vmaddr_slide(i) as usize };
+ if !text_fileoff_zero {
+ let adjust = segments[first_text].stated_virtual_memory_address;
+ for segment in segments.iter_mut() {
+ segment.stated_virtual_memory_address -= adjust;
+ }
+ slide += adjust;
+ }
+
+ Some(Library {
+ name: OsStr::from_bytes(name.to_bytes()).to_owned(),
+ segments,
+ bias: slide,
+ })
+}