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use std::cmp::min;
use super::*;
use crate::{minidump_cpu::RawContextCPU, minidump_writer::CrashingThreadContext};
// The following kLimit* constants are for when minidump_size_limit_ is set
// and the minidump size might exceed it.
//
// Estimate for how big each thread's stack will be (in bytes).
const LIMIT_AVERAGE_THREAD_STACK_LENGTH: usize = 8 * 1024;
// Number of threads whose stack size we don't want to limit. These base
// threads will simply be the first N threads returned by the dumper (although
// the crashing thread will never be limited). Threads beyond this count are
// the extra threads.
const LIMIT_BASE_THREAD_COUNT: usize = 20;
// Maximum stack size to dump for any extra thread (in bytes).
const LIMIT_MAX_EXTRA_THREAD_STACK_LEN: usize = 2 * 1024;
// Make sure this number of additional bytes can fit in the minidump
// (exclude the stack data).
const LIMIT_MINIDUMP_FUDGE_FACTOR: u64 = 64 * 1024;
#[derive(Debug, Clone, Copy)]
enum MaxStackLen {
None,
Len(usize),
}
pub fn write(
config: &mut MinidumpWriter,
buffer: &mut DumpBuf,
dumper: &PtraceDumper,
) -> Result<MDRawDirectory, errors::SectionThreadListError> {
let num_threads = dumper.threads.len();
// Memory looks like this:
// <num_threads><thread_1><thread_2>...
let list_header = MemoryWriter::<u32>::alloc_with_val(buffer, num_threads as u32)?;
let mut dirent = MDRawDirectory {
stream_type: MDStreamType::ThreadListStream as u32,
location: list_header.location(),
};
let mut thread_list = MemoryArrayWriter::<MDRawThread>::alloc_array(buffer, num_threads)?;
dirent.location.data_size += thread_list.location().data_size;
// If there's a minidump size limit, check if it might be exceeded. Since
// most of the space is filled with stack data, just check against that.
// If this expects to exceed the limit, set extra_thread_stack_len such
// that any thread beyond the first kLimitBaseThreadCount threads will
// have only kLimitMaxExtraThreadStackLen bytes dumped.
let mut extra_thread_stack_len = MaxStackLen::None; // default to no maximum
if let Some(minidump_size_limit) = config.minidump_size_limit {
let estimated_total_stack_size = (num_threads * LIMIT_AVERAGE_THREAD_STACK_LENGTH) as u64;
let curr_pos = buffer.position();
let estimated_minidump_size =
curr_pos + estimated_total_stack_size + LIMIT_MINIDUMP_FUDGE_FACTOR;
if estimated_minidump_size > minidump_size_limit {
extra_thread_stack_len = MaxStackLen::Len(LIMIT_MAX_EXTRA_THREAD_STACK_LEN);
}
}
for (idx, item) in dumper.threads.clone().iter().enumerate() {
let mut thread = MDRawThread {
thread_id: item.tid.try_into()?,
suspend_count: 0,
priority_class: 0,
priority: 0,
teb: 0,
stack: MDMemoryDescriptor::default(),
thread_context: MDLocationDescriptor::default(),
};
// We have a different source of information for the crashing thread. If
// we used the actual state of the thread we would find it running in the
// signal handler with the alternative stack, which would be deeply
// unhelpful.
if config.crash_context.is_some() && thread.thread_id == config.blamed_thread as u32 {
let crash_context = config.crash_context.as_ref().unwrap();
let instruction_ptr = crash_context.get_instruction_pointer();
let stack_pointer = crash_context.get_stack_pointer();
fill_thread_stack(
config,
buffer,
dumper,
&mut thread,
instruction_ptr,
stack_pointer,
MaxStackLen::None,
)?;
// Copy 256 bytes around crashing instruction pointer to minidump.
let ip_memory_size: usize = 256;
// Bound it to the upper and lower bounds of the memory map
// it's contained within. If it's not in mapped memory,
// don't bother trying to write it.
for mapping in &dumper.mappings {
if instruction_ptr < mapping.start_address
|| instruction_ptr >= mapping.start_address + mapping.size
{
continue;
}
// Try to get 128 bytes before and after the IP, but
// settle for whatever's available.
