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


/* This file is part of the SvarCOM project and is published under the terms
 * of the MIT license.
 *
 * Copyright (C) 2021 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.
 */
 
/*
 * routines used to manipulate the environment block
 */
 
#include <i86.h>
#include <string.h>
 
#include "env.h"
 
/* looks for varname in environment block and returns a far ptr to it if
 * found, NULL otherwise. varname MUST be in upper-case and MUST be terminated
 * by either a = sign or a NULL terminator */
char far *env_lookup(unsigned short env_seg, const char *varname) {
  char far *env = MK_FP(env_seg, 0);
  int i;
  for (;;) {
    /* is this it? */
    for (i = 0;; i++) {
      if ((varname[i] == '=') || (varname[i] == 0)) {
        if (env[i] == '=') return(env); /* FOUND! */
        break; /* else look for next string */
      }
      if (varname[i] != env[i]) break;
    }
    /* move env to end of current string */
    while (*env != 0) env++;
    /* if there's another trailing zero, then that is the end of environment */
    env++;
    if (*env == 0) return(NULL);
  }
}
 
 
/* returns the size, in bytes, of the allocated environment block */
unsigned short env_allocsz(unsigned short env_seg) {
  unsigned short far *mcbsz = MK_FP(env_seg - 1, 3); /* block size is a word at offset +3 in the MCB */
  return(*mcbsz * 16); /* return size in bytes, not paragraphs */
}
 
 
/* remove a variable from environment, if present. returns 0 on success, non-zero if variable not found */
int env_dropvar(unsigned short env_seg, const char *varname) {
  unsigned short blocksz, traillen;
  unsigned short len;
  char far *varptr = env_lookup(env_seg, varname);
 
  /* if variable not found in environment, quit now */
  if (varptr == NULL) return(-1);
 
  for (len = 0; varptr[len] != 0; len++); /* compute length of variable (without trailing null) */
  blocksz = env_allocsz(env_seg);           /* total environment size */
  traillen = blocksz - (FP_OFF(varptr) + len + 1); /* how much bytes are present after the variable */
  _fmemset(varptr, 0, len);               /* zero out the variable */
  if (traillen != 0) {
    _fmemmove(varptr, varptr + len + 1, traillen); /* move rest of memory */
  }
  return(0);
}
 
 
/* Writes a variable to environment block. The variable must in the form
 * "VARNAME=value". If variable is already present in the environment block,
 * then the value will be updated. If the new value is empty, then the
 * existing variable (if any) is removed.
 * VARNAME *MUST* be all-uppercase.
 *
 * This function returns:
 *   ENV_SUCCESS = success
 *   ENV_NOTENOM = not enough available space in memory block
 *   ENV_INVSYNT = invalid syntax
 */
int env_setvar(unsigned short env_seg, const char *v) {
  unsigned short envlen;
  unsigned short envfree;
  unsigned short vlen, veqpos;
  char far *env = MK_FP(env_seg, 0);
 
  /* remove variable from environment, if already set */
  env_dropvar(env_seg, v);
 
  /* compute v length and find the position of the eq sign */
  veqpos = 0xffff;
  for (vlen = 0; v[vlen] != 0; vlen++) {
    if (v[vlen] == '=') {
      if (veqpos != 0xffff) return(ENV_INVSYNT); /* equal sign is forbidden in value */
      veqpos = vlen;
    }
  }
 
  /* if variable empty, stop here */
  if (veqpos == vlen - 1) return(ENV_SUCCESS);
 
  /* compute current size of the environment */
  for (envlen = 0; env[envlen] != 0; envlen++) {
    while (env[envlen] != 0) envlen++; /* consume a string */
  }
 
  /* compute free space available in environment */
  envfree = env_allocsz(env_seg);
  envfree -= envlen;
  envfree -= 1; /* 1 byte for the environment's NULL terminator */
 
  /* do I have enough env space for the new var? */
  if (envfree < vlen + 1) return(ENV_NOTENOM);
 
  /* write the new variable (with its NULL terminator) to environment tail */
  _fmemcpy(env + envlen, v, vlen + 1);
 
  /* add the environment's NULL terminator */
  env[envlen + vlen + 1] = 0;
 
  return(ENV_SUCCESS);
}
 

Rev 397	Rev 421
-		1	`/* This file is part of the SvarCOM project and is published under the terms`
-		2	`* of the MIT license.`
-		3	`*`
-		4	`* Copyright (C) 2021 Mateusz Viste`
-		5	`*`
-		6	`* Permission is hereby granted, free of charge, to any person obtaining a`
-		7	`* copy of this software and associated documentation files (the "Software"),`
-		8	`* to deal in the Software without restriction, including without limitation`
-		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`
-		11	`* Software is furnished to do so, subject to the following conditions:`
-		12	`*`
-		13	`* The above copyright notice and this permission notice shall be included in`
-		14	`* all copies or substantial portions of the Software.`
-		15	`*`
-		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,`
-		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`
-		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`
-		22	`* DEALINGS IN THE SOFTWARE.`
-		23	`*/`
-		24
1	`/*`	25	`/*`
2	`* routines used to manipulate the environment block`	26	`* routines used to manipulate the environment block`
3	`*/`	27	`*/`
4		28
5	`#include <i86.h>`	29	`#include <i86.h>`
6	`#include <string.h>`	30	`#include <string.h>`
7		31
8	`#include "env.h"`	32	`#include "env.h"`
9		33
10	`/* looks for varname in environment block and returns a far ptr to it if`	34	`/* looks for varname in environment block and returns a far ptr to it if`
11	`* found, NULL otherwise. varname MUST be in upper-case and MUST be terminated`	35	`* found, NULL otherwise. varname MUST be in upper-case and MUST be terminated`
12	`* by either a = sign or a NULL terminator */`	36	`* by either a = sign or a NULL terminator */`
13	`char far env_lookup(unsigned short env_seg, const char varname) {`	37	`char far env_lookup(unsigned short env_seg, const char varname) {`
14	`char far *env = MK_FP(env_seg, 0);`	38	`char far *env = MK_FP(env_seg, 0);`
15	`int i;`	39	`int i;`
16	`for (;;) {`	40	`for (;;) {`
17	`/* is this it? */`	41	`/* is this it? */`
18	`for (i = 0;; i++) {`	42	`for (i = 0;; i++) {`
19	`if ((varname[i] == '=') \|\| (varname[i] == 0)) {`	43	`if ((varname[i] == '=') \|\| (varname[i] == 0)) {`
20	`if (env[i] == '=') return(env); /* FOUND! */`	44	`if (env[i] == '=') return(env); /* FOUND! */`
21	`break; /* else look for next string */`	45	`break; /* else look for next string */`
22	`}`	46	`}`
23	`if (varname[i] != env[i]) break;`	47	`if (varname[i] != env[i]) break;`
24	`}`	48	`}`
25	`/* move env to end of current string */`	49	`/* move env to end of current string */`
26	`while (*env != 0) env++;`	50	`while (*env != 0) env++;`
27	`/* if there's another trailing zero, then that is the end of environment */`	51	`/* if there's another trailing zero, then that is the end of environment */`
28	`env++;`	52	`env++;`
29	`if (*env == 0) return(NULL);`	53	`if (*env == 0) return(NULL);`
30	`}`	54	`}`
31	`}`	55	`}`
32		56
33		57
34	`/* returns the size, in bytes, of the allocated environment block */`	58	`/* returns the size, in bytes, of the allocated environment block */`
35	`unsigned short env_allocsz(unsigned short env_seg) {`	59	`unsigned short env_allocsz(unsigned short env_seg) {`
36	`unsigned short far mcbsz = MK_FP(env_seg - 1, 3); / block size is a word at offset +3 in the MCB */`	60	`unsigned short far mcbsz = MK_FP(env_seg - 1, 3); / block size is a word at offset +3 in the MCB */`
37	`return(mcbsz 16); /* return size in bytes, not paragraphs */`	61	`return(mcbsz 16); /* return size in bytes, not paragraphs */`
38	`}`	62	`}`
39		63
40		64
41	`/* remove a variable from environment, if present. returns 0 on success, non-zero if variable not found */`	65	`/* remove a variable from environment, if present. returns 0 on success, non-zero if variable not found */`
42	`int env_dropvar(unsigned short env_seg, const char *varname) {`	66	`int env_dropvar(unsigned short env_seg, const char *varname) {`
43	`unsigned short blocksz, traillen;`	67	`unsigned short blocksz, traillen;`
44	`unsigned short len;`	68	`unsigned short len;`
45	`char far *varptr = env_lookup(env_seg, varname);`	69	`char far *varptr = env_lookup(env_seg, varname);`
46		70
47	`/* if variable not found in environment, quit now */`	71	`/* if variable not found in environment, quit now */`
48	`if (varptr == NULL) return(-1);`	72	`if (varptr == NULL) return(-1);`
49		73
50	`for (len = 0; varptr[len] != 0; len++); /* compute length of variable (without trailing null) */`	74	`for (len = 0; varptr[len] != 0; len++); /* compute length of variable (without trailing null) */`
