Parse fat files

Author: alexcrichton

src/symbolize/gimli.rs

@@ -176,6 +176,7 @@ cfg_if::cfg_if! {
         use std::os::unix::prelude::*;
         use std::ffi::{OsStr, CStr};
         use object::{Bytes, NativeEndian};
+        use object::macho;
         use object::read::macho::{MachHeader, Section, Segment as _, Nlist};
 
         #[cfg(target_pointer_width = "32")]
@@ -248,6 +249,69 @@ cfg_if::cfg_if! {
             }
         }
 
+        fn find_header(mut data: Bytes<'_>) -> Option<(&'_ Mach, Bytes<'_>)> {
+            use object::endian::BigEndian;
+
+            let desired_cpu = || {
+                if cfg!(target_arch = "x86") {
+                    Some(macho::CPU_TYPE_X86)
+                } else if cfg!(target_arch = "x86_64") {
+                    Some(macho::CPU_TYPE_X86_64)
+                } else if cfg!(target_arch = "arm") {
+                    Some(macho::CPU_TYPE_ARM)
+                } else if cfg!(target_arch = "aarch64") {
+                    Some(macho::CPU_TYPE_ARM64)
+                } else {
+                    None
+                }
+            };
+
+            match data.clone().read::<object::endian::U32<NativeEndian>>().ok()?.get(NativeEndian) {
+                macho::MH_MAGIC_64
+                | macho::MH_MAGIC
+                | macho::MH_CIGAM_64
+                | macho::MH_CIGAM => {}
+
+                macho::FAT_MAGIC
+                | macho::FAT_CIGAM => {
+                    let mut header_data = data;
+                    let endian = BigEndian;
+                    let header = header_data.read::<macho::FatHeader>().ok()?;
+                    let nfat = header.nfat_arch.get(endian);
+                    let arch = (0..nfat)
+                        .filter_map(|_| header_data.read::<macho::FatArch32>().ok())
+                        .find(|arch| desired_cpu() == Some(arch.cputype.get(endian)))?;
+                    let offset = arch.offset.get(endian);
+                    let size = arch.size.get(endian);
+                    data = data.read_bytes_at(
+                        offset.try_into().ok()?,
+                        size.try_into().ok()?,
+                    ).ok()?;
+                }
+
+                macho::FAT_MAGIC_64
+                | macho::FAT_CIGAM_64 => {
+                    let mut header_data = data;
+                    let endian = BigEndian;
+                    let header = header_data.read::<macho::FatHeader>().ok()?;
+                    let nfat = header.nfat_arch.get(endian);
+                    let arch = (0..nfat)
+                        .filter_map(|_| header_data.read::<macho::FatArch64>().ok())
+                        .find(|arch| desired_cpu() == Some(arch.cputype.get(endian)))?;
+                    let offset = arch.offset.get(endian);
+                    let size = arch.size.get(endian);
+                    data = data.read_bytes_at(
+                        offset.try_into().ok()?,
+                        size.try_into().ok()?,
+                    ).ok()?;
+                }
+
+                _ => return None,
+            }
+
+            Mach::parse(data).ok().map(|h| (h, data))
+        }
+
         #[allow(deprecated)]
         fn native_libraries() -> Vec<Library> {
             let mut ret = Vec::new();
@@ -476,8 +540,7 @@ impl Mapping {
         // First up we need to load the unique UUID which is stored in the macho
         // header of the file we're reading, specified at `path`.
         let map = mmap(path)?;
-        let data = Bytes(&map);
-        let macho = Mach::parse(data).ok()?;
+        let (macho, data) = find_header(Bytes(&map))?;
         let endian = macho.endian().ok()?;
         let uuid = macho.uuid(endian, data).ok()??;
 
@@ -513,8 +576,7 @@ impl Mapping {
             for entry in dir.read_dir().ok()? {
                 let entry = entry.ok()?;
                 let map = mmap(&entry.path())?;
-                let data = Bytes(&map);
-                let macho = Mach::parse(data).ok()?;
+                let (macho, data) = find_header(Bytes(&map))?;
                 let endian = macho.endian().ok()?;
                 let entry_uuid = macho.uuid(endian, data).ok()??;
                 if entry_uuid != uuid {