improve behaviour under VPC, fixes from nicolas tittley.

[minix.git] / commands / elle / eefile.c

/* ELLE - Copyright 1982, 1984, 1987 by Ken Harrenstien, SRI International
 *      This software is quasi-public; it may be used freely with
 *      like software, but may NOT be sold or made part of licensed
         *      products without permission of the author.
 */
/*
 * EEFILE       File reading/writing functions
 */

#include "elle.h"
#include <stdio.h>      /* Use "standard" I/O package for writing */
#ifndef BUFSIZ
#define BUFSIZ BUFSIZE  /* Some places use wrong name in stdio.h */
#endif /*-BUFSIZ*/
#if V6
        struct stat {
                int st_dev;
                int st_ino;
                char *st_mode;
                char st_nlink;
                char st_uid;
                char st_gid;
                char st_size0;
                char st_size;
                int st_addr[8];
                long st_atime;
                long st_mtime;
        };
#define ENOENT (2)      /* Syscall error - no such file or dir */
#else
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#endif /*-V6*/

#if TOPS20
#include <sys/file.h>           /* Get open mode bits */
#endif

extern char *strerror();                /* Return error string for errno */
extern struct buffer *make_buf(), *find_buf();

char *fncons(), *last_fname();

int hoardfd = -1;       /* Retain a FD here to ensure we can always write */

/* Flags for iwritfile() */
#define WF_SMASK 07     /* Source Mask */
#define WF_SBUFF  0     /*   source: Buffer */
#define WF_SREG   1     /*   source: Region */
#define WF_SKILL 2      /*   source: Last Kill */
#define WF_ASK 010      /* Ask for filename to write to */
static int iwritfile();
\f
/* EFUN: "Find File" */
/*      Ask user for a filename and do a find_file for it.
 *      If buffer exists for that filename, select that buffer.
 *      Else create a buffer for it, and read in the file if it exists.
 */
f_ffile()
{       int find_file();
#if IMAGEN
        hack_file("Visit file: ", find_file);
#else
        hack_file("Find file: ", find_file);
#endif /*-IMAGEN*/
}

/* EFUN: "Read File" */
/*      User read_file function, asks user for a filename and reads it
 */
f_rfile() { u_r_file("Read file: "); }

/* EFUN: "Visit File" */
/*      Same as Read File, with different prompt.
 */
f_vfile() { u_r_file("Visit file: "); }


u_r_file(prompt)
char *prompt;
{       register char *f_name;
        register struct buffer *b;

        if((f_name = ask (prompt))==0)  /* prompt user for filename */
                return;                         /* user punted... */
        b = cur_buf;
        if(*f_name == '\0')
          {     if (b -> b_fn == 0)
                        ding("No default file name.");
                else read_file(b -> b_fn);
          }
        else read_file(f_name);
        chkfree(f_name);
}

/* EFUN: "Insert File" */
/*      Asks for a filename and inserts the file at current location.
 *      Point is left at beginning, and the mark at the end.
 */
f_ifile()
{       int ins_file();
        hack_file("Insert file: ", ins_file);
}
\f
/* EFUN: "Save File" */
/*      Save current buffer to its default file name
 */
f_sfile()
{       if(cur_buf->b_flags&B_MODIFIED)
                return(iwritfile(WF_SBUFF));    /* Write buffer, don't ask */
        else
          {     saynow("(No changes need to be written)");
                return(1);
          }
}

#if FX_SAVEFILES || FX_WFEXIT
/* EFUN: "Save All Files" */
/*  F_SAVEFILES - Offer to save all modified files.
 *      With argument, doesn't ask.
 *      Returns 0 if user aborts or if an error happened.
 */
f_savefiles()
{       register struct buffer *b, *savb;
        register int res = 1;
        char *ans;

        savb = cur_buf;
        for (b = buf_head; res && b; b = b->b_next)
                if ((b->b_flags & B_MODIFIED) && b->b_fn)
                  {     if(exp_p)               /* If arg, */
                          {     chg_buf(b);     /* just save, don't ask */
                                res = f_sfile();
                                continue;       /* Check next buffer */
                          }
                        /* Ask user whether to save */
                        ans = ask("Buffer %s contains changes - write out? ",
                                        b->b_name);
                        if(ans == 0)
                          {     res = 0;        /* User aborted */
                                break;
                          }
                        if (upcase(*ans) == 'Y')
                          {     chg_buf(b);
                                res = f_sfile();        /* Save File */
                          }
                        chkfree(ans);
                  }
        chg_buf(savb);
        return(res);
}
#endif /*FX_SAVEFILES||FX_WFEXIT*/
\f
/* EFUN: "Write File" */
/*      Write out the buffer to an output file.
 */
f_wfile()
{       return iwritfile(WF_ASK|WF_SBUFF);
}

