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/* This file is part of the SvarCOM project and is published under the terms
* of the MIT license.
*
* Copyright (C) 2021-2024 Mateusz Viste
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#include <dos.h> /* MK_FP(), FP_SEG(), FP_OFF()... */
#include "svarlang.lib/svarlang.h"
#include "cmd.h"
#include "env.h"
#include "helpers.h"
#include "redir.h"
#include "rmodinit.h"
#include "sayonara.h"
#include "version.h"
#include "rmodcore.h" /* rmod binary inside a BUFFER array */
/* this version byte is used to tag RMOD so I can easily make sure that
* the RMOD struct I find in memory is one that I know. Should the version
* mismatch, then it would likely mean that SvarCOM has been upgraded and
* RMOD should not be accessed as its structure might no longer be in sync
* with what I think it is.
* *** INCREMENT THIS AT EACH NEW SVARCOM RELEASE! ***
* (or at least whenever RMOD's struct is changed) */
#define BYTE_VERSION 7
struct config {
unsigned char flags; /* command.com flags, as defined in rmodinit.h */
char *execcmd;
unsigned short envsiz;
};
/* max length of the cmdline storage (bytes) - includes also max length of
* line loaded from a BAT file (no more than 255 bytes!) */
#define CMDLINE_MAXLEN 255
/* sets guard values at a few places in memory for later detection of
* overflows via memguard_check() */
static void memguard_set(char *cmdlinebuf) {
BUFFER[sizeof(BUFFER) - 1] = 0xC7;
cmdlinebuf[CMDLINE_MAXLEN] = 0xC7;
}
/* checks for valguards at specific memory locations, returns 0 on success */
static int memguard_check(unsigned short rmodseg, char *cmdlinebuf) {
/* check RMOD signature (would be overwritten in case of stack overflow */
static char msg[] = "!! MEMORY CORRUPTION ## DETECTED !!";
unsigned short far *rmodsig = MK_FP(rmodseg, 0x100 + 6);
unsigned char far *rmod = MK_FP(rmodseg, 0);
if (*rmodsig != 0x2019) {
msg[22] = '1';
goto FAIL;
}
/* check last BUFFER byte */
if (BUFFER[sizeof(BUFFER) - 1] != 0xC7) {
msg[22] = '2';
goto FAIL;
}
/* check last cmdlinebuf byte */
if (cmdlinebuf[CMDLINE_MAXLEN] != 0xC7) {
msg[22] = '3';
goto FAIL;
}
/* check rmod exec buf */
if (rmod[RMOD_OFFSET_EXECPROG + 127] != 0) {
msg[22] = '4';
goto FAIL;
}
/* check rmod exec stdin buf */
if (rmod[RMOD_OFFSET_STDINFILE + 127] != 0) {
msg[22] = '5';
goto FAIL;
}
/* check rmod exec stdout buf */
if (rmod[RMOD_OFFSET_STDOUTFILE + 127] != 0) {
msg[22] = '6';
goto FAIL;
}
/* else all good */
return(0);
/* error handling */
FAIL:
outputnl(msg);
return(1);
}
/* exit do DOS with exist code */
static void EXIT(char code);
#pragma aux EXIT = \
"mov ah, 0x4c" \
"int 0x21" \
parm [al]
/* DR-DOS specific boot processing: check for F5/F8 boot key presses and reset
* the wild pointer to DR-DOS kernel (CONFIG.SYS) environment because it is not
* allocated memory hence will be overwritten soon.
* details: https://github.com/SvarDOS/edrdos/issues/83
* this function returns 0, FLAG_SKIP_AUTOEXEC or FLAG_STEPBYSTEP */
static void drdos_init(struct config *cfg) {
unsigned short kernenvseg = 0;
unsigned char far *e;
unsigned short far *scancode;
/* If I am init then query kernel's private data via INT 21,4458 (DR-DOS).
* On success (CF not set) ES:BX contains a pointer to the private data.
* Segment of kernel's environment is at offset 12h. This environment may
* be terminated by a 1Ah code followed by a boot key scan code to record
* an F5 or F8 key press during boot time. */
_asm {
push ax
push bx
push es
mov ax, 0x4458 /* DR-DOS 5+ get ptr to internal variable table */
int 0x21 /* ES:BX contains the ptr to the var table */
jc FAIL /* not DR-DOS */
add bx, 0x12
mov ax, es:[bx] /* read the segment of the kernel environment */
mov kernenvseg, ax /* save the kern env segment for later */
mov word ptr [es:bx], 0 /* reset the pointer to kernel env as done by DR COMMAND.COM */
/* if DR-DOS env is at seg 0x60 then overwrite my own env in PSP with this.
