119 lines
2.7 KiB
C++
119 lines
2.7 KiB
C++
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/* Record locking */
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/* Copyright (c) Mix Software 1988 */
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#include "locking.h"
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int locking(fd, mode, nbyte)
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int fd;
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int mode;
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long nbyte;
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{
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struct intlong {
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unsigned int lower;
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unsigned int upper;
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};
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union {
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long l;
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struct intlong words;
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} v;
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union REGS lock;
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union REGS time;
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union REGS answer;
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extern int errno;
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int status;
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int trycount, sec;
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lock.x.ax = 0x5c00;
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lock.x.bx = fd;
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v.l = nbyte;
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lock.x.si = v.words.upper;
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lock.x.di = v.words.lower;
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v.l = lseek(fd,0L,1);
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lock.x.cx = v.words.upper;
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lock.x.dx = v.words.lower;
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if (mode == LK_UNLCK) lock.h.al = 0x01;
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trycount = (mode == LK_LOCK || mode == LK_RLCK) ? 10 : 1;
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do {
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status = intdos(&lock,&answer);
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if (answer.x.cflag == 0) return 0;
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if (status != 0x21) { errno = status; return -1; }
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if (--trycount) {
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time.h.ah = 0x2c;
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intdos(&time,&answer);
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sec = answer.h.dh;
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do {
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intdos(&time,&answer);
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} while (sec == answer.h.dh);
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}
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} while (trycount);
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errno = (mode == LK_LOCK || mode == LK_RLCK) ? EDEADLOCK : EACCES;
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return -1;
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} /* locking */
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int lock(fd, offset, length)
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int fd;
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long offset;
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long length;
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{
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union {
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long l;
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struct {
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unsigned int lower;
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unsigned int upper;
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} words;
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} v;
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union REGS lockfl, time, answer;
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extern int errno;
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int status;
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int trycount = 4;
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int sec;
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lockfl.x.ax = 0x5c00;
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lockfl.x.bx = fd;
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v.l = length;
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lockfl.x.si = v.words.upper;
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lockfl.x.di = v.words.lower;
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v.l = offset;
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lockfl.x.cx = v.words.upper;
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lockfl.x.dx = v.words.lower;
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while (--trycount) {
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status = intdos(&lockfl,&answer);
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if (answer.x.cflag == 0) return 0;
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if (status != 0x21) { errno = status; return -1; }
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time.h.ah = 0x2c;
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intdos(&time,&answer);
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sec = answer.h.dh;
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do {
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intdos(&time,&answer);
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} while (sec == answer.h.dh);
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}
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return -1;
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} /* lock */
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int unlock(fd, offset, length)
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int fd;
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long offset;
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long length;
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{
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union {
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long l;
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struct {
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unsigned int lower;
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unsigned int upper;
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} words;
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} v;
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union REGS lockfl, answer;
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extern int errno;
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int status;
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lockfl.x.ax = 0x5c01;
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lockfl.x.bx = fd;
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v.l = length;
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lockfl.x.si = v.words.upper;
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lockfl.x.di = v.words.lower;
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v.l = offset;
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lockfl.x.cx = v.words.upper;
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lockfl.x.dx = v.words.lower;
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status = intdos(&lockfl,&answer);
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if (answer.x.cflag == 0) return 0;
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errno = status;
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return -1;
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} /* unlock */
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