/* roll.c - sequetial read/write cache programs
 * This is the part of the Tar program (see file tar.c)
 * Author: T.V.Shaporev
 * Prepared for release 19 Oct 1990
 * Called by store() (see file store.c)
 */
#include "sysup.h"

#include <stdio.h>
#ifdef TRACE
	extern FILE *myout;
#	define Printf  (void)printf
#endif

#ifdef MSDOS
#   include <string.h>
#   include <stdlib.h>
#   include <fcntl.h>
#   include <io.h>
#   ifdef __TURBOC__
#      include <dir.h>
#      define write _write
#      define read  _read
#   else
#      include <direct.h>
#      include <sys\types.h>
#   endif
#   include <sys\stat.h>
#   define CREATE(x) open((x),O_CREAT+O_TRUNC+O_RDWR+O_BINARY,S_IREAD+S_IWRITE)
#   define FREE(x)   free(x)
#else
#   define CREATE(x) creat((x),0600)
#   define FREE(x)   free((char *)(x))

    int  strlen();
    char *malloc(), *strncpy(), *strncat(), *getenv(), *mktemp();
    int  creat(), read(), write(), close(), unlink();
    long lseek();
    void free();
#endif

#ifdef UNIX
#	define TMPDIR   "/usr/tmp"
#       define DIR      "/"
#	define DEV      '\0'
#	define MAXFNAME 512 /* Analagous to MAXNAMSIZ */
#endif

#ifdef VMS
#	define TMPDIR   "SYS$SCRATCH:"
#       define DIR      "]"
#	define DEV      ':'
#       define MAXFNAME 512 /* ??? */
#endif

#ifdef MSDOS
#	define TMPDIR   ""
#       define DIR      "\\"
#	define DEV      ':'
#	define MAXFNAME MAXPATH
#endif

#define MAXPAGE  64   /* max cash is 0.5M */
#define PAGESIZE 8192 /* Be careful !!! */

typedef struct {
                  unsigned char * page[MAXPAGE];
                  int             poz, npage, maxpage;
                  char            name[MAXFNAME+1];
                  int             handle;
               } roll;

#include "roll.h"

static roll *r = (roll *)0;

int newroll(templ)
char *templ;
{
   register i;
   char *e;

   if (r) return 0;

   r = (roll *)malloc(sizeof(roll));
   if (!r) return -1;
   (r->page)[0] = (unsigned char *)malloc(PAGESIZE);
   if (!((r->page)[0])) {
      FREE((char *)r);
      return -1;
   }
   for (i=1; i<MAXPAGE; i++) (r->page)[i] = (unsigned char *)0;
   r->maxpage = MAXPAGE - 1;
   r->npage   = 0;
   r->poz     = 0;

   if ((e = getenv("TMP")) == (char *)0) {
      (void)strncpy(r->name, TMPDIR, MAXFNAME);
   } else {
      (void)strncpy(r->name, e, MAXFNAME);
   }
#ifndef VMS
   i = strlen(r->name) - 1;
   if (r->name[i]!= *DIR
#     ifdef DEV
                         && r->name[i]!=DEV
#     endif
      ) (void)strncat(r->name,DIR,MAXFNAME);
#endif
   (void)mktemp(strncat(r->name, templ, MAXFNAME));

   r->handle  = -1;
#ifdef TRACE
  Printf("new roll: poz = %4d page = %d max = %2d handle = %d\n",
                    r->poz,   r->npage, r->maxpage, r->handle);
#endif
   return 0;
}

void delroll()
{
   register i;

   if (!r) return;
#ifdef TRACE
  Printf("del roll: poz = %4d page = %d max = %2d handle = %d\n",
                    r->poz,   r->npage, r->maxpage, r->handle);
#endif
   for (i=0; i<MAXPAGE && (r->page)[i]; i++) FREE((r->page)[i]);
   if (r->handle >= 0) {
      (void)close (r->handle);
      (void)unlink(r->name);
   }
   r = (roll *)0;
}

