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    Length: 2720 (0xaa0)
    Types: TextFile
    Names: »files_rw.c«

└─⟦b20c6495f⟧ Bits:30007238 EUUGD18: Wien-båndet, efterår 1987
    └─⟦this⟧ »EUUGD18/General/Gb/files_rw.c« 

TextFile

/*
 * Galactic Bloodshed (Robert Chansky, smq@b)
 *  disk input/output routines
 *    most read routines lock the data they just accessed (the file is not
 *    closed).  write routines close and thus unlock that area.
 *    Neither will work if the file LOCK_ALL exists, unless Ignore_lockfile
 *    is true, or Ignore_file_locks.
 *
 *  Fileread(p, num, file, posn, routine); -- generic file read
 *  Filewrite(p, num, file, posn, routine); -- generic file write
 *
 */

#include "tweakables.h"
#include "files.h"
#include <sys/file.h>
#include <signal.h>
#include <errno.h>
int sys_nerr;
char *sys_errlist[];
extern int errno;


int Ignore_lockfile=0,Ignore_filelocks=0,Ignore_readerrors=0;

Fileread(fd, p, num, file, posn)
int fd;
char *p;
int num;
char *file;
int posn;
{
 int lockt = NUM_TIMES_TO_WAIT_FOR_LOCK;
 int lerr,n2;

/* printf(" fread fd=%d,reading %d bytes %s posn %d \n",fd,num,file,posn);*/
if (!Ignore_lockfile) {		/* we are running for the shell filestuff */

 if (access(LOCK_ALL, F_OK)==0) {	/* if file exists */
	printf("doing update. Please come back later.\n");
	exit(0);
 }



/*#ifdef UNIX_VERSION4.3
 lseek(fd, posn, L_SET);
 if (!Ignore_filelocks) {
 	while ((lerr=lockf(fd, F_TLOCK, (long)num))== -1 && errno==EACCES) {
		close(fd);
		if (!lockt--) {
			printf("too long. exit.\n");
			exit();
		}
		printf("waiting on %s lock...\n",file);
		sleep(2);
		fd = open(file,O_RDWR,0777);
 		lseek(fd, posn, L_SET);
 	}
 	if (lerr<0 && errno!=EACCES) {
		printf("weird error.\n");
		perror("Fileread 2");
		exit();
 	}
 }
#else*/
 if (!Ignore_filelocks) {
 	while ((lerr=flock(fd, LOCK_SH|LOCK_EX|LOCK_NB ))== -1 && errno==EWOULDBLOCK) {
		if (!lockt--) {
			printf("too long. exit.\n");
			exit(-1);
		}
		printf("waiting on %s lock...\n",file);
		sleep(2);
 	}
 	if (lerr<0 && errno!=EWOULDBLOCK) {
		perror("Fileread 2");
		exit(-1);
 	}
  }

 }

 if (lseek(fd, posn, L_SET) < 0) {
	perror("file read");
	return;
 }
 if ((n2=read(fd,p,num))!=num && !Ignore_readerrors) {
	printf("read: bad # of bytes read (%d != %d).\n",n2,num);
	perror("fileread");
	return;
 }

}


Filewrite(fd, p, num, file, posn)
int fd;
char *p;
int num;
char *file;
int posn;
{
int mask;
int lockfd,n2;

  if (!Ignore_lockfile) {
   if (access(LOCK_ALL, F_OK)==0) {
	printf("doing update. Please come back later.\n");
	exit(-1);
   }
   mask = sigblock(SIGINT | SIGQUIT | SIGSTOP);
  }

 /*printf(" fd =%d writing %d bytes to %s posn %d.\n",fd,num,file,posn);*/

 if (lseek(fd, posn, L_SET) < 0) {
	perror(file);
	return;
 }

 if ((n2=write(fd,p,num))!=num && !Ignore_readerrors) {
	printf("write: bad # of bytes written. (%d!=%d)\n",n2,num);
	perror(file);
	return;
 }

 if (!Ignore_lockfile)
   sigsetmask(mask);
}