Define bindings to ‘mkdirat’ when the C function exists.

* configure.ac: Detect if ‘mkdirat’ exists.
* libguile/filesys.c (scm_mkdirat): Define the Scheme binding.
* doc/ref/posix.texi (File System): Document it.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

configure.ac

@@ -517,7 +517,7 @@ AC_CHECK_HEADERS([crt_externs.h])
 #
 AC_CHECK_FUNCS([DINFINITY DQNAN cexp chsize clog clog10 ctermid         \
   fesetround ftime ftruncate fchown fchmod fchdir readlinkat		\
-  symlinkat getcwd geteuid getsid							\
+  symlinkat mkdirat getcwd geteuid getsid				\
   gettimeofday getuid getgid gmtime_r ioctl lstat mkdir mkdtemp mknod   \
   nice readlink rmdir setegid seteuid                            \
   setuid setgid setpgid setsid sigaction siginterrupt stat64  \

doc/ref/posix.texi

@@ -924,6 +924,12 @@ Otherwise they are set to the value specified with @var{mode}.
 The return value is unspecified.
 @end deffn
 
+@deffn {Scheme Procedure} mkdirat dir path [mode]
+@deffnx {C Function} scm_mkdirat (dir, path, mode)
+Like @code{mkdir}, but resolve @var{path} relative to the directory
+referred to by the file port @var{dir} instead.
+@end deffn
+
 @deffn {Scheme Procedure} rmdir path
 @deffnx {C Function} scm_rmdir (path)
 Remove the existing directory named by @var{path}.  The directory must

libguile/filesys.c

@@ -1351,6 +1351,31 @@ SCM_DEFINE (scm_mkdir, "mkdir", 1, 1, 0,
 }
 #undef FUNC_NAME
 
+#ifdef HAVE_MKDIRAT
+SCM_DEFINE (scm_mkdirat, "mkdirat", 2, 1, 0,
+            (SCM dir, SCM path, SCM mode),
+            "Like @code{mkdir}, but resolve @var{path} relative to the directory\n"
+            "referred to by the file port @var{dir} instead.")
+#define FUNC_NAME s_scm_mkdirat
+{
+  int rv;
+  int dir_fdes;
+  mode_t c_mode;
+
+  c_mode = SCM_UNBNDP (mode) ? 0777 : scm_to_uint (mode);
+  SCM_VALIDATE_OPFPORT (SCM_ARG1, dir);
+  dir_fdes = SCM_FPORT_FDES (dir);
+
+  STRING_SYSCALL (path, c_path, rv = mkdirat (dir_fdes, c_path, c_mode));
+  if (rv != 0)
+    SCM_SYSERROR;
+
+  scm_remember_upto_here_1 (dir);
+  return SCM_UNSPECIFIED;
+}
+#undef FUNC_NAME
+#endif
+
 SCM_DEFINE (scm_rmdir, "rmdir", 1, 0, 0, 
             (SCM path),
 	    "Remove the existing directory named by @var{path}.  The directory must\n"

libguile/filesys.h

@@ -50,6 +50,7 @@ SCM_API SCM scm_link (SCM oldpath, SCM newpath);
 SCM_API SCM scm_rename (SCM oldname, SCM newname);
 SCM_API SCM scm_delete_file (SCM str);
 SCM_API SCM scm_mkdir (SCM path, SCM mode);
+SCM_API SCM scm_mkdirat (SCM dir, SCM path, SCM mode);
 SCM_API SCM scm_rmdir (SCM path);
 SCM_API SCM scm_directory_stream_p (SCM obj);
 SCM_API SCM scm_opendir (SCM dirname);

test-suite/tests/filesys.test

@@ -29,6 +29,8 @@
   (data-file-name "filesys-test.tmp"))
 (define (test-symlink)
   (data-file-name "filesys-test-link.tmp"))
+(define (test-directory)
+  (data-file-name "filesys-test-dir.tmp"))
 
 
 ;;;
@@ -394,3 +396,39 @@
       (throw 'unsupported))
     (symlinkat (call-with-port (open "." O_RDONLY) identity)
                (test-file) (test-symlink))))
+
+(with-test-prefix "mkdirat"
+  (define (skip-if-unsupported)
+    (unless (defined? 'mkdirat)
+      (throw 'unsupported)))
+  (define (maybe-delete-directory)
+    (when (file-exists? (test-directory))
+      (rmdir (test-directory))))
+  (maybe-delete-directory)
+
+  (pass-if-equal "create" 'directory
+    (skip-if-unsupported)
+    (call-with-port
+     (open "." O_RDONLY)
+     (lambda (port)
+       (mkdirat port (test-directory))
+       (stat:type (stat (test-directory))))))
+  (maybe-delete-directory)
+
+  (pass-if-equal "explicit perms" (logand #o111 (lognot (umask)))
+    (skip-if-unsupported)
+    (call-with-port
+     (open "." O_RDONLY)
+     (lambda (port)
+       (mkdirat port (test-directory) #o111)
+       (stat:perms (stat (test-directory))))))
+  (maybe-delete-directory)
+
+  (pass-if-equal "create, implicit perms" (logand #o777 (lognot (umask)))
+    (skip-if-unsupported)
+    (call-with-port
+     (open "." O_RDONLY)
+     (lambda (port)
+       (mkdirat port (test-directory))
+       (stat:perms (stat (test-directory))))))
+  (maybe-delete-directory))