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git/t/t1503-rev-parse-verify.sh
Jeff King 3f7bd767ed files_read_raw_ref: avoid infinite loop on broken symlinks
Our ref resolution first runs lstat() on any path we try to
look up, because we want to treat symlinks specially (by
resolving them manually and considering them symrefs). But
if the results of `readlink` do _not_ look like a ref, we
fall through to treating it like a normal file, and just
read the contents of the linked path.

Since fcb7c76 (resolve_ref_unsafe(): close race condition
reading loose refs, 2013-06-19), that "normal file" code
path will stat() the file and if we see ENOENT, will jump
back to the lstat(), thinking we've seen inconsistent
results between the two calls. But for a symbolic ref, this
isn't a race: the lstat() found the symlink, and the stat()
is looking at the path it points to. We end up in an
infinite loop calling lstat() and stat().

We can fix this by avoiding the retry-on-inconsistent jump
when we know that we found a symlink. While we're at it,
let's add a comment explaining why the symlink case gets to
this code in the first place; without that, it is not
obvious that the correct solution isn't to avoid the stat()
code path entirely.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-10-10 10:53:16 -07:00

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#!/bin/sh
#
# Copyright (c) 2008 Christian Couder
#
test_description='test git rev-parse --verify'
exec </dev/null
. ./test-lib.sh
add_line_into_file()
{
_line=$1
_file=$2
if [ -f "$_file" ]; then
echo "$_line" >> $_file || return $?
MSG="Add <$_line> into <$_file>."
else
echo "$_line" > $_file || return $?
git add $_file || return $?
MSG="Create file <$_file> with <$_line> inside."
fi
test_tick
git commit --quiet -m "$MSG" $_file
}
HASH1=
HASH2=
HASH3=
HASH4=
test_expect_success 'set up basic repo with 1 file (hello) and 4 commits' '
add_line_into_file "1: Hello World" hello &&
HASH1=$(git rev-parse --verify HEAD) &&
add_line_into_file "2: A new day for git" hello &&
HASH2=$(git rev-parse --verify HEAD) &&
add_line_into_file "3: Another new day for git" hello &&
HASH3=$(git rev-parse --verify HEAD) &&
add_line_into_file "4: Ciao for now" hello &&
HASH4=$(git rev-parse --verify HEAD)
'
test_expect_success 'works with one good rev' '
rev_hash1=$(git rev-parse --verify $HASH1) &&
test "$rev_hash1" = "$HASH1" &&
rev_hash2=$(git rev-parse --verify $HASH2) &&
test "$rev_hash2" = "$HASH2" &&
rev_hash3=$(git rev-parse --verify $HASH3) &&
test "$rev_hash3" = "$HASH3" &&
rev_hash4=$(git rev-parse --verify $HASH4) &&
test "$rev_hash4" = "$HASH4" &&
rev_master=$(git rev-parse --verify master) &&
test "$rev_master" = "$HASH4" &&
rev_head=$(git rev-parse --verify HEAD) &&
test "$rev_head" = "$HASH4"
'
test_expect_success 'fails with any bad rev or many good revs' '
test_must_fail git rev-parse --verify 2>error &&
grep "single revision" error &&
test_must_fail git rev-parse --verify foo 2>error &&
grep "single revision" error &&
test_must_fail git rev-parse --verify HEAD bar 2>error &&
grep "single revision" error &&
test_must_fail git rev-parse --verify baz HEAD 2>error &&
grep "single revision" error &&
test_must_fail git rev-parse --verify $HASH2 HEAD 2>error &&
grep "single revision" error
'
test_expect_success 'fails silently when using -q' '
test_must_fail git rev-parse --verify --quiet 2>error &&
test_must_be_empty error &&
test_must_fail git rev-parse -q --verify foo 2>error &&
test_must_be_empty error &&
test_must_fail git rev-parse --verify -q HEAD bar 2>error &&
test_must_be_empty error &&
test_must_fail git rev-parse --quiet --verify baz HEAD 2>error &&
test_must_be_empty error &&
test_must_fail git rev-parse -q --verify $HASH2 HEAD 2>error &&
test_must_be_empty error
'
test_expect_success 'fails silently when using -q with deleted reflogs' '
ref=$(git rev-parse HEAD) &&
git update-ref --create-reflog -m "message for refs/test" refs/test "$ref" &&
git reflog delete --updateref --rewrite refs/test@{0} &&
test_must_fail git rev-parse -q --verify refs/test@{0} >error 2>&1 &&
test_must_be_empty error
'
test_expect_success 'fails silently when using -q with not enough reflogs' '
ref=$(git rev-parse HEAD) &&
git update-ref --create-reflog -m "message for refs/test2" refs/test2 "$ref" &&
test_must_fail git rev-parse -q --verify refs/test2@{999} >error 2>&1 &&
test_must_be_empty error
'
test_expect_success 'succeeds silently with -q and reflogs that do not go far back enough in time' '
ref=$(git rev-parse HEAD) &&
git update-ref --create-reflog -m "message for refs/test3" refs/test3 "$ref" &&
git rev-parse -q --verify refs/test3@{1.year.ago} >actual 2>error &&
test_must_be_empty error &&
echo "$ref" >expect &&
test_cmp expect actual
'
test_expect_success 'no stdout output on error' '
test -z "$(git rev-parse --verify)" &&
test -z "$(git rev-parse --verify foo)" &&
test -z "$(git rev-parse --verify baz HEAD)" &&
test -z "$(git rev-parse --verify HEAD bar)" &&
test -z "$(git rev-parse --verify $HASH2 HEAD)"
'
test_expect_success 'use --default' '
git rev-parse --verify --default master &&
git rev-parse --verify --default master HEAD &&
git rev-parse --default master --verify &&
git rev-parse --default master --verify HEAD &&
git rev-parse --verify HEAD --default master &&
test_must_fail git rev-parse --verify foo --default master &&
test_must_fail git rev-parse --default HEAD --verify bar &&
test_must_fail git rev-parse --verify --default HEAD baz &&
test_must_fail git rev-parse --default foo --verify &&
test_must_fail git rev-parse --verify --default bar
'
test_expect_success 'master@{n} for various n' '
N=$(git reflog | wc -l) &&
Nm1=$(($N-1)) &&
Np1=$(($N+1)) &&
git rev-parse --verify master@{0} &&
git rev-parse --verify master@{1} &&
git rev-parse --verify master@{$Nm1} &&
test_must_fail git rev-parse --verify master@{$N} &&
test_must_fail git rev-parse --verify master@{$Np1}
'
test_expect_success SYMLINKS 'ref resolution not confused by broken symlinks' '
ln -s does-not-exist .git/refs/heads/broken &&
test_must_fail git rev-parse --verify broken
'
test_done