Source
pub fn getLineNumberInfo(self: *Pdb, module: *Module, address: u64) !std.debug.SourceLocation {
std.debug.assert(module.populated);
const subsect_info = module.subsect_info;
var sect_offset: usize = 0;
var skip_len: usize = undefined;
const checksum_offset = module.checksum_offset orelse return error.MissingDebugInfo;
while (sect_offset != subsect_info.len) : (sect_offset += skip_len) {
const subsect_hdr: *align(1) pdb.DebugSubsectionHeader = @ptrCast(&subsect_info[sect_offset]);
skip_len = subsect_hdr.length;
sect_offset += @sizeOf(pdb.DebugSubsectionHeader);
switch (subsect_hdr.kind) {
.lines => {
var line_index = sect_offset;
const line_hdr: *align(1) pdb.LineFragmentHeader = @ptrCast(&subsect_info[line_index]);
if (line_hdr.reloc_segment == 0)
return error.MissingDebugInfo;
line_index += @sizeOf(pdb.LineFragmentHeader);
const frag_vaddr_start = line_hdr.reloc_offset;
const frag_vaddr_end = frag_vaddr_start + line_hdr.code_size;
if (address >= frag_vaddr_start and address < frag_vaddr_end) {
// There is an unknown number of LineBlockFragmentHeaders (and their accompanying line and column records)
// from now on. We will iterate through them, and eventually find a SourceLocation that we're interested in,
// breaking out to :subsections. If not, we will make sure to not read anything outside of this subsection.
const subsection_end_index = sect_offset + subsect_hdr.length;
while (line_index < subsection_end_index) {
const block_hdr: *align(1) pdb.LineBlockFragmentHeader = @ptrCast(&subsect_info[line_index]);
line_index += @sizeOf(pdb.LineBlockFragmentHeader);
const start_line_index = line_index;
const has_column = line_hdr.flags.have_columns;
// All line entries are stored inside their line block by ascending start address.
// Heuristic: we want to find the last line entry
// that has a vaddr_start <= address.
// This is done with a simple linear search.
var line_i: u32 = 0;
while (line_i < block_hdr.num_lines) : (line_i += 1) {
const line_num_entry: *align(1) pdb.LineNumberEntry = @ptrCast(&subsect_info[line_index]);
line_index += @sizeOf(pdb.LineNumberEntry);
const vaddr_start = frag_vaddr_start + line_num_entry.offset;
if (address < vaddr_start) {
break;
}
}
// line_i == 0 would mean that no matching pdb.LineNumberEntry was found.
if (line_i > 0) {
const subsect_index = checksum_offset + block_hdr.name_index;
const chksum_hdr: *align(1) pdb.FileChecksumEntryHeader = @ptrCast(&module.subsect_info[subsect_index]);
const strtab_offset = @sizeOf(pdb.StringTableHeader) + chksum_hdr.file_name_offset;
try self.string_table.?.seekTo(strtab_offset);
const source_file_name = try self.string_table.?.reader().readUntilDelimiterAlloc(self.allocator, 0, 1024);
const line_entry_idx = line_i - 1;
const column = if (has_column) blk: {
const start_col_index = start_line_index + @sizeOf(pdb.LineNumberEntry) * block_hdr.num_lines;
const col_index = start_col_index + @sizeOf(pdb.ColumnNumberEntry) * line_entry_idx;
const col_num_entry: *align(1) pdb.ColumnNumberEntry = @ptrCast(&subsect_info[col_index]);
break :blk col_num_entry.start_column;
} else 0;
const found_line_index = start_line_index + line_entry_idx * @sizeOf(pdb.LineNumberEntry);
const line_num_entry: *align(1) pdb.LineNumberEntry = @ptrCast(&subsect_info[found_line_index]);
return .{
.file_name = source_file_name,
.line = line_num_entry.flags.start,
.column = column,
};
}
}
// Checking that we are not reading garbage after the (possibly) multiple block fragments.
if (line_index != subsection_end_index) {
return error.InvalidDebugInfo;
}
}
},
else => {},
}
if (sect_offset > subsect_info.len)
return error.InvalidDebugInfo;
}
return error.MissingDebugInfo;
}