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int21: add missing break after AH=51/62 - #309
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Commit 81ee617 put the AH=8C handler right after "Get PSP", so AH=51/62 fell through into it. With AL=2 (_SIGHUP) that installed a signal handler from DS:DX and returned the previous handler offset in BX instead of the PSP; with any other AL it set CF and AX=1. Phar Lap 286 loader (Crusader demo) calls AH=62 with AL=2 and got a bogus PSP, failing with "Initialization failed -- error code 8".
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Before: since 81ee617 (AH=8Ch), int 21h AH=51h/62h falls through into the new AH=8Ch case. With AL=2 it installs a SIGHUP handler from DS:DX and returns the previous handler offset in BX instead of the PSP; with any other AL it returns CF=1, AX=1.
After: AH=51h/62h return the current PSP and leave AX, flags and the signal state alone.
The Phar Lap 286 loader in the Crusader demo calls AH=62h with AL=2 left over from an earlier call. It got 0829h instead of its PSP 9CEEh, read the environment selector from the wrong segment and stopped with "Initialization failed -- error code 8". With the
breakit loads and runs.How: one
break;afterirp->BX = cu_psp;inint21_syscall().