LibELF+LibCoreDump: Add a ProcessInfo notes entry

This is a new NotesEntry type which contains information related to the
coredump's process:

- PID
- executable path

Having these in the coredump explicitly avoids having to parse them from
the coredump filename and backtrace, respectively.

3 files changed, 39 insertions, 9 deletions

diff --git a/Libraries/LibCoreDump/Reader.cpp b/Libraries/LibCoreDump/Reader.cpp
index 7aae04fb8f..e1bdbeed37 100644
--- a/Libraries/LibCoreDump/Reader.cpp
+++ b/Libraries/LibCoreDump/Reader.cpp
@@ -66,7 +66,8 @@ Reader::NotesEntryIterator::NotesEntryIterator(const u8* notes_data)
 
 ELF::Core::NotesEntryHeader::Type Reader::NotesEntryIterator::type() const
 {
-    ASSERT(m_current->header.type == ELF::Core::NotesEntryHeader::Type::MemoryRegionInfo
+    ASSERT(m_current->header.type == ELF::Core::NotesEntryHeader::Type::ProcessInfo
+        || m_current->header.type == ELF::Core::NotesEntryHeader::Type::MemoryRegionInfo
         || m_current->header.type == ELF::Core::NotesEntryHeader::Type::ThreadInfo
         || m_current->header.type == ELF::Core::NotesEntryHeader::Type::Null);
     return m_current->header.type;
@@ -80,15 +81,24 @@ const ELF::Core::NotesEntry* Reader::NotesEntryIterator::current() const
 void Reader::NotesEntryIterator::next()
 {
     ASSERT(!at_end());
-    if (type() == ELF::Core::NotesEntryHeader::Type::ThreadInfo) {
-        const ELF::Core::ThreadInfo* current = (const ELF::Core::ThreadInfo*)m_current;
-        m_current = (const ELF::Core::NotesEntry*)(current + 1);
-        return;
+    switch (type()) {
+    case ELF::Core::NotesEntryHeader::Type::ProcessInfo: {
+        const auto* current = reinterpret_cast<const ELF::Core::ProcessInfo*>(m_current);
+        m_current = reinterpret_cast<const ELF::Core::NotesEntry*>(current->executable_path + strlen(current->executable_path) + 1);
+        break;
     }
-    if (type() == ELF::Core::NotesEntryHeader::Type::MemoryRegionInfo) {
-        const ELF::Core::MemoryRegionInfo* current = (const ELF::Core::MemoryRegionInfo*)m_current;
-        m_current = (const ELF::Core::NotesEntry*)(current->region_name + strlen(current->region_name) + 1);
-        return;
+    case ELF::Core::NotesEntryHeader::Type::ThreadInfo: {
+        const auto* current = reinterpret_cast<const ELF::Core::ThreadInfo*>(m_current);
+        m_current = reinterpret_cast<const ELF::Core::NotesEntry*>(current + 1);
+        break;
+    }
+    case ELF::Core::NotesEntryHeader::Type::MemoryRegionInfo: {
+        const auto* current = reinterpret_cast<const ELF::Core::MemoryRegionInfo*>(m_current);
+        m_current = reinterpret_cast<const ELF::Core::NotesEntry*>(current->region_name + strlen(current->region_name) + 1);
+        break;
+    }
+    default:
+        ASSERT_NOT_REACHED();
     }
 }
 
@@ -108,6 +118,16 @@ Optional<uint32_t> Reader::peek_memory(FlatPtr address) const
     return *(const uint32_t*)(&region_data[offset_in_region]);
 }
 
+const ELF::Core::ProcessInfo& Reader::process_info() const
+{
+    for (NotesEntryIterator it((const u8*)m_coredump_image.program_header(m_notes_segment_index).raw_data()); !it.at_end(); it.next()) {
+        if (it.type() != ELF::Core::NotesEntryHeader::Type::ProcessInfo)
+            continue;
+        return reinterpret_cast<const ELF::Core::ProcessInfo&>(*it.current());
+    }
+    ASSERT_NOT_REACHED();
+}
+
 const ELF::Core::MemoryRegionInfo* Reader::region_containing(FlatPtr address) const
 {
     const ELF::Core::MemoryRegionInfo* ret = nullptr;
diff --git a/Libraries/LibCoreDump/Reader.h b/Libraries/LibCoreDump/Reader.h
index e754488b48..ee7dd82ed2 100644
--- a/Libraries/LibCoreDump/Reader.h
+++ b/Libraries/LibCoreDump/Reader.h
@@ -44,6 +44,8 @@ public:
 
     Reader(OwnPtr<MappedFile>&&);
 
+    const ELF::Core::ProcessInfo& process_info() const;
+
     template<typename Func>
     void for_each_memory_region_info(Func func) const;
 
diff --git a/Libraries/LibELF/CoreDump.h b/Libraries/LibELF/CoreDump.h
index 531f5eadde..3ff21d38bb 100644
--- a/Libraries/LibELF/CoreDump.h
+++ b/Libraries/LibELF/CoreDump.h
@@ -36,6 +36,7 @@ struct [[gnu::packed]] NotesEntryHeader
 {
     enum Type : u8 {
         Null = 0, // Terminates segment
+        ProcessInfo,
         ThreadInfo,
         MemoryRegionInfo,
     };
@@ -48,6 +49,13 @@ struct [[gnu::packed]] NotesEntry
     char data[];
 };
 
+struct [[gnu::packed]] ProcessInfo
+{
+    NotesEntryHeader header;
+    int pid;
+    char executable_path[]; // Null terminated
+};
+
 struct [[gnu::packed]] ThreadInfo
 {
     NotesEntryHeader header;