* Seg 0x60 is used since https://github.com/SvarDOS/edrdos/issues/88 and
* it is safe to be used as it won't be overwritten */
cmp ax, 0x60
jne FAIL
mov bx, 0x2C /* environment segment field in my PSP */
mov [bx], ax
FAIL:
pop es
pop bx
pop ax
}
if (kernenvseg == 0) return; /* either not DR-DOS, or kern env was read already or something failed */
/* now I know that 1) I am running under (E)DR-DOS and 2) I am init, so /P implied */
cfg->flags |= FLAG_PERMANENT;
/* DR-DOS kernel environment present: make sure to ask SvarCOM to alloc its
* own environment, because the kernel's environment might vanish eventually */
if (cfg->envsiz < 256) cfg->envsiz = 256;
e = MK_FP(kernenvseg, 0);
/*
printf("kernel env seg is at %04X and starts with bytes 0x%02X 0x%02X 0x%02X 0x%02X\r\n", kernenvseg, e[0], e[1], e[2], e[3]);
{
int i;
printf("=== KERNEL ENV BEGINS ===\r\n");
for (i = 0; i < 100; i++) {
printf("%c", e[i]);
}
printf("\r\n=== KERNEL ENV ENDS, DUMP FOLLOWS ===\r\n");
for (i = 0; i < 260; i++) {
if ((i > 0) && ((i % 26) == 0)) printf("\r\n");
printf("%02X ", e[i]);
}
printf("\r\n=== DUMP ENDS ===\r\n");
}
*/
/* move forward until the DRDOS' environment 1Ah terminator is found */
while (*e != 0x1A) e++;
e++;
/* next I have the boot key press scancode: either 0x0000, 0x3F00 or 0x4200
* 0x3F00 means "F5 was pressed" while 0x4200 is for F8 */
scancode = (void far *)e;
if (*scancode == 0x3F00) {
cfg->flags |= FLAG_SKIP_AUTOEXEC;
} else if (*scancode == 0x4200) {
cfg->flags |= FLAG_STEPBYSTEP;
}
}
/* parses command line the hard way (directly from PSP) */
static void parse_argv(struct config *cfg) {
unsigned char *cmdlinelen = (void *)0x80;
char *cmdline = (void *)0x81;
/* The arg tail at [81h] needs some care when being processed.
*
* Its length should be provided in [80h], but it is not always exact:
* https://github.com/SvarDOS/bugz/issues/67
*
* The tail string itself is usually terminated by a CR character. But
* sometimes it might be terminated by a nul. Or by nothing at all.
*
* The cautious approach is therefore to read the tail up until the length
* mentionned at [80h] or to first CR or nul, whichever comes first.
*/
sv_bzero(cfg, sizeof(*cfg));
/* Make sure that the advertised cmdline length is no more than 126 bytes
* because the PSP ends at [0xff] and there ought to be at least 1 byte of
* room for the CR-terminator.
* According to Matthias Paul cmdlines longer than 126 (and even longer than
* 127) might happen with some buggy implementations. */
if (*cmdlinelen > 126) *cmdlinelen = 126;
/* trim out any trailing CR garbage (see the issue 67 mentioned above) */
while ((*cmdlinelen > 0) && (cmdline[*cmdlinelen - 1] == '\r')) (*cmdlinelen)--;
/* normalize the cmd so it is nul-terminated - this is expected later in a
* few places in the codeflow, among others in run_as_external() */
cmdline[*cmdlinelen] = 0;
/* process the parameters given to COMMAND.COM */
while (*cmdline != 0) {
/* skip over any leading spaces */
if (*cmdline == ' ') {
cmdline++;
continue;
}
if (*cmdline != '/') {
nls_output(0,6); /* "Invalid parameter" */
output(": ");
outputnl(cmdline);
goto SKIP_TO_NEXT_ARG;
}
/* got a slash */
cmdline++; /* skip the slash */
switch (*cmdline) {
case 'c': /* /C = execute command and quit */
case 'C':
cfg->flags |= FLAG_EXEC_AND_QUIT;
/* FALLTHRU */
case 'k': /* /K = execute command and keep running */
case 'K':
cmdline++;
cfg->execcmd = cmdline;
return; /* further arguments are for the executed program, not for me */
case 'y': /* /Y = execute batch file step-by-step (with /P, /K or /C) */
case 'Y':
cfg->flags |= FLAG_STEPBYSTEP;
break;
case 'd': /* /D = skip autoexec.bat processing */
case 'D':
cfg->flags |= FLAG_SKIP_AUTOEXEC;
break;
case 'e': /* preset the initial size of the environment block */
case 'E':
cmdline++;
if (*cmdline == ':') cmdline++; /* could be /E:size */
atous(&(cfg->envsiz), cmdline);
if (cfg->envsiz < 64) cfg->envsiz = 0;
break;
case 'p': /* permanent shell (can't exit + run autoexec.bat) */
case 'P':
cfg->flags |= FLAG_PERMANENT;
break;
case '?':
nls_outputnl(1,0); /* "Starts the SvarCOM command interpreter" */
outputnl("");
nls_outputnl(1,1); /* "COMMAND /E:nnn [/[C|K] [/P] [/D] command]" */
outputnl("");
nls_outputnl(1,2); /* "/D Skip AUTOEXEC.BAT processing (makes sense only with /P)" */
nls_outputnl(1,3); /* "/E:nnn Sets the environment size to nnn bytes" */
nls_outputnl(1,4); /* "/P Makes the new command interpreter permanent and run AUTOEXEC.BAT" */
nls_outputnl(1,5); /* "/C Executes the specified command and returns" */
