On Mon, Aug 29, 2022 at 05:10:10AM -0600, Theo de Raadt wrote:
> I would really prefer if this did not need floating point.

In that case, how about this scissor-patch?
It has the added benefit of removing the existing floating-point usage.

Best,

-- >8 --
Subject: [PATCH] Correctly (per POSIX) round up df usage percentage

Quoth POSIX Issue 7:
  <percentage used>
    The percentage of the normally available space that is currently
    allocated to all files on the file system. This shall be calculated
    using the fraction:
      <space used>/(<space used> + <space free>)
    expressed as a percentage. This percentage may be greater than 100
    if <space free> is less than zero. The percentage value shall be
    expressed as a positive integer, with any fractional result causing
    it to be rounded to the next highest integer.

Nominally this only applies to -P and -Pk behaviour (the last hunk),
but for consistency it may be best to apply that everywhere
---
 bin/df/df.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/bin/df/df.c b/bin/df/df.c
index fd51f906f89..1f235dadeb4 100644
--- a/bin/df/df.c
+++ b/bin/df/df.c
@@ -51,6 +51,7 @@ int            bread(int, off_t, void *, int);
 static void     bsdprint(struct statfs *, long, int);
 char           *getmntpt(char *);
 static void     maketypelist(char *);
+static int      percent(u_int64_t, u_int64_t);
 static void     posixprint(struct statfs *, long, int);
 static void     prthuman(struct statfs *sfsp, unsigned long long);
 static void     prthumanval(long long);
@@ -323,13 +324,12 @@ prtstat(struct statfs *sfsp, int maxwidth, int headerlen, 
int blocksize)
                    fsbtoblk(sfsp->f_blocks, sfsp->f_bsize, blocksize),
                    fsbtoblk(used, sfsp->f_bsize, blocksize),
                    fsbtoblk(sfsp->f_bavail, sfsp->f_bsize, blocksize));
-       (void)printf(" %5.0f%%",
-           availblks == 0 ? 100.0 : (double)used / (double)availblks * 100.0);
+       (void)printf(" %5d%%", percent(used, availblks));
        if (iflag) {
                inodes = sfsp->f_files;
                used = inodes - sfsp->f_ffree;
-               (void)printf(" %7llu %7llu %5.0f%% ", used, sfsp->f_ffree,
-                  inodes == 0 ? 100.0 : (double)used / (double)inodes * 100.0);
+               (void)printf(" %7llu %7llu %5d%% ", used, sfsp->f_ffree,
+                  percent(used, inodes));
        } else
                (void)printf("  ");
        (void)printf("  %s\n", sfsp->f_mntonname);
@@ -372,6 +372,12 @@ bsdprint(struct statfs *mntbuf, long mntsize, int maxwidth)
        return;
 }
 
+static int
+percent(u_int64_t used, u_int64_t avail)
+{
+       return avail ? (100 * used + (avail - 1)) / avail : 100;
+}
+
 /*
  * Print in format defined by POSIX 1002.2, invoke with -P option.
  */
@@ -383,7 +389,6 @@ posixprint(struct statfs *mntbuf, long mntsize, int 
maxwidth)
        char *blockstr;
        struct statfs *sfsp;
        long long used, avail;
-       double percentused;
 
        if (kflag) {
                blocksize = 1024;
@@ -401,18 +406,14 @@ posixprint(struct statfs *mntbuf, long mntsize, int 
maxwidth)
                sfsp = &mntbuf[i];
                used = sfsp->f_blocks - sfsp->f_bfree;
                avail = sfsp->f_bavail + used;
-               if (avail == 0)
-                       percentused = 100.0;
-               else
-                       percentused = (double)used / (double)avail * 100.0;
 
-               (void) printf ("%-*.*s %*lld %10lld %11lld %5.0f%%   %s\n",
+               (void) printf ("%-*.*s %*lld %10lld %11lld %5d%%   %s\n",
                        maxwidth, maxwidth, sfsp->f_mntfromname,
                        (int)strlen(blockstr),
                        fsbtoblk(sfsp->f_blocks, sfsp->f_bsize, blocksize),
                        fsbtoblk(used, sfsp->f_bsize, blocksize),
                        fsbtoblk(sfsp->f_bavail, sfsp->f_bsize, blocksize),
-                       percentused, sfsp->f_mntonname);
+                       percent(used, avail), sfsp->f_mntonname);
        }
 }
 
-- 
2.30.2

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