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Update man pages and clarify a number of options.

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Rework block count calculations to work correctly with small "block" sizes.

MFC after:	14 days
This commit is contained in:
Greg Lehey 2012-11-16 03:33:34 +00:00
parent 370cbbf20d
commit 71cfc6780e
2 changed files with 65 additions and 35 deletions
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87
bin/df/df.1
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@ -29,7 +29,7 @@
.\" @(#)df.1 8.3 (Berkeley) 5/8/95
.\" $FreeBSD$
.\"
.Dd March 3, 2012
.Dd November 16, 2012
.Dt DF 1
.Os
.Sh NAME
@ -50,7 +50,8 @@ displays statistics about the amount of free disk space on the specified
or on the file system of which
.Ar file
is a part.
Values are displayed in 512-byte per block counts.
By default block counts are displayed with an assumed block size of
512 bytes.
If neither a file or a file system operand is specified,
statistics for all mounted file systems are displayed
(subject to the
@ -65,46 +66,54 @@ Show all mount points, including those that were mounted with the
flag.
This is implied for file systems specified on the command line.
.It Fl b
Use 512-byte blocks rather than the default.
This overrides the
Explicitly use 512 byte blocks, overriding any
.Ev BLOCKSIZE
specification from the environment.
This is the same as the
.Fl P
option.
The
.Fl k
option overrides this option.
.It Fl c
Display a grand total.
.It Fl g
Use 1073741824-byte (1-Gbyte) blocks rather than the default.
This overrides the
Use 1073741824 byte (1 Gibibyte) blocks rather than the default.
This overrides any
.Ev BLOCKSIZE
specification from the environment.
.It Fl H
.Dq Human-readable
output.
Use unit suffixes: Byte, Kilobyte, Megabyte,
Gigabyte, Terabyte and Petabyte in order to reduce the number of
digits to four or fewer using base 10 for sizes.
Use unit suffixes: Byte, Kibibyte, Mebibyte, Gibibyte, Tebibyte and
Pebibyte (based on powers of 1024) in order to reduce the number of
digits to four or fewer.
.It Fl h
.Dq Human-readable
output.
Use unit suffixes: Byte, Kilobyte, Megabyte,
Gigabyte, Terabyte and Petabyte in order to reduce the number of
digits to four or fewer using base 2 for sizes.
Inodes statistics, if enabled with
.Fl i ,
are always printed in base 10.
Gigabyte, Terabyte and Petabyte (based on powers of 1000) in order to
reduce the number of
digits to four or fewer.
.It Fl i
Include statistics on the number of free inodes.
Include statistics on the number of free and used inodes.
In conjunction with the
.Fl h
or
.Fl H
options, the number of inodes is scaled by powers of 1000.
.It Fl k
Use 1024-byte (1-Kbyte) blocks rather than the default.
Use 1024 byte (1 Kibibyte) blocks rather than the default.
This overrides the
.Ev BLOCKSIZE
specification from the environment and the
.Fl P
option.
option and any
.Ev BLOCKSIZE
specification from the environment.
.It Fl l
Only display information about locally-mounted file systems.
.It Fl m
Use 1048576-byte (1-Mbyte) blocks rather than the default.
This overrides the
Use 1048576 byte (1 Mebibyte) blocks rather than the default.
This overrides any
.Ev BLOCKSIZE
specification from the environment.
.It Fl n
@ -117,10 +126,12 @@ When this option is specified,
will not request new statistics from the file systems, but will respond
with the possibly stale statistics that were previously obtained.
.It Fl P
Use POSIX compliant output of 512-byte blocks rather than the default.
This overrides the
Explicitly use 512 byte blocks, overriding any
.Ev BLOCKSIZE
specification from the environment.
This is the same as the
.Fl b
option.
The
.Fl k
option overrides this option.
@ -160,9 +171,18 @@ option has no effect.
.Sh ENVIRONMENT
.Bl -tag -width BLOCKSIZE
.It Ev BLOCKSIZE
If the environment variable
.Ev BLOCKSIZE
is set, the block counts will be displayed in units of that size block.
Specifies the units in which to report block counts.
This uses
.Xr getbsize 3 ,
which allows units of bytes or numbers scaled with the letters
.Em k
(for multiples of 1024 bytes),
.Em m
(for multiples of 1048576 bytes) or
.Em g
(for gibibytes).
The allowed range is 512 bytes to 1 GB.
If the value is outside, it will be set to the appropriate limit.
.El
.Sh SEE ALSO
.Xr lsvfs 1 ,
@ -170,13 +190,12 @@ is set, the block counts will be displayed in units of that size block.
.Xr fstatfs 2 ,
.Xr getfsstat 2 ,
.Xr statfs 2 ,
.Xr getbsize 3 ,
.Xr getmntinfo 3 ,
.Xr localeconv 3 ,
.Xr fstab 5 ,
.Xr mount 8 ,
.Xr pstat 8 ,
.Xr quot 8 ,
.Xr swapinfo 8
.Xr quot 8 .
.Sh STANDARDS
With the exception of most options,
the
@ -200,3 +219,13 @@ flag is ignored if a file or file system is specified.
Also, if a mount
point is not accessible by the user, it is possible that the file system
information could be stale.
.Pp
The
.Fl b
and
.Fl P
options are identical.
The former comes from the BSD tradition, and the latter is required
for
.St -p1003.1-2004
conformity.

13
bin/df/df.c
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@ -393,16 +393,11 @@ prthumanvalinode(int64_t bytes)
/*
* Convert statfs returned file system size into BLOCKSIZE units.
* Attempts to avoid overflow for large file systems.
*/
static intmax_t
fsbtoblk(int64_t num, uint64_t fsbs, u_long bs)
{
if (fsbs != 0 && fsbs < bs)
return (num / (intmax_t)(bs / fsbs));
else
return (num * (intmax_t)(fsbs / bs));
return (num * (intmax_t) fsbs / bs);
}
/*
@ -453,6 +448,12 @@ prtstat(struct statfs *sfsp, struct maxwidths *mwp)
}
(void)printf(" Mounted on\n");
}
/* Check for 0 block size. Can this happen? */
if (sfsp->f_bsize == 0) {
warnx ("File system %s does not have a block size, assuming 512.",
sfsp->f_mntonname);
sfsp->f_bsize = 512;
}
(void)printf("%-*s", mwp->mntfrom, sfsp->f_mntfromname);
if (Tflag)
(void)printf(" %-*s", mwp->fstype, sfsp->f_fstypename);