usr/src/cmd/ex/expreserve.c

/* Copyright (c) 1980 Regents of the University of California */
static char *sccsid = "@(#)expreserve.c 6.1 10/18/80";
#include <stdio.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/dir.h>
#include <pwd.h>
#include "local/uparm.h"

#ifdef VMUNIX
#define HBLKS   2
#else
#define HBLKS   1
#endif

/*
 * Expreserve - preserve a file in usrpath(preserve)
 * Bill Joy UCB November 13, 1977
 *
 * This routine is very naive - it doesn't remove anything from
 * usrpath(preserve)... this may mean that we will be unable to preserve
 * stuff there... the danger in doing anything with usrpath(preserve)
 * is that the clock may be screwed up and we may get confused.
 *
 * We are called in two ways - first from the editor with no argumentss
 * and the standard input open on the temp file. Second with an argument
 * to preserve the entire contents of /tmp (root only).
 *
 * BUG: should do something about preserving Rx... (register contents)
 *      temporaries.
 */

#ifndef VMUNIX
#define LBLKS   125
#else
#define LBLKS   900
#endif
#define FNSIZE  128

struct  header {
        time_t  Time;                   /* Time temp file last updated */
        short   Uid;                    /* This users identity */
#ifndef VMUNIX
        short   Flines;                 /* Number of lines in file */
#else
        int     Flines;
#endif
        char    Savedfile[FNSIZE];      /* The current file name */
        short   Blocks[LBLKS];          /* Blocks where line pointers stashed */
} H;

#ifdef  lint
#define ignore(a)       Ignore(a)
#define ignorl(a)       Ignorl(a)
#else
#define ignore(a)       a
#define ignorl(a)       a
#endif

struct  passwd *getpwuid();
off_t   lseek();
FILE    *popen();

#define eq(a, b) strcmp(a, b) == 0

main(argc)
        int argc;
{
        register FILE *tf;
        struct direct dirent;
        struct stat stbuf;

        /*
         * If only one argument, then preserve the standard input.
         */
        if (argc == 1) {
                if (copyout((char *) 0))
                        exit(1);
                exit(0);
        }

        /*
         * If not super user, then can only preserve standard input.
         */
        if (getuid()) {
                fprintf(stderr, "NOT super user\n");
                exit(1);
        }

        /*
         * ... else preserve all the stuff in /tmp, removing
         * it as we go.
         */
        if (chdir("/tmp") < 0) {
                perror("/tmp");
                exit(1);
        }

        tf = fopen(".", "r");
        if (tf == NULL) {
                perror("/tmp");
                exit(1);
        }
        while (fread((char *) &dirent, sizeof dirent, 1, tf) == 1) {
                if (dirent.d_ino == 0)
                        continue;
                /*
                 * Ex temporaries must begin with Ex;
                 * we check that the 10th character of the name is null
                 * so we won't have to worry about non-null terminated names
                 * later on.
                 */
                if (dirent.d_name[0] != 'E' || dirent.d_name[1] != 'x' || dirent.d_name[10])
                        continue;
                if (stat(dirent.d_name, &stbuf))
                        continue;
                if ((stbuf.st_mode & S_IFMT) != S_IFREG)
                        continue;
                /*
                 * Save the bastard.
                 */
                ignore(copyout(dirent.d_name));
        }
        exit(0);
}

char    pattern[] =     usrpath(preserve/Exaa`XXXXX);

/*
 * Copy file name into usrpath(preserve)/...
 * If name is (char *) 0, then do the standard input.
 * We make some checks on the input to make sure it is
 * really an editor temporary, generate a name for the
 * file (this is the slowest thing since we must stat
 * to find a unique name), and finally copy the file.
 */
copyout(name)
        char *name;
{
        int i;
        static int reenter;
        char buf[BUFSIZ];

        /*
         * The first time we put in the digits of our
         * process number at the end of the pattern.
         */
        if (reenter == 0) {
                mkdigits(pattern);
                reenter++;
        }

        /*
         * If a file name was given, make it the standard
         * input if possible.
         */
        if (name != 0) {
                ignore(close(0));
                /*
                 * Need read/write access for arcane reasons
                 * (see below).
                 */
                if (open(name, 2) < 0)
                        return (-1);
        }

        /*
         * Get the header block.
         */
        ignorl(lseek(0, 0l, 0));
        if (read(0, (char *) &H, sizeof H) != sizeof H) {
format:
                if (name == 0)
                        fprintf(stderr, "Buffer format error\t");
                return (-1);
        }

