New module 'stat-size'.

[gnulib.git] / lib / stat-size.h

diff --git a/lib/stat-size.h b/lib/stat-size.h
new file mode 100644 (file)
index 0000000..1e47500
--- /dev/null
+++ b/lib/stat-size.h
@@ -0,0 +1,111 @@
+/* macros useful in interpreting size-related values in struct stat.
+   Copyright (C) 1989, 1991-2011 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+/*
+   Macros defined by this file (s is an rvalue of type struct stat):
+
+   DEV_BSIZE:       The device blocksize.  But use ST_NBLOCKSIZE instead.
+   ST_BLKSIZE(s):   Preferred (in the sense of best performance) I/O blocksize
+                    for the file, in bytes.
+   ST_NBLOCKS(s):   Number of blocks in the file, including indirect blocks.
+   ST_NBLOCKSIZE:   Size of blocks used when calculating ST_NBLOCKS.
+ */
+#ifndef STAT_SIZE_H
+#define STAT_SIZE_H
+
+/* sys/param.h may define DEV_BSIZE */
+#if HAVE_SYS_PARAM_H
+# include <sys/param.h>
+#endif
+
+
+/* Much of the remainder of this file is not indented consistently
+   with the above, in order to make it easier to see that the text
+   is almost identical to part of the system.h header in coreutils.
+*/
+/* Get or fake the disk device blocksize.
+   Usually defined by sys/param.h (if at all).  */
+#if !defined DEV_BSIZE && defined BSIZE
+# define DEV_BSIZE BSIZE
+#endif
+#if !defined DEV_BSIZE && defined BBSIZE /* SGI sys/param.h */
+# define DEV_BSIZE BBSIZE
+#endif
+#ifndef DEV_BSIZE
+# define DEV_BSIZE 4096
+#endif
+
+
+
+/* Extract or fake data from a `struct stat'.
+   ST_BLKSIZE: Preferred I/O blocksize for the file, in bytes.
+   ST_NBLOCKS: Number of blocks in the file, including indirect blocks.
+   ST_NBLOCKSIZE: Size of blocks used when calculating ST_NBLOCKS.  */
+#ifndef HAVE_STRUCT_STAT_ST_BLOCKS
+# define ST_BLKSIZE(statbuf) DEV_BSIZE
+  /* coreutils' fileblocks.c also uses BSIZE.  */
+# if defined _POSIX_SOURCE || !defined BSIZE
+#  define ST_NBLOCKS(statbuf) \
+  ((statbuf).st_size / ST_NBLOCKSIZE + ((statbuf).st_size % ST_NBLOCKSIZE != 0))
+# else
+   /* This definition calls st_blocks, which is in the fileblocks module. */
+#  define ST_NBLOCKS(statbuf) \
+  (S_ISREG ((statbuf).st_mode) || S_ISDIR ((statbuf).st_mode) ? \
+   st_blocks ((statbuf).st_size) : 0)
+# endif
+#else
+/* Some systems, like Sequents, return st_blksize of 0 on pipes.
+   Also, when running `rsh hpux11-system cat any-file', cat would
+   determine that the output stream had an st_blksize of 2147421096.
+   Conversely st_blksize can be 2 GiB (or maybe even larger) with XFS
+   on 64-bit hosts.  Somewhat arbitrarily, limit the `optimal' block
+   size to SIZE_MAX / 8 + 1.  (Dividing SIZE_MAX by only 4 wouldn't
+   suffice, since "cat" sometimes multiplies the result by 4.)  If
+   anyone knows of a system for which this limit is too small, please
+   report it as a bug in this code.  */
+# define ST_BLKSIZE(statbuf) ((0 < (statbuf).st_blksize \
+                               && (statbuf).st_blksize <= ((size_t)-1) / 8 + 1) \
+                              ? (statbuf).st_blksize : DEV_BSIZE)
+# if defined hpux || defined __hpux__ || defined __hpux
+  /* HP-UX counts st_blocks in 1024-byte units.
+     This loses when mixing HP-UX and BSD file systems with NFS.  */
+#  define ST_NBLOCKSIZE 1024
+# else /* !hpux */
+#  if defined _AIX && defined _I386
+    /* AIX PS/2 counts st_blocks in 4K units.  */
+#   define ST_NBLOCKSIZE (4 * 1024)
+#  else
+#   if defined _CRAY
+#    define ST_NBLOCKS(statbuf) \
+  (S_ISREG ((statbuf).st_mode) || S_ISDIR ((statbuf).st_mode) \
+   ? (statbuf).st_blocks * ST_BLKSIZE (statbuf) / ST_NBLOCKSIZE : 0)
+#   endif
+#  endif
+# endif
+#endif
+
+#ifndef ST_NBLOCKS
+# define ST_NBLOCKS(statbuf) ((statbuf).st_blocks)
+#endif
+
+#ifndef ST_NBLOCKSIZE
+# ifdef S_BLKSIZE
+#  define ST_NBLOCKSIZE S_BLKSIZE
+# else
+#  define ST_NBLOCKSIZE 512
+# endif
+#endif
+
+#endif /* STAT_SIZE_H */