nls_outputnl(1,6); /* "/K Executes the specified command and continues running" */
nls_outputnl(1,7); /* "/Y Executes the batch program step by step" */
EXIT(1);
break;
default:
nls_output(0,2); /* invalid switch */
output(": /");
outputnl(cmdline);
break;
}
/* move to next argument or quit processing if end of cmdline */
SKIP_TO_NEXT_ARG:
while ((*cmdline != 0) && (*cmdline != ' ') && (*cmdline != '/')) cmdline++;
}
}
/* returns current DOS drive (0 = A: ; 1 = B: etc) */
static unsigned char _dosgetcurdrive(void);
#pragma aux _dosgetcurdrive = \
"mov ah, 0x19" /* DOS 1+ - GET CURRENT DRIVE */ \
"int 0x21" \
modify [ah] \
value [al]
static void _dosgetcurdir(char near *s);
#pragma aux _dosgetcurdir = \
"mov ah, 0x47" /* DOS 2+ - CWD - GET CURRENT DIRECTORY */ \
"xor dl, dl" /* DL = drive number (00h = default, 01h = A:, etc) */ \
"mov [si], 0" /* set empty dir in case of failure (unformatted floppy) */ \
"int 0x21" \
parm [si] \
modify [ax dl]
/* builds the prompt string and displays it. buff is filled with a zero-terminated copy of the prompt. */
static void build_and_display_prompt(char *buff, unsigned short envseg) {
char *s = buff;
/* locate the prompt variable or use the default pattern */
const char far *fmt = env_lookup_val(envseg, "PROMPT");
if ((fmt == NULL) || (*fmt == 0)) fmt = "$p$g"; /* fallback to default if empty */
/* build the prompt string based on pattern */
for (; *fmt != 0; fmt++) {
if (*fmt != '$') {
*s = *fmt;
s++;
continue;
}
/* escape code ($P, etc) */
fmt++;
switch (*fmt) {
case 'Q': /* $Q = = (equal sign) */
case 'q':
*s = '=';
s++;
break;
case '$': /* $$ = $ (dollar sign) */
*s = '$';
s++;
break;
case 'T': /* $t = current time */
case 't':
{
struct nls_patterns nls;
unsigned char h, m, sec;
if (nls_getpatterns(&nls) != 0) {
s += sv_strcpy(s, "ERR");
} else {
dos_get_time(&h, &m, &sec);
s += nls_format_time(s, h, m, sec, &nls);
}
break;
}
case 'D': /* $D = current date */
case 'd':
{
struct nls_patterns nls;
unsigned short y;
unsigned char m, d;
if (nls_getpatterns(&nls) != 0) {
s += sv_strcpy(s, "ERR");
} else {
dos_get_date(&y, &m, &d);
s += nls_format_date(s, y, m, d, &nls);
}
break;
}
case 'P': /* $P = current drive and path */
case 'p':
*s = _dosgetcurdrive() + 'A';
s++;
*s = ':';
s++;
*s = '\\';
s++;
_dosgetcurdir(s);
/* move s ptr forward to end (0-termintor) of pathname */
while (*s != 0) s++;
break;
case 'V': /* $V = version number */
case 'v':
s += sv_strcpy(s, PVER);
break;
case 'N': /* $N = current drive */
case 'n':
*s = _dosgetcurdrive() + 'A';
s++;
break;
case 'G': /* $G = > (greater-than sign) */
case 'g':
*s = '>';
s++;
break;
case 'L': /* $L = < (less-than sign) */
case 'l':
*s = '<';
s++;
break;
case 'B': /* $B = | (pipe) */
case 'b':
*s = '|';
s++;
break;
case 'H': /* $H = backspace (erases previous character) */
case 'h':
*s = '\b';
s++;
break;
case 'E': /* $E = Escape code (ASCII 27) */
case 'e':
*s = 27;
s++;
break;
case '_': /* $_ = CR+LF */
*s = '\r';
s++;
*s = '\n';
s++;
break;
}
}
*s = 0;
output(buff);
}
static void dos_fname2fcb(char far *fcb, const char near *cmd);
#pragma aux dos_fname2fcb = \
"mov ax, 0x2900" /* DOS 1+ - parse filename into FCB (DS:SI=fname, ES:DI=FCB) */ \
"int 0x21" \
parm [es di] [si] \
modify [ax si]
/* parses cmdtail and fills fcb1 and fcb2 with first and second arguments,
* respectively. an FCB is 12 bytes long:
* drive (0=default, 1=A, 2=B, etc)
* fname (8 chars, blank-padded)
* fext (3 chars, blank-padded) */
static void cmdtail_to_fcb(char far *fcb1, char far *fcb2, const char *cmdtail) {
/* skip any leading spaces */
while (*cmdtail == ' ') cmdtail++;
/* convert first arg */
dos_fname2fcb(fcb1, cmdtail);
/* skip to next arg */
while ((*cmdtail != ' ') && (*cmdtail != 0)) cmdtail++;
while (*cmdtail == ' ') cmdtail++;
/* convert second arg */
dos_fname2fcb(fcb2, cmdtail);
}
/* a few internal flags */
#define DELETE_STDIN_FILE 1
#define CALL_FLAG 2
#define LOADHIGH_FLAG 4
static void run_as_external(char *buff, const char *cmdline, unsigned short envseg, struct rmod_props far *rmod, struct redir_data *redir, unsigned char flags) {
char *cmdfile = buff + 512;
const char far *pathptr;
int lookup;
unsigned short i;
const char *ext;
char *cmd = buff + 1024;
const char *cmdtail;
char far *rmod_execprog = MK_FP(rmod->rmodseg, RMOD_OFFSET_EXECPROG);
char far *rmod_cmdtail = MK_FP(rmod->rmodseg, 0x81);
_Packed struct {
unsigned short envseg;
unsigned long cmdtail;
unsigned long fcb1;
unsigned long fcb2;
} far *ExecParam = MK_FP(rmod->rmodseg, RMOD_OFFSET_EXECPARAM);
/* find cmd and cmdtail */
