1 files changed, 217 insertions, 0 deletions
diff --git a/toolkit/crashreporter/mozannotation_server/src/lib.rs b/toolkit/crashreporter/mozannotation_server/src/lib.rs
new file mode 100644
index 0000000000..4ecb8ec919
--- /dev/null
+++ b/toolkit/crashreporter/mozannotation_server/src/lib.rs
@@ -0,0 +1,217 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+mod errors;
+mod process_reader;
+
+use crate::errors::*;
+use process_reader::ProcessReader;
+
+use mozannotation_client::{Annotation, AnnotationContents, AnnotationMutex};
+use nsstring::nsCString;
+use std::cmp::min;
+use std::iter::FromIterator;
+use std::mem::size_of;
+use std::ptr::null_mut;
+use thin_vec::ThinVec;
+
+#[repr(C)]
+pub enum AnnotationData {
+    Empty,
+    UsizeData(usize),
+    NSCStringData(nsCString),
+    ByteBuffer(ThinVec<u8>),
+}
+
+#[repr(C)]
+pub struct CAnnotation {
+    id: u32,
+    data: AnnotationData,
+}
+
+#[cfg(target_os = "windows")]
+type ProcessHandle = winapi::shared::ntdef::HANDLE;
+#[cfg(any(target_os = "linux", target_os = "android"))]
+type ProcessHandle = libc::pid_t;
+#[cfg(any(target_os = "macos"))]
+type ProcessHandle = mach2::mach_types::task_t;
+
+/// Return the annotations of a given process.
+///
+/// This function will be exposed to C++
+#[no_mangle]
+pub extern "C" fn mozannotation_retrieve(
+    process: usize,
+    max_annotations: usize,
+) -> *mut ThinVec<CAnnotation> {
+    let result = retrieve_annotations(process as _, max_annotations);
+    match result {
+        // Leak the object as it will be owned by the C++ code from now on
+        Ok(annotations) => Box::into_raw(annotations) as *mut _,
+        Err(_) => null_mut(),
+    }
+}
+
+/// Free the annotations returned by `mozannotation_retrieve()`.
+///
+/// # Safety
+///
+/// `ptr` must contain the value returned by a call to
+/// `mozannotation_retrieve()` and be called only once.
+#[no_mangle]
+pub unsafe extern "C" fn mozannotation_free(ptr: *mut ThinVec<CAnnotation>) {
+    // The annotation vector will be automatically destroyed when the contents
+    // of this box are automatically dropped at the end of the function.
+    let _box = Box::from_raw(ptr);
+}
+
+pub fn retrieve_annotations(
+    process: ProcessHandle,
+    max_annotations: usize,
+) -> Result<Box<ThinVec<CAnnotation>>, RetrievalError> {
+    let reader = ProcessReader::new(process)?;
+    let address = reader.find_annotations()?;
+
+    let mut mutex = reader.copy_object_shallow::<AnnotationMutex>(address)?;
+    let mutex = unsafe { mutex.assume_init_mut() };
+
+    // TODO: we should clear the poison value here before getting the mutex
+    // contents. Right now we have to fail if the mutex was poisoned.
