WebSVN – SvarDOS – Diff – /svarcom/trunk/rmodinit.c


/* 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 <i86.h>
#include <string.h>
 
#include "env.h"
#include "helpers.h"
 
#include "rmodinit.h"
 
 
/* returns far pointer to rmod's settings block on success */
struct rmod_props far *rmod_install(unsigned short envsize, unsigned char *rmodcore, unsigned short rmodcore_len) {
  char far *myptr, far *mcb;
  unsigned short far *owner;
  const unsigned short sizeof_rmodandprops_paras = (0x100 + rmodcore_len + sizeof(struct rmod_props) + 15) / 16;
  unsigned short rmodseg = 0xffff;
  unsigned short envseg, origenvseg;
  struct rmod_props far *res;
 
  /* read my current env segment from PSP and save it */
  envseg = *((unsigned short *)0x2c);
  origenvseg = envseg;
 
  /* printf("original (PSP) env buffer at %04X\r\n", envseg); */
 
  /* if envseg is zero, then enforce our own one (MSDOS 5 does not provide a default env) */
  if ((envseg == 0) && (envsize == 0)) envsize = 256;
 
  /* if custom envsize requested, convert it to number of paragraphs */
  if (envsize != 0) {
    envsize += 15;
    envsize /= 16;
  }
 
  _asm {
    /* link in the UMB memory chain for enabling high-memory allocation (and save initial status on stack) */
    mov ax, 0x5802  /* GET UMB LINK STATE */
    int 0x21
    xor ah, ah
    push ax         /* save link state on stack */
    mov ax, 0x5803  /* SET UMB LINK STATE */
    mov bx, 1
    int 0x21
    /* get current allocation strategy and save it in DX */
    mov ax, 0x5800
    int 0x21
    push ax
    pop dx
    /* set strategy to 'last fit, try high then low memory' */
    mov ax, 0x5801
    mov bx, 0x0082
    int 0x21
    /* ask for a memory block and save the given segment to rmodseg */
    mov ah, 0x48
    mov bx, sizeof_rmodandprops_paras
    int 0x21
    jc ALLOC_FAIL
    mov rmodseg, ax
    /* ask for a memory block for the environment and save it to envseg (only if custom size requested) */
    mov bx, envsize
    test bx, bx
    jz ALLOC_FAIL
    mov ah, 0x48
    int 0x21
    jc ALLOC_FAIL
    mov envseg, ax
 
    ALLOC_FAIL:
    /* restore initial allocation strategy */
    mov ax, 0x5801
    mov bx, dx
    int 0x21
    /* restore initial UMB memory link state */
    mov ax, 0x5803
    pop bx       /* pop initial UMB link state from stack */
    int 0x21
  }
 
  if (rmodseg == 0xffff) {
    outputnl("malloc error");
    return(NULL);
  }
 
  /* copy rmod to its destination, prefixed with a copy of my own PSP */
  myptr = MK_FP(rmodseg, 0);
  {
    unsigned short i;
    char *mypsp = (void *)0;
    for (i = 0; i < 0x100; i++) myptr[i] = mypsp[i];
  }
  myptr = MK_FP(rmodseg, 0x100);
  _fmemcpy(myptr, rmodcore, rmodcore_len);
 
  /* mark rmod memory as "self owned" */
  mcb = MK_FP(rmodseg - 1, 0);
  owner = (void far *)(mcb + 1);
  *owner = rmodseg;
  _fmemcpy(mcb + 8, "SVARCOM", 8);
 
  /* mark env memory as "owned by rmod" */
  mcb = MK_FP(envseg - 1, 0);
  owner = (void far *)(mcb + 1);
  *owner = rmodseg;
  _fmemcpy(mcb + 8, "SVARENV", 8);
 
  /* if env block is newly allocated, fill it with a few NULLs */
  if (envsize != 0) {
    owner = MK_FP(envseg, 0);
    owner[0] = 0;
    owner[1] = 0;
  }
 
  /* set CTRL+BREAK handler to rmod */
  _asm {
    push ax
    push dx
    push ds
    mov ax, 0x2523
    mov ds, rmodseg
    mov dx, RMOD_OFFSET_BRKHANDLER
    int 0x21
    pop ds
    pop dx
    pop ax
  }
 
  /* mark the input buffer as empty */
  myptr = MK_FP(rmodseg, RMOD_OFFSET_INPUTBUF);
  myptr[0] = 128;  /* max acceptable length */
  myptr[1] = 0;    /* len of currently stored history string */
  myptr[2] = '\r'; /* string terminator */
  myptr[3] = 0xCA; /* signature to detect stack overflow damaging the buffer */
  myptr[4] = 0xFE; /* 2nd byte of the signature */
 
  /* prepare result (rmod props) */
  res = MK_FP(rmodseg, 0x100 + rmodcore_len);
  _fmemset(res, 0, sizeof(*res));  /* zero out */
  res->rmodseg = rmodseg;          /* rmod segment */
  res->origenvseg = origenvseg;    /* original environment segment */
 