i = 0;
cmdtail = cmdline;
while (*cmdtail == ' ') cmdtail++; /* skip any leading spaces */
while ((*cmdtail != ' ') && (*cmdtail != '/') && (*cmdtail != '+') && (*cmdtail != 0)) {
cmd[i++] = *cmdtail;
cmdtail++;
}
cmd[i] = 0;
/* is this a command in curdir? */
lookup = lookup_cmd(cmdfile, cmd, NULL, &ext);
if (lookup == 0) {
/* printf("FOUND LOCAL EXEC FILE: '%s'\r\n", cmdfile); */
goto RUNCMDFILE;
} else if (lookup == -2) {
/* puts("NOT FOUND"); */
return;
}
/* try matching something in PATH */
pathptr = env_lookup_val(envseg, "PATH");
/* try each path in %PATH% */
while (pathptr) {
for (i = 0;; i++) {
buff[i] = *pathptr;
if ((buff[i] == 0) || (buff[i] == ';')) break;
pathptr++;
}
buff[i] = 0;
lookup = lookup_cmd(cmdfile, cmd, buff, &ext);
if (lookup == 0) goto RUNCMDFILE;
if (lookup == -2) return;
if (*pathptr == ';') {
pathptr++;
} else {
break;
}
}
/* last chance: is it an executable link? (trim extension from cmd first) */
for (i = 0; (cmd[i] != 0) && (cmd[i] != '.') && (i < 9); i++) buff[128 + i] = cmd[i];
buff[128 + i] = 0;
if ((i < 9) && (link_computefname(buff, buff + 128, envseg) == 0)) {
/* try opening the link file (if it exists) and read it into buff */
i = 0;
_asm {
push ax
push bx
push cx
push dx
mov ax, 0x3d00 /* DOS 2+ - OPEN EXISTING FILE, READ-ONLY */
mov dx, buff /* file name */
int 0x21
jc ERR_FOPEN
/* file handle in AX, read from file now */
mov bx, ax /* file handle */
mov ah, 0x3f /* Read from file via handle bx */
mov cx, 128 /* up to 128 bytes */
/* mov dx, buff */ /* dest buffer (already set) */
int 0x21 /* read up to 256 bytes from file and write to buff */
jc ERR_READ
mov i, ax
ERR_READ:
mov ah, 0x3e /* close file handle in BX */
int 0x21
ERR_FOPEN:
pop dx
pop cx
pop bx
pop ax
}
/* did I read anything? */
if (i != 0) {
buff[i] = 0;
/* trim buff at first \n or \r, just in case someone fiddled with the
* link file using a text editor */
for (i = 0; (buff[i] != 0) && (buff[i] != '\r') && (buff[i] != '\n'); i++);
buff[i] = 0;
/* lookup check */
if (buff[0] != 0) {
lookup = lookup_cmd(cmdfile, cmd, buff, &ext);
if (lookup == 0) goto RUNCMDFILE;
}
}
}
/* all failed (ie. executable file not found) */
return;
RUNCMDFILE:
/* special handling of batch files */
if ((ext != NULL) && (imatch(ext, "bat"))) {
struct batctx far *newbat;
/* remember the echo flag (in case bat file disables echo, only when starting first bat) */
if (rmod->bat == NULL) {
rmod->flags &= ~FLAG_ECHO_BEFORE_BAT;
if (rmod->flags & FLAG_ECHOFLAG) rmod->flags |= FLAG_ECHO_BEFORE_BAT;
}
/* if bat is not called via a CALL, then free the bat-context linked list */
if ((flags & CALL_FLAG) == 0) rmod_free_bat_llist(rmod);
/* allocate a new bat context */
newbat = rmod_fcalloc(sizeof(struct batctx), rmod->rmodseg, "SVBATCTX");
if (newbat == NULL) {
nls_outputnl_doserr(8); /* insufficient memory */
return;
}
/* fill the newly allocated batctx structure */
sv_strcpy_far(newbat->fname, cmdfile); /* truename of the BAT file */
newbat->flags = flags & FLAG_STEPBYSTEP;
/* explode args of the bat file and store them in rmod buff */
cmd_explode(buff, cmdline, NULL);
memcpy_ltr_far(newbat->argv, buff, sizeof(newbat->argv));
/* push the new bat to the top of rmod's linked list */
newbat->parent = rmod->bat;
rmod->bat = newbat;
return;
}
/* copy full filename to execute, along with redirected files (if any) */
sv_strcpy_far(rmod_execprog, cmdfile);
/* copy stdin file if a redirection is needed */
if (redir->stdinfile) {
char far *farptr = MK_FP(rmod->rmodseg, RMOD_OFFSET_STDINFILE);
char far *delstdin = MK_FP(rmod->rmodseg, RMOD_OFFSET_STDIN_DEL);
sv_strcpy_far(farptr, redir->stdinfile);
if (flags & DELETE_STDIN_FILE) {
*delstdin = redir->stdinfile[0];
} else {
*delstdin = 0;
}
}
/* same for stdout file */
if (redir->stdoutfile) {
char far *farptr = MK_FP(rmod->rmodseg, RMOD_OFFSET_STDOUTFILE);
unsigned short far *farptr16 = MK_FP(rmod->rmodseg, RMOD_OFFSET_STDOUTAPP);
sv_strcpy_far(farptr, redir->stdoutfile);
/* openflag */
*farptr16 = redir->stdout_openflag;
}
/* copy cmdtail to rmod's PSP and compute its len */
for (i = 0; cmdtail[i] != 0; i++) rmod_cmdtail[i] = cmdtail[i];
rmod_cmdtail[i] = '\r';
rmod_cmdtail[-1] = i;
/* set up rmod to execute the command */
/* loadhigh? */
if (flags & LOADHIGH_FLAG) {
unsigned char far *farptr = MK_FP(rmod->rmodseg, RMOD_OFFSET_EXEC_LH);
*farptr = 1;
}
ExecParam->envseg = envseg;
ExecParam->cmdtail = (unsigned long)MK_FP(rmod->rmodseg, 0x80); /* farptr, must be in PSP format (lenbyte args \r) */
/* far pointers to unopened FCB entries (stored in RMOD's own PSP) */