/* EFUN: "Write Region" */
/*      Write region out to a file
 */
f_wreg()
{       return iwritfile(WF_ASK|WF_SREG);       /* Ask, write region */
}

#if FX_WLASTKILL
/* EFUN: "Write Last Kill" (not EMACS) */
/*      Write current kill buffer out to a file.
**      This is mainly for MINIX.
*/
extern int kill_ptr;            /* From EEF3 */
extern SBSTR *kill_ring[];

f_wlastkill()
{       return iwritfile(WF_ASK|WF_SKILL);
}
#endif
\f

/* HACK_FILE - intermediate subroutine
 */
hack_file(prompt, rtn)
char *prompt;
int (*rtn)();
{       register char *f_name;

        if((f_name = ask(prompt)) == 0)
                return;
        if (*f_name != '\0')                    /* Check for null answer */
                (*rtn)(f_name);
        chkfree(f_name);
}

/* FIND_FILE(f_name)
 *      If there is a buffer whose fn == f_name, select that buffer.
 *      Else create one with name of the last section of f_name and
 *      read the file into that buffer.
 */
find_file(f_name)
register char *f_name;
{       register struct buffer *b;
        register char *ans;
        char *lastn;
        int fd;

#if IMAGEN
        char real_name[128];            /* File name w/ expanded ~ and $ */
        expand_file(real_name, f_name);
        f_name = real_name;
#endif /*IMAGEN*/

        for (b = buf_head; b; b = b -> b_next)
                if(b->b_fn && (strcmp (b -> b_fn, f_name) == 0))
                        break;
        if (b)                          /* if we found one */
          {     sel_buf(b);             /* go there */
                return;                 /* and we are done */
          }
        if((fd = open(f_name,0)) < 0)   /* See if file exists */
          {     if(errno != ENOENT)     /* No, check reason */
                  {     ferr_ropn();    /* Strange error, complain */
                        return;         /* and do nothing else. */
                  }
          }
        else close(fd);                 /* Found!  Close FD, since the */
                                        /* read_file rtn will re-open. */

        lastn = last_fname(f_name);     /* Find buffer name */
        b = find_buf(lastn);            /* Is there a buffer of that name? */
        if (b && (ex_blen(b) || b->b_fn))
          {     ans = ask("Buffer %s contains %s, which buffer shall I use? ",
                        b -> b_name, b->b_fn ? b->b_fn : "something");
                if(ans == 0) return;            /* Aborted */
                if (*ans != '\0')               /* if null answer, use b */
                        b = make_buf(ans);      /* else use ans */
                chkfree(ans);
          }
        else
                b = make_buf(lastn);
        sel_buf(b);
        if(fd < 0)              /* If file doesn't exist, */
          {     set_fn(f_name); /* just say "new" and set filename */
                return;         /* and return right away. */
          }
        if (read_file(f_name)==0)       /* File exists, read it in! */
          {     if(b->b_fn)             /* Failed... if filename, */
                  {     chkfree(b->b_fn);       /* flush the filename. */
                        b->b_fn = 0;
                  }
          }
}

/* READ_FILE(f_name)
 *      Reads file into current buffer, flushing any
 *      previous contents (if buffer modified, will ask about saving)
 *      Returns 0 if failed.
 */
read_file(f_name)
char *f_name;
{
#if IMAGEN
        struct stat s;
        char real_name[128];            /* File name w/ expanded ~ and $ */
#endif /*IMAGEN*/

        if(!zap_buffer())       /* Flush the whole buffer */
                return;         /* Unless user aborts */
#if IMAGEN
        expand_file(real_name, f_name);
        f_name = real_name;             /* Hack, hack! */
#endif /*IMAGEN*/
        set_fn(f_name);
        if (ins_file(f_name)==0)
                return 0;
        f_bufnotmod();          /* Say not modified now */
#if IMAGEN
        stat(f_name, &s);               /* Get file stat */
        cur_buf->b_mtime = s.st_mtime;  /*  and pick out last-modified time */
#endif /*IMAGEN*/
        return 1;
}

