Re: [PATCH 2/2] update-ref: fix verify command with missing oldvalue

[Brad King]

On 12/10/2014 6:47 PM, Michael Haggerty wrote:
 set have_old unconditionally and set old_sha1 to null_sha1.

Reviewed-by: Brad King brad.k...@kitware.com

-Brad
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[PATCH 2/2] update-ref: fix verify command with missing oldvalue

[Michael Haggerty]

If git update-ref --stdin was given a verify command with no
newvalue at all (not even zeros), the code was mistakenly setting
have_old=0 (and leaving old_sha1 uninitialized). But this is
incorrect: this command is supposed to verify that the reference
doesn't exist. So in this case we really need old_sha1 to be set to
null_sha1 and have_old to be set to 1.

Moreover, since have_old was being set to zero, *no* check of the old
value was being done, so the new value of the reference was being set
unconditionally to the value in new_sha1. new_sha1, in turn, was set
to null_sha1 in the expectation that that was the old value and it
shouldn't be changed. But because the precondition was not being
checked, the result was that the reference was being deleted
unconditionally.

So, if oldvalue is missing, set have_old unconditionally and set
old_sha1 to null_sha1.

Signed-off-by: Michael Haggerty mhag...@alum.mit.edu
---
 builtin/update-ref.c  | 14 +-
 t/t1400-update-ref.sh |  4 ++--
 2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 6c9be05..1993529 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -282,26 +282,22 @@ static const char *parse_cmd_verify(struct 
ref_transaction *transaction,
char *refname;
unsigned char new_sha1[20];
unsigned char old_sha1[20];
-   int have_old;
 
refname = parse_refname(input, next);
if (!refname)
die(verify: missing ref);
 
if (parse_next_sha1(input, next, old_sha1, verify, refname,
-   PARSE_SHA1_OLD)) {
-   hashclr(new_sha1);
-   have_old = 0;
-   } else {
-   hashcpy(new_sha1, old_sha1);
-   have_old = 1;
-   }
+   PARSE_SHA1_OLD))
+   hashclr(old_sha1);
+
+   hashcpy(new_sha1, old_sha1);
 
if (*next != line_termination)
die(verify %s: extra input: %s, refname, next);
 
if (ref_transaction_update(transaction, refname, new_sha1, old_sha1,
-  update_flags, have_old, msg, err))
+  update_flags, 1, msg, err))
die(%s, err.buf);
 
update_flags = 0;
diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index 6a3cdd1..6805b9e 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -655,7 +655,7 @@ test_expect_success 'stdin verify fails for mistaken null 
value' '
test_cmp expect actual
 '
 
-test_expect_failure 'stdin verify fails for mistaken empty value' '
+test_expect_success 'stdin verify fails for mistaken empty value' '
M=$(git rev-parse $m) 
test_when_finished git update-ref $m $M 
git rev-parse $m expect 
@@ -1020,7 +1020,7 @@ test_expect_success 'stdin -z verify fails for mistaken 
null value' '
test_cmp expect actual
 '
 
-test_expect_failure 'stdin -z verify fails for mistaken empty value' '
+test_expect_success 'stdin -z verify fails for mistaken empty value' '
M=$(git rev-parse $m) 
test_when_finished git update-ref $m $M 
git rev-parse $m expect 
-- 
2.1.3

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Re: [PATCH 2/2] update-ref: fix verify command with missing oldvalue

[Stefan Beller]

On Thu, Dec 11, 2014 at 12:47:52AM +0100, Michael Haggerty wrote:
 If git update-ref --stdin was given a verify command with no
 newvalue at all (not even zeros), the code was mistakenly setting
 have_old=0 (and leaving old_sha1 uninitialized). But this is
 incorrect: this command is supposed to verify that the reference
 doesn't exist. So in this case we really need old_sha1 to be set to
 null_sha1 and have_old to be set to 1.
 
 Moreover, since have_old was being set to zero, *no* check of the old
 value was being done, so the new value of the reference was being set
 unconditionally to the value in new_sha1. new_sha1, in turn, was set
 to null_sha1 in the expectation that that was the old value and it
 shouldn't be changed. But because the precondition was not being
 checked, the result was that the reference was being deleted
 unconditionally.
 
 So, if oldvalue is missing, set have_old unconditionally and set
 old_sha1 to null_sha1.
 
 Signed-off-by: Michael Haggerty mhag...@alum.mit.edu

This is reviewed by me as well.
Reviewed-by: Stefan Beller sbel...@google.com

 ---
  builtin/update-ref.c  | 14 +-
  t/t1400-update-ref.sh |  4 ++--
  2 files changed, 7 insertions(+), 11 deletions(-)
 
 diff --git a/builtin/update-ref.c b/builtin/update-ref.c
 index 6c9be05..1993529 100644
 --- a/builtin/update-ref.c
 +++ b/builtin/update-ref.c
 @@ -282,26 +282,22 @@ static const char *parse_cmd_verify(struct 
 ref_transaction *transaction,
   char *refname;
   unsigned char new_sha1[20];
   unsigned char old_sha1[20];
 - int have_old;
  
   refname = parse_refname(input, next);
   if (!refname)
   die(verify: missing ref);
  
   if (parse_next_sha1(input, next, old_sha1, verify, refname,
 - PARSE_SHA1_OