/* Listing starts here */ #include #include #include #include #include #include #include /* Emulates Dave Jewell's version only if there is only one COMMAND.COM */ #define JAYCODE 1 /* Set this for JA Youngman's changes */ #define DEBUG 0 /* Set this to show PSPs as we track them */ /* JA Youngman's code */ /* Prototypes */ void get_env_info( unsigned int *, unsigned int *); unsigned int env_back (int); unsigned int psp_back(unsigned int, int); void panic(const char *); /* Code */ void get_env_info( unsigned int * ParentEnv, unsigned int *envSize ) { /* Find a certain environment, and its size. */ int back; char ch; if ( _argc >= 3 ) back = atoi( _argv[2] ); else back = -1; /* Go back as far as possible = Master Block */ /* i.e. emulate Dave Jewell's version */ /* EXCEPT for the case of more than 1 */ /* COMMAND.COM in memory */ *ParentEnv = env_back( back ); /* Find Environment size */ ch = * (char far *)MK_FP(*ParentEnv-1, 0); if (ch != 'M' && ch != 'Z') panic("can't find MCB for environment"); *envSize = 16 * (* (unsigned int far *)MK_FP(*ParentEnv-1, 3)); } unsigned int env_back (int count) /* Find ancestor environment */ { return * (unsigned int far *)MK_FP(psp_back(_psp,count),0x2C); } unsigned int psp_back(unsigned int psp_at, int count) /* Ancestor PSP */ { /* Move back count PSPs. */ /* Uses word at offset 0x16 in PSP */ unsigned int last; while (count--) { last = psp_at; psp_at = * (unsigned int far *)MK_FP(psp_at, 0x16); #ifndef NDEBUG printf("PSP at %X\n", psp_at); #endif if (psp_at == last) break; /* Found *_ANY_* COMMAND.COM */ else if (psp_at == 0) panic ("can't find parent PSP"); } return psp_at; } void panic(const char *msg) { fprintf(stderr, "fatal error: %s\n", msg); exit(-1); } // Dave Jewell's code follows. char far * findVar (char far * masterEnv, char * name, unsigned * end) { int len; char far * found = NULL; len = strlen(name); while (*masterEnv != '\0') { if (masterEnv [len] == '=' && found == NULL) { // Lengths match, now see if name matches masterEnv [ len] = '\0'; if ( _fstrcmp(masterEnv, name) == 0) found = masterEnv + len + 1; masterEnv [len] = '='; } masterEnv += _fstrlen (masterEnv) + 1; } *end = FP_OFF (masterEnv); return found; } unsigned keyPress (void) { char ch; return (ch = getch()) != '\0' ? ch : 0x8000 | getch(); } void SetCursor (unsigned size) { asm mov ah,1 asm mov cx,size asm push bp asm int 10h asm pop bp } char *EditString (char far * p, int free ) { int x, y, redo = 1; int rootx, rooty; int index = 0; int insert = 1; static char buff [256]; unsigned ch; #ifdef JAYCODE int length; #endif rootx = wherex(); rooty = wherey(); _fstrcpy (buff, p); p = buff; printf(buff); for(;;) { if (redo) { redo ^= 1; gotoxy(1,1); printf("Free bytes in master environment = %u ", free); gotoxy(rootx, rooty); printf("%s",buff); } x = rootx; y = rooty; while ( x + index > 80) { x -= 80; y++; } gotoxy (x + index, y); SetCursor( insert ? 0x0107 : 0x0607); switch (ch = keyPress() ) { case 0x1B: SetCursor(0x0607); return (NULL); // ESC case 0x0D: SetCursor(0x0607); return (buff); // Enter case 0x8047: index = 0; break; // Home case 0x8052: insert ^= 1; break; // Insert toggle case 0x804B: if (index > 0 ) index--; // Left arrow break; case 0x804D: if (index < strlen(buff)) index++;// Right arrow break; case 0x804F: index = strlen(buff); break; // End case '\b': if (index == 0) break; // BS else index--; case 0x8053: if (index < strlen(buff)) // Del { redo ^= 1; free++; strcpy(&buff[index], &buff[index+1]); #ifdef JAYCODE length = strlen(buff); /* Normalise coordinates */ while ( x + length > 80) { x -= 80; y++; } gotoxy (x + length, y); putchar(' '); #endif } break; default: if (free == 0 || ch < ' ' || ch >= 127) putch ('\a'); else { if (index == strlen(buff)) { buff[index++] = ch; buff[index] = '\0'; redo ^= 1; free--; } else if (insert == 0) { buff[index++] = ch; redo ^= 1; } else { memmove(buff+index+1, buff+index, strlen(&buff[index])+1); b uff [index++] = ch; redo ^= 1; free--; } } break; } } } void eset (char *name) { char ch; unsigned end; char far *p; char * newstr; char far * src; char far * dest; char far * newEnv; char far * MasterEnv = NULL; unsigned envSize; #ifdef JAYCODE unsigned int MasterEnvSeg; get_env_info( &MasterEnvSeg, &envSize); MasterEnv = MK_FP(MasterEnvSeg, 0); #else // Locate the master Environment asm mov ax, 352Eh // get int $2E address asm int 21h // result in ES:BX asm mov ax,es:2Ch // load master env seg asm mov word ptr MasterEnv+2,ax // save it in C-land asm dec ax // Point at MCB asm mov es,ax // ES addresses it asm mov ax,es:3 // get size word asm mov cl,4 // 4 shifts asm shl ax,cl // multiply by 16 asm mov envSize,ax // save it for later #endif if (( p = findVar (MasterEnv, strupr(name), &end)) == NULL) { printf ("Environment variable '%s' not found. Add it (Y/N) ? : ", name); printf ("%c\n", ch = getch()); if (ch != 'y' && ch != 'Y') return; p = ""; } #ifdef JAYCODE if (envSize - end < 10) { printf("There is not enough space left " "in your environment (%i bytes of %i used).\n", end, envSize ); exit(1); } #endif clrscr(); gotoxy(1,3); printf("%s=", name); newstr = EditString (p, envSize - end - 10); clrscr(); if (newstr == NULL) printf ("No changes made\n"); else { // Build a new master environment block dest = newEnv = farmalloc(envSize ); src = MasterEnv; if ( *p == '\0') // New environment variable { while (*dest++ = *name++) ; * (dest - 1) = '='; while (*dest++ = *newstr++) ; } else { while (src != p - strlen (name) - 1) *dest++ = *src++; if (*newstr == '\0') printf ("Environment variable '%s' deleted\n", name); else { while (*dest++ = *name++) ; *(dest - 1) = '='; while (*dest++ = *newstr++) ; } src = p + _fstrlen (p) + 1; } while (FP_OFF(src) != end) *des t++ = *src++; *dest++ = *src++; *dest++ = *src++; *dest++ = *src++; while (*dest++ = *newstr++) ; _fmemcpy(MasterEnv, newEnv, envSize); } } void main (int argc, char *argv[]) { if (argc < 2) printf("Usage: envset envvar\n"); else eset (argv [1]); } /* Listing ends here */