1: /* basename.c -- return the last element in a file name
    2: 
    3:    Copyright (C) 1990, 1998, 1999, 2000, 2001, 2003, 2004, 2005, 2006 Free
    4:    Software Foundation, Inc.
    5: 
    6:    This program is free software; you can redistribute it and/or modify
    7:    it under the terms of the GNU General Public License as published by
    8:    the Free Software Foundation; either version 2, or (at your option)
    9:    any later version.
   10: 
   11:    This program is distributed in the hope that it will be useful,
   12:    but WITHOUT ANY WARRANTY; without even the implied warranty of
   13:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   14:    GNU General Public License for more details.
   15: 
   16:    You should have received a copy of the GNU General Public License
   17:    along with this program; if not, write to the Free Software Foundation,
   18:    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
   19: 
   20: #include <config.h>
   21: 
   22: #include "dirname.h"
   23: 
   24: #include <string.h>
   25: #include "xalloc.h"
   26: #include "xstrndup.h"
   27: 
   28: /* Return the address of the last file name component of NAME.  If
   29:    NAME has no relative file name components because it is a file
   30:    system root, return the empty string.  */
   31: 
   32: char *
   33: last_component (char const *name)
   34: {
   35:   char const *base = name + FILE_SYSTEM_PREFIX_LEN (name);
   36:   char const *p;
   37:   bool saw_slash = false;
   38: 
   39:   while (ISSLASH (*base))
   40:     base++;
   41: 
   42:   for (p = base; *p; p++)
   43:     {
   44:       if (ISSLASH (*p))
   45:         saw_slash = true;
   46:       else if (saw_slash)
   47:         {
   48:           base = p;
   49:           saw_slash = false;
   50:         }
   51:     }
   52: 
   53:   return (char *) base;
   54: }
   55: 
   56: 
   57: /* In general, we can't use the builtin `basename' function if available,
   58:    since it has different meanings in different environments.
   59:    In some environments the builtin `basename' modifies its argument.
   60: 
   61:    Return the last file name component of NAME, allocated with
   62:    xmalloc.  On systems with drive letters, a leading "./"
   63:    distinguishes relative names that would otherwise look like a drive
   64:    letter.  Unlike POSIX basename(), NAME cannot be NULL,
   65:    base_name("") returns "", and the first trailing slash is not
   66:    stripped.
   67: 
   68:    If lstat (NAME) would succeed, then { chdir (dir_name (NAME));
   69:    lstat (base_name (NAME)); } will access the same file.  Likewise,
   70:    if the sequence { chdir (dir_name (NAME));
   71:    rename (base_name (NAME), "foo"); } succeeds, you have renamed NAME
   72:    to "foo" in the same directory NAME was in.  */
   73: 
   74: char *
   75: base_name (char const *name)
   76: {
   77:   char const *base = last_component (name);
   78:   size_t length;
   79: 
   80:   /* If there is no last component, then name is a file system root or the
   81:      empty string.  */
   82:   if (! *base)
   83:     return xstrndup (name, base_len (name));
   84: 
   85:   /* Collapse a sequence of trailing slashes into one.  */
   86:   length = base_len (base);
   87:   if (ISSLASH (base[length]))
   88:     length++;
   89: 
   90:   /* On systems with drive letters, `a/b:c' must return `./b:c' rather
   91:      than `b:c' to avoid confusion with a drive letter.  On systems
   92:      with pure POSIX semantics, this is not an issue.  */
   93:   if (FILE_SYSTEM_PREFIX_LEN (base))
   94:     {
   95:       char *p = xmalloc (length + 3);
   96:       p[0] = '.';
   97:       p[1] = '/';
   98:       memcpy (p + 2, base, length);
   99:       p[length + 2] = '\0';
  100:       return p;
  101:     }
  102: 
  103:   /* Finally, copy the basename.  */
  104:   return xstrndup (base, length);
  105: }
  106: 
  107: /* Return the length of the basename NAME.  Typically NAME is the
  108:    value returned by base_name or last_component.  Act like strlen
  109:    (NAME), except omit all trailing slashes.  */
  110: 
  111: size_t
  112: base_len (char const *name)
  113: {
  114:   size_t len;
  115:   size_t prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
  116: 
  117:   for (len = strlen (name);  1 < len && ISSLASH (name[len - 1]);  len--)
  118:     continue;
  119: 
  120:   if (DOUBLE_SLASH_IS_DISTINCT_ROOT && len == 1
  121:       && ISSLASH (name[0]) && ISSLASH (name[1]) && ! name[2])
  122:     return 2;
  123: 
  124:   if (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE && prefix_len
  125:       && len == prefix_len && ISSLASH (name[prefix_len]))
  126:     return prefix_len + 1;
  127: 
  128:   return len;
  129: }