  /* write env segment to rmod's PSP */
  owner = MK_FP(rmodseg, RMOD_OFFSET_ENVSEG);
  *owner = envseg;
 
  /* write boot drive to rmod bootdrive field */
  _asm {
    push ax
    push bx
    push dx
    push ds
    mov ax, 0x3305 /* DOS 4.0+ - GET BOOT DRIVE */
    int 0x21 /* boot drive is in DL now (1=A:, 2=B:, etc) */
    add dl, 'A'-1 /* convert to a proper ASCII letter */
    /* set DS to rmodseg */
    mov ax, rmodseg
    mov ds, ax
    /* write boot drive to rmod bootdrive field */
    mov bx, RMOD_OFFSET_BOOTDRIVE
    mov [bx], dl
    pop ds
    pop dx
    pop bx
    pop ax
  }
 
  /* save my original parent in rmod's memory */
  res->origparent = *((unsigned long *)0x0a); /* original parent seg:off is at 0x0a of my PSP */
 
  /* set the int22 handler in my PSP to rmod so DOS jumps to rmod after I
   * terminate and save the original handler in rmod's memory */
  {
    unsigned short *ptr = (void *)0x0a; /* int22 handler is at 0x0A of the PSP */
    ptr[0] = RMOD_OFFSET_ROUTINE;
    ptr[1] = rmodseg;
  }
 
  return(res);
}
 
 
/* look up my parent: if it's rmod then return a ptr to its props struct,
 * otherwise return NULL
 * I look at PSP[Ch] to locate RMOD (ie. the "terminate address") */
struct rmod_props far *rmod_find(unsigned short rmodcore_len) {
  unsigned short *parent = (void *)0x0C;
  unsigned short far *ptr;
  const unsigned short sig[] = {0x1983, 0x1985, 0x2017, 0x2019};
  unsigned char *cmdtail = (void *)0x80;
  unsigned char i;
  /* is it rmod? */
  ptr = MK_FP(*parent, 0x100);
  for (i = 0; i < 4; i++) if (ptr[i] != sig[i]) return(NULL);
  /* match successfull (rmod is my parent) - but is it really a respawn?
   * command-line tail should contain a single character '\r' */
  if ((cmdtail[0] != 1) || (cmdtail[1] != '\n')) return(NULL);
  cmdtail[0] = 0;
  cmdtail[1] = '\r';
  /* */
  return(MK_FP(*parent, 0x100 + rmodcore_len));
}
 
 
/* update rmod's pointer to comspec */
void rmod_updatecomspecptr(unsigned short rmod_seg, unsigned short env_seg) {
  unsigned short far *comspecptr = MK_FP(rmod_seg, RMOD_OFFSET_COMSPECPTR);
  char far *comspecfp = env_lookup_val(env_seg, "COMSPEC");
  if (comspecfp != NULL) {
    *comspecptr = FP_OFF(comspecfp);
  } else {
    *comspecptr = 0;
  }
}
 
 
/* allocates bytes of far memory, flags it as belonging to rmod
 * the new block can be optionally flagged as 'ident' (if not null) and zero
 * out the newly allocated memory.
 * returns a far ptr to the allocated block, or NULL on error */
void far *rmod_fcalloc(unsigned short bytes, unsigned short rmod_seg, char *ident) {
  unsigned short far *owner;
  unsigned short newseg = 0;
 
  /* ask DOS for a memory block (as high as possible) */
  _asm {
    push bx /* save initial value in BX so I can restore it later */
 
    /* get current allocation strategy and save it on stack */
    mov ax, 0x5800
    int 0x21
    push ax
 
    /* set strategy to 'last fit, try high then low memory' */
    mov ax, 0x5801
    mov bx, 0x0082
    int 0x21
 
    /* ask for a memory block and save the given segment to rmodseg */
    mov ah, 0x48  /* Allocate Memory */
    mov bx, bytes
    add bx, 15    /* convert bytes to paragraphs */
    shr bx, 1     /* bx /= 16 */
    shr bx, 1
    shr bx, 1
    shr bx, 1
    int 0x21
 
    /* error handling */
    jc FAIL
 
    /* save newly allocated segment to newseg */
    mov newseg, ax
 
    FAIL:
    /* restore initial allocation strategy */
    mov ax, 0x5801
    pop bx
    int 0x21
 
    pop bx /* restore BX to its initial value */
  }
 
  if (newseg == 0) return(NULL);
 
  /* mark memory as "owned by rmod" */
  owner = (void far *)(MK_FP(newseg - 1, 1));
  *owner = rmod_seg;
 
  /* set the MCB description to ident, if provided */
  if (ident) {
    char far *mcbdesc = MK_FP(newseg - 1, 8);
    int i;
    _fmemset(mcbdesc, 0, 8);
    for (i = 0; (i < 8) && (ident[i] != 0); i++) { /* field's length is limited to 8 bytes max */
      mcbdesc[i] = ident[i];
    }
  }
 
