diff --git a/src/other/pbsh.s b/src/other/pbsh.s new file mode 100644 index 0000000..87d4f44 --- /dev/null +++ b/src/other/pbsh.s @@ -0,0 +1,434 @@ +" -*-fundamental-*- +" sh -- a shell +" started by p budne 3/4/2016 +" with code from cat.s, init.s, and looking at the v1 (pdp-11) shell + +" XXX cat.s seems to write error output on fd 8 + +start: +" XXX take command line argument (script file to open), suppress prompt?? +" NOTE!!! 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!!! +" if non-interactive, "dzm prompt", jump to newcom + +interactive: + -1 + sys intrp " make shell uninterruptable + sys getuid + sma " <0? + jmp newline " no, a mundane + lac hash " yes: superuser + dac prompt " change prompt + +newline: + lac d1; sys write; prompt; 1 " output prompt +newcom: + dzm char " clear saved char + dzm infile " clear input redirect file name + dzm outfile " clear output redirect file name + lac iopt " reset output pointer + dac opt + dac nextarg + +" reset high memory + dzm argc " clear arg count + lac argcptr + dac argptr + dzm argv0 " clear out argv0 for chdir comparison + dzm argv0+1 + dzm argv0+2 + +newarg: + -8 " save 8 chars + dac bcount + dzm redirect + + lac opt " save start for print (TEMP) + dac nextarg + + jms blank " skip whitespace + jms delim " newline? + jmp eol " yes + sad lt " input redirect? + jmp redirin + sad gt " output redirect? + jmp redirout + jmp 3f + +redirin: " saw < + dac redirect " flag redirect + lac infilep + dac opt + jmp newchar " v1 behavior? no whitespace eater + +redirout: " saw > + dac redirect " flag redirect + lac outfilep + dac opt + " v1 behavior? no whitespace eater! + " fall + +newchar: + jms getc + sad o40 " space? + jmp ws " yes + jms delim + jmp eoname +3: jms putc " save + isz bcount " loop unless full + jmp newchar + +" here after 8 chars: discard until terminator seen +discard: + jms getc + dac char + sad o4 + jmp eof + jms delim " end of line? + jmp eoname + sad o40 + jmp eoname + jmp discard + +" here with EOF in command: process command? +eof: + sys exit " quit, for now? + +" name ended (short) with whitespace or newline +" pad out last name to 8 with spaces +ws: + dac char " save terminator +1: lac o40 + jms putc " no: copy into argv + isz bcount " loop until full + jmp 1b + +" saw end of name +eoname: + dac char + lac redirect + sza + jmp 2f " last name was a redirect file, skip increment + + lac argc " increment argc + tad d4 + dac argc + lac nextarg + tad d4 " advance nextarg + dac nextarg + +2: + dzm redirect " clear redirect flag + lac nextarg + dac opt + + lac char + jms delim + jmp eol + + -maxargs + tad argc + sza + jmp newarg + +" too many args, (complain?). for now eat rest of line +4: jms getc + jms delim + skp + jmp 4b + lac d1; sys write; toomany; ltoomany + jmp newline + +" here at end of line +eol: + sad delimchar " save eol character + lac argc " check for empty command line + sna " get anything? + jmp 2f " no, go back for another + +" check for built-in "chdir" command + lac argv0 + sad chdirstr + skp + jmp 1f + lac argv0+1 + sad chdirstr+1 + skp + jmp 1f + lac argv0+2 + sad chdirstr+2 + jmp changedir + +1: +" comment these out to test "exec" + sys fork + jmp parent + +" here in child + lac d2; sys close " close fd 2 + sys unlink; exectemp " remove temp file + +" try to link binary from "system" directory to "exectemp" file +" sys link; system; argv0; exectemp +" spa +" jmp notsys +" sys open; exectemp; 0 +" spa +" jmp error +" sys unlink; exectemp +" jmp 1f +"notsys: " not found in "system" + + sys open; argv0; 0 " try cwd + spa + jmp cmderr + + cla " check for input redirection + sad infile + jmp 1f + sys close " close fd 0 + sys open; infile; 0 " open redirected + spa sna + jmp inerror + cla +1: sad outfile + jmp exec + lac d1; sys close " close fd 1 + lac o17 + sys creat; outfile " open output redirect + spa + jmp outerror + +" here to "exec" file open on fd 2, adapted from init.s +exec: + law boot-1 " Get source addr + dac 8 " set up index 8 (pre-increments) + law bootloc-1 " Copy "boot" code into high memory + dac 9 " set up index 9 (pre-increments) +1: lac 8 i + dac 9 i + isz bootcount " can only do this once! + jmp 1b + jmp bootloc " and then jump to the code + +" copied up to bootloc in high memory (below argc) +boot: + lac d2 " Load fd 2 (the opened executable) + lmq " Save the fd into MQ + sys read; userbase; userlen " read executable in + lacq " Get the fd back and close the file + sys close + jmp userbase " and jump to the beginning of the executable +bootlen=.