1 files changed, 100 insertions, 0 deletions
diff --git a/tools/profiler/rust-helper/src/elf.rs b/tools/profiler/rust-helper/src/elf.rs
new file mode 100644
index 0000000000..168f5f8837
--- /dev/null
+++ b/tools/profiler/rust-helper/src/elf.rs
@@ -0,0 +1,100 @@
+/* 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/. */
+
+use compact_symbol_table::CompactSymbolTable;
+use goblin::elf;
+use object::read::{ElfFile, Object};
+use object::SymbolKind;
+use std::cmp;
+use std::collections::HashMap;
+use uuid::Uuid;
+
+const UUID_SIZE: usize = 16;
+const PAGE_SIZE: usize = 4096;
+
+fn get_symbol_map<'a, 'b, T>(object_file: &'b T) -> HashMap<u32, &'a str>
+where
+    T: Object<'a, 'b>,
+{
+    object_file
+        .dynamic_symbols()
+        .chain(object_file.symbols())
+        .filter(|(_, symbol)| symbol.kind() == SymbolKind::Text)
+        .filter_map(|(_, symbol)| symbol.name().map(|name| (symbol.address() as u32, name)))
+        .collect()
+}
+
+pub fn get_compact_symbol_table(
+    buffer: &[u8],
+    breakpad_id: Option<&str>,
+) -> Option<CompactSymbolTable> {
+    let elf_file = ElfFile::parse(buffer).ok()?;
+    let elf_id = get_elf_id(&elf_file, buffer)?;
+    if !breakpad_id.map_or(true, |id| id == format!("{:X}0", elf_id.to_simple_ref())) {
+        return None;
+    }
+    return Some(CompactSymbolTable::from_map(get_symbol_map(&elf_file)));
+}
+
+fn create_elf_id(identifier: &[u8], little_endian: bool) -> Uuid {
+    // Make sure that we have exactly UUID_SIZE bytes available
+    let mut data = [0 as u8; UUID_SIZE];
+    let len = cmp::min(identifier.len(), UUID_SIZE);
+    data[0..len].copy_from_slice(&identifier[0..len]);
+
+    if little_endian {
+        // The file ELF file targets a little endian architecture. Convert to
+        // network byte order (big endian) to match the Breakpad processor's
+        // expectations. For big endian object files, this is not needed.
+        data[0..4].reverse(); // uuid field 1
+        data[4..6].reverse(); // uuid field 2
+        data[6..8].reverse(); // uuid field 3
+    }
+
+    Uuid::from_bytes(data)
+}
+
+/// Tries to obtain the object identifier of an ELF object.
+///
+/// As opposed to Mach-O, ELF does not specify a unique ID for object files in
+/// its header. Compilers and linkers usually add either `SHT_NOTE` sections or
+/// `PT_NOTE` program header elements for this purpose. If one of these notes
+/// is present, ElfFile's build_id() method will find it.
+///
+/// If neither of the above are present, this function will hash the first page
+/// of the `.text` section (program code). This matches what the Breakpad
+/// processor does.
+///
+/// If all of the above fails, this function will return `None`.
+pub fn get_elf_id(elf_file: &ElfFile, data: &[u8]) -> Option<Uuid> {
+    if let Some(identifier) = elf_file.build_id() {
+        return Some(create_elf_id(identifier, elf_file.elf().little_endian));
+    }
+
+    // We were not able to locate the build ID, so fall back to hashing the
+    // first page of the ".text" (program code) section. This algorithm XORs
+    // 16-byte chunks directly into a UUID buffer.
+    if let Some(section_data) = find_text_section(elf_file.elf(), data) {
+        let mut hash = [0; UUID_SIZE];
+        for i in 0..cmp::min(section_data.len(), PAGE_SIZE) {
+            hash[i % UUID_SIZE] ^= section_data[i];
+        }
+
+        return Some(create_elf_id(&hash, elf_file.elf().little_endian));
+    }
+
+    None
+}
+
+/// Returns a reference to the data of the the .text section in an ELF binary.
+fn find_text_section<'elf, 'data>(elf: &'elf elf::Elf, data: &'data [u8]) -> Option<&'data [u8]> {
+    elf.section_headers.iter().find_map(|header| {
+        match (header.sh_type, elf.shdr_strtab.get(header.sh_name)) {
+            (elf::section_header::SHT_PROGBITS, Some(Ok(".text"))) => {
+                Some(&data[header.sh_offset as usize..][..header.sh_size as usize])
+            }
+            _ => None,
+        }
+    })
+}