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Include <limits.h>.

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(CHAR_BIT, EXTRACT_TOP_BIT, PROPAGATE_TOP_BIT): New macros.
(get_fs_usage): If top bit of system variable corresponding to
fsu_bavail is set, then set fsu_bavail_top_bit_set, and
sign-extend the value when storing it into fsu_bavail.
This commit is contained in:
Jim Meyering
1998-03-19 22:18:04 +00:00
parent 33179975d7
commit b48e78e3b7
1 changed files with 27 additions and 4 deletions
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31
lib/fsusage.c
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@@ -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
@@ -107,7 +127,8 @@ 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);
@@ -141,7 +162,8 @@ get_fs_usage (path, disk, fsp)
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));
@@ -226,7 +248,8 @@ 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);