-boot " length of bootstrap + +bootcount: -bootlen " isz loop count for bootstrap copy + +" error in child process: +inerror: " error opening input redirection + lac infilep + jmp error +outerror: " error opening new stdout (stdout closed!) + lac outfilep + skp +cmderr: " error opening command + lac argv0p +error: " error in child: filename pointer in AC + dac 1f " save filename to complain about + lac d1; sys write; 1: 0; 4 + lac d1; sys write; qmnl; 1 + lac d2; sys close + sys exit + +" chdir command: executed in shell process +changedir: +" XXX check if argc == 4 (no directories) and complain?? + lac argv0p + skp +1: lac 0f " increment argvp + tad d4 + sad 0f + -4 " decrement argc + tad argc + dac argc + sna " done? + jmp 2f " yes: join parent code + sys chdir; 0:0 + sma " error? + jmp 1b " no: look for another directory + +" chdir call failed + lac 0b + dac 0f + lac d1; sys write; 0:0; 4 + lac d1; sys write; qmnl; 1 + jmp 2f " join parent code + +" here in parent, child pid in AC +parent: +" https://www.bell-labs.com/usr/dmr/www/hist.html +" The message facility was used as follows: the parent shell, after +" creating a process to execute a command, sent a message to the new +" process by smes; when the command terminated (assuming it did not +" try to read any messages) the shell's blocked smes call returned an +" error indication that the target process did not exist. Thus the +" shell's smes became, in effect, the equivalent of wait. + dac pid + lac delimchar + sad o46 " ampersand? + jmp newcom " yes: go back without wait + lac pid + sys smes " hang until child exits +2: lac delimchar + sad o73 " semi? + jmp newcom " yes: look for another command w/o prompt + jmp newline " no: output prompt + +" ================ +" subroutines + +" eat spaces +" v1 routine name: +blank: 0 +1: jms getc + sad o40 + jmp 1b + jmp blank i + +" give skip return if AC *NOT* a command delimiter +" v1 routine name: +delim: 0 + sad o12 " newline + jmp delim i + sad o46 " ampersand + jmp delim i + sad o73 " semi + jmp delim i + isz delim " ran the gauntlet: skip home + jmp delim i + +" from cat.s +getc: 0 + lac ipt " Load pointer to next word in the buffer + sad eipt + jmp 1f " end of the buffer, so read more + dac 2f " Save the pointer + add o400000 " flip MSB, increment pointer on overflow + dac ipt + ral " Move the msb into the link register + lac 2f i " Load the word from the buffer + szl " Skip if second character in word + lrss 9 " first char: shift down the top character + and o177 " Keep the lowest 7 bits + sna + jmp getc+1 " Skip a NUL characters and read another one + jmp getc i " Return the character from the subroutine + +1: + cla " Buffer is empty, read another 64 characters + sys read; ibuf; 64 + sna + jmp 1f " No characters were read in + tad iipt " Add the word count to the base of the buffer + dac eipt " and store in the end buffer pointer + lac iipt " Reset the ipt to the base of the buffer + dac ipt + jmp getc+1 " and loop back to get one character +1: + lac o4 " No character, return with ctrl-D + jmp getc i " return from subroutine + +putc: 0 + and o177 " Keep the lowest 7 bits and save into 2f+1 + dac 2f+1 + lac opt " Save the pointer to the empty buffer + dac 2f " position to 2f + add o400000 " Flip the msb and save back into opt + dac opt " This also has the effect of incrementing + " the opt pointer every second addition! + + spa " If the bit was set, we already have one + jmp 1f " character at 2f+1. If no previous character, + lac 2f i " merge the old and new character together + xor 2f+1 + jmp 3f " and go to the "save it in buffer" code +1: + lac 2f+1 " Move the character up into the top half + alss 9 +3: + dac 2f i " Save the word into the buffer + jmp putc i " No, so return (more room still in the buffer) + +2: 0;0 " Current input and output word pointers +ipt: 0 " Current input buffer base +eipt: 0 " Pointer to end of data read in input buffer +iipt: ibuf +ibuf: .=.+64 + +" literals +d1: 1 +d2: 2 +o4:d4: 4 +o12: 012 " newline +o17: 017 +o40: 040 " space +o46: 046 " ampersand +o73: 046 " semi +o74:lt: 074 " < +o76:gt: 076 " > +o177: 0177 " 7-bit (ASCII) mask +o400000: 0400000 " MSB + +hash: <#> " superuser prompt +qmnl: ;;; 040040 + +exectemp: + ;;; " temporary link for file being exec'ed + +chdirstr: + ;; " + +toomany: ; ;;;< a>;; " v1 prompt +pid: 0 " "other" pid +char: 0 " white space char +redirect: 0 " last file was a redirect (lt or gt) +bcount: 0 " byte counter for current filename +delimchar: 0 " character that terminated line + +iopt:argv0p: argv0 " initial value for nextarg, opt +nextarg: 0 " next slot in argv to fill +opt: 0 " "output pointer" (may point to in/outfile) + +infilep: infile +outfilep: outfile + +outfile: .=.+4 " buffer for output redirect file name +infile: .=.+4 " buffer for input redirect file name + +argcptr: argc + +" leave room for maxargs items of 4 words each +maxargs=8 + +userbase=010000 " user starts at 4K +argptr=017777 " last word points to argc + argv data +argc=argptr-maxargs-maxargs-maxargs-maxargs-1 " argc followed by argv + +" arguments in 4 word blocks follow argc +argv0=argc+1 + +" "bootstrap" (reads executable into userbase) JUST below argc +bootloc=argc-bootlen " location of bootstrap + +userlen=bootloc-userbase " max executable +