Port file-system-info to non-Microsoft

* admin/merge-gnulib (GNULIB_MODULES): Add fsusage.
* doc/emacs/files.texi (Directories): Remove documentation of
now-obsolete directory-free-space-program and
directory-free-space-args.
* etc/NEWS: Mention change.
* etc/PROBLEMS: Slow df is no longer a problem.
* lib/fsusage.c, lib/fsusage.h, m4/fsusage.m4:
New files, copied from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lisp/dired.el (dired-free-space-program)
(dired-free-space-args): These aliases are now obsolete.
* lisp/files.el (directory-free-space-program)
(directory-free-space-args): Now obsolete.
(get-free-disk-space): Just call file-system-info instead
of the now-obsolete directory-free-space-program.
* nt/gnulib-cfg.mk (OMIT_GNULIB_MODULE_fsusage): New macro.
* src/fileio.c: Include fsusage.h.
(blocks_to_bytes, Ffile_system_info) [!DOS_NT]: New functions.
(syms_of_fileio) [!DOS_NT]: Defsubr file-system-info.

1 files changed, 39 insertions, 0 deletions

diff --git a/src/fileio.c b/src/fileio.c
index adb3534532c..11370279d1b 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -96,6 +96,7 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include <acl.h>
 #include <allocator.h>
 #include <careadlinkat.h>
+#include <fsusage.h>
 #include <stat-time.h>
 #include <tempname.h>
 
@@ -5765,6 +5766,40 @@ effect except for flushing STREAM's data.  */)
   return (set_binary_mode (fileno (fp), binmode) == O_BINARY) ? Qt : Qnil;
 }
 
+#ifndef DOS_NT
+
+/* Yield a Lisp float as close as possible to BLOCKSIZE * BLOCKS, with
+   the result negated if NEGATE.  */
+static Lisp_Object
+blocks_to_bytes (uintmax_t blocksize, uintmax_t blocks, bool negate)
+{
+  /* On typical platforms the following code is accurate to 53 bits,
+     which is close enough.  BLOCKSIZE is invariably a power of 2, so
+     converting it to double does not lose information.  */
+  double bs = blocksize;
+  return make_float (negate ? -bs * -blocks : bs * blocks);
+}
+
+DEFUN ("file-system-info", Ffile_system_info, Sfile_system_info, 1, 1, 0,
+       doc: /* Return storage information about the file system FILENAME is on.
+Value is a list of numbers (TOTAL FREE AVAIL), where TOTAL is the total
+storage of the file system, FREE is the free storage, and AVAIL is the
+storage available to a non-superuser.  All 3 numbers are in bytes.
+If the underlying system call fails, value is nil.  */)
+  (Lisp_Object filename)
+{
+  Lisp_Object encoded = ENCODE_FILE (Fexpand_file_name (filename, Qnil));
+  struct fs_usage u;
+  if (get_fs_usage (SSDATA (encoded), NULL, &u) != 0)
+    return Qnil;
+  return list3 (blocks_to_bytes (u.fsu_blocksize, u.fsu_blocks, false),
+                blocks_to_bytes (u.fsu_blocksize, u.fsu_bfree, false),
+                blocks_to_bytes (u.fsu_blocksize, u.fsu_bavail,
+                                 u.fsu_bavail_top_bit_set));
+}
+
+#endif /* !DOS_NT */
+
 void
 init_fileio (void)
 {
@@ -6115,6 +6150,10 @@ This includes interactive calls to `delete-file' and
 
   defsubr (&Sset_binary_mode);
 
+#ifndef DOS_NT
+  defsubr (&Sfile_system_info);
+#endif
+
 #ifdef HAVE_SYNC
   defsubr (&Sunix_sync);
 #endif