  /* zero out the memory before handing it out */
  _fmemset(MK_FP(newseg, 0), 0, bytes);
 
  return(MK_FP(newseg, 0));
}
 
 
/* free memory previously allocated by rmod_fcalloc() */
void rmod_ffree(void far *ptr) {
  unsigned short ptrseg;
  unsigned short myseg = 0;
  unsigned short far *owner;
  if (ptr == NULL) return;
  ptrseg = FP_SEG(ptr);
 
  /* get my own segment */
  _asm {
    mov myseg, cs
  }
 
  /* mark memory in MCB as my own, otherwise DOS might refuse to free it */
  owner = MK_FP(ptrseg - 1, 1);
  *owner = myseg;
 
  /* free the memory block */
  _asm {
    push es
    mov ah, 0x49  /* Free Memory Block */
    mov es, ptrseg
    int 0x21
    pop es
  }
}
 
 
/* free the entire linked list of bat ctx nodes (and set its rmod ptr to NULL) */
void rmod_free_bat_llist(struct rmod_props far *rmod) {
  while (rmod->bat != NULL) {
    struct batctx far *victim = rmod->bat;
    rmod->bat = rmod->bat->parent;
    rmod_ffree(victim);
  }
}
 

Rev 983	Rev 987
1	`/* This file is part of the SvarCOM project and is published under the terms`	1	`/* This file is part of the SvarCOM project and is published under the terms`
2	`* of the MIT license.`	2	`* of the MIT license.`
3	`*`	3	`*`
4	`* Copyright (C) 2021-2022 Mateusz Viste`	4	`* Copyright (C) 2021-2022 Mateusz Viste`
5	`*`	5	`*`
6	`* Permission is hereby granted, free of charge, to any person obtaining a`	6	`* Permission is hereby granted, free of charge, to any person obtaining a`
7	`* copy of this software and associated documentation files (the "Software"),`	7	`* copy of this software and associated documentation files (the "Software"),`
8	`* to deal in the Software without restriction, including without limitation`	8	`* to deal in the Software without restriction, including without limitation`
9	`* the rights to use, copy, modify, merge, publish, distribute, sublicense,`	9	`* the rights to use, copy, modify, merge, publish, distribute, sublicense,`
10	`* and/or sell copies of the Software, and to permit persons to whom the`	10	`* and/or sell copies of the Software, and to permit persons to whom the`
11	`* Software is furnished to do so, subject to the following conditions:`	11	`* Software is furnished to do so, subject to the following conditions:`
12	`*`	12	`*`
13	`* The above copyright notice and this permission notice shall be included in`	13	`* The above copyright notice and this permission notice shall be included in`
14	`* all copies or substantial portions of the Software.`	14	`* all copies or substantial portions of the Software.`
15	`*`	15	`*`
16	`* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR`	16	`* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR`
17	`* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,`	17	`* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,`
18	`* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE`	18	`* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE`
19	`* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER`	19	`* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER`
20	`* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING`	20	`* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING`
21	`* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER`	21	`* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER`
22	`* DEALINGS IN THE SOFTWARE.`	22	`* DEALINGS IN THE SOFTWARE.`
23	`*/`	23	`*/`
24		24
25	`#include <i86.h>`	25	`#include <i86.h>`
26	`#include <string.h>`	26	`#include <string.h>`
27		27
28	`#include "env.h"`	28	`#include "env.h"`
29	`#include "helpers.h"`	29	`#include "helpers.h"`
30		30
31	`#include "rmodinit.h"`	31	`#include "rmodinit.h"`
32		32
33		33
34	`/* returns far pointer to rmod's settings block on success */`	34	`/* returns far pointer to rmod's settings block on success */`
