read: add ObjectSection::dynamic_relocations

crates/examples/src/objdump.rs

@@ -211,6 +211,16 @@ fn dump_parsed_object<W: Write, E: Write>(w: &mut W, e: &mut E, file: &object::F
                 writeln!(w, "{:x?}", relocation)?;
             }
         }
+        if section.dynamic_relocations().next().is_some() {
+            writeln!(
+                w,
+                "\n{} dynamic relocations",
+                section.name().unwrap_or("<invalid name>")
+            )?;
+            for relocation in section.dynamic_relocations() {
+                writeln!(w, "{:x?}", relocation)?;
+            }
+        }
     }
 
     writeln!(w)?;

crates/examples/testfiles/elf/base-aarch64.objdump

@@ -123,6 +123,13 @@ Symbols
 86: Symbol { name: "printf@@GLIBC_2.17", address: 0, size: 0, kind: Text, section: Undefined, scope: Unknown, weak: false, flags: Elf { st_info: 12, st_other: 0 } }
 87: Symbol { name: "_init", address: 598, size: 0, kind: Text, section: Section(SectionIndex(b)), scope: Dynamic, weak: false, flags: Elf { st_info: 12, st_other: 0 } }
 
+.got dynamic relocations
+(10f98, Relocation { kind: Unknown, encoding: Generic, size: 0, target: Symbol(SymbolIndex(4)), addend: 0, implicit_addend: false, flags: Elf { r_type: 402 } })
+(10fa0, Relocation { kind: Unknown, encoding: Generic, size: 0, target: Symbol(SymbolIndex(5)), addend: 0, implicit_addend: false, flags: Elf { r_type: 402 } })
+(10fa8, Relocation { kind: Unknown, encoding: Generic, size: 0, target: Symbol(SymbolIndex(6)), addend: 0, implicit_addend: false, flags: Elf { r_type: 402 } })
+(10fb0, Relocation { kind: Unknown, encoding: Generic, size: 0, target: Symbol(SymbolIndex(7)), addend: 0, implicit_addend: false, flags: Elf { r_type: 402 } })
+(10fb8, Relocation { kind: Unknown, encoding: Generic, size: 0, target: Symbol(SymbolIndex(9)), addend: 0, implicit_addend: false, flags: Elf { r_type: 402 } })
+
 Dynamic symbols
 1: Symbol { name: "", address: 598, size: 0, kind: Section, section: Section(SectionIndex(b)), scope: Compilation, weak: false, flags: Elf { st_info: 3, st_other: 0 } }
 2: Symbol { name: "", address: 11000, size: 0, kind: Section, section: Section(SectionIndex(15)), scope: Compilation, weak: false, flags: Elf { st_info: 3, st_other: 0 } }

crates/examples/testfiles/elf/base.objdump

@@ -102,6 +102,9 @@ Symbols
 62: Symbol { name: "__cxa_finalize@@GLIBC_2.2.5", address: 0, size: 0, kind: Text, section: Undefined, scope: Unknown, weak: true, flags: Elf { st_info: 22, st_other: 0 } }
 63: Symbol { name: "_init", address: 520, size: 0, kind: Text, section: Section(SectionIndex(c)), scope: Dynamic, weak: false, flags: Elf { st_info: 12, st_other: 0 } }
 
+.got dynamic relocations
+(200fd0, Relocation { kind: Unknown, encoding: Generic, size: 0, target: Symbol(SymbolIndex(2)), addend: 0, implicit_addend: false, flags: Elf { r_type: 7 } })
+
 Dynamic symbols
 1: Symbol { name: "_ITM_deregisterTMCloneTable", address: 0, size: 0, kind: Unknown, section: Undefined, scope: Unknown, weak: true, flags: Elf { st_info: 20, st_other: 0 } }
 2: Symbol { name: "printf", address: 0, size: 0, kind: Text, section: Undefined, scope: Unknown, weak: false, flags: Elf { st_info: 12, st_other: 0 } }

src/read/any.rs

@@ -789,6 +789,17 @@ impl<'data, 'file, R: ReadRef<'data>> ObjectSection<'data> for Section<'data, 'f
         }
     }
 
+    fn dynamic_relocations(&self) -> SectionRelocationIterator<'data, 'file, R> {
+        SectionRelocationIterator {
+            inner: map_inner!(
+                self.inner,
+                SectionInternal,
+                SectionRelocationIteratorInternal,
+                |x| x.dynamic_relocations()
+            ),
+        }
+    }
+
     fn relocation_map(&self) -> Result<RelocationMap> {
         with_inner!(self.inner, SectionInternal, |x| x.relocation_map())
     }

src/read/coff/section.rs

@@ -414,6 +414,13 @@ impl<'data, 'file, R: ReadRef<'data>, Coff: CoffHeader> ObjectSection<'data>
         }
     }
 
