azm dies on dumps from some early boot tapes

[Eric Swenson]

Multics crashed during early initialization and BCE offered to make a dump. read_early_dump_tape had no trouble reading the resulting dump tape, and the obsolete ol_dump progrom also had no trouble analyzing the dump. However, azm died with the following out_of_bounds error:

Error: out_of_bounds at amu_fdump_translate_$to_temp_seg|610
(>system_library_tools>bound_amu_)
referencing >dumps>040519.1142.1.1234|776000
Attempt to access beyond end of segment.
r 15:31 0.504 525 level 2

[Eric Swenson]

The fix is trivial:

cpa [lpn amu_fdump_translate_.pl1] amu_fdump_translate_.pl1

Inserted in B:
B252 if total_lth = 0 then do;
B253 base = null ();
B254 base_2 = null ();
B255 return;
B256 end;
B257
Preceding:
A252 if (offset + total_lth) <= fdump_info.dump_seg_lth (dump_seg_idx) then do;

Comparison finished: 1 difference, 6 lines.
r 15:38 0.975 52

[Eric Swenson]

The above fix is to the locate_segment procedure, which does the wrong thing if total_lth ends up being zero (segment not in dump). The fix sets base and base_2 to null(), which the caller handles as indicating that the segment isn't found.

[Eric Swenson]

​https://s3.amazonaws.com/eswenson-multics/public/mcrs/MCR10064.pdf

[Eric Swenson]

Milestone renamed