source: trunk/minix/commands/elvis/elvrec.c@ 20

/* 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);
}