include/filename.h

   1 /* Basic filename support macros.
   2    Copyright (C) 2001-2024 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 */