let mut ip_memory_d = MDMemoryDescriptor {
start_of_memory_range: std::cmp::max(
mapping.start_address,
instruction_ptr - ip_memory_size / 2,
) as u64,
..Default::default()
};
let end_of_range = std::cmp::min(
mapping.start_address + mapping.size,
instruction_ptr + ip_memory_size / 2,
) as u64;
ip_memory_d.memory.data_size =
(end_of_range - ip_memory_d.start_of_memory_range) as u32;
let memory_copy = PtraceDumper::copy_from_process(
thread.thread_id as i32,
ip_memory_d.start_of_memory_range as _,
ip_memory_d.memory.data_size as usize,
)?;
let mem_section = MemoryArrayWriter::alloc_from_array(buffer, &memory_copy)?;
ip_memory_d.memory = mem_section.location();
config.memory_blocks.push(ip_memory_d);
break;
}
// let cpu = MemoryWriter::alloc(buffer, &memory_copy)?;
let mut cpu: RawContextCPU = Default::default();
let crash_context = config.crash_context.as_ref().unwrap();
crash_context.fill_cpu_context(&mut cpu);
let cpu_section = MemoryWriter::alloc_with_val(buffer, cpu)?;
thread.thread_context = cpu_section.location();
config.crashing_thread_context =
CrashingThreadContext::CrashContext(cpu_section.location());
} else {
let info = dumper.get_thread_info_by_index(idx)?;
let max_stack_len =
if config.minidump_size_limit.is_some() && idx >= LIMIT_BASE_THREAD_COUNT {
extra_thread_stack_len
} else {
MaxStackLen::None // default to no maximum for this thread
};
let instruction_ptr = info.get_instruction_pointer();
fill_thread_stack(
config,
buffer,
dumper,
&mut thread,
instruction_ptr,
info.stack_pointer,
max_stack_len,
)?;
let mut cpu = RawContextCPU::default();
info.fill_cpu_context(&mut cpu);
let cpu_section = MemoryWriter::<RawContextCPU>::alloc_with_val(buffer, cpu)?;
thread.thread_context = cpu_section.location();
if item.tid == config.blamed_thread {
// This is the crashing thread of a live process, but
// no context was provided, so set the crash address
// while the instruction pointer is already here.
config.crashing_thread_context = CrashingThreadContext::CrashContextPlusAddress((
cpu_section.location(),
instruction_ptr,
));
}
}
thread_list.set_value_at(buffer, thread, idx)?;
}
Ok(dirent)
}
fn fill_thread_stack(
config: &mut MinidumpWriter,
buffer: &mut DumpBuf,
dumper: &PtraceDumper,
thread: &mut MDRawThread,
instruction_ptr: usize,
stack_ptr: usize,
max_stack_len: MaxStackLen,
) -> Result<(), errors::SectionThreadListError> {
thread.stack.start_of_memory_range = stack_ptr.try_into()?;
thread.stack.memory.data_size = 0;
thread.stack.memory.rva = buffer.position() as u32;
if let Ok((valid_stack_ptr, stack_len)) = dumper.get_stack_info(stack_ptr) {
let stack_len = if let MaxStackLen::Len(max_stack_len) = max_stack_len {
min(stack_len, max_stack_len)
} else {
stack_len
};
let mut stack_bytes = PtraceDumper::copy_from_process(
thread.thread_id.try_into()?,
valid_stack_ptr,
stack_len,
)?;
let stack_pointer_offset = stack_ptr.saturating_sub(valid_stack_ptr);
if config.skip_stacks_if_mapping_unreferenced {
if let Some(principal_mapping) = &config.principal_mapping {
let low_addr = principal_mapping.system_mapping_info.start_address;
let high_addr = principal_mapping.system_mapping_info.end_address;
if (instruction_ptr < low_addr || instruction_ptr > high_addr)
&& !principal_mapping
.stack_has_pointer_to_mapping(&stack_bytes, stack_pointer_offset)
{
return Ok(());
}
} else {
return Ok(());
}
}
if config.sanitize_stack {
dumper.sanitize_stack_copy(&mut stack_bytes, stack_ptr, stack_pointer_offset)?;
}
let stack_location = MDLocationDescriptor {
data_size: stack_bytes.len() as u32,
rva: buffer.position() as u32,
};
buffer.write_all(&stack_bytes);
thread.stack.start_of_memory_range = valid_stack_ptr as u64;
thread.stack.memory = stack_location;
config.memory_blocks.push(thread.stack);
}
Ok(())
}