X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Ffsusage.c;h=a7ebf2417ce88cbfd3a3d31c5a4db2ce8f265091;hb=c3c259f0bef8cfd8d47606475348f088f7b0e120;hp=16f0beddeb5a349ecbe3a95d79b30535cf6997ab;hpb=86e7bdec3d9214ec41dcba45c01ac860b3328091;p=gnulib.git

diff --git a/lib/fsusage.c b/lib/fsusage.c
index 16f0bedde..a7ebf2417 100644
--- a/lib/fsusage.c
+++ b/lib/fsusage.c
@@ -1,5 +1,5 @@
 /* fsusage.c -- return space usage of mounted filesystems
-   Copyright (C) 1991, 1992, 1996, 1998 Free Software Foundation, Inc.
+   Copyright (C) 1991, 1992, 1996, 1998, 1999 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
@@ -26,6 +26,13 @@
 #include <sys/stat.h>
 #include "fsusage.h"
 
+#if HAVE_LIMITS_H
+# include <limits.h>
+#endif
+#ifndef CHAR_BIT
+# define CHAR_BIT 8
+#endif
+
 int statfs ();
 
 #if HAVE_SYS_PARAM_H
@@ -68,9 +75,22 @@ int statvfs ();
 /* Many space usage primitives use all 1 bits to denote a value that is
    not applicable or unknown.  Propagate this information by returning
    a uintmax_t value that is all 1 bits if the argument is all 1 bits,
-   even if the argument is unsigned and smaller than unitmax_t.  */
+   even if the argument is unsigned and smaller than uintmax_t.  */
 #define PROPAGATE_ALL_ONES(x) ((x) == -1 ? (uintmax_t) -1 : (uintmax_t) (x))
 
+/* Extract the top bit of X as an uintmax_t value.  */
+#define EXTRACT_TOP_BIT(x) ((x) \
+			    & ((uintmax_t) 1 << (sizeof (x) * CHAR_BIT - 1)))
+
+/* If a value is negative, many space usage primitives store it into an
+   integer variable by assignment, even if the variable's type is unsigned.
+   So, if a space usage variable X's top bit is set, convert X to the
+   uintmax_t value V such that (- (uintmax_t) V) is the negative of
+   the original value.  If X's top bit is clear, just yield X.
+   Use PROPAGATE_TOP_BIT if the original value might be negative;
+   otherwise, use PROPAGATE_ALL_ONES.  */
+#define PROPAGATE_TOP_BIT(x) ((x) | ~ (EXTRACT_TOP_BIT (x) - 1))
+
 int safe_read ();
 
 /* Fill in the fields of FSP with information about space usage for
@@ -81,10 +101,7 @@ int safe_read ();
    ERRNO is either a system error value, or zero if DISK is NULL
    on a system that requires a non-NULL value.  */
 int
-get_fs_usage (path, disk, fsp)
-     const char *path;
-     const char *disk;
-     struct fs_usage *fsp;
+get_fs_usage (const char *path, const char *disk, struct fs_usage *fsp)
 {
 #ifdef STAT_STATFS3_OSF1
 
@@ -107,7 +124,8 @@ get_fs_usage (path, disk, fsp)
   fsp->fsu_blocksize = 1024;
   fsp->fsu_blocks = PROPAGATE_ALL_ONES (fsd.fd_req.btot);
   fsp->fsu_bfree = PROPAGATE_ALL_ONES (fsd.fd_req.bfree);
-  fsp->fsu_bavail = PROPAGATE_ALL_ONES (fsd.fd_req.bfreen);
+  fsp->fsu_bavail = PROPAGATE_TOP_BIT (fsd.fd_req.bfreen);
+  fsp->fsu_bavail_top_bit_set = EXTRACT_TOP_BIT (fsd.fd_req.bfreen) != 0;
   fsp->fsu_files = PROPAGATE_ALL_ONES (fsd.fd_req.gtot);
   fsp->fsu_ffree = PROPAGATE_ALL_ONES (fsd.fd_req.gfree);
 
@@ -138,10 +156,11 @@ get_fs_usage (path, disk, fsp)
     }
   close (fd);
 
-  fsp->fsu_blocksize = fsd.s_type == Fs2b ? 1024 : 512;
+  fsp->fsu_blocksize = (fsd.s_type == Fs2b ? 1024 : 512);
   fsp->fsu_blocks = PROPAGATE_ALL_ONES (fsd.s_fsize);
   fsp->fsu_bfree = PROPAGATE_ALL_ONES (fsd.s_tfree);
-  fsp->fsu_bavail = PROPAGATE_ALL_ONES (fsd.s_tfree);
+  fsp->fsu_bavail = PROPAGATE_TOP_BIT (fsd.s_tfree);
+  fsp->fsu_bavail_top_bit_set = EXTRACT_TOP_BIT (fsd.s_tfree) != 0;
   fsp->fsu_files = (fsd.s_isize == -1
 		    ? (uintmax_t) -1
 		    : (fsd.s_isize - 2) * INOPB * (fsd.s_type == Fs2b ? 2 : 1));
@@ -165,7 +184,7 @@ get_fs_usage (path, disk, fsp)
      truncation, presumably without botching the 4.1.1 case, in which
      the values are not truncated.  The correct counts are stored in
      undocumented spare fields.  */
-  if (fsd.f_blocks == 0x1fffff && fsd.f_spare[0] > 0)
+  if (fsd.f_blocks == 0x7fffffff / fsd.f_bsize && fsd.f_spare[0] > 0)
     {
       fsd.f_blocks = fsd.f_spare[0];
       fsd.f_bfree = fsd.f_spare[1];
@@ -226,7 +245,8 @@ get_fs_usage (path, disk, fsp)
 
   fsp->fsu_blocks = PROPAGATE_ALL_ONES (fsd.f_blocks);
   fsp->fsu_bfree = PROPAGATE_ALL_ONES (fsd.f_bfree);
-  fsp->fsu_bavail = PROPAGATE_ALL_ONES (fsd.f_bavail);
+  fsp->fsu_bavail = PROPAGATE_TOP_BIT (fsd.f_bavail);
+  fsp->fsu_bavail_top_bit_set = EXTRACT_TOP_BIT (fsd.f_bavail) != 0;
   fsp->fsu_files = PROPAGATE_ALL_ONES (fsd.f_files);
   fsp->fsu_ffree = PROPAGATE_ALL_ONES (fsd.f_ffree);
 
@@ -239,9 +259,7 @@ get_fs_usage (path, disk, fsp)
 /* AIX PS/2 does not supply statfs.  */
 
 int
-statfs (path, fsb)
-     char *path;
-     struct statfs *fsb;
+statfs (char *path, struct statfs *fsb)
 {
   struct stat stats;
   struct dustat fsd;