uwu

shell.nix

@@ -1,13 +1,9 @@
 { pkgs ? import <nixpkgs> { } }: pkgs.mkShell {
   buildInputs = with pkgs; [
-    rustup
     gcc
-    clang_16
+    clang_21
-    llvmPackages_16.bintools
+    llvmPackages_21.bintools
   ];
-  shellHook = ''
-    export PATH=$PATH:''${CARGO_HOME:-~/.cargo}/bin
-  '';
   packages = (with pkgs; [
     gef
     rust-bindgen

src/dwarf/divination.rs

@@ -43,6 +43,7 @@ struct EhFrameHeader {
     eh_frame_ptr_enc: Encoding,
     fde_count_enc: Encoding,
     table_enc: Encoding,
+    rest: (),
 }
 
 #[instrument]
@@ -93,9 +94,9 @@ pub(crate) fn eh_frame(addr: Addr) -> Option<*const u8> {
 
         trace!("eh_frame_hdr: {:?}", header);
 
-        let (read_size, eh_frame_ptr) = read_encoded(ptr, header.eh_frame_ptr_enc);
+        let (read_size, eh_frame_ptr) = read_encoded(ptr, header.eh_frame_ptr_enc, None);
         let ptr = ptr.add(read_size);
-        let (_read_size, fde_count) = read_encoded(ptr, header.fde_count_enc);
+        let (_read_size, fde_count) = read_encoded(ptr, header.fde_count_enc, None);
 
         trace!("eh_frame: {eh_frame_ptr:?}");
         trace!("fde_count: {fde_count:?}");
@@ -108,3 +109,96 @@ pub(crate) fn eh_frame(addr: Addr) -> Option<*const u8> {
         Some(eh_frame_ptr as *const u8)
     }
 }
+
+#[instrument]
+pub(crate) fn frame_info(addr: Addr) -> Option<()> {
+    unsafe {
+        let header_ptr = eh_frame_hdr_ptr(addr)?;
+        let eh_frame_header_addr = header_ptr.addr();
+        let header = header_ptr.read();
+
+        let ptr = (&raw const (*header_ptr).rest).cast::<u8>();
+        let (eh_frame_ptr_size, eh_frame_ptr) = read_encoded(ptr, header.eh_frame_ptr_enc, None);
+        let ptr = ptr.add(eh_frame_ptr_size);
+
+        let (fde_count_size, fde_count) =
+            read_encoded(ptr, header.fde_count_enc, Some(eh_frame_ptr));
+
+        trace!(?header.table_enc);
+
+        let table_ptr = ptr.add(fde_count_size);
+
+        let mut walk_table_ptr = table_ptr;
+        for i in 0..fde_count {
+            let (read, initial_loc) =
+                read_encoded(walk_table_ptr, header.table_enc, Some(eh_frame_header_addr));
+            walk_table_ptr = walk_table_ptr.add(read);
+            let (read, address) =
+                read_encoded(walk_table_ptr, header.table_enc, Some(eh_frame_header_addr));
+            walk_table_ptr = walk_table_ptr.add(read);
+
+            trace!(idx = ?i, "eh_frame_hdr table initial_loc={initial_loc:x} address={address:x}");
+        }
+
+        let table_half_entry_size = header.table_enc.size();
+
+        let mut base = 0;
+        let mut len = fde_count;
+        let found_fde;
+        loop {
+            if len == 1 {
+                found_fde = Some(base);
+                break;
+            }
+
+            let mid = base + len / 2;
+            let mid_ptr = table_ptr.byte_add(mid * table_half_entry_size * 2);
+
+            let (_, value) = read_encoded(mid_ptr, header.table_enc, Some(eh_frame_header_addr));
+
+            debug!(
+                ?base,
+                ?len,
+                ?mid,
+                "binary searching for {addr:?}: {value:x}"
+            );
+
+            match addr.addr().cmp(&value) {
+                core::cmp::Ordering::Less => {
+                    len = mid - base;
+                }
+                core::cmp::Ordering::Equal => {
+                    found_fde = Some(mid);
+                    break;
+                }
+                core::cmp::Ordering::Greater => {
+                    len = len - (mid - base);
+                    base = mid;
+                }
+            }
+        }
+
+        debug!("found FDE idx in binary search {found_fde:?}");
+
+        let fde_table_ptr = table_ptr.byte_add(found_fde.unwrap() * table_half_entry_size * 2);
+        let (_, fde_address) = read_encoded(
+            fde_table_ptr.byte_add(table_half_entry_size),
+            header.table_enc,
+            Some(eh_frame_header_addr),
+        );
+
+        trace!("found FDE at address {fde_address:x}");
+
+        let fde_ptr = core::ptr::with_exposed_provenance::<u8>(fde_address);
+
+        fde_ptr.read_volatile();
+
+        trace!("ptr is valid");
+
+        trace!("FDE offset to .eh_frame: {:x}", fde_ptr.addr() - (eh_frame_ptr));
+
+        let fde = crate::dwarf::parse::parse_fde_from_ptr(fde_ptr, eh_frame_ptr).unwrap();
+
+        todo!()
+    }
+}

src/dwarf/mod.rs

@@ -5,12 +5,13 @@
 //! interpreter (yes, that shit is basically a programming language).
 //! See https://dwarfstd.org/doc/DWARF5.pdf §6.4 for more information if more information is desired.
 //! Note that https://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
-//! contains more details on the precise format, which is slightly different from .debug_frame from DWARF.
+//! contains more details on the precise format, which is slightly different
+//! from .debug_frame from DWARF.
 
