tildexpand.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  *
   6  * As far as I am concerned, the code I have written for this software
   7  * can be used freely for any purpose.  Any derived versions of this
   8  * software must be clearly marked as such, and if the derived work is
   9  * incompatible with the protocol description in the RFC file, it must be
  10  * called by a name other than "ssh" or "Secure Shell".
  11  */
  12
  13 #include "includes.h"
  14 RCSID("$OpenBSD: tildexpand.c,v 1.15 2004/05/21 08:43:03 markus Exp $");
  15
  16 #include "xmalloc.h"
  17 #include "log.h"
  18 #include "misc.h"
  19
  20 /*
  21  * Expands tildes in the file name.  Returns data allocated by xmalloc.
  22  * Warning: this calls getpw*.
  23  */
  24 char *
  25 tilde_expand_filename(const char *filename, uid_t my_uid)
  26 {
  27         const char *cp;
  28         u_int userlen;
  29         char *expanded;
  30         struct passwd *pw;
  31         char user[100];
  32         int len;
  33
  34         /* Return immediately if no tilde. */
  35         if (filename[0] != '~')
  36                 return xstrdup(filename);
  37
  38         /* Skip the tilde. */
  39         filename++;
  40
  41         /* Find where the username ends. */
  42         cp = strchr(filename, '/');
  43         if (cp)
  44                 userlen = cp - filename;        /* Something after username. */
  45         else
  46                 userlen = strlen(filename);     /* Nothing after username. */
  47         if (userlen == 0)
  48                 pw = getpwuid(my_uid);          /* Own home directory. */
  49         else {
  50                 /* Tilde refers to someone elses home directory. */
  51                 if (userlen > sizeof(user) - 1)
  52                         fatal("User name after tilde too long.");
  53                 memcpy(user, filename, userlen);
  54                 user[userlen] = 0;
  55                 pw = getpwnam(user);
  56         }
  57         if (!pw)
  58                 fatal("Unknown user %100s.", user);
  59
  60         /* If referring to someones home directory, return it now. */
  61         if (!cp) {
  62                 /* Only home directory specified */
  63                 return xstrdup(pw->pw_dir);
  64         }
  65         /* Build a path combining the specified directory and path. */
  66         len = strlen(pw->pw_dir) + strlen(cp + 1) + 2;
  67         if (len > MAXPATHLEN)
  68                 fatal("Home directory too long (%d > %d", len-1, MAXPATHLEN-1);
  69         expanded = xmalloc(len);
  70         snprintf(expanded, len, "%s%s%s", pw->pw_dir,
  71             strcmp(pw->pw_dir, "/") ? "/" : "", cp + 1);
  72         return expanded;
  73 }