[PATCH] build: Fix potential type error when generating human-friendly byte count strings.

[Steve Sprang <steve.sprang@gmail.com>]

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This is a follow up tweak to my previous "progress bar" patch. With a
really slow throughput it's possible to get fractional sub-KiB byte counts,
so I added some additional number massaging.

-Steve

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From daccd58e5fbe366ebcd33092f70ca45bc79285e0 Mon Sep 17 00:00:00 2001
From: Steve Sprang <scs@stevesprang.com>
Date: Wed, 9 Sep 2015 13:59:52 -0700
Subject: [PATCH] build: Fix potential type error when generating
 human-friendly byte count strings.

* guix/build/download.scm (number->integer): New function.
  (seconds->string): Use new rounding function.
  (byte-count->string):  Use new rounding function.
---
 guix/build/download.scm | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/guix/build/download.scm b/guix/build/download.scm
index 6e85174..a0b8d92 100644
--- a/guix/build/download.scm
+++ b/guix/build/download.scm
@@ -49,6 +49,10 @@
   ;; Size of the HTTP receive buffer.
   65536)
 
+(define (number->integer n)
+  "Given an arbitrary number N, round it and return the exact result."
+  (inexact->exact (round n)))
+
 (define (duration->seconds duration)
   "Return the number of seconds represented by DURATION, a 'time-duration'
 object, as an inexact number."
@@ -60,7 +64,7 @@ object, as an inexact number."
 format."
   (if (not (number? duration))
       "00:00:00"
-      (let* ((total-seconds (inexact->exact (round duration)))
+      (let* ((total-seconds (number->integer duration))
              (extra-seconds (modulo total-seconds 3600))
              (hours         (quotient total-seconds 3600))
              (mins          (quotient extra-seconds 60))
@@ -75,8 +79,8 @@ way."
         (GiB (expt 1024. 3))
         (TiB (expt 1024. 4)))
     (cond
-     ((< size KiB) (format #f "~dB" (inexact->exact size)))
-     ((< size MiB) (format #f "~dKiB" (inexact->exact (round (/ size KiB)))))
+     ((< size KiB) (format #f "~dB"     (number->integer size)))
+     ((< size MiB) (format #f "~dKiB"   (number->integer (/ size KiB))))
      ((< size GiB) (format #f "~,1fMiB" (/ size MiB)))
      ((< size TiB) (format #f "~,2fGiB" (/ size GiB)))
      (else         (format #f "~,3fTiB" (/ size TiB))))))
-- 
2.5.0