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pbsh.s: update comments, increase maxargs to 10

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This commit is contained in:
Phil Budne 2016-03-25 00:28:43 -04:00
parent 2b7ff69251
commit bb683cd754
1 changed files with 18 additions and 11 deletions
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29
src/other/pbsh.s
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@ -7,25 +7,32 @@
" are copied from the v1 shell:
" redirection must occur at the start of a name (after whitespace)
" includes ';' and '&' (unknown if available in v0 shell)
" does NOT (yet) include quoting (backslash or single quote)
" no "globbing" (performed by /etc/glob in v1 shell)
" includes ';' and '&' (which are mentioned as added close after "fork")
" does NOT include quoting (backslash or single quote)
" v0 cat.s seems to write error output on fd 8, *BUT* shell doesn't
" know what device is on stdout (passed by init, and init doesn't pass
" fd 8), and there isn't a "dup" call, nor does init appear to be an
" "indirect" device like /dev/tty, nor does init make an equivalent link!!
" No "globbing" (performed by /etc/glob in v1 shell);
" McIlroy's "Reader" paper reports that cp/mv syntax
" changed in response to the introduction of globbing,
" the the surviving "cp" command takes src dest pairs.
" cat.s seems to write error output on fd 8, *BUT* shell doesn't know
" what device is on stdout (passed by init, and init doesn't pass fd 8)
" and there isn't a "dup" call, an "indirect" device like /dev/tty,
" nor does init make an equivalent link!!
" Arguments for new processes are located at the end of memory.
" Location 17777 points to a word with the argument count (argc),
" followed by blocks of four words with (filename) arguments.
" Currently leave room for ONLY maxargs items.
maxargs=8
" 10 is enough to build "cold start" system (sop + s1-9):
maxargs=10
" v1 shell expects "-" as argument from init or login, will read
" filename passed as argument. *BUT* v0 init.s doesn't set up the
" argv at the top of memory, so the v0 shell may not have taken
" command line arguments!!!
" filename passed as argument. *BUT* init.s doesn't set up the argv
" at the top of memory, so the v0 shell may not have taken command
" line arguments!!! You can still invoke "sh <rc" but the shell has
" no way to know input is not a tty (no sgtty/fstat calls) to suppress
" the prompt (or make the sub-shell interruptable)
lac d1
sys intrp " make shell uninterruptable