/* INS_FILE(f_name)
 *      Inserts file named f_name into current buffer at current point
 *      Point is not moved; mark is set to end of inserted stuff.
 *      Returns 0 if failed, 1 if won.
 */
ins_file (f_name)
char *f_name;
{       register int ifd;
        register SBSTR *sd;
        chroff insdot;                  /* To check for range of mods */

#if IMAGEN
        char real_name[128];            /* File name w/ expanded ~ and $ */
        expand_file(real_name, f_name);
        f_name = real_name;
#endif /*IMAGEN*/
#if !(TOPS20)
        if((ifd = open(f_name,0)) < 0)
#else
        if((ifd = open(f_name,O_RDONLY|O_UNCONVERTED)) < 0)
#endif /*TOPS20*/
          {     ferr_ropn();            /* Can't open, complain */
                return 0;               /* no redisplay */
          }
        errno = 0;
        if((sd = sb_fduse(ifd)) == 0)
          {     if (ifd >= SB_NFILES)
                        dingtoo(" Cannot read - too many internal files");
                else if (errno)
                        ferr_ropn();
                else errbarf("SB rtn cannot read file?");
                close(ifd);
                return 0;
          }
        sb_sins(cur_buf,sd);
        insdot = e_dot();
        f_setmark();                    /* Set mark at current ptr */
        if(cur_dot != insdot)           /* If pointer was advanced, */
                buf_tmat(insdot);       /* then stuff was inserted */
        e_gocur();
        return 1;
}

ferr_ropn() { ferr(" Cannot read"); }
ferr_wopn() { ferr(" Cannot write"); }
ferr(str)
char *str;
{       saytoo(str);
        saytoo(" - ");
        dingtoo(strerror(errno));
}
\f

/* IWRITFILE - auxiliary for writing files.
**      Returns 1 if write successful, 0 if not.
*/
static int
iwritfile(flags)
int flags;
{       register struct buffer *b;
        register char *o_name;          /* output file name */
        int styp = flags & WF_SMASK;    /* Source type, one of WF_Sxxx */
        char *prompt;
#ifdef STDWRITE
        register FILE *o_file;          /* output file pointer */
        char obuf[BUFSIZ];
        chroff dotcnt;
#endif /*STDWRITE*/
        int ofd;                        /* output file FD */
        SBSTR *sd;
        char fname[FNAMSIZ];            /* To avoid chkfree hassle */
        char newname[FNAMSIZ];          /* for robustness */
        char oldname[FNAMSIZ];          /* ditto */
        int res;
        struct stat statb;
        int statres;
#if IMAGEN
        struct stat s;
        char real_name[128];            /* File name w/ expanded ~ and $ */
#endif /*IMAGEN*/
        res = 1;                        /* Let's keep track of success */

        /* Check for existence of source, and set prompt string */
        switch(styp)
          {
                case WF_SBUFF:
                        prompt = "Write File: ";
                        break;
                case WF_SREG:
                        if(!mark_p)
                          {     dingtoo(" No Mark!");
                                return(0);
                          }
                        prompt = "Write Region: ";
                        break;
#if FX_WLASTKILL
                case WF_SKILL:
                        if(!kill_ring[kill_ptr])
                          {     dingtoo("No killed stuff");
                                return(0);
                          }
                        prompt = "Write Last Kill: ";
                        break;
#endif
                default:                        /* Internal error */
                        errbarf("bad iwritfile arg");
                        return 0;
          }

        if (flags&WF_ASK)
          {     if((o_name = ask(prompt))==0)
                        return(0);              /* User punted. */
                strcpy(&fname[0], o_name);      /* Copy filename onto stack */
                chkfree(o_name);
          }
        o_name = &fname[0];
        b = cur_buf;
        if (!(flags&WF_ASK) || (*o_name == '\0'))
          {     if (b->b_fn == 0)
                  {     ding("No default file name.");
                        return(0);
                  }
                strcpy(o_name, b->b_fn);
          }

#if IMAGEN
        expand_file(real_name, o_name);
        o_name = real_name;             /* Hack, hack */
#endif /*IMAGEN*/

        statres = stat(o_name,&statb);  /* Get old file's info (if any) */

#if IMAGEN
        /* Now, make sure someone hasn't written the file behind our backs */
        if ((styp==WF_SBUFF) && !(flags&WF_ASK)
          && b->b_fn && stat(b->b_fn, &s) >= 0)
                if (s.st_mtime != b->b_mtime)
                  {     char *ans;
                        ans = ask("Since you last read \"%s\", someone has changed it.\nDo you want to write it anyway (NOT RECOMMENDED!)? ",
                                   b->b_fn);
                        if (ans == 0 || upcase(*ans) != 'Y')
                          {
                                ding("I suggest you either read it again, or\nwrite it to a temporary file, and merge the two versions manually.");
                                if (ans) chkfree(ans);
                                return(0);
                          }
                        if (ans) chkfree(ans);
                  }
#endif /*IMAGEN*/

