From: Jonathan Nieder <jrnieder@gmail.com>
To: Brian Gernhardt <brian@gernhardtsoftware.com>
Cc: "git@vger.kernel.org List" <git@vger.kernel.org>,
David Barr <david.barr@cordelta.com>,
Junio C Hamano <gitster@pobox.com>
Subject: [PATCH jn/fast-import-blob-access] t9300: avoid short reads from dd
Date: Mon, 13 Dec 2010 00:31:51 -0600 [thread overview]
Message-ID: <20101213063151.GB20812@burratino> (raw)
In-Reply-To: <2F4185D2-5846-45CB-BC92-6BC07AE5CEC8@gernhardtsoftware.com>
dd is a thin wrapper around read(2). As open group Issue 7 explains:
It shall read the input one block at a time, using the specified
input block size; it shall then process the block of data
actually returned, which could be smaller than the requested
block size.
Any short read --- for example from a pipe whose capacity cannot fill
a block --- results in that block being truncated. As a result, the
first cat-blob test (9300.114) fails on Mac OS X, where the pipe
capacity is around 8 KiB.
Fix the test by using a block size of 1. Each read will block until
the next byte of input is available.
It would be even nicer to use head -c which expresses the intention
more clearly. Alas, IRIX "head" does not support the -c option.
Reported-by: Brian Gernhardt <brian@gernhardtsoftware.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
t/t9300-fast-import.sh | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index 055ddc6..ed28d3c 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -1794,7 +1794,7 @@ test_expect_success PIPE 'R: copy using cat-file' '
read blob_id type size <&3 &&
echo "$blob_id $type $size" >response &&
- dd of=blob bs=$size count=1 <&3 &&
+ dd of=blob bs=1 count=$size <&3 &&
read newline <&3 &&
cat <<EOF &&
@@ -1845,7 +1845,7 @@ test_expect_success PIPE 'R: print blob mid-commit' '
EOF
read blob_id type size <&3 &&
- dd of=actual bs=$size count=1 <&3 &&
+ dd of=actual bs=1 count=$size <&3 &&
read newline <&3 &&
echo
@@ -1880,7 +1880,7 @@ test_expect_success PIPE 'R: print staged blob within commit' '
echo "cat-blob $to_get" &&
read blob_id type size <&3 &&
- dd of=actual bs=$size count=1 <&3 &&
+ dd of=actual bs=1 count=$size <&3 &&
read newline <&3 &&
echo deleteall
--
1.7.2.4
next prev parent reply other threads:[~2010-12-13 6:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-12 20:49 SIGPIPE in t9300-fast-import Brian Gernhardt
2010-12-12 21:49 ` Jonathan Nieder
2010-12-12 22:04 ` Brian Gernhardt
2010-12-13 6:31 ` Jonathan Nieder [this message]
2010-12-13 7:21 ` [PATCH jn/fast-import-blob-access] t9300: avoid short reads from dd Junio C Hamano
2010-12-13 9:28 ` [PATCH jn/fast-import-blob-access] t9300: use perl "head -c" clone in place of "dd bs=1 count=16000" kluge Jonathan Nieder
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20101213063151.GB20812@burratino \
--to=jrnieder@gmail.com \
--cc=brian@gernhardtsoftware.com \
--cc=david.barr@cordelta.com \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).