 mod divination;
 mod parse;
 
-pub(crate) use divination::eh_frame;
+pub(crate) use divination::{eh_frame, frame_info};
 
 /// The `.eh_frame` section contains a list of call frame information records.
 /// Each CFI contains a CIE followed be one or more FDE records.

src/dwarf/parse.rs

@@ -362,23 +362,29 @@ pub unsafe fn parse_cfi(mut ptr: *const u8) {
 struct Cursor<'a>(&'a [u8]);
 
 /// Returns `(read_size, value)`
-pub(super) unsafe fn read_encoded(ptr: *const u8, encoding: Encoding) -> (usize, usize) {
+pub(super) unsafe fn read_encoded(
+    ptr: *const u8,
+    encoding: Encoding,
+    datarel_base: Option<usize>,
+) -> (usize, usize) {
     let (read_size, value) = match encoding.format() {
         ValueFormat::DW_EH_PE_uleb128 => todo!("uleb128"),
         ValueFormat::DW_EH_PE_udata2 => (2, ptr.cast::<u16>().read_unaligned() as usize),
         ValueFormat::DW_EH_PE_udata4 => (4, ptr.cast::<u32>().read_unaligned() as usize),
         ValueFormat::DW_EH_PE_udata8 => (8, ptr.cast::<u64>().read_unaligned() as usize),
         ValueFormat::DW_EH_PE_sleb128 => todo!("sleb128"),
-        ValueFormat::DW_EH_PE_sdata2 => (2, ptr.cast::<i16>().read_unaligned() as usize),
+        ValueFormat::DW_EH_PE_sdata2 => (2, ptr.cast::<i16>().read_unaligned() as isize as usize),
-        ValueFormat::DW_EH_PE_sdata4 => (4, ptr.cast::<i32>().read_unaligned() as usize),
+        ValueFormat::DW_EH_PE_sdata4 => (4, ptr.cast::<i32>().read_unaligned() as isize as usize),
-        ValueFormat::DW_EH_PE_sdata8 => (8, ptr.cast::<i64>().read_unaligned() as usize),
+        ValueFormat::DW_EH_PE_sdata8 => (8, ptr.cast::<i64>().read_unaligned() as isize as usize),
     };
 
     let value = match encoding.application() {
         ValueApplication::DW_EH_PE_absptr => value,
         ValueApplication::DW_EH_PE_pcrel => ((value as isize) + (ptr as isize)) as usize,
         ValueApplication::DW_EH_PE_textrel => todo!("textrel"),
-        ValueApplication::DW_EH_PE_datarel => todo!("datarel"),
+        ValueApplication::DW_EH_PE_datarel => {
+            ((value as isize) + (datarel_base.unwrap() as isize)) as usize
+        }
         ValueApplication::DW_EH_PE_funcrel => todo!("funcrel"),
         ValueApplication::DW_EH_PE_aligned => todo!("aligned"),
     };
@@ -387,6 +393,7 @@ pub(super) unsafe fn read_encoded(ptr: *const u8, encoding: Encoding) -> (usize,
 }
 
 #[derive(PartialEq, Clone, Copy)]
+#[repr(transparent)]
 pub(super) struct Encoding(u8);
 impl Encoding {
     fn format(&self) -> ValueFormat {
@@ -413,6 +420,18 @@ impl Encoding {
             v => panic!("invalid header value application: {v}"),
         }
     }
+    pub(crate) fn size(&self) -> usize {
+        match self.format() {
+            ValueFormat::DW_EH_PE_uleb128 => panic!("uleb128 has no known size"),
+            ValueFormat::DW_EH_PE_udata2 => 2,
+            ValueFormat::DW_EH_PE_udata4 => 4,
+            ValueFormat::DW_EH_PE_udata8 => 8,
+            ValueFormat::DW_EH_PE_sleb128 => panic!("sleb128 has no known size"),
+            ValueFormat::DW_EH_PE_sdata2 => 2,
+            ValueFormat::DW_EH_PE_sdata4 => 4,
+            ValueFormat::DW_EH_PE_sdata8 => 8,
+        }
+    }
 }
 