  /* Try to get around major UNIX screw of smashing files.
   * This still isn't perfect (screws up with long filenames) but...
   * 1. Write out to <newname>
   * 2. Rename <name> to <oldname> (may have to delete existing <oldname>)
   * 3. Rename <newname> to <name>.
   */
        fncons(oldname,ev_fno1,o_name,ev_fno2); /* Set up "old" filename */
        fncons(newname,ev_fnn1,o_name,ev_fnn2); /* Set up "new" filename */
        unlink(newname);                        /* Ensure we don't clobber */
        unhoard();                              /* Now give up saved FD */
#if !(V6)       /* Standard V6 doesn't have access call */
        if(statres >= 0)                        /* If file exists, */
          {     if(access(o_name, 2) != 0)      /* check for write access */
                  {     ferr_wopn();
                        res = 0;        /* Failure */
                        goto wdone;
                  }
          }
#endif /*-V6*/
#ifdef STDWRITE
        if(flags&WF_ASK)
          {     if((o_file = fopen(newname, "w")) ==0)  /* Create new output file */
                  {     ferr_wopn();
                        res = 0;                /* Failure */
                        goto wdone;
                  }
                setbuf(o_file,obuf);    /* Ensure always have buffer */
          }
        else    /* New stuff */
#endif /*STDWRITE*/
          {
#if !(TOPS20)
                if((ofd = creat(newname,ev_filmod)) < 0)
#else
                if((ofd = open(newname,O_WRONLY|O_UNCONVERTED)) < 0)
#endif /*TOPS20*/
                  {     ferr_wopn();
                        res = 0;                /* Failure */
                        goto wdone;
                  }
          }
        if (styp==WF_SBUFF)
                set_fn(o_name);         /* Won, so set default fn for buff */
#if IMAGEN
        saynow("Writing ");
        switch(styp)
          {     case WF_SBUFF:  saytoo(b->b_fn); break;
                case WF_SREG:   saytoo("region"); break;
#if FX_WLASTKILL
                case WF_SKILL:  saytoo("last kill"); break;
#endif
          }
        sayntoo("...");
#else
        saynow("Writing...");
#endif /*-IMAGEN*/

#if !(TOPS20)                   /* T20 does all this already */
        if(statres >= 0)                /* Get old file's modes */
          {                             /* Try to duplicate them */
                /* Do chmod first since after changing owner we may not
                ** have permission to change mode, at least on V6.
                */
                chmod(newname,statb.st_mode & 07777);
#if V6
                chown(newname, (statb.st_gid<<8)|(statb.st_uid&0377));
#else
                chown(newname,statb.st_uid,statb.st_gid);
#endif /*-V6*/
          }
#if V6
        /* If no old file existed, and we are a V6 system, try to set
         * the modes explicitly.  On V7 we're OK because the user can
         * diddle "umask" to get whatever is desired.
         * On TOPS-20 of course everything is all peachy.
         */
        else chmod(newname, ev_filmod);
#endif /*V6*/
#endif /*TOPS20*/


#ifdef STDWRITE
        if(flags&WF_ASK)
          {     switch(styp)
                  {
                        case WF_SBUFF:
                                dotcnt = e_blen();
                                e_gobob();
                                break;
                        case WF_SREG:
                                if((dotcnt = mark_dot - cur_dot) < 0)
                                  {     e_goff(dotcnt);
                                        dotcnt = -dotcnt;
                                  }
                                else e_gocur();
                                break;
                        /* WF_SKILL not implemented here */
                  }
                while(--dotcnt >= 0)
                        putc(sb_getc(((SBBUF *)b)), o_file);
                e_gocur();
                fflush(o_file);                 /* Force everything out */
                res = ferror(o_file);           /* Save result of stuff */
                fclose(o_file);                 /* Now flush FD */
          }
        else    /* New stuff */
#endif /*STDWRITE*/
          {
                switch(styp)
                  {
                        case WF_SBUFF:
                                res = sb_fsave((SBBUF *)b, ofd);
                                break;
                        case WF_SREG:
                                e_gocur();
                                sd = e_copyn((chroff)(mark_dot - cur_dot));
                                res = sbx_aout(sd, 2, ofd);
                                sbs_del(sd);
                                break;
#if FX_WLASTKILL
                        case WF_SKILL:
                                res = sbx_aout(kill_ring[kill_ptr], 2, ofd);
                                break;
#endif
                  }
                close(ofd);
          }
        if(errno = res)
          {     ferr(" Output error");
                res = 0;                /* Failure */
                goto wdone;
          }
        else
                res = 1;                /* Success so far */
        if(styp == WF_SBUFF)
                f_bufnotmod();          /* Reset "buffer modified" flag */

