fix: Write STACK WIN records correctly

[loewenheim]

The structure of STACK WIN records is described in https://github.com/google/breakpad/blob/master/docs/symbol_files.md#stack-win-records. In particular:

• The has_program_string flag should be
  • For FrameData (type 4) records: 1 if the record has a program string, 0 otherwise;
  • For FPO (type 0) records: always 0.
• The last argument should be
  • For FrameData records: the program string if it exists, empty otherwise;
  • For FPO records: 1 if the frame pointer register is used as a general-purpose register, 0 otherwise.

However, this is not what the current code does; we instead unify has_program_string and uses_base_pointer into one flag. Kudos to rust-minidump for discarding the resulting invalid records and logging this fact.

[codecov-commenter]

Codecov Report

Merging #513 (12cb239) into master (7810fee) will decrease coverage by 0.00%.
The diff coverage is 28.57%.

❗ Current head 12cb239 differs from pull request most recent head 0fa67cd. Consider uploading reports for the commit 0fa67cd to get more accurate results

@@            Coverage Diff             @@
##           master     #513      +/-   ##
==========================================
- Coverage   68.73%   68.73%   -0.01%     
==========================================
  Files          84       84              
  Lines       17500    17503       +3     
==========================================
+ Hits        12029    12031       +2     
- Misses       5471     5472       +1     

[Gankra]

oh is this the reason we were hitting this: rust-minidump/rust-minidump#252 (comment)

[Gankra]

This matches my understanding of the format

[jan-auer]

For reference, this is Breakpad's dump_syms implementation: https://github.com/google/breakpad/blob/04a9ffbe592378a988dd736f4d30dd524f01706a/src/common/windows/pdb_source_line_writer.cc#L691-L700

And here's also the correct writer when processing Breakpad syms directly:

symbolic/symbolic-minidump/src/cfi.rs

Lines 339 to 346 in e6c6760

	if r.program_string.is_some() { "1" } else { "0" },
	if let Some(ps) = r.program_string {
	ps
	} else if r.uses_base_pointer {
	"1"
	} else {
	"0"
	}

My bad :)