Fix encoding of .eh_frame for small LSDA encoding (#704)

gimli-rs · Mar 30, 2024 · 7294ff0 · 7294ff0
1 parent 1130ac1
commit 7294ff0
Showing 1 changed file with 19 additions and 8 deletions.
diff --git a/src/write/cfi.rs b/src/write/cfi.rs
@@ -341,16 +341,18 @@ impl FrameDescriptionEntry {
         }
 
         if cie.has_augmentation() {
-            let mut augmentation_length = 0u64;
-            if self.lsda.is_some() {
-                augmentation_length += u64::from(encoding.address_size);
-            }
-            w.write_uleb128(augmentation_length)?;
+            let augmentation_length_offset = w.len();
+            w.write_u8(0)?;
+            let augmentation_length_base = w.len();
 
             debug_assert_eq!(self.lsda.is_some(), cie.lsda_encoding.is_some());
             if let (Some(lsda), Some(lsda_encoding)) = (self.lsda, cie.lsda_encoding) {
                 w.write_eh_pointer(lsda, lsda_encoding, encoding.address_size)?;
             }
+
+            let augmentation_length = (w.len() - augmentation_length_base) as u64;
+            debug_assert!(augmentation_length < 0x80);
+            w.write_udata_at(augmentation_length_offset, augmentation_length, 1)?;
         }
 
         let mut prev_offset = 0;
@@ -911,9 +913,18 @@ mod tests {
                     frames.add_fde(cie2_id, fde4.clone());
 
                     let mut cie3 = CommonInformationEntry::new(encoding, 1, 8, X86_64::RA);
-                    cie3.fde_address_encoding = constants::DW_EH_PE_pcrel;
-                    cie3.lsda_encoding = Some(constants::DW_EH_PE_pcrel);
-                    cie3.personality = Some((constants::DW_EH_PE_pcrel, Address::Constant(0x1235)));
+                    cie3.fde_address_encoding = constants::DwEhPe(
+                        constants::DW_EH_PE_pcrel.0 | constants::DW_EH_PE_sdata4.0,
+                    );
+                    cie3.lsda_encoding = Some(constants::DwEhPe(
+                        constants::DW_EH_PE_pcrel.0 | constants::DW_EH_PE_sdata4.0,
+                    ));
+                    cie3.personality = Some((
+                        constants::DwEhPe(
+                            constants::DW_EH_PE_pcrel.0 | constants::DW_EH_PE_sdata4.0,
+                        ),
+                        Address::Constant(0x1235),
+                    ));
                     cie3.signal_trampoline = true;
                     let cie3_id = frames.add_cie(cie3.clone());
                     assert_ne!(cie2_id, cie3_id);