 impl fmt::Debug for Encoding {
@@ -456,7 +475,8 @@ enum ValueApplication {
     DW_EH_PE_pcrel = 0x10,
     ///	Value is relative to the beginning of the .text section.
     DW_EH_PE_textrel = 0x20,
-    ///	Value is relative to the beginning of the .got or .eh_frame_hdr section.
+    ///	Value is relative to the beginning of the .got or .eh_frame_hdr
+    /// section.
     DW_EH_PE_datarel = 0x30,
     ///	Value is relative to the beginning of the function.
     DW_EH_PE_funcrel = 0x40,
@@ -556,10 +576,11 @@ unsafe fn parse_frame_info<'a>(
 unsafe fn parse_frame_head<'a>(ptr: *const u8) -> Result<(u32, &'a [u8], *const u8)> {
     let len = ptr.cast::<u32>().read();
     if len == 0xffffffff {
+        // be careful, if you handle this you need to adjust the callers offsets lol lmao
         todo!("loooong dwarf, cannot handle.");
     }
     let data = &mut Cursor(core::slice::from_raw_parts(ptr.add(4), len as usize));
-    trace!("frame info entry: {:x?}", data.0);
+    trace!("frame info entry (without len): {:x?}", data.0);
 
     let cie_id = read_u32(data)?;
     let new_ptr = ptr.add(4).add(len as _);
@@ -606,6 +627,37 @@ fn parse_cie<'a>(data: &mut Cursor<'a>) -> Result<Cie<'a>> {
     Ok(cie)
 }
 
+pub(crate) unsafe fn parse_fde_from_ptr<'a>(
+    ptr: *const u8,
+    eh_frame_base: usize,
+) -> Result<Fde<'a>> {
+    let (fde_cie_id, fde_data, _) = parse_frame_head(ptr)?;
+    let fde_data = &mut Cursor(fde_data);
+
+    if fde_cie_id == 0 {
+        return Err(Error(format!("FDE's CIE Pointer is 0")));
+    }
+    trace!("FDE's CIE pointer: {fde_cie_id}");
+
+    let cie_ptr = ptr.byte_add(4 /* length */).byte_sub(fde_cie_id as usize);
+
+    trace!(
+        "CIE offset to .eh_frame: {:x}",
+        cie_ptr.addr() - (eh_frame_base)
+    );
+
+    let (cie_cie_id, cie_data, _) = parse_frame_head(cie_ptr)?;
+    if cie_cie_id != 0 {
+        return Err(Error(format!("CIE must have cie_id=0")));
+    }
+    let cie_data = &mut Cursor(cie_data);
+    let cie = parse_cie(cie_data)?;
+
+    let fde = parse_fde(fde_data, fde_cie_id, &cie)?;
+
+    Ok(fde)
+}
+
 #[instrument(skip(data))]
 fn parse_fde<'a>(data: &mut Cursor<'a>, cie_id: u32, cie: &Cie<'_>) -> Result<Fde<'a>> {
     trace!("FDE {:x?}", data.0);
@@ -621,10 +673,10 @@ fn parse_fde<'a>(data: &mut Cursor<'a>, cie_id: u32, cie: &Cie<'_>) -> Result<Fd
         Error("pointer encoding not present in augmentation for CIE with FDEs".into())
     })?;
 
-    let (read_size, pc_begin) = unsafe { read_encoded(data.0.as_ptr(), pointer_encoding) };
+    let (read_size, pc_begin) = unsafe { read_encoded(data.0.as_ptr(), pointer_encoding, None) };
     data.0 = &data.0[read_size..];
 
-    let (read_size, pc_range) = unsafe { read_encoded(data.0.as_ptr(), pointer_encoding) };
+    let (read_size, pc_range) = unsafe { read_encoded(data.0.as_ptr(), pointer_encoding, None) };
     data.0 = &data.0[read_size..];
 
     // This is only present if the aug data of the CIE contains z. But that is
@@ -682,7 +734,7 @@ fn parse_augmentation_data(string: &str, data: &[u8]) -> Result<AugmentationData
             b'P' => {
                 trace!("P");
                 let encoding = Encoding(read_u8(data)?);
-                let (read_size, value) = unsafe { read_encoded(data.0.as_ptr(), encoding) };
+                let (read_size, value) = unsafe { read_encoded(data.0.as_ptr(), encoding, None) };
                 data.0 = &data.0[read_size..];
                 aug_data.personality = Some(value);
             }

src/lib.rs

@@ -25,14 +25,20 @@ impl Addr {
     fn voidptr(self) -> *const ffi::c_void {
         self.0.cast()
     }
+
+    fn addr(&self) -> usize {
+        self.0.addr()
+    }
 }
 
 #[allow(nonstandard_style)]
-pub unsafe extern "C" fn _UnwindRaiseException(
+pub unsafe extern "C-unwind" fn _UnwindRaiseException(
     exception_object: *mut uw::_Unwind_Exception,
 ) -> uw::_Unwind_Reason_Code {
     let _span = info_span!("_UnwindRaiseException", ?exception_object).entered();
 
+    let frame = crate::dwarf::frame_info(arch::get_rip());
+
     let eh_frame = crate::dwarf::eh_frame(arch::get_rip()).unwrap();
     crate::dwarf::uwutables(eh_frame);
 

test-program/src/main.rs

@@ -1,5 +1,4 @@
-use tracing_subscriber::{layer::SubscriberExt, EnvFilter};
+use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt, EnvFilter};
-use tracing_subscriber::util::SubscriberInitExt;
 use uwuwind::uw;
 
 #[repr(C)]