        /* Here we effect the screw-prevention steps explained earlier. */
        /* TOPS-20, with generation numbers, need not worry about this. */
#if TOPS20
        saynow("Written");

#else /*-TOPS20*/
#if IMAGEN      /* KLH -- This conditional bracketting is prone to lossage */
        /* Only create the .BAK file once per editing session!! */
        if ((styp==WF_SBUFF) || !(b->b_flags & B_BACKEDUP))
          {     if (styp==WF_SBUFF)
                        b->b_flags |= B_BACKEDUP;
#endif /*IMAGEN*/
        unlink(oldname);        /* remove any existing "old" file */
        if(link(o_name,oldname) == 0)   /* Rename current to "old" */
                unlink(o_name);
                /* Here is the critical point... if we stop here, there is no
                 * longer any file with the appropriate filename!!!
                 */
#if IMAGEN
          }
        else
                unlink(o_name);
#endif /*IMAGEN*/
        if(link(newname,o_name) == 0)   /* Rename "new" to current */
          {     unlink(newname);
#if IMAGEN
                sayntoo("OK");
#else
                saynow("Written");
#endif /*-IMAGEN*/
          }
        else
          {     dingtoo("rename error!");
                res = 0;
          }
#endif /*-TOPS20*/

#if IMAGEN
        /* Update the last-modified time for the file in this buffer */
        if ((styp == WF_SBUFF) && b->b_fn)
          {     stat(b->b_fn, &s);
                b->b_mtime = s.st_mtime;
          }
#endif /*IMAGEN*/

wdone:
        hoard();                        /* Get back a retained FD */
        return(res);
}
\f
/* FNCONS(dest,pre,f_name,post)
 *      Specialized routine to cons up a filename string into "dest",
 *      given prefix and postfix strings to be added onto last component of
 *      filename.
 */
char *
fncons(dest, pre, f_name, post)
char *dest,*pre,*f_name,*post;
{       register char *cp, *cp2;
        char *last_fname();

        cp = dest;
        *cp = 0;                        /* Make dest string null initially */
        cp2 = last_fname(f_name);       /* Get pointer to beg of last name */
        strncat(cp,f_name,cp2-f_name);  /* Copy first part of filename */
        if(pre) strcat(cp, pre);        /* If prefix exists, add it on */
        cp = last_fname(cp);            /* Recheck in case levels added */
        strcat(cp, cp2);                /* Now add last name */
        if(cp2 = post)                  /* If there's a postfix, must check */
          {     cp[FNAMELEN-strlen(cp2)] = 0;   /* and cut dest so postfix */
                strcat(cp, cp2);                /* will fit on end. */
          }
        return(dest);
}

/* LAST_FNAME(string)
 *      Get the last component of a file name.  Returns pointer to
 *      start of component; does NOT copy string!
 */
char *
last_fname(f_name)
char *f_name;
{       register char *cp, *p;
        register int c;

        p = f_name;             /* pointer to last slash */
        cp = p;
        while(c = *cp++)
                if(c == '/')
                        p = cp;         /* point to after the slash */
        return(p);
}

