1  /* Basic filename support macros.
       2     Copyright (C) 2001-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  /* From Paul Eggert and Jim Meyering.  */
      20  
      21  #ifndef _FILENAME_H
      22  #define _FILENAME_H
      23  
      24  #include <string.h>
      25  
      26  #ifdef __cplusplus
      27  extern "C" {
      28  #endif
      29  
      30  
      31  /* Filename support.
      32     ISSLASH(C)                  tests whether C is a directory separator
      33                                 character.
      34     HAS_DEVICE(Filename)        tests whether Filename contains a device
      35                                 specification.
      36     FILE_SYSTEM_PREFIX_LEN(Filename)  length of the device specification
      37                                       at the beginning of Filename,
      38                                       index of the part consisting of
      39                                       alternating components and slashes.
      40     FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE
      41                                 1 when a non-empty device specification
      42                                 can be followed by an empty or relative
      43                                 part,
      44                                 0 when a non-empty device specification
      45                                 must be followed by a slash,
      46                                 0 when device specification don't exist.
      47     IS_ABSOLUTE_FILE_NAME(Filename)
      48                                 tests whether Filename is independent of
      49                                 any notion of "current directory".
      50     IS_RELATIVE_FILE_NAME(Filename)
      51                                 tests whether Filename may be concatenated
      52                                 to a directory filename.
      53     Note: On native Windows, OS/2, DOS, "c:" is neither an absolute nor a
      54     relative file name!
      55     IS_FILE_NAME_WITH_DIR(Filename)  tests whether Filename contains a device
      56                                      or directory specification.
      57   */
      58  #if defined _WIN32 || defined __CYGWIN__ \
      59      || defined __EMX__ || defined __MSDOS__ || defined __DJGPP__
      60    /* Native Windows, Cygwin, OS/2, DOS */
      61  # define ISSLASH(C) ((C) == '/' || (C) == '\\')
      62    /* Internal macro: Tests whether a character is a drive letter.  */
      63  # define _IS_DRIVE_LETTER(C) \
      64      (((C) >= 'A' && (C) <= 'Z') || ((C) >= 'a' && (C) <= 'z'))
      65    /* Help the compiler optimizing it.  This assumes ASCII.  */
      66  # undef _IS_DRIVE_LETTER
      67  # define _IS_DRIVE_LETTER(C) \
      68      (((unsigned int) (C) | ('a' - 'A')) - 'a' <= 'z' - 'a')
      69  # define HAS_DEVICE(Filename) \
      70      (_IS_DRIVE_LETTER ((Filename)[0]) && (Filename)[1] == ':')
      71  # define FILE_SYSTEM_PREFIX_LEN(Filename) (HAS_DEVICE (Filename) ? 2 : 0)
      72  # ifdef __CYGWIN__
      73  #  define FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE 0
      74  # else
      75     /* On native Windows, OS/2, DOS, the system has the notion of a
      76        "current directory" on each drive.  */
      77  #  define FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE 1
      78  # endif
      79  # if FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE
      80  #  define IS_ABSOLUTE_FILE_NAME(Filename) \
      81       ISSLASH ((Filename)[FILE_SYSTEM_PREFIX_LEN (Filename)])
      82  # else
      83  #  define IS_ABSOLUTE_FILE_NAME(Filename) \
      84       (ISSLASH ((Filename)[0]) || HAS_DEVICE (Filename))
      85  # endif
      86  # define IS_RELATIVE_FILE_NAME(Filename) \
      87      (! (ISSLASH ((Filename)[0]) || HAS_DEVICE (Filename)))
      88  # define IS_FILE_NAME_WITH_DIR(Filename) \
      89      (strchr ((Filename), '/') != NULL || strchr ((Filename), '\\') != NULL \
      90       || HAS_DEVICE (Filename))
      91  #else
      92    /* Unix */
      93  # define ISSLASH(C) ((C) == '/')
      94  # define HAS_DEVICE(Filename) ((void) (Filename), 0)
      95  # define FILE_SYSTEM_PREFIX_LEN(Filename) ((void) (Filename), 0)
      96  # define FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE 0
      97  # define IS_ABSOLUTE_FILE_NAME(Filename) ISSLASH ((Filename)[0])
      98  # define IS_RELATIVE_FILE_NAME(Filename) (! ISSLASH ((Filename)[0]))
      99  # define IS_FILE_NAME_WITH_DIR(Filename) (strchr ((Filename), '/') != NULL)
     100  #endif
     101  
     102  /* Deprecated macros.  For backward compatibility with old users of the
     103     'filename' module.  */
     104  #define IS_ABSOLUTE_PATH IS_ABSOLUTE_FILE_NAME
     105  #define IS_PATH_WITH_DIR IS_FILE_NAME_WITH_DIR
     106  
     107  
     108  #ifdef __cplusplus
     109  }
     110  #endif
     111  
     112  #endif /* _FILENAME_H */