{
char far *farptr;
/* prep the unopened FCBs */
farptr = MK_FP(rmod->rmodseg, 0x5C);
sv_bzero(farptr, 36); /* first FCB is 16 bytes long, second is 20 bytes long */
cmdtail_to_fcb(farptr, farptr + 16, cmdtail);
/* set (far) pointers in the ExecParam block */
ExecParam->fcb1 = (unsigned long)MK_FP(rmod->rmodseg, 0x5C);
ExecParam->fcb2 = (unsigned long)MK_FP(rmod->rmodseg, 0x6C);
}
EXIT(0); /* let rmod do the job now */
}
static void set_comspec_to_self(unsigned short envseg) {
unsigned short *psp_envseg = (void *)(0x2c); /* pointer to my env segment field in the PSP */
char far *myenv = MK_FP(*psp_envseg, 0);
unsigned short varcount;
char buff[256] = "COMSPEC=";
char *buffptr = buff + 8;
/* who am i? look into my own environment, at the end of it should be my EXEPATH string */
while (*myenv != 0) {
/* consume a NULL-terminated string */
while (*myenv != 0) myenv++;
/* move to next string */
myenv++;
}
/* get next word, if 1 then EXEPATH follows */
myenv++;
varcount = *myenv;
myenv++;
varcount |= (*myenv << 8);
myenv++;
if (varcount != 1) return; /* NO EXEPATH FOUND */
while (*myenv != 0) {
*buffptr = *myenv;
buffptr++;
myenv++;
}
*buffptr = 0;
/* printf("EXEPATH: '%s'\r\n", buff); */
env_setvar(envseg, buff);
}
/* wait for user input */
static void cmdline_getinput(unsigned short inpseg, unsigned short inpoff);
#pragma aux cmdline_getinput = \
"push ds" \
/* set up buffered input to inpseg:inpoff */ \
"push ax" \
"pop ds" \
\
/* is DOSKEY support present? (INT 2Fh, AX=4800h, returns non-zero in AL if present) */ \
"mov ax, 0x4800" \
"int 0x2f" \
\
/* execute either DOS input or DOSKEY */ \
"test al, al" /* al=0 if no DOSKEY present */ \
"jnz DOSKEY" \
\
/* buffered string input */ \
"mov ah, 0x0a" \
"int 0x21" \
"jmp short DONE" \
\
"DOSKEY:" \
"mov ax, 0x4810" \
"int 0x2f" \
\
"DONE:" \
/* terminate command with a CR/LF */ \
"mov ah, 0x02" /* display character in dl */ \
"mov dl, 0x0d" \
"int 0x21" \
"mov dl, 0x0a" \
"int 0x21" \
"pop ds" \
parm [ax] [dx] \
modify [ax dl]
/* fetches a line from batch file and write it to buff (NULL-terminated),
* increments rmod counter and returns 0 on success. */
static int getbatcmd(char *buff, unsigned char buffmaxlen, struct rmod_props far *rmod) {
unsigned short i;
unsigned short batname_seg = FP_SEG(rmod->bat->fname);
unsigned short batname_off = FP_OFF(rmod->bat->fname);
unsigned short filepos_cx = rmod->bat->nextline >> 16;
unsigned short filepos_dx = rmod->bat->nextline & 0xffff;
unsigned char blen = 0;
unsigned short errv = 0;
/* open file, jump to offset filpos, and read data into buff.
* result in blen (unchanged if EOF or failure). */
_asm {
push ax
push bx
push cx
push dx
/* open file (read-only) */
mov bx, 0xffff /* preset BX to 0xffff to detect error conditions */
mov dx, batname_off
mov ax, batname_seg
push ds /* save DS */
mov ds, ax
mov ax, 0x3d00
int 0x21 /* handle in ax on success */
pop ds /* restore DS */
jc ERR
mov bx, ax /* save handle to bx */
/* jump to file offset CX:DX */
mov ax, 0x4200
mov cx, filepos_cx
mov dx, filepos_dx
int 0x21 /* CF clear on success, DX:AX set to cur pos */
jc ERR
/* read the line into buff */
mov ah, 0x3f
xor ch, ch
mov cl, buffmaxlen
mov dx, buff
int 0x21 /* CF clear on success, AX=number of bytes read */
jc ERR
mov blen, al
jmp CLOSEANDQUIT
ERR:
mov errv, ax
CLOSEANDQUIT:
/* close file (if bx contains a handle) */
cmp bx, 0xffff
je DONE
mov ah, 0x3e
int 0x21
DONE:
pop dx
pop cx
pop bx
pop ax
}
/* printf("blen=%u filepos_cx=%u filepos_dx=%u\r\n", blen, filepos_cx, filepos_dx); */
if (errv != 0) nls_outputnl_doserr(errv);
/* on EOF - abort processing the bat file */
if (blen == 0) goto OOPS;
/* find nearest \n to inc batch offset and replace \r by NULL terminator
* I support all CR/LF, CR- and LF-terminated batch files */
for (i = 0; i < blen; i++) {
if ((buff[i] == '\r') || (buff[i] == '\n')) {
if ((buff[i] == '\r') && ((i+1) < blen) && (buff[i+1] == '\n')) rmod->bat->nextline += 1;
break;
}
}
buff[i] = 0;
rmod->bat->nextline += i + 1;
return(0);
OOPS:
rmod->bat->fname[0] = 0;
rmod->bat->nextline = 0;
return(-1);
}
/* replaces %-variables in a BAT line with resolved values:
* %PATH% -> replaced by the contend of the PATH env variable
* %UNDEFINED% -> undefined variables are replaced by nothing ("")
* %NOTCLOSED -> NOTCLOSED
* %1 -> first argument of the batch file (or nothing if no arg) */
static void batpercrepl(char *res, unsigned short ressz, const char *line, const struct rmod_props far *rmod, unsigned short envseg) {