35	`struct rmod_props far rmod_install(unsigned short envsize, unsigned char rmodcore, unsigned short rmodcore_len) {`	35	`struct rmod_props far rmod_install(unsigned short envsize, unsigned char rmodcore, unsigned short rmodcore_len) {`
36	`char far myptr, far mcb;`	36	`char far myptr, far mcb;`
37	`unsigned short far *owner;`	37	`unsigned short far *owner;`
38	`const unsigned short sizeof_rmodandprops_paras = (0x100 + rmodcore_len + sizeof(struct rmod_props) + 15) / 16;`	38	`const unsigned short sizeof_rmodandprops_paras = (0x100 + rmodcore_len + sizeof(struct rmod_props) + 15) / 16;`
39	`unsigned short rmodseg = 0xffff;`	39	`unsigned short rmodseg = 0xffff;`
40	`unsigned short envseg, origenvseg;`	40	`unsigned short envseg, origenvseg;`
41	`struct rmod_props far *res;`	41	`struct rmod_props far *res;`
42		42
43	`/* read my current env segment from PSP and save it */`	43	`/* read my current env segment from PSP and save it */`
44	`envseg = ((unsigned short )0x2c);`	44	`envseg = ((unsigned short )0x2c);`
45	`origenvseg = envseg;`	45	`origenvseg = envseg;`
46		46
47	`/* printf("original (PSP) env buffer at %04X\r\n", envseg); */`	47	`/* printf("original (PSP) env buffer at %04X\r\n", envseg); */`
48		48
49	`/* if envseg is zero, then enforce our own one (MSDOS 5 does not provide a default env) */`	49	`/* if envseg is zero, then enforce our own one (MSDOS 5 does not provide a default env) */`
50	`if ((envseg == 0) && (envsize == 0)) envsize = 256;`	50	`if ((envseg == 0) && (envsize == 0)) envsize = 256;`
51		51
52	`/* if custom envsize requested, convert it to number of paragraphs */`	52	`/* if custom envsize requested, convert it to number of paragraphs */`
53	`if (envsize != 0) {`	53	`if (envsize != 0) {`
54	`envsize += 15;`	54	`envsize += 15;`
55	`envsize /= 16;`	55	`envsize /= 16;`
56	`}`	56	`}`
57		57
58	`_asm {`	58	`_asm {`
59	`/* link in the UMB memory chain for enabling high-memory allocation (and save initial status on stack) */`	59	`/* link in the UMB memory chain for enabling high-memory allocation (and save initial status on stack) */`
60	`mov ax, 0x5802 /* GET UMB LINK STATE */`	60	`mov ax, 0x5802 /* GET UMB LINK STATE */`
61	`int 0x21`	61	`int 0x21`
62	`xor ah, ah`	62	`xor ah, ah`
63	`push ax /* save link state on stack */`	63	`push ax /* save link state on stack */`
64	`mov ax, 0x5803 /* SET UMB LINK STATE */`	64	`mov ax, 0x5803 /* SET UMB LINK STATE */`
65	`mov bx, 1`	65	`mov bx, 1`
66	`int 0x21`	66	`int 0x21`
67	`/* get current allocation strategy and save it in DX */`	67	`/* get current allocation strategy and save it in DX */`
68	`mov ax, 0x5800`	68	`mov ax, 0x5800`
69	`int 0x21`	69	`int 0x21`
70	`push ax`	70	`push ax`
71	`pop dx`	71	`pop dx`
72	`/* set strategy to 'last fit, try high then low memory' */`	72	`/* set strategy to 'last fit, try high then low memory' */`
73	`mov ax, 0x5801`	73	`mov ax, 0x5801`
74	`mov bx, 0x0082`	74	`mov bx, 0x0082`
75	`int 0x21`	75	`int 0x21`
76	`/* ask for a memory block and save the given segment to rmodseg */`	76	`/* ask for a memory block and save the given segment to rmodseg */`
77	`mov ah, 0x48`	77	`mov ah, 0x48`
78	`mov bx, sizeof_rmodandprops_paras`	78	`mov bx, sizeof_rmodandprops_paras`
79	`int 0x21`	79	`int 0x21`
80	`jc ALLOC_FAIL`	80	`jc ALLOC_FAIL`
81	`mov rmodseg, ax`	81	`mov rmodseg, ax`
82	`/* ask for a memory block for the environment and save it to envseg (only if custom size requested) */`	82	`/* ask for a memory block for the environment and save it to envseg (only if custom size requested) */`
83	`mov bx, envsize`	83	`mov bx, envsize`
84	`test bx, bx`	84	`test bx, bx`
85	`jz ALLOC_FAIL`	85	`jz ALLOC_FAIL`
86	`mov ah, 0x48`	86	`mov ah, 0x48`
87	`int 0x21`	87	`int 0x21`
88	`jc ALLOC_FAIL`	88	`jc ALLOC_FAIL`
89	`mov envseg, ax`	89	`mov envseg, ax`