/* SET_FN(string)
 *      Set the default filename for current buffer to "string".
 */
set_fn (string)
char *string;
{       register struct buffer *b;
        register char *str;
#if IMAGEN
        register char *cp;
        register int len;
#endif /*IMAGEN*/
        char *strdup();

        b = cur_buf;
        str = strdup(string);           /* Copy now in case copying self */
        if(b->b_fn)
                chkfree(b->b_fn);
        b -> b_fn = str;
#if IMAGEN
        /* Do mode determination based on file name (HACK HACK) */
        len = strlen(str);
        b->b_flags &= ~(B_CMODE|B_TEXTMODE);
        if (len > 4)
          {     if (strcmp(&str[len - 5], "draft") == 0)
                        b->b_flags |= B_TEXTMODE;
                else
                  {     cp = &str[len - 4];
                        if (strcmp(cp, ".txt") == 0 ||
                            strcmp(cp, ".mss") == 0)
                                b->b_flags |= B_TEXTMODE;
                  }
          }
        if (len > 2)
          {     cp = &str[len - 2];
                if (strcmp(cp, ".h") == 0 || strcmp(cp, ".c") == 0)
                        b->b_flags |= B_CMODE;
          }
#endif /*IMAGEN*/
        redp(RD_MODE);
}
\f
/* SAVEWORLD - Attempt to save all changes user has made.
 *      Currently this amounts to writing out all modified buffers
 *      to the files $HOME/+buffername.  If a buffer is given as argument,
 *      only that buffer is saved.
 *      This is only called from the error handling routines with
 *      the TTY either gone or in normal (non-edit) mode.  The "grunt"
 *      flag says whether to output feedback during the saving process.
 */
saveworld(bp, grunt)
struct buffer *bp;
int grunt;
{       register struct buffer *b;
        register int wfd;
        char sfname[FNAMSIZ];
        struct buffer *sel_mbuf();

        unhoard();              /* Ensure a FD is free for writing */
        if(b = bp) goto once;
        while(!bp && (b = sel_mbuf(b)))
          {
        once:   strcat(strcat(strcpy(sfname,homedir),"/+"),b->b_name);
                if(grunt) printf("Saving %s...",sfname);
#if !(TOPS20)
                if((wfd = creat(sfname, ev_filmod)) < 0)
#else
                if((wfd = open(sfname,O_WRONLY|O_UNCONVERTED)) < 0)
#endif /*TOPS20*/
                  {     if(grunt)
                                printf(" error - %s\n", strerror(errno));
                  }
                else
                  {     sb_fsave((SBBUF *)b, wfd);
                        close(wfd);
                        if(grunt) printf("\n");
                  }
                b->b_flags &= ~B_MODIFIED;
          }
        hoard();
}

/* HOARD, UNHOARD - Routines to save a FD for writing, to make sure
 *      that we can always write out a buffer no matter how many
 *      file descriptors we are currently using.
 */
hoard()                 /* Stash away a FD */
{       if(hoardfd <= 0)
#if !(TOPS20)
                hoardfd = open("nul:", 1);
#else
                hoardfd = open("/dev/null", 1);
#endif
}
unhoard()               /* Give up our stashed FD so it can be re-used */
{       close(hoardfd);
        hoardfd = -1;
}
\f
#if IMAGEN
#include <pwd.h>
#include <ctype.h>

/*
 * expand_file: expand any ~user-name/ or $env-var/ prefixes in sfn,
 * producing the full name in dfn
 */
expand_file(dfn, sfn)
register char *dfn, *sfn;
{
        register char *sp, *tp;
        register int c;
        register struct passwd *pw;
        char ts[128];

        /* HORRIBLE, GROSS, DISGUSTING HACK: if the destination and
         * source strings are identical (same pointer), then do not
         * do any expansion--this happens to work with the current
         * structure very well, since multiple expansions may happen.
         */
        if (dfn == sfn)
                return;

        ts[0] = 0;

        /* If have a leading $, then expand environment variable */
        if (*sfn == '$')
          {     ++sfn;
                tp = ts;
                while (*tp++ = *sfn)
                        if (!isalnum(*sfn))
                                break;
                        else
                                ++sfn;
                *--tp = 0;              /* Just in case */
                strcpy(ts, getenv(ts)); /* MARGINAL!! */
          }
        /* If have leading ~, then expand login name (null means $HOME) */
        else if (*sfn == '~')
          {     ++sfn;
                if (*sfn == '/' || *sfn == 0)
                        strcpy(ts, getenv("HOME"));
                else
                  {     tp = ts;
                        while (*sfn && *sfn != '/')
                                *tp++ = *sfn++;
                        *tp = 0;
                        pw = (struct passwd *)getpwnam(ts);
                        if (! pw)
                                strcpy(ts, "???");
                        else
                                strcpy(ts, pw->pw_dir);
                  }
          }

        /* Now, ts is either empty or contains the expansion;
         * sfn has been updated correctly.
         */
        strcpy(dfn, ts);
        strcat(dfn, sfn);
}
#endif /*IMAGEN*/