unsigned short lastperc = 0xffff;
unsigned short reslen = 0;
if (ressz == 0) return;
ressz--; /* reserve one byte for the NULL terminator */
for (; (reslen < ressz) && (*line != 0); line++) {
/* if not a percent, I don't care */
if (*line != '%') {
res[reslen++] = *line;
continue;
}
/* *** perc char handling *** */
/* closing perc? */
if (lastperc != 0xffff) {
/* %% is '%' */
if (lastperc == reslen) {
res[reslen++] = '%';
} else { /* otherwise variable name */
const char far *ptr;
res[reslen] = 0;
reslen = lastperc;
nls_strtoup(res + reslen); /* turn varname uppercase before lookup */
ptr = env_lookup_val(envseg, res + reslen);
if (ptr != NULL) {
while ((*ptr != 0) && (reslen < ressz)) {
res[reslen++] = *ptr;
ptr++;
}
}
}
lastperc = 0xffff;
continue;
}
/* digit? (bat arg) */
if ((line[1] >= '0') && (line[1] <= '9')) {
unsigned short argid = line[1] - '0';
unsigned short i;
const char far *argv = "";
if ((rmod != NULL) && (rmod->bat != NULL)) argv = rmod->bat->argv;
/* locate the proper arg */
for (i = 0; i != argid; i++) {
/* if string is 0, then end of list reached */
if (*argv == 0) break;
/* jump to next arg */
while (*argv != 0) argv++;
argv++;
}
/* copy the arg to result */
for (i = 0; (argv[i] != 0) && (reslen < ressz); i++) {
res[reslen++] = argv[i];
}
line++; /* skip the digit */
continue;
}
/* opening perc */
lastperc = reslen;
}
res[reslen] = 0;
}
/* process the ongoing forloop, returns 0 on success, non-zero otherwise (no
more things to process) */
static int forloop_process(char *res, struct forctx far *forloop) {
unsigned short i, t;
struct DTA *dta = (void *)0x80; /* default DTA at 80h in PSP */
char *fnameptr = dta->fname;
char *pathprefix = BUFFER + 256;
*pathprefix = 0;
TRYAGAIN:
/* dta_inited: FindFirst() or FindNext()? */
if (forloop->dta_inited == 0) {
/* copy next awaiting pattern to BUFFER (and skip all delimiters until
* next pattern or end of list) */
t = 0;
for (i = 0;; i++) {
BUFFER[i] = forloop->cmd[forloop->nextpat + i];
/* is this a delimiter? (all delimiters are already normalized to a space here) */
if (BUFFER[i] == ' ') {
BUFFER[i] = 0;
t = 1;
} else if (BUFFER[i] == 0) {
/* end of patterns list */
break;
} else {
/* quit if I got a pattern already */
if (t == 1) break;
}
}
if (i == 0) return(-1);
/* remember position of current pattern */
forloop->curpat = forloop->nextpat;
/* move nextpat forward to next pattern */
i += forloop->nextpat;
forloop->nextpat = i;
/* if this is a string and not a pattern, skip all the FindFirst business
* a file pattern has a wildcard (* or ?), a message doesn't */
for (i = 0; (BUFFER[i] != 0) && (BUFFER[i] != '?') && (BUFFER[i] != '*'); i++);
if (BUFFER[i] == 0) {
fnameptr = BUFFER;
goto SKIP_DTA;
}
/* FOR in MSDOS 6 includes hidden and system files, but not directories nor volumes */
if (findfirst(dta, BUFFER, DOS_ATTR_RO | DOS_ATTR_HID | DOS_ATTR_SYS | DOS_ATTR_ARC) != 0) {
goto TRYAGAIN;
}
forloop->dta_inited = 1;
} else { /* dta in progress */
/* copy forloop DTA to my local copy */
memcpy_ltr_far(dta, &(forloop->dta), sizeof(*dta));
/* findnext() call */
if (findnext(dta) != 0) {
forloop->dta_inited = 0;
goto TRYAGAIN;
}
}
/* copy updated DTA to rmod */
memcpy_ltr_far(&(forloop->dta), dta, sizeof(*dta));
/* prefill pathprefix with the prefix (path) of the files */
{
short lastbk = -1;
char far *c = forloop->cmd + forloop->curpat;
for (i = 0;; i++) {
pathprefix[i] = c[i];
if (pathprefix[i] == '\\') lastbk = i;
if ((pathprefix[i] == ' ') || (pathprefix[i] == 0)) break;
}
pathprefix[lastbk+1] = 0;
}
SKIP_DTA:
/* fill res with command, replacing varname by actual filename */
/* full filename is to be built with path of curpat and fname from dta */
t = 0;
i = 0;
for (;;) {
if ((forloop->cmd[forloop->exec + t] == '%') && (forloop->cmd[forloop->exec + t + 1] == forloop->varname)) {
sv_strcpy(res + i, pathprefix);
sv_strcat(res + i, fnameptr);
for (; res[i] != 0; i++);
t += 2;
} else {
res[i] = forloop->cmd[forloop->exec + t];
t++;
if (res[i++] == 0) break;
}
}
return(0);
}
int main(void) {
static struct config cfg;
static unsigned short far *rmod_envseg;
static struct rmod_props far *rmod;
static char cmdlinebuf[CMDLINE_MAXLEN + 2]; /* 1 extra byte for 0-terminator and another for memguard */
static char *cmdline;
static struct redir_data redirprops;
static enum cmd_result cmdres;
static unsigned short i; /* general-purpose variable for short-lived things */
static unsigned char flags;
static unsigned char far *rmod_farptr;
rmod = rmod_find(BUFFER_len);
if (rmod == NULL) {