90		90
91	`ALLOC_FAIL:`	91	`ALLOC_FAIL:`
92	`/* restore initial allocation strategy */`	92	`/* restore initial allocation strategy */`
93	`mov ax, 0x5801`	93	`mov ax, 0x5801`
94	`mov bx, dx`	94	`mov bx, dx`
95	`int 0x21`	95	`int 0x21`
96	`/* restore initial UMB memory link state */`	96	`/* restore initial UMB memory link state */`
97	`mov ax, 0x5803`	97	`mov ax, 0x5803`
98	`pop bx /* pop initial UMB link state from stack */`	98	`pop bx /* pop initial UMB link state from stack */`
99	`int 0x21`	99	`int 0x21`
100	`}`	100	`}`
101		101
102	`if (rmodseg == 0xffff) {`	102	`if (rmodseg == 0xffff) {`
103	`outputnl("malloc error");`	103	`outputnl("malloc error");`
104	`return(NULL);`	104	`return(NULL);`
105	`}`	105	`}`
106		106
107	`/* copy rmod to its destination, prefixed with a copy of my own PSP */`	107	`/* copy rmod to its destination, prefixed with a copy of my own PSP */`
108	`myptr = MK_FP(rmodseg, 0);`	108	`myptr = MK_FP(rmodseg, 0);`
109	`{`	109	`{`
110	`unsigned short i;`	110	`unsigned short i;`
111	`char mypsp = (void )0;`	111	`char mypsp = (void )0;`
112	`for (i = 0; i < 0x100; i++) myptr[i] = mypsp[i];`	112	`for (i = 0; i < 0x100; i++) myptr[i] = mypsp[i];`
113	`}`	113	`}`
114	`myptr = MK_FP(rmodseg, 0x100);`	114	`myptr = MK_FP(rmodseg, 0x100);`
115	`_fmemcpy(myptr, rmodcore, rmodcore_len);`	115	`_fmemcpy(myptr, rmodcore, rmodcore_len);`
116		116
117	`/* mark rmod memory as "self owned" */`	117	`/* mark rmod memory as "self owned" */`
118	`mcb = MK_FP(rmodseg - 1, 0);`	118	`mcb = MK_FP(rmodseg - 1, 0);`
119	`owner = (void far *)(mcb + 1);`	119	`owner = (void far *)(mcb + 1);`
120	`*owner = rmodseg;`	120	`*owner = rmodseg;`
121	`_fmemcpy(mcb + 8, "SVARCOM", 8);`	121	`_fmemcpy(mcb + 8, "SVARCOM", 8);`
122		122
123	`/* mark env memory as "owned by rmod" */`	123	`/* mark env memory as "owned by rmod" */`
124	`mcb = MK_FP(envseg - 1, 0);`	124	`mcb = MK_FP(envseg - 1, 0);`
125	`owner = (void far *)(mcb + 1);`	125	`owner = (void far *)(mcb + 1);`
126	`*owner = rmodseg;`	126	`*owner = rmodseg;`
127	`_fmemcpy(mcb + 8, "SVARENV", 8);`	127	`_fmemcpy(mcb + 8, "SVARENV", 8);`
128		128
129	`/* if env block is newly allocated, fill it with a few NULLs */`	129	`/* if env block is newly allocated, fill it with a few NULLs */`
130	`if (envsize != 0) {`	130	`if (envsize != 0) {`
131	`owner = MK_FP(envseg, 0);`	131	`owner = MK_FP(envseg, 0);`
132	`owner[0] = 0;`	132	`owner[0] = 0;`
133	`owner[1] = 0;`	133	`owner[1] = 0;`
134	`}`	134	`}`
135		135
136	`/* set CTRL+BREAK handler to rmod */`	136	`/* set CTRL+BREAK handler to rmod */`
137	`_asm {`	137	`_asm {`
138	`push ax`	138	`push ax`
139	`push dx`	139	`push dx`
140	`push ds`	140	`push ds`
141	`mov ax, 0x2523`	141	`mov ax, 0x2523`
142	`mov ds, rmodseg`	142	`mov ds, rmodseg`
143	`mov dx, RMOD_OFFSET_BRKHANDLER`	143	`mov dx, RMOD_OFFSET_BRKHANDLER`
144	`int 0x21`	144	`int 0x21`
145	`pop ds`	145	`pop ds`
146	`pop dx`	146	`pop dx`
147	`pop ax`	147	`pop ax`
148	`}`	148	`}`
149		149
150	`/* mark the input buffer as empty */`	150	`/* mark the input buffer as empty */`
151	`myptr = MK_FP(rmodseg, RMOD_OFFSET_INPUTBUF);`	151	`myptr = MK_FP(rmodseg, RMOD_OFFSET_INPUTBUF);`
152	`myptr[0] = 128;`	152	`myptr[0] = 128; /* max acceptable length */`
153	`myptr[1] = 0;`	153	`myptr[1] = 0; /* len of currently stored history string */`
154	`myptr[2] = '\r';`	154	`myptr[2] = '\r'; /* string terminator */`
-		155	`myptr[3] = 0xCA; /* signature to detect stack overflow damaging the buffer */`
-		156	`myptr[4] = 0xFE; /* 2nd byte of the signature */`
155		157
156	`/* prepare result (rmod props) */`	158	`/* prepare result (rmod props) */`
157	`res = MK_FP(rmodseg, 0x100 + rmodcore_len);`	159	`res = MK_FP(rmodseg, 0x100 + rmodcore_len);`
158	`_fmemset(res, 0, sizeof(res)); / zero out */`	160	`_fmemset(res, 0, sizeof(res)); / zero out */`
