/*
 * dba	dbm analysis/recovery
 */

#include <stdio.h>
#ifdef LiamSysV
# include <fcntl.h>
#else
# include <sys/file.h>
#endif
#include "sdbm.h"

#define empty(page)	(((short *) page)[0] == 0)

static char *progname;

int
main(argc, argv)
char **argv;
{
	int n;
	char *p;
	char *name;
	int pagf;

	progname = argv[0];

	if (p = argv[1]) {
		name = (char *) malloc((n = strlen(p)) + 5);
		strcpy(name, p);
		strcpy(name + n, ".pag");

		if ((pagf = open(name, O_RDONLY)) < 0)
			oops("cannot open %s.", name);

		sdump(pagf);
	}
	else
		oops("usage: %s dbname", progname);
	return 0;
}

sdump(pagf)
int pagf;
{
	register r;
	register n = 0;
	register o = 0;
	char pag[PBLKSIZ];

	while ((r = read(pagf, pag, PBLKSIZ)) > 0) {
		if (!chkpage(pag))
			fprintf(stderr, "%d: bad page.\n", n);
		else if (empty(pag))
			o++;
		else
			dispage(pag);
		n++;
	}

	if (r == 0)
		fprintf(stderr, "%d pages (%d holes).\n", n, o);
	else
		oops("read failed: block %d", n);
}

dispage(pag)
char *pag;
{
	register i, n;
	register off;
	register short *ino = (short *) pag;

	off = PBLKSIZ;
	for (i = 1; i < ino[0]; i += 2) {
		for (n = ino[i]; n < off; n++)
			if (pag[n] != 0)
				putchar(pag[n]);
		putchar('\t');
		off = ino[i];
		for (n = ino[i + 1]; n < off; n++)
			if (pag[n] != 0)
				putchar(pag[n]);
		putchar('\n');
		off = ino[i + 1];
	}
}

chkpage(pag)
char *pag;
{
	register unsigned n;
	register off;
	register short *ino = (short *) pag;

	if ((n = ino[0]) > PBLKSIZ / sizeof(short))
		return (0);

	if (!n)
		return (1);

	off = PBLKSIZ;
	for (ino++; n; ino += 2) {
		if (ino[0] > off || ino[1] > off ||
		    ino[1] > ino[0])
			return (0);
		off = ino[1];
		n -= 2;
	}

	return (1);
}

oops(s1, s2)
register char *s1;
register char *s2;
{
	extern int errno, sys_nerr;
	extern char *sys_errlist[];
	extern char *progname;

	if (progname)
		printf("%s: ", progname);
	printf(s1, s2);
	if (errno > 0 && errno < sys_nerr)
		printf(" (%s)", sys_errlist[errno]);
	printf("\n");
	exit(1);
}