minix/commands/elvis/elvrec.c

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2005-04-21 16:53:53 +02:00
/* elvrec.c */
/* This file contains the file recovery program */
/* Author:
* Steve Kirkendall
* 14407 SW Teal Blvd. #C
* Beaverton, OR 97005
* kirkenda@cs.pdx.edu
*/
#include <stdio.h>
#include "config.h"
#include "vi.h"
#include <sys/stat.h>
void recover(basename, outname)
char *basename; /* the name of the file to recover */
char *outname; /* the name of the file to write to */
{
char pathname[500]; /* full pathname of the file to recover */
char line[600]; /* a line from the /usr/preserve/Index file */
int ch; /* a character from the text being recovered */
FILE *from; /* the /usr/preserve file, or /usr/preserve/Index */
FILE *to; /* the user's text file */
char *ptr;
struct stat st;
#if OSK
int uid;
#endif
/* convert basename to a full pathname */
if (basename)
{
#ifndef CRUNCH
# if MSDOS || TOS
if (!basename[0] || basename[1] != ':')
# else
if (basename[0] != SLASH)
# endif
{
ptr = getcwd(pathname, sizeof pathname);
if (ptr != pathname)
{
strcpy(pathname, ptr);
}
ptr = pathname + strlen(pathname);
*ptr++ = SLASH;
strcpy(ptr, basename);
}
else
#endif
{
strcpy(pathname, basename);
}
}
#if OSK
uid = getuid();
if(setuid(0))
exit(_errmsg(errno, "Can't set uid\n"));
#endif
/* scan the /usr/preserve/Index file, for the *oldest* unrecovered
* version of this file.
*/
from = fopen(PRSVINDEX, "r");
while (from && fgets(line, sizeof line, from))
{
/* strip off the newline from the end of the string */
line[strlen(line) - 1] = '\0';
/* parse the line into a "preserve" name and a "text" name */
for (ptr = line; *ptr != ' '; ptr++)
{
}
*ptr++ = '\0';
/* If the "preserve" file is missing, then ignore this line
* because it describes a file that has already been recovered.
*/
if (stat(line, &st) < 0)
{
continue;
}
/* are we looking for a specific file? */
if (basename)
{
/* quit if we found it */
if (!strcmp(ptr, pathname))
{
break;
}
}
else
{
/* list this file as "available for recovery" */
puts(ptr);
}
}
/* file not found? */
if (!basename || !from || feof(from))
{
if (from != NULL) fclose(from);
if (basename)
{
fprintf(stderr, "%s: no recovered file has that exact name\n", pathname);
}
return;
}
if (from != NULL) fclose(from);
/* copy the recovered text back into the user's file... */
/* open the /usr/preserve file for reading */
from = fopen(line, "r");
if (!from)
{
perror(line);
exit(2);
}
#if ANY_UNIX
/* Be careful about user-id. We want to be running under the user's
* real id when we open/create the user's text file... but we want
* to be superuser when we delete the /usr/preserve file. For UNIX,
* we accomplish this by deleting the /usr/preserve file *now*,
* when it is open but before we've read it. Then we revert to the
* user's real id.
*/
unlink(line);
setuid(getuid());
#endif
#if OSK
setuid(uid);
#endif
if (outname == NULL) return;
/* open the user's file for writing */
to = fopen(outname, "w");
if (!to)
{
perror(ptr);
exit(2);
}
/* copy the text */
while ((ch = getc(from)) != EOF)
{
putc(ch, to);
}
#if !ANY_UNIX
#if OSK
fclose(from);
setuid(0);
#endif
/* delete the /usr/preserve file */
unlink(line);
#if OSK
setuid(uid);
#endif
#endif
}
main(argc, argv)
int argc;
char **argv;
{
/* check arguments */
if (argc > 3)
{
fprintf(stderr, "usage: %s [preserved_file [recovery_file]]\n", argv[0]);
exit(1);
}
/* recover the requested file, or list recoverable files */
if (argc == 3)
{
/* recover the file, but write it to a different filename */
recover (argv[1], argv[2]);
}
else if (argc == 2)
{
/* recover the file */
recover(argv[1], argv[1]);
}
else
{
/* list the recoverable files */
recover((char *)0, (char *)0);
}
/* success! */
exit(0);
}