159	`res->rmodseg = rmodseg; /* rmod segment */`	161	`res->rmodseg = rmodseg; /* rmod segment */`
160	`res->origenvseg = origenvseg; /* original environment segment */`	162	`res->origenvseg = origenvseg; /* original environment segment */`
161		163
162	`/* write env segment to rmod's PSP */`	164	`/* write env segment to rmod's PSP */`
163	`owner = MK_FP(rmodseg, RMOD_OFFSET_ENVSEG);`	165	`owner = MK_FP(rmodseg, RMOD_OFFSET_ENVSEG);`
164	`*owner = envseg;`	166	`*owner = envseg;`
165		167
166	`/* write boot drive to rmod bootdrive field */`	168	`/* write boot drive to rmod bootdrive field */`
167	`_asm {`	169	`_asm {`
168	`push ax`	170	`push ax`
169	`push bx`	171	`push bx`
170	`push dx`	172	`push dx`
171	`push ds`	173	`push ds`
172	`mov ax, 0x3305 /* DOS 4.0+ - GET BOOT DRIVE */`	174	`mov ax, 0x3305 /* DOS 4.0+ - GET BOOT DRIVE */`
173	`int 0x21 /* boot drive is in DL now (1=A:, 2=B:, etc) */`	175	`int 0x21 /* boot drive is in DL now (1=A:, 2=B:, etc) */`
174	`add dl, 'A'-1 /* convert to a proper ASCII letter */`	176	`add dl, 'A'-1 /* convert to a proper ASCII letter */`
175	`/* set DS to rmodseg */`	177	`/* set DS to rmodseg */`
176	`mov ax, rmodseg`	178	`mov ax, rmodseg`
177	`mov ds, ax`	179	`mov ds, ax`
178	`/* write boot drive to rmod bootdrive field */`	180	`/* write boot drive to rmod bootdrive field */`
179	`mov bx, RMOD_OFFSET_BOOTDRIVE`	181	`mov bx, RMOD_OFFSET_BOOTDRIVE`
180	`mov [bx], dl`	182	`mov [bx], dl`
181	`pop ds`	183	`pop ds`
182	`pop dx`	184	`pop dx`
183	`pop bx`	185	`pop bx`
184	`pop ax`	186	`pop ax`
185	`}`	187	`}`
186		188
187	`/* save my original parent in rmod's memory */`	189	`/* save my original parent in rmod's memory */`
188	`res->origparent = ((unsigned long )0x0a); /* original parent seg:off is at 0x0a of my PSP */`	190	`res->origparent = ((unsigned long )0x0a); /* original parent seg:off is at 0x0a of my PSP */`
189		191
190	`/* set the int22 handler in my PSP to rmod so DOS jumps to rmod after I`	192	`/* set the int22 handler in my PSP to rmod so DOS jumps to rmod after I`
191	`* terminate and save the original handler in rmod's memory */`	193	`* terminate and save the original handler in rmod's memory */`
192	`{`	194	`{`
193	`unsigned short ptr = (void )0x0a; /* int22 handler is at 0x0A of the PSP */`	195	`unsigned short ptr = (void )0x0a; /* int22 handler is at 0x0A of the PSP */`
194	`ptr[0] = RMOD_OFFSET_ROUTINE;`	196	`ptr[0] = RMOD_OFFSET_ROUTINE;`
195	`ptr[1] = rmodseg;`	197	`ptr[1] = rmodseg;`
196	`}`	198	`}`
197		199
198	`return(res);`	200	`return(res);`
199	`}`	201	`}`
200		202
201		203
202	`/* look up my parent: if it's rmod then return a ptr to its props struct,`	204	`/* look up my parent: if it's rmod then return a ptr to its props struct,`
203	`* otherwise return NULL`	205	`* otherwise return NULL`
204	`* I look at PSP[Ch] to locate RMOD (ie. the "terminate address") */`	206	`* I look at PSP[Ch] to locate RMOD (ie. the "terminate address") */`
205	`struct rmod_props far *rmod_find(unsigned short rmodcore_len) {`	207	`struct rmod_props far *rmod_find(unsigned short rmodcore_len) {`
206	`unsigned short parent = (void )0x0C;`	208	`unsigned short parent = (void )0x0C;`
207	`unsigned short far *ptr;`	209	`unsigned short far *ptr;`
208	`const unsigned short sig[] = {0x1983, 0x1985, 0x2017, 0x2019};`	210	`const unsigned short sig[] = {0x1983, 0x1985, 0x2017, 0x2019};`
209	`unsigned char cmdtail = (void )0x80;`	211	`unsigned char cmdtail = (void )0x80;`
210	`unsigned char i;`	212	`unsigned char i;`
211	`/* is it rmod? */`	213	`/* is it rmod? */`
212	`ptr = MK_FP(*parent, 0x100);`	214	`ptr = MK_FP(*parent, 0x100);`
213	`for (i = 0; i < 4; i++) if (ptr[i] != sig[i]) return(NULL);`	215	`for (i = 0; i < 4; i++) if (ptr[i] != sig[i]) return(NULL);`