/* look at command line parameters (in case env size if set there) */
parse_argv(&cfg);
/* DR-DOS specific: if I am the init shell (zeroed env seg) then detect F5/F8 now
* This must be done BEFORE rmod_install() because DR-DOS's boot environment
* is located at an unallocated memory location that is likely to be overwritten
* by rmod_install(). */
drdos_init(&cfg);
rmod = rmod_install(cfg.envsiz, BUFFER, BUFFER_len, &(cfg.flags));
if (rmod == NULL) {
nls_outputnl_err(2,1); /* "FATAL ERROR: rmod_install() failed" */
return(1);
}
/* copy flags to rmod's storage (and enable ECHO) */
rmod->flags = cfg.flags | FLAG_ECHOFLAG;
/* printf("rmod installed at %Fp\r\n", rmod); */
rmod->version = BYTE_VERSION;
} else {
/* printf("rmod found at %Fp\r\n", rmod); */
/* if I was spawned by rmod and FLAG_EXEC_AND_QUIT is set, then I should
* die asap, because the command has been executed already, so I no longer
* have a purpose in life, UNLESS I still have a batch file to run or
* a FOR loop to execute */
if ((rmod->flags & FLAG_EXEC_AND_QUIT) && (rmod->bat == NULL) && (rmod->forloop == NULL)) {
sayonara(rmod);
}
/* halt if RMOD version is not the same as myself - this can happen after
* a SvarCOM update */
if (rmod->version != BYTE_VERSION) {
nls_outputnl_err(2,0);
_asm {
HALT:
hlt
jmp HALT
}
}
}
/* general (far) pointer to RMOD, useful to check some of its internal fields */
rmod_farptr = MK_FP(rmod->rmodseg, 0);
rmod_envseg = MK_FP(rmod->rmodseg, RMOD_OFFSET_ENVSEG);
/* install a few guardvals in memory to detect some cases of overflows */
memguard_set(cmdlinebuf);
/* if last operation was ended by CTRL+C then make sure to abort any
* ongoing BAT file or FOR loop */
if (rmod_farptr[RMOD_OFFSET_CTRLCFLAG] != 0) {
/* reset the flag */
rmod_farptr[RMOD_OFFSET_CTRLCFLAG] = 0;
/* clear up the forloop node */
if (rmod->forloop != NULL) {
rmod_ffree(rmod->forloop);
rmod->forloop = NULL;
}
/* clear up the batch linked list */
if (rmod->bat != NULL) {
while (rmod->bat != NULL) {
struct batctx far *batnode;
batnode = rmod->bat;
rmod->bat = rmod->bat->parent;
rmod_ffree(batnode);
}
rmod->flags &= ~FLAG_ECHOFLAG;
if (rmod->flags & FLAG_ECHO_BEFORE_BAT) rmod->flags |= FLAG_ECHOFLAG;
}
}
/* make COMSPEC point to myself */
set_comspec_to_self(*rmod_envseg);
/* on /P check for the presence of AUTOEXEC.BAT and execute it if found,
* but skip this check if /D was also passed */
if ((cfg.flags & (FLAG_PERMANENT | FLAG_SKIP_AUTOEXEC)) == FLAG_PERMANENT) {
if (file_getattr("AUTOEXEC.BAT") >= 0) cfg.execcmd = "AUTOEXEC.BAT";
}
do {
/* update rmod's ptr to COMSPEC so it is always up to date - this needs to be
* done early so it is up to date even if this instance of SvarCOM dies
* early (for example because of a CTRL+C event) */
rmod_updatecomspecptr(rmod->rmodseg, *rmod_envseg);
/* terminate previous command with a CR/LF if ECHO ON (but not during BAT processing) */
if ((rmod->flags & FLAG_ECHOFLAG) && (rmod->bat == NULL)) outputnl("");
SKIP_NEWLINE:
/* memory check */
memguard_check(rmod->rmodseg, cmdlinebuf);
/* preset cmdline to point at the dedicated buffer */
cmdline = cmdlinebuf;
/* (re)load translation strings if needed */
nls_langreload(BUFFER, rmod->rmodseg);
/* am I inside a FOR loop? */
if (rmod->forloop) {
if (forloop_process(cmdlinebuf, rmod->forloop) != 0) {
rmod_ffree(rmod->forloop);
rmod->forloop = NULL;
continue; /* needed so we quit if the FOR loop was ran through COMMAND/C */
} else {
/* output prompt and command on screen if echo on and command is not
* inhibiting it with the @ prefix */
if (rmod->flags & FLAG_ECHOFLAG) {
build_and_display_prompt(BUFFER, *rmod_envseg);
outputnl(cmdline);
}
/* jump to command processing */
goto EXEC_CMDLINE;
}
}
/* load awaiting command, if any (used to run piped commands) */
if (rmod->awaitingcmd[0] != 0) {
sv_strcpy_far(cmdline, rmod->awaitingcmd);
rmod->awaitingcmd[0] = 0;
flags |= DELETE_STDIN_FILE;
goto EXEC_CMDLINE;
} else {
flags &= ~DELETE_STDIN_FILE;
}
/* skip user input if I have a command to exec (/C or /K or /P) */
if (cfg.execcmd != NULL) {
cmdline = cfg.execcmd;
cfg.execcmd = NULL;
/* */
if (cfg.flags & FLAG_STEPBYSTEP) flags |= FLAG_STEPBYSTEP;
goto EXEC_CMDLINE;
}
/* if batch file is being executed -> fetch next line */
if (rmod->bat != NULL) {
if (getbatcmd(BUFFER, CMDLINE_MAXLEN, rmod) != 0) { /* end of batch */
struct batctx far *victim = rmod->bat;
rmod->bat = rmod->bat->parent;
rmod_ffree(victim);
/* end of batch? then restore echo flag as it was before running the (first) bat file */
if (rmod->bat == NULL) {
rmod->flags &= ~FLAG_ECHOFLAG;
