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/* This file is part of the SvarCOM project and is published under the terms
* of the MIT license.
*
* Copyright (C) 2021-2022 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 <string.h> /* memset() */
#include "env.h"
#include "helpers.h"
#include "rmodinit.h"
#include "redir.h"
static unsigned short oldstdout = 0xffff;
/* compute a filename to be used for pipes */
static unsigned short gentmpfile(char *s, unsigned short envseg) {
unsigned short err = 0;
unsigned short i;
/* do I have a %temp% path? */
i = env_lookup_valcopy(s, 116, envseg, "TEMP");
if (i > 0) {
/* make sure it is terminated by a backslash (required by int 0x21, ah=5a) */
if (s[i - 1] != '\\') {
s[i++] = '\\';
s[i] = 0;
}
} else {
/* if fails, then use truename(.\) */
if (file_truename(".\\", s) != 0) *s = 0;
}
/* create file */
_asm {
mov ah, 0x5a
mov dx, s
xor cx, cx /* file attributes */
int 0x21
jnc CLOSEFILE
mov err, ax
jmp DONE
/* close file handle (handle still in BX) */
CLOSEFILE:
mov bx, ax
mov ah, 0x3e
int 0x21
DONE:
}
return(err);
}
/* parse commandline and performs necessary redirections. cmdline is
* modified so all redirections are cut out.
* piped commands are moved to awaitingcmd for later execution
* returns 0 on success, DOS err on failure */
unsigned short redir_parsecmd(struct redir_data *d, char *cmdline, char far *awaitingcmd, unsigned short envseg) {
unsigned short i;
unsigned short pipescount = 0;
/* NOTES:
*
* 1. while it is possible to type a command with multiple
* redirections, MSDOS executes only the last redirection.
*
* 2. the order in which >, < and | are provided on the command line does
* not seem to matter for MSDOS. piped commands are executed first (in
* the order they appear) and the result of the last one is redirected to
* whenever the last > points at.
* stdin redirection (<) is (obviously) applied to the first command only
*/
/* preset oldstdout to 0xffff in case no redirection is required */
oldstdout = 0xffff;
/* clear out the redir_data struct */
memset(d, 0, sizeof(*d));
*awaitingcmd = 0;
/* parse the command line and fill struct with pointers */
for (i = 0;; i++) {
if (cmdline[i] == '>') {
cmdline[i] = 0;
if (cmdline[i + 1] == '>') {
i++;
d->stdout_openflag = 0x11; /* used during int 21h,AH=6C */
} else {
d->stdout_openflag = 0x12;
}
d->stdoutfile = cmdline + i + 1;
while (d->stdoutfile[0] == ' ') d->stdoutfile++;
} else if (cmdline[i] == '<') {
cmdline[i] = 0;
d->stdinfile = cmdline + i + 1;
while (d->stdinfile[0] == ' ') d->stdinfile++;
} else if (cmdline[i] == '|') {
cmdline[i] = 0;
if (pipescount < REDIR_MAX_PIPES) {
d->pipes[pipescount++] = cmdline + i + 1;
while (d->pipes[pipescount][0] == ' ') d->pipes[pipescount]++;
}
} else if (cmdline[i] == 0) {
break;
}
}
/* if pipes present, write them to awaitingcmd (and stdout redirection too) */
if (pipescount != 0) {
static char tmpfile[130];
for (i = 0; i < pipescount; i++) {
if (i != 0) _fstrcat(awaitingcmd, "|");
_fstrcat(awaitingcmd, d->pipes[i]);
}
/* append stdout redirection so I don't forget about it for the last command of the pipe queue */
if (d->stdoutfile != NULL) {
if (d->stdout_openflag == 0x11) {
_fstrcat(awaitingcmd, ">>");
} else {
_fstrcat(awaitingcmd, ">");
}
d->stdoutfile = NULL;
}
/* redirect stdin of next command from a temp file (that is used as my output) */
_fstrcat(awaitingcmd, "<");
i = gentmpfile(tmpfile, envseg);
if (i != 0) return(i);
_fstrcat(awaitingcmd, tmpfile);
/* same file is used as my stdout */
d->stdoutfile = tmpfile;
d->stdout_openflag = 0x12;
}
return(0);
}
/* apply stdout redirections defined in redir_data, returns 0 on success */
int redir_apply(const struct redir_data *d) {
if (d->stdoutfile != NULL) {
unsigned short openflag = d->stdout_openflag;
unsigned short errcode = 0;
unsigned short handle = 0;
const char *myptr = d->stdoutfile;
/* */
_asm {
push ax
push bx
push cx
push dx
push si
mov ax, 0x6c00 /* Extended Open/Create */
mov bx, 1 /* access mode (0=read, 1=write, 2=r+w */
xor cx, cx /* attributes when(if) creating the file (0=normal) */
mov dx, [openflag] /* action if file exists (0x11=open, 0x12=truncate)*/
mov si, myptr /* ASCIIZ filename */
int 0x21 /* AX=handle on success (CF clear), otherwise dos err */
mov handle, ax /* save the file handler */
jnc JMPEOF
mov errcode, ax
jmp DONE
JMPEOF:
cmp openflag, word ptr 0x11
jne DUPSTDOUT
/* jump to the end of the file (required for >> redirections) */
mov ax, 0x4202 /* jump to position EOF - CX:DX in handle BX */
mov bx, handle
xor cx, cx
xor dx, dx
int 0x21
/* save (duplicate) current stdout so I can revert it later */
DUPSTDOUT:
mov ah, 0x45 /* duplicate file handle */
mov bx, 1 /* handle to dup (1=stdout) */
int 0x21 /* ax = new file handle */
mov oldstdout, ax
/* redirect the stdout handle */
mov bx, handle /* dst handle */
mov cx, 1 /* src handle (1=stdout) */
mov ah, 0x46 /* redirect a handle */
int 0x21
/* close the original file handle (no longer needed) */
mov ah, 0x3e /* close a file handle (handle in BX) */
int 0x21
DONE:
pop si
pop dx
pop cx
pop bx
pop ax
}
if (errcode != 0) {
nls_outputnl_doserr(errcode);
return(-1);
}
}
return(0);
}
/* restores previous stdout handle if is has been redirected */
void redir_revert(void) {
_asm {
/* if oldstdout is 0xffff then not redirected */
mov bx, [oldstdout] /* dst handle */
cmp bx, 0xffff
je DONE
/* redirect the stdout handle (handle already in BX) */
mov cx, 1 /* src handle (1=stdout) */
mov ah, 0x46 /* redirect a handle */
int 0x21
/* close old handle (in bx already) */
mov ah, 0x3e
int 0x21
mov [oldstdout], 0xffff
DONE:
}
}