+    let annotation_table = mutex.get_mut().map_err(|_e| RetrievalError::InvalidData)?;
+
+    if !annotation_table.verify() {
+        return Err(RetrievalError::InvalidAnnotationTable);
+    }
+
+    let vec_pointer = annotation_table.get_ptr();
+    let length = annotation_table.len();
+    let mut annotations = ThinVec::<CAnnotation>::with_capacity(min(max_annotations, length));
+
+    for i in 0..length {
+        let annotation_address = unsafe { vec_pointer.add(i) };
+        if let Ok(annotation) = read_annotation(&reader, annotation_address as usize) {
+            annotations.push(annotation);
+        }
+    }
+
+    Ok(Box::new(annotations))
+}
+
+// Read an annotation from the given address
+fn read_annotation(reader: &ProcessReader, address: usize) -> Result<CAnnotation, ReadError> {
+    let raw_annotation = reader.copy_object::<Annotation>(address)?;
+    let mut annotation = CAnnotation {
+        id: raw_annotation.id,
+        data: AnnotationData::Empty,
+    };
+
+    match raw_annotation.contents {
+        AnnotationContents::Empty => {}
+        AnnotationContents::NSCString => {
+            let string = copy_nscstring(reader, raw_annotation.address)?;
+            annotation.data = AnnotationData::NSCStringData(string);
+        }
+        AnnotationContents::CString => {
+            let string = copy_null_terminated_string_pointer(reader, raw_annotation.address)?;
+            annotation.data = AnnotationData::NSCStringData(string);
+        }
+        AnnotationContents::CharBuffer => {
+            let string = copy_null_terminated_string(reader, raw_annotation.address)?;
+            annotation.data = AnnotationData::NSCStringData(string);
+        }
+        AnnotationContents::USize => {
+            let value = reader.copy_object::<usize>(raw_annotation.address)?;
+            annotation.data = AnnotationData::UsizeData(value);
+        }
+        AnnotationContents::ByteBuffer(size) => {
+            let value = copy_bytebuffer(reader, raw_annotation.address, size)?;
+            annotation.data = AnnotationData::ByteBuffer(value);
+        }
+    };
+
+    Ok(annotation)
+}
+
+fn copy_null_terminated_string_pointer(
+    reader: &ProcessReader,
+    address: usize,
+) -> Result<nsCString, ReadError> {
+    let buffer_address = reader.copy_object::<usize>(address)?;
+    copy_null_terminated_string(reader, buffer_address)
+}
+
+fn copy_null_terminated_string(
+    reader: &ProcessReader,
+    address: usize,
+) -> Result<nsCString, ReadError> {
+    // Try copying the string word-by-word first, this is considerably faster
+    // than one byte at a time.
+    if let Ok(string) = copy_null_terminated_string_word_by_word(reader, address) {
+        return Ok(string);
+    }
+
+    // Reading the string one word at a time failed, let's try again one byte
+    // at a time. It's slow but it might work in situations where the string
+    // alignment causes word-by-word access to straddle page boundaries.
+    let mut length = 0;
+    let mut string = Vec::<u8>::new();
+
+    loop {
+        let char = reader.copy_object::<u8>(address + length)?;
+        length += 1;
+        string.push(char);
+
+        if char == 0 {
+            break;
+        }
+    }
+
+    Ok(nsCString::from(&string[..length]))
+}
+
+fn copy_null_terminated_string_word_by_word(
+    reader: &ProcessReader,
+    address: usize,
+) -> Result<nsCString, ReadError> {
+    const WORD_SIZE: usize = size_of::<usize>();
+    let mut length = 0;
+    let mut string = Vec::<u8>::new();
+
+    loop {
+        let mut array = reader.copy_array::<u8>(address + length, WORD_SIZE)?;
+        let null_terminator = array.iter().position(|&e| e == 0);
+        length += null_terminator.unwrap_or(WORD_SIZE);
+        string.append(&mut array);
+
+        if null_terminator.is_some() {
+            break;
+        }
+    }
+
+    Ok(nsCString::from(&string[..length]))
+}
+
+fn copy_nscstring(reader: &ProcessReader, address: usize) -> Result<nsCString, ReadError> {
+    // HACK: This assumes the layout of the string
+    let length_address = address + size_of::<usize>();
+    let length = reader.copy_object::<u32>(length_address)?;
+
+    if length > 0 {
+        let data_address = reader.copy_object::<usize>(address)?;
+        reader
+            .copy_array::<u8>(data_address, length as _)
+            .map(nsCString::from)
+    } else {
+        Ok(nsCString::new())
+    }
+}
+
+fn copy_bytebuffer(
+    reader: &ProcessReader,
+    address: usize,
+    size: u32,
+) -> Result<ThinVec<u8>, ReadError> {
+    let value = reader.copy_array::<u8>(address, size as _)?;
+    Ok(ThinVec::<u8>::from_iter(value.into_iter()))
+}