if (rmod->flags & FLAG_ECHO_BEFORE_BAT) rmod->flags |= FLAG_ECHOFLAG;
}
continue;
}
/* %-decoding of variables (%PATH%, %1, %%...), result in cmdline */
batpercrepl(cmdline, CMDLINE_MAXLEN, BUFFER, rmod, *rmod_envseg);
/* skip any leading spaces */
while (*cmdline == ' ') cmdline++;
/* skip batch labels */
if (*cmdline == ':') continue;
/* step-by-step execution? */
if (rmod->bat->flags & FLAG_STEPBYSTEP) {
if (*cmdline == 0) continue; /* skip empty lines */
if (askchoice(cmdline, svarlang_str(0,10)) != 0) continue;
}
/* output prompt and command on screen if echo on and command is not
* inhibiting it with the @ prefix */
if ((rmod->flags & FLAG_ECHOFLAG) && (cmdline[0] != '@')) {
build_and_display_prompt(BUFFER, *rmod_envseg);
outputnl(cmdline);
}
/* skip the @ prefix if present, it is no longer useful */
if (cmdline[0] == '@') cmdline++;
} else {
unsigned char far *rmod_inputbuf = MK_FP(rmod->rmodseg, RMOD_OFFSET_INPUTBUF);
/* invalidate input history if it appears to be damaged (could occur
* because of a stack overflow, for example if some stack-hungry TSR is
* being used) */
if ((rmod_inputbuf[0] != 128) || (rmod_inputbuf[rmod_inputbuf[1] + 2] != '\r') || (rmod_inputbuf[rmod_inputbuf[1] + 3] != 0xCA) || (rmod_inputbuf[rmod_inputbuf[1] + 4] != 0xFE)) {
rmod_inputbuf[0] = 128; /* max allowed input length */
rmod_inputbuf[1] = 0; /* string len stored in buffer */
rmod_inputbuf[2] = '\r'; /* string terminator */
rmod_inputbuf[3] = 0xCA; /* trailing signature */
rmod_inputbuf[4] = 0xFE; /* trailing signature */
nls_outputnl_err(2,2); /* "stack overflow detected, command history flushed" */
}
/* interactive mode: display prompt (if echo enabled) and wait for user
* command line */
if (rmod->flags & FLAG_ECHOFLAG) build_and_display_prompt(BUFFER, *rmod_envseg);
/* collect user input */
cmdline_getinput(rmod->rmodseg, RMOD_OFFSET_INPUTBUF);
/* append stack-overflow detection signature to the end of the input buffer */
rmod_inputbuf[rmod_inputbuf[1] + 3] = 0xCA; /* trailing signature */
rmod_inputbuf[rmod_inputbuf[1] + 4] = 0xFE; /* trailing signature */
/* copy it to local cmdline */
if (rmod_inputbuf[1] != 0) memcpy_ltr_far(cmdline, rmod_inputbuf + 2, rmod_inputbuf[1]);
cmdline[rmod_inputbuf[1]] = 0; /* zero-terminate local buff (original is '\r'-terminated) */
}
/* if nothing entered, loop again (but without appending an extra CR/LF) */
if (cmdline[0] == 0) goto SKIP_NEWLINE;
/* I jump here when I need to exec an initial command (/C or /K) */
EXEC_CMDLINE:
/* move pointer forward to skip over any leading spaces */
while (*cmdline == ' ') cmdline++;
/* sanitize separators into spaces */
for (i = 0; cmdline[i] != 0; i++) {
switch (cmdline[i]) {
case '\t':
cmdline[i] = ' ';
}
}
/* handle redirections (if any) */
i = redir_parsecmd(&redirprops, cmdline, rmod->awaitingcmd, *rmod_envseg);
if (i != 0) {
nls_outputnl_doserr(i);
rmod->awaitingcmd[0] = 0;
continue;
}
/* try matching (and executing) an internal command */
cmdres = cmd_process(rmod, *rmod_envseg, cmdline, BUFFER, sizeof(BUFFER), &redirprops, flags & DELETE_STDIN_FILE);
if ((cmdres == CMD_OK) || (cmdres == CMD_FAIL)) {
/* internal command executed */
} else if (cmdres == CMD_CHANGED) { /* cmdline changed, needs to be reprocessed */
goto EXEC_CMDLINE;
} else if (cmdres == CMD_CHANGED_BY_CALL) { /* cmdline changed *specifically* by CALL */
/* the distinction is important since it changes the way batch files are processed */
flags |= CALL_FLAG;
goto EXEC_CMDLINE;
} else if (cmdres == CMD_CHANGED_BY_LH) { /* cmdline changed *specifically* by LH */
flags |= LOADHIGH_FLAG;
goto EXEC_CMDLINE;
} else if (cmdres == CMD_NOTFOUND) {
/* this was not an internal command, try matching an external command */
run_as_external(BUFFER, cmdline, *rmod_envseg, rmod, &redirprops, flags);
/* is it a newly launched BAT file? */
if ((rmod->bat != NULL) && (rmod->bat->nextline == 0)) goto SKIP_NEWLINE;
/* run_as_external() does not return on success, if I am still alive then
* external command failed to execute */
nls_outputnl(0,5); /* "Bad command or file name" */
} else {
/* I should never ever land here */
outputnl("INTERNAL ERR: INVALID CMDRES");
}
/* reset one-time only flags */
flags &= ~CALL_FLAG;
flags &= ~FLAG_STEPBYSTEP;
flags &= ~LOADHIGH_FLAG;
/* repeat unless /C was asked - but always finish running an ongoing batch
* file (otherwise only first BAT command would be executed with /C) */
} while (((rmod->flags & FLAG_EXEC_AND_QUIT) == 0) || (rmod->bat != NULL) || (rmod->forloop != NULL));
sayonara(rmod);
return(0);
}