+    fn dynamic_relocations(&self) -> CoffRelocationIterator<'data, 'file, R, Coff> {
+        CoffRelocationIterator {
+            file: self.file,
+            iter: [].iter(),
+        }
+    }
+
     fn relocation_map(&self) -> read::Result<RelocationMap> {
         RelocationMap::new(self.file, self)
     }

src/read/elf/file.rs

@@ -46,6 +46,7 @@ where
     pub(super) segments: &'data [Elf::ProgramHeader],
     pub(super) sections: SectionTable<'data, Elf, R>,
     pub(super) relocations: RelocationSections,
+    pub(super) dynamic_relocations: RelocationSections,
     pub(super) symbols: SymbolTable<'data, Elf, R>,
     pub(super) dynamic_symbols: SymbolTable<'data, Elf, R>,
 }
@@ -66,6 +67,8 @@ where
         let dynamic_symbols = sections.symbols(endian, data, elf::SHT_DYNSYM)?;
         // The API we provide requires a mapping from section to relocations, so build it now.
         let relocations = sections.relocation_sections(endian, symbols.section())?;
+        let dynamic_relocations =
+            sections.relocation_sections(endian, dynamic_symbols.section())?;
 
         Ok(ElfFile {
             endian,
@@ -74,6 +77,7 @@ where
             segments,
             sections,
             relocations,
+            dynamic_relocations,
             symbols,
             dynamic_symbols,
         })

src/read/elf/relocation.rs

@@ -190,6 +190,7 @@ where
     /// The current pointer in the chain of relocation sections.
     pub(super) section_index: SectionIndex,
     pub(super) file: &'file ElfFile<'data, Elf, R>,
+    pub(super) relocation_sections: &'file RelocationSections,
     pub(super) relocations: Option<ElfRelaIterator<'data, Elf>>,
 }
 
@@ -211,7 +212,7 @@ where
                 }
                 self.relocations = None;
             }
-            self.section_index = self.file.relocations.get(self.section_index)?;
+            self.section_index = self.relocation_sections.get(self.section_index)?;
             // The construction of RelocationSections ensures section_index is valid.
             let section = self.file.sections.section(self.section_index).unwrap();
             match section.sh_type(endian) {

src/read/elf/section.rs

@@ -663,6 +663,16 @@ where
         ElfSectionRelocationIterator {
             section_index: self.index,
             file: self.file,
+            relocation_sections: &self.file.relocations,
+            relocations: None,
+        }
+    }
+
+    fn dynamic_relocations(&self) -> ElfSectionRelocationIterator<'data, 'file, Elf, R> {
+        ElfSectionRelocationIterator {
+            section_index: self.index,
+            file: self.file,
+            relocation_sections: &self.file.dynamic_relocations,
             relocations: None,
         }
     }

src/read/macho/section.rs

@@ -226,6 +226,13 @@ where
         }
     }
 
+    fn dynamic_relocations(&self) -> MachORelocationIterator<'data, 'file, Mach, R> {
+        MachORelocationIterator {
+            file: self.file,
+            relocations: [].iter(),
+        }
+    }
+
     fn relocation_map(&self) -> read::Result<RelocationMap> {
         RelocationMap::new(self.file, self)
     }

src/read/pe/section.rs

@@ -320,6 +320,10 @@ where
         PeRelocationIterator(PhantomData)
     }
 
+    fn dynamic_relocations(&self) -> PeRelocationIterator<'data, 'file, R> {
+        PeRelocationIterator(PhantomData)
+    }
+
     fn relocation_map(&self) -> read::Result<RelocationMap> {
         RelocationMap::new(self.file, self)
     }

src/read/traits.rs

@@ -454,6 +454,15 @@ pub trait ObjectSection<'data>: read::private::Sealed {
     /// Get the relocations for this section.
     fn relocations(&self) -> Self::RelocationIterator;
 
+    /// Get the dynamic relocations for this section.
+    ///
+    /// Symbol indices in these relocations refer to the dynamic symbol table.
+    ///
+    /// Only ELF has dynamic relocations. This may not return all of the dynamic
+    /// relocations for the section; it can only return relocations from sections
+    /// that have their `sh_info` set to the index of this section.
+    fn dynamic_relocations(&self) -> Self::RelocationIterator;
+
     /// Construct a relocation map for this section.
     fn relocation_map(&self) -> Result<RelocationMap>;
 

src/read/wasm.rs

@@ -736,6 +736,10 @@ impl<'data, 'file, R: ReadRef<'data>> ObjectSection<'data> for WasmSection<'data
         WasmRelocationIterator(PhantomData)
     }
 
+    fn dynamic_relocations(&self) -> WasmRelocationIterator<'data, 'file, R> {
+        WasmRelocationIterator(PhantomData)
+    }
+
     fn relocation_map(&self) -> read::Result<RelocationMap> {
         RelocationMap::new(self.file, self)
     }

src/read/xcoff/section.rs

@@ -206,6 +206,13 @@ where
         }
     }
 
+    fn dynamic_relocations(&self) -> Self::RelocationIterator {
+        XcoffRelocationIterator {
+            file: self.file,
+            relocations: [].iter(),
+        }
+    }
+
     fn relocation_map(&self) -> read::Result<RelocationMap> {
         RelocationMap::new(self.file, self)
     }