int rewroll(flread)
int flread;
{
#ifdef TRACE
   Printf("rew roll: poz = %4d page = %d max = %2d handle = %d\n",
                     r->poz,   r->npage, r->maxpage, r->handle);
#endif
   if (r->handle >= 0 && r->npage >= r->maxpage) {
      if (write(r->handle,(char*)((r->page)[r->maxpage]),PAGESIZE)!=PAGESIZE)
	 return -1;
      if (lseek(r->handle, 0L, 0) < 0) return -1;
      if (flread && r->maxpage < 1) {
	 if (read(r->handle, (char*)((r->page)[0]), PAGESIZE) != PAGESIZE)
	    return -1;
      }
   }
   r->npage = 0;
   r->poz   = 0;
   return 0;
}

int rputc(i)
int i;
{
   register unsigned char *p;

   if (r->poz >= PAGESIZE) {
#ifdef TRACE
     Printf("  roll 1: poz = %4d page = %d max = %2d handle = %d\n",
                       r->poz,   r->npage, r->maxpage, r->handle);
#endif
      if (r->npage < r->maxpage) {
         p = (r->page)[(r->npage)+1];
         if (p) {
            r->npage += 1;
         } else if (r->handle < 0) {
            p = (unsigned char *)malloc(PAGESIZE);
	    if (p) {
	       (r->page)[++(r->npage)] = p;
	       r->poz = 0;
	    } else {
	       r->maxpage = r->npage;
	    }
         }
      } else {
         p = (unsigned char *)0;
      }
      if (!p) {
         if (r->handle < 0) {
	    if ((r->handle = CREATE(r->name)) < 0) return EOF;
	 }
	 if (write(r->handle, (char*)((r->page)[r->maxpage]), PAGESIZE) !=
	     PAGESIZE)
	    return EOF;
      }
      r->poz = 0;
#ifdef TRACE
      Printf("  roll 2: poz = %4d page = %d max = %2d handle = %d\n",
                        r->poz,   r->npage, r->maxpage, r->handle);
#endif
   }
   *((r->page)[r->npage] + (r->poz)++) = i;
#ifdef TRACE
   if (r->npage < 0 || r->npage >= MAXPAGE || r->npage > r->maxpage) {
      (void)fprintf(myout, "Alarm! npage out of range\n");
   }
   if (r->poz < 0 || r->poz > PAGESIZE) {
      (void)fprintf(myout, "Alarm! poz out of range\n");
   }
#endif
   return 0;
}

int rgetc()
{
   if (r->poz >= PAGESIZE) {
#ifdef TRACE
      Printf("  roll 1: poz = %4d page = %d max = %2d handle = %d\n",
                       r->poz,   r->npage, r->maxpage, r->handle);
#endif
      if (r->handle >= 0 && (r->npage)+1 >= r->maxpage) {
	 if (read(r->handle, (char*)((r->page)[r->maxpage]), PAGESIZE) !=
	     PAGESIZE) {
	    return EOF;
	 }
	 r->npage = r->maxpage;
      } else {
	 if (r->handle < 0 && r->npage >= MAXPAGE) return EOF;
	 if (!(r->page)[++(r->npage)]) return EOF;
      }
      r->poz = 0;
#ifdef TRACE
      Printf("  roll 2: poz = %4d page = %d max = %2d handle = %d\n",
                        r->poz,   r->npage, r->maxpage, r->handle);
#endif
   }
#ifdef TRACE
   if (r->npage < 0 || r->npage >= MAXPAGE || r->npage > r->maxpage) {
      (void)fprintf(myout, "Alarm! npage out of range\n");
   }
   if (r->poz < 0 || r->poz >= PAGESIZE) {
      (void)fprintf(myout, "Alarm! poz out of range\n");
   }
#endif
   return *((r->page)[r->npage] + (r->poz)++);
}