1 files changed, 146 insertions, 0 deletions
diff --git a/third_party/rust/minidump-writer/src/linux/android.rs b/third_party/rust/minidump-writer/src/linux/android.rs
new file mode 100644
index 0000000000..0c8195cc0f
--- /dev/null
+++ b/third_party/rust/minidump-writer/src/linux/android.rs
@@ -0,0 +1,146 @@
+use crate::errors::AndroidError;
+use crate::maps_reader::MappingInfo;
+use crate::ptrace_dumper::PtraceDumper;
+use crate::thread_info::Pid;
+use goblin::elf;
+#[cfg(target_pointer_width = "32")]
+use goblin::elf::dynamic::dyn32::{Dyn, SIZEOF_DYN};
+#[cfg(target_pointer_width = "64")]
+use goblin::elf::dynamic::dyn64::{Dyn, SIZEOF_DYN};
+#[cfg(target_pointer_width = "32")]
+use goblin::elf::header::header32 as elf_header;
+#[cfg(target_pointer_width = "64")]
+use goblin::elf::header::header64 as elf_header;
+#[cfg(target_pointer_width = "32")]
+use goblin::elf::program_header::program_header32::ProgramHeader;
+#[cfg(target_pointer_width = "64")]
+use goblin::elf::program_header::program_header64::ProgramHeader;
+use std::ffi::c_void;
+
+type Result<T> = std::result::Result<T, AndroidError>;
+
+// From /usr/include/elf.h of the android SDK
+// #define DT_ANDROID_REL (DT_LOOS + 2)
+// #define DT_ANDROID_RELSZ (DT_LOOS + 3)
+// #define DT_ANDROID_RELA (DT_LOOS + 4)
+// #define DT_ANDROID_RELASZ (DT_LOOS + 5)
+#[cfg(target_pointer_width = "64")]
+const DT_ANDROID_REL: u64 = elf::dynamic::DT_LOOS + 2;
+#[cfg(target_pointer_width = "64")]
+const DT_ANDROID_RELA: u64 = elf::dynamic::DT_LOOS + 4;
+#[cfg(target_pointer_width = "32")]
+const DT_ANDROID_REL: u32 = (elf::dynamic::DT_LOOS + 2) as u32;
+#[cfg(target_pointer_width = "32")]
+const DT_ANDROID_RELA: u32 = (elf::dynamic::DT_LOOS + 4) as u32;
+
+struct DynVaddresses {
+    min_vaddr: usize,
+    dyn_vaddr: usize,
+    dyn_count: usize,
+}
+
+fn has_android_packed_relocations(pid: Pid, load_bias: usize, vaddrs: DynVaddresses) -> Result<()> {
+    let dyn_addr = load_bias + vaddrs.dyn_vaddr;
+    for idx in 0..vaddrs.dyn_count {
+        let addr = (dyn_addr + SIZEOF_DYN * idx) as *mut c_void;
+        let dyn_data = PtraceDumper::copy_from_process(pid, addr, SIZEOF_DYN)?;
+        // TODO: Couldn't find a nice way to use goblin for that, to avoid the unsafe-block
+        let dyn_obj: Dyn;
+        unsafe {
+            dyn_obj = std::mem::transmute::<[u8; SIZEOF_DYN], Dyn>(dyn_data.as_slice().try_into()?);
+        }
+
+        if dyn_obj.d_tag == DT_ANDROID_REL || dyn_obj.d_tag == DT_ANDROID_RELA {
+            return Ok(());
+        }
+    }
+    Err(AndroidError::NoRelFound)
+}
+
+fn get_effective_load_bias(pid: Pid, ehdr: &elf_header::Header, address: usize) -> usize {
+    let ph = parse_loaded_elf_program_headers(pid, ehdr, address);
+    // If |min_vaddr| is non-zero and we find Android packed relocation tags,
+    // return the effective load bias.
+
+    if ph.min_vaddr != 0 {
+        let load_bias = address - ph.min_vaddr;
+        if has_android_packed_relocations(pid, load_bias, ph).is_ok() {
+            return load_bias;
+        }
+    }
+    // Either |min_vaddr| is zero, or it is non-zero but we did not find the
+    // expected Android packed relocations tags.
+    address
+}
+
+fn parse_loaded_elf_program_headers(
+    pid: Pid,
+    ehdr: &elf_header::Header,
+    address: usize,
+) -> DynVaddresses {
+    let phdr_addr = address + ehdr.e_phoff as usize;
+    let mut min_vaddr = usize::MAX;
+    let mut dyn_vaddr = 0;
+    let mut dyn_count = 0;
+
+    let phdr_opt = PtraceDumper::copy_from_process(
+        pid,
+        phdr_addr as *mut c_void,
+        elf_header::SIZEOF_EHDR * ehdr.e_phnum as usize,
+    );
+    if let Ok(ph_data) = phdr_opt {
+        // TODO: The original C code doesn't have error-handling here at all.
+        //       We silently ignore "not parsable" for now, but might bubble it up.
+        // TODO2: `from_bytes` might panic, `parse()` would return a Result<>, so maybe better
+        //        to switch to that at some point.
+        for phdr in ProgramHeader::from_bytes(&ph_data, ehdr.e_phnum as usize) {
+            let p_vaddr = phdr.p_vaddr as usize;
+            if phdr.p_type == elf::program_header::PT_LOAD && p_vaddr < min_vaddr {
+                min_vaddr = p_vaddr;
+            }
+
+            if phdr.p_type == elf::program_header::PT_DYNAMIC {
+                dyn_vaddr = p_vaddr;
+                dyn_count = phdr.p_memsz as usize / SIZEOF_DYN;
+            }
+        }
+    }
+
+    DynVaddresses {
+        min_vaddr,
+        dyn_vaddr,
+        dyn_count,
+    }
+}
+
+pub fn late_process_mappings(pid: Pid, mappings: &mut [MappingInfo]) -> Result<()> {
+    // Only consider exec mappings that indicate a file path was mapped, and
+    // where the ELF header indicates a mapped shared library.
+    for mut map in mappings
+        .iter_mut()
+        .filter(|m| m.executable && m.name.as_ref().map_or(false, |n| n.starts_with("/")))
+    {
+        let ehdr_opt = PtraceDumper::copy_from_process(
+            pid,
+            map.start_address as *mut c_void,
+            elf_header::SIZEOF_EHDR,
+        )
+        .ok()
+        .and_then(|x| elf_header::Header::parse(&x).ok());
+
+        if let Some(ehdr) = ehdr_opt {
+            if ehdr.e_type == elf_header::ET_DYN {
+                // Compute the effective load bias for this mapped library, and update
+                // the mapping to hold that rather than |start_addr|, at the same time
+                // adjusting |size| to account for the change in |start_addr|. Where
+                // the library does not contain Android packed relocations,
+                // GetEffectiveLoadBias() returns |start_addr| and the mapping entry
+                // is not changed.
+                let load_bias = get_effective_load_bias(pid, &ehdr, map.start_address);
+                map.size += map.start_address - load_bias;
+                map.start_address = load_bias;
+            }
+        }
+    }
+    Ok(())
+}