        /*
         * Consistency checsks so we don't copy out garbage.
         */
        if (H.Flines < 0) {
#ifdef DEBUG
                fprintf(stderr, "Negative number of lines\n");
#endif
                goto format;
        }
        if (H.Blocks[0] != HBLKS || H.Blocks[1] != HBLKS+1) {
#ifdef DEBUG
                fprintf(stderr, "Blocks %d %d\n", H.Blocks[0], H.Blocks[1]);
#endif
                goto format;
        }
        if (name == 0 && H.Uid != getuid()) {
#ifdef DEBUG
                fprintf(stderr, "Wrong user-id\n");
#endif
                goto format;
        }
        if (lseek(0, 0l, 0)) {
#ifdef DEBUG
                fprintf(stderr, "Negative number of lines\n");
#endif
                goto format;
        }

        /*
         * If no name was assigned to the file, then give it the name
         * LOST, by putting this in the header.
         */
        if (H.Savedfile[0] == 0) {
                strcpy(H.Savedfile, "LOST");
                ignore(write(0, (char *) &H, sizeof H));
                H.Savedfile[0] = 0;
                lseek(0, 0l, 0);
        }

        /*
         * File is good.  Get a name and create a file for the copy.
         */
        mknext(pattern);
        ignore(close(1));
        if (creat(pattern, 0600) < 0) {
                if (name == 0)
                        perror(pattern);
                return (1);
        }

        /*
         * Make the target be owned by the owner of the file.
         */
        ignore(chown(pattern, H.Uid, 0));

        /*
         * Copy the file.
         */
        for (;;) {
                i = read(0, buf, BUFSIZ);
                if (i < 0) {
                        if (name)
                                perror("Buffer read error");
                        ignore(unlink(pattern));
                        return (-1);
                }
                if (i == 0) {
                        if (name)
                                ignore(unlink(name));
                        notify(H.Uid, H.Savedfile, (int) name);
                        return (0);
                }
                if (write(1, buf, i) != i) {
                        if (name == 0)
                                perror(pattern);
                        unlink(pattern);
                        return (-1);
                }
        }
}

/*
 * Blast the last 5 characters of cp to be the process number.
 */
mkdigits(cp)
        char *cp;
{
        register int i, j;

        for (i = getpid(), j = 5, cp += strlen(cp); j > 0; i /= 10, j--)
                *--cp = i % 10 | '0';
}

/*
 * Make the name in cp be unique by clobbering up to
 * three alphabetic characters into a sequence of the form 'aab', 'aac', etc.
 * Mktemp gets weird names too quickly to be useful here.
 */
mknext(cp)
        char *cp;
{
        char *dcp;
        struct stat stb;

        dcp = cp + strlen(cp) - 1;
        while (isdigit(*dcp))
                dcp--;
whoops:
        if (dcp[0] == 'z') {
                dcp[0] = 'a';
                if (dcp[-1] == 'z') {
                        dcp[-1] = 'a';
                        if (dcp[-2] == 'z')
                                fprintf(stderr, "Can't find a name\t");
                        dcp[-2]++;
                } else
                        dcp[-1]++;
        } else
                dcp[0]++;
        if (stat(cp, &stb) == 0)
                goto whoops;
}

/*
 * Notify user uid that his file fname has been saved.
 */
notify(uid, fname, flag)
        int uid;
        char *fname;
{
        struct passwd *pp = getpwuid(uid);
        register FILE *mf;
        char cmd[BUFSIZ];

        if (pp == NULL)
                return;
        sprintf(cmd, "mail %s", pp->pw_name);
        mf = popen(cmd, "w");
        if (mf == NULL)
                return;
        setbuf(mf, cmd);
        if (fname[0] == 0) {
                fprintf(mf,
"A copy of an editor buffer of yours was saved when %s.\n",
                flag ? "the system went down" : "the editor was killed");
                fprintf(mf,
"No name was associated with this buffer so it has been named \"LOST\".\n");
        } else
                fprintf(mf,
"A copy of an editor buffer of your file \"%s\"\nwas saved when %s.\n", fname,
                /*
                 * "the editor was killed" is perhaps still not an ideal
                 * error message.  Usually, either it was forcably terminated
                 * or the phone was hung up, but we don't know which.
                 */
                flag ? "the system went down" : "the editor was killed");
        fprintf(mf,
"This buffer can be retrieved using the \"recover\" command of the editor.\n");
        fprintf(mf,
"An easy way to do this is to give the command \"ex -r %s\".\n",fname);
        fprintf(mf,
"This works for \"edit\" and \"vi\" also.\n");
        pclose(mf);
}

/*
 *      people making love
 *      never exactly the same
 *      just like a snowflake
 */

#ifdef lint
Ignore(a)
        int a;
{

        a = a;
}

Ignorl(a)
        long a;
{

        a = a;
}
#endif