51	`blocksz = env_allocsz(env_seg); /* total environment size */`	75	`blocksz = env_allocsz(env_seg); /* total environment size */`
52	`traillen = blocksz - (FP_OFF(varptr) + len + 1); /* how much bytes are present after the variable */`	76	`traillen = blocksz - (FP_OFF(varptr) + len + 1); /* how much bytes are present after the variable */`
53	`_fmemset(varptr, 0, len); /* zero out the variable */`	77	`_fmemset(varptr, 0, len); /* zero out the variable */`
54	`if (traillen != 0) {`	78	`if (traillen != 0) {`
55	`_fmemmove(varptr, varptr + len + 1, traillen); /* move rest of memory */`	79	`_fmemmove(varptr, varptr + len + 1, traillen); /* move rest of memory */`
56	`}`	80	`}`
57	`return(0);`	81	`return(0);`
58	`}`	82	`}`
59		83
60		84
61	`/* Writes a variable to environment block. The variable must in the form`	85	`/* Writes a variable to environment block. The variable must in the form`
62	`* "VARNAME=value". If variable is already present in the environment block,`	86	`* "VARNAME=value". If variable is already present in the environment block,`
63	`* then the value will be updated. If the new value is empty, then the`	87	`* then the value will be updated. If the new value is empty, then the`
64	`* existing variable (if any) is removed.`	88	`* existing variable (if any) is removed.`
65	`* VARNAME MUST be all-uppercase.`	89	`* VARNAME MUST be all-uppercase.`
66	`*`	90	`*`
67	`* This function returns:`	91	`* This function returns:`
68	`* ENV_SUCCESS = success`	92	`* ENV_SUCCESS = success`
69	`* ENV_NOTENOM = not enough available space in memory block`	93	`* ENV_NOTENOM = not enough available space in memory block`
70	`* ENV_INVSYNT = invalid syntax`	94	`* ENV_INVSYNT = invalid syntax`
71	`*/`	95	`*/`
72	`int env_setvar(unsigned short env_seg, const char *v) {`	96	`int env_setvar(unsigned short env_seg, const char *v) {`
73	`unsigned short envlen;`	97	`unsigned short envlen;`
74	`unsigned short envfree;`	98	`unsigned short envfree;`
75	`unsigned short vlen, veqpos;`	99	`unsigned short vlen, veqpos;`
76	`char far *env = MK_FP(env_seg, 0);`	100	`char far *env = MK_FP(env_seg, 0);`
77		101
78	`/* remove variable from environment, if already set */`	102	`/* remove variable from environment, if already set */`
79	`env_dropvar(env_seg, v);`	103	`env_dropvar(env_seg, v);`
80		104
81	`/* compute v length and find the position of the eq sign */`	105	`/* compute v length and find the position of the eq sign */`
82	`veqpos = 0xffff;`	106	`veqpos = 0xffff;`
83	`for (vlen = 0; v[vlen] != 0; vlen++) {`	107	`for (vlen = 0; v[vlen] != 0; vlen++) {`
84	`if (v[vlen] == '=') {`	108	`if (v[vlen] == '=') {`
85	`if (veqpos != 0xffff) return(ENV_INVSYNT); /* equal sign is forbidden in value */`	109	`if (veqpos != 0xffff) return(ENV_INVSYNT); /* equal sign is forbidden in value */`
86	`veqpos = vlen;`	110	`veqpos = vlen;`
87	`}`	111	`}`
88	`}`	112	`}`
89		113
90	`/* if variable empty, stop here */`	114	`/* if variable empty, stop here */`
91	`if (veqpos == vlen - 1) return(ENV_SUCCESS);`	115	`if (veqpos == vlen - 1) return(ENV_SUCCESS);`
92		116
93	`/* compute current size of the environment */`	117	`/* compute current size of the environment */`
94	`for (envlen = 0; env[envlen] != 0; envlen++) {`	118	`for (envlen = 0; env[envlen] != 0; envlen++) {`
95	`while (env[envlen] != 0) envlen++; /* consume a string */`	119	`while (env[envlen] != 0) envlen++; /* consume a string */`
96	`}`	120	`}`
97		121
98	`/* compute free space available in environment */`	122	`/* compute free space available in environment */`
99	`envfree = env_allocsz(env_seg);`	123	`envfree = env_allocsz(env_seg);`
100	`envfree -= envlen;`	124	`envfree -= envlen;`
101	`envfree -= 1; /* 1 byte for the environment's NULL terminator */`	125	`envfree -= 1; /* 1 byte for the environment's NULL terminator */`
102		126
103	`/* do I have enough env space for the new var? */`	127	`/* do I have enough env space for the new var? */`
104	`if (envfree < vlen + 1) return(ENV_NOTENOM);`	128	`if (envfree < vlen + 1) return(ENV_NOTENOM);`
105		129
106	`/* write the new variable (with its NULL terminator) to environment tail */`	130	`/* write the new variable (with its NULL terminator) to environment tail */`
107	`_fmemcpy(env + envlen, v, vlen + 1);`	131	`_fmemcpy(env + envlen, v, vlen + 1);`
108		132
109	`/* add the environment's NULL terminator */`	133	`/* add the environment's NULL terminator */`
110	`env[envlen + vlen + 1] = 0;`	134	`env[envlen + vlen + 1] = 0;`
111		135
112	`return(ENV_SUCCESS);`	136	`return(ENV_SUCCESS);`
113	`}`	137	`}`
114		138

Subversion Repositories SvarDOS

(root)/svarcom/trunk/env.c – Rev 397 → 421