214	`/* match successfull (rmod is my parent) - but is it really a respawn?`	216	`/* match successfull (rmod is my parent) - but is it really a respawn?`
215	`* command-line tail should contain a single character '\r' */`	217	`* command-line tail should contain a single character '\r' */`
216	`if ((cmdtail[0] != 1) \|\| (cmdtail[1] != '\n')) return(NULL);`	218	`if ((cmdtail[0] != 1) \|\| (cmdtail[1] != '\n')) return(NULL);`
217	`cmdtail[0] = 0;`	219	`cmdtail[0] = 0;`
218	`cmdtail[1] = '\r';`	220	`cmdtail[1] = '\r';`
219	`/* */`	221	`/* */`
220	`return(MK_FP(*parent, 0x100 + rmodcore_len));`	222	`return(MK_FP(*parent, 0x100 + rmodcore_len));`
221	`}`	223	`}`
222		224
223		225
224	`/* update rmod's pointer to comspec */`	226	`/* update rmod's pointer to comspec */`
225	`void rmod_updatecomspecptr(unsigned short rmod_seg, unsigned short env_seg) {`	227	`void rmod_updatecomspecptr(unsigned short rmod_seg, unsigned short env_seg) {`
226	`unsigned short far *comspecptr = MK_FP(rmod_seg, RMOD_OFFSET_COMSPECPTR);`	228	`unsigned short far *comspecptr = MK_FP(rmod_seg, RMOD_OFFSET_COMSPECPTR);`
227	`char far *comspecfp = env_lookup_val(env_seg, "COMSPEC");`	229	`char far *comspecfp = env_lookup_val(env_seg, "COMSPEC");`
228	`if (comspecfp != NULL) {`	230	`if (comspecfp != NULL) {`
229	`*comspecptr = FP_OFF(comspecfp);`	231	`*comspecptr = FP_OFF(comspecfp);`
230	`} else {`	232	`} else {`
231	`*comspecptr = 0;`	233	`*comspecptr = 0;`
232	`}`	234	`}`
233	`}`	235	`}`
234		236
235		237
236	`/* allocates bytes of far memory, flags it as belonging to rmod`	238	`/* allocates bytes of far memory, flags it as belonging to rmod`
237	`* the new block can be optionally flagged as 'ident' (if not null) and zero`	239	`* the new block can be optionally flagged as 'ident' (if not null) and zero`
238	`* out the newly allocated memory.`	240	`* out the newly allocated memory.`
239	`* returns a far ptr to the allocated block, or NULL on error */`	241	`* returns a far ptr to the allocated block, or NULL on error */`
240	`void far rmod_fcalloc(unsigned short bytes, unsigned short rmod_seg, char ident) {`	242	`void far rmod_fcalloc(unsigned short bytes, unsigned short rmod_seg, char ident) {`
241	`unsigned short far *owner;`	243	`unsigned short far *owner;`
242	`unsigned short newseg = 0;`	244	`unsigned short newseg = 0;`
243		245
244	`/* ask DOS for a memory block (as high as possible) */`	246	`/* ask DOS for a memory block (as high as possible) */`
245	`_asm {`	247	`_asm {`
246	`push bx /* save initial value in BX so I can restore it later */`	248	`push bx /* save initial value in BX so I can restore it later */`
247		249
248	`/* get current allocation strategy and save it on stack */`	250	`/* get current allocation strategy and save it on stack */`
249	`mov ax, 0x5800`	251	`mov ax, 0x5800`
250	`int 0x21`	252	`int 0x21`
251	`push ax`	253	`push ax`
252		254
253	`/* set strategy to 'last fit, try high then low memory' */`	255	`/* set strategy to 'last fit, try high then low memory' */`
254	`mov ax, 0x5801`	256	`mov ax, 0x5801`
255	`mov bx, 0x0082`	257	`mov bx, 0x0082`
256	`int 0x21`	258	`int 0x21`
257		259
258	`/* ask for a memory block and save the given segment to rmodseg */`	260	`/* ask for a memory block and save the given segment to rmodseg */`
259	`mov ah, 0x48 /* Allocate Memory */`	261	`mov ah, 0x48 /* Allocate Memory */`
260	`mov bx, bytes`	262	`mov bx, bytes`
261	`add bx, 15 /* convert bytes to paragraphs */`	263	`add bx, 15 /* convert bytes to paragraphs */`
262	`shr bx, 1 /* bx /= 16 */`	264	`shr bx, 1 /* bx /= 16 */`
263	`shr bx, 1`	265	`shr bx, 1`
264	`shr bx, 1`	266	`shr bx, 1`
265	`shr bx, 1`	267	`shr bx, 1`
266	`int 0x21`	268	`int 0x21`
267		269
268	`/* error handling */`	270	`/* error handling */`
269	`jc FAIL`	271	`jc FAIL`
270		272
