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<h3 class="section">18.2 Host Filesystem</h3>
<p><a name="index-configuration-file-5028"></a><a name="index-g_t_0040file_007bxm_002d_0040var_007bmachine_007d_002eh_007d-5029"></a>
GCC needs to know a number of things about the semantics of the host
machine's filesystem. Filesystems with Unix and MS-DOS semantics are
automatically detected. For other systems, you can define the
following macros in <samp><span class="file">xm-</span><var>machine</var><span class="file">.h</span></samp>.
<dl>
<dt><code>HAVE_DOS_BASED_FILE_SYSTEM</code><a name="index-HAVE_005fDOS_005fBASED_005fFILE_005fSYSTEM-5030"></a><dd>This macro is automatically defined by <samp><span class="file">system.h</span></samp> if the host
file system obeys the semantics defined by MS-DOS instead of Unix.
DOS file systems are case insensitive, file specifications may begin
with a drive letter, and both forward slash and backslash (‘<samp><span class="samp">/</span></samp>’
and ‘<samp><span class="samp">\</span></samp>’) are directory separators.
<br><dt><code>DIR_SEPARATOR</code><a name="index-DIR_005fSEPARATOR-5031"></a><dt><code>DIR_SEPARATOR_2</code><a name="index-DIR_005fSEPARATOR_005f2-5032"></a><dd>If defined, these macros expand to character constants specifying
separators for directory names within a file specification.
<samp><span class="file">system.h</span></samp> will automatically give them appropriate values on
Unix and MS-DOS file systems. If your file system is neither of
these, define one or both appropriately in <samp><span class="file">xm-</span><var>machine</var><span class="file">.h</span></samp>.
<p>However, operating systems like VMS, where constructing a pathname is
more complicated than just stringing together directory names
separated by a special character, should not define either of these
macros.
<br><dt><code>PATH_SEPARATOR</code><a name="index-PATH_005fSEPARATOR-5033"></a><dd>If defined, this macro should expand to a character constant
specifying the separator for elements of search paths. The default
value is a colon (‘<samp><span class="samp">:</span></samp>’). DOS-based systems usually, but not
always, use semicolon (‘<samp><span class="samp">;</span></samp>’).
<br><dt><code>VMS</code><a name="index-VMS-5034"></a><dd>Define this macro if the host system is VMS.
<br><dt><code>HOST_OBJECT_SUFFIX</code><a name="index-HOST_005fOBJECT_005fSUFFIX-5035"></a><dd>Define this macro to be a C string representing the suffix for object
files on your host machine. If you do not define this macro, GCC will
use ‘<samp><span class="samp">.o</span></samp>’ as the suffix for object files.
<br><dt><code>HOST_EXECUTABLE_SUFFIX</code><a name="index-HOST_005fEXECUTABLE_005fSUFFIX-5036"></a><dd>Define this macro to be a C string representing the suffix for
executable files on your host machine. If you do not define this macro,
GCC will use the null string as the suffix for executable files.
<br><dt><code>HOST_BIT_BUCKET</code><a name="index-HOST_005fBIT_005fBUCKET-5037"></a><dd>A pathname defined by the host operating system, which can be opened as
a file and written to, but all the information written is discarded.
This is commonly known as a <dfn>bit bucket</dfn> or <dfn>null device</dfn>. If
you do not define this macro, GCC will use ‘<samp><span class="samp">/dev/null</span></samp>’ as the bit
bucket. If the host does not support a bit bucket, define this macro to
an invalid filename.
<br><dt><code>UPDATE_PATH_HOST_CANONICALIZE (</code><var>path</var><code>)</code><a name="index-UPDATE_005fPATH_005fHOST_005fCANONICALIZE-_0028_0040var_007bpath_007d_0029-5038"></a><dd>If defined, a C statement (sans semicolon) that performs host-dependent
canonicalization when a path used in a compilation driver or
preprocessor is canonicalized. <var>path</var> is a malloc-ed path to be
canonicalized. If the C statement does canonicalize <var>path</var> into a
different buffer, the old path should be freed and the new buffer should
have been allocated with malloc.
<br><dt><code>DUMPFILE_FORMAT</code><a name="index-DUMPFILE_005fFORMAT-5039"></a><dd>Define this macro to be a C string representing the format to use for
constructing the index part of debugging dump file names. The resultant
string must fit in fifteen bytes. The full filename will be the
concatenation of: the prefix of the assembler file name, the string
resulting from applying this format to an index number, and a string
unique to each dump file kind, e.g. ‘<samp><span class="samp">rtl</span></samp>’.
<p>If you do not define this macro, GCC will use ‘<samp><span class="samp">.%02d.</span></samp>’. You should
define this macro if using the default will create an invalid file name.
<br><dt><code>DELETE_IF_ORDINARY</code><a name="index-DELETE_005fIF_005fORDINARY-5040"></a><dd>Define this macro to be a C statement (sans semicolon) that performs
host-dependent removal of ordinary temp files in the compilation driver.
<p>If you do not define this macro, GCC will use the default version. You
should define this macro if the default version does not reliably remove
the temp file as, for example, on VMS which allows multiple versions
of a file.
<br><dt><code>HOST_LACKS_INODE_NUMBERS</code><a name="index-HOST_005fLACKS_005fINODE_005fNUMBERS-5041"></a><dd>Define this macro if the host filesystem does not report meaningful inode
numbers in struct stat.
</dl>
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