271	`/* save newly allocated segment to newseg */`	273	`/* save newly allocated segment to newseg */`
272	`mov newseg, ax`	274	`mov newseg, ax`
273		275
274	`FAIL:`	276	`FAIL:`
275	`/* restore initial allocation strategy */`	277	`/* restore initial allocation strategy */`
276	`mov ax, 0x5801`	278	`mov ax, 0x5801`
277	`pop bx`	279	`pop bx`
278	`int 0x21`	280	`int 0x21`
279		281
280	`pop bx /* restore BX to its initial value */`	282	`pop bx /* restore BX to its initial value */`
281	`}`	283	`}`
282		284
283	`if (newseg == 0) return(NULL);`	285	`if (newseg == 0) return(NULL);`
284		286
285	`/* mark memory as "owned by rmod" */`	287	`/* mark memory as "owned by rmod" */`
286	`owner = (void far *)(MK_FP(newseg - 1, 1));`	288	`owner = (void far *)(MK_FP(newseg - 1, 1));`
287	`*owner = rmod_seg;`	289	`*owner = rmod_seg;`
288		290
289	`/* set the MCB description to ident, if provided */`	291	`/* set the MCB description to ident, if provided */`
290	`if (ident) {`	292	`if (ident) {`
291	`char far *mcbdesc = MK_FP(newseg - 1, 8);`	293	`char far *mcbdesc = MK_FP(newseg - 1, 8);`
292	`int i;`	294	`int i;`
293	`_fmemset(mcbdesc, 0, 8);`	295	`_fmemset(mcbdesc, 0, 8);`
294	`for (i = 0; (i < 8) && (ident[i] != 0); i++) { /* field's length is limited to 8 bytes max */`	296	`for (i = 0; (i < 8) && (ident[i] != 0); i++) { /* field's length is limited to 8 bytes max */`
295	`mcbdesc[i] = ident[i];`	297	`mcbdesc[i] = ident[i];`
296	`}`	298	`}`
297	`}`	299	`}`
298		300
299	`/* zero out the memory before handing it out */`	301	`/* zero out the memory before handing it out */`
300	`_fmemset(MK_FP(newseg, 0), 0, bytes);`	302	`_fmemset(MK_FP(newseg, 0), 0, bytes);`
301		303
302	`return(MK_FP(newseg, 0));`	304	`return(MK_FP(newseg, 0));`
303	`}`	305	`}`
304		306
305		307
306	`/* free memory previously allocated by rmod_fcalloc() */`	308	`/* free memory previously allocated by rmod_fcalloc() */`
307	`void rmod_ffree(void far *ptr) {`	309	`void rmod_ffree(void far *ptr) {`
308	`unsigned short ptrseg;`	310	`unsigned short ptrseg;`
309	`unsigned short myseg = 0;`	311	`unsigned short myseg = 0;`
310	`unsigned short far *owner;`	312	`unsigned short far *owner;`
311	`if (ptr == NULL) return;`	313	`if (ptr == NULL) return;`
312	`ptrseg = FP_SEG(ptr);`	314	`ptrseg = FP_SEG(ptr);`
313		315
314	`/* get my own segment */`	316	`/* get my own segment */`
315	`_asm {`	317	`_asm {`
316	`mov myseg, cs`	318	`mov myseg, cs`
317	`}`	319	`}`
318		320
319	`/* mark memory in MCB as my own, otherwise DOS might refuse to free it */`	321	`/* mark memory in MCB as my own, otherwise DOS might refuse to free it */`
320	`owner = MK_FP(ptrseg - 1, 1);`	322	`owner = MK_FP(ptrseg - 1, 1);`
321	`*owner = myseg;`	323	`*owner = myseg;`
322		324
323	`/* free the memory block */`	325	`/* free the memory block */`
324	`_asm {`	326	`_asm {`
325	`push es`	327	`push es`
326	`mov ah, 0x49 /* Free Memory Block */`	328	`mov ah, 0x49 /* Free Memory Block */`
327	`mov es, ptrseg`	329	`mov es, ptrseg`
328	`int 0x21`	330	`int 0x21`
329	`pop es`	331	`pop es`
330	`}`	332	`}`
331	`}`	333	`}`
332		334
333		335
334	`/* free the entire linked list of bat ctx nodes (and set its rmod ptr to NULL) */`	336	`/* free the entire linked list of bat ctx nodes (and set its rmod ptr to NULL) */`
335	`void rmod_free_bat_llist(struct rmod_props far *rmod) {`	337	`void rmod_free_bat_llist(struct rmod_props far *rmod) {`
336	`while (rmod->bat != NULL) {`	338	`while (rmod->bat != NULL) {`
337	`struct batctx far *victim = rmod->bat;`	339	`struct batctx far *victim = rmod->bat;`
338	`rmod->bat = rmod->bat->parent;`	340	`rmod->bat = rmod->bat->parent;`
339	`rmod_ffree(victim);`	341	`rmod_ffree(victim);`
340	`}`	342	`}`
341	`}`	343	`}`
342		344

Subversion Repositories SvarDOS

(root)/svarcom/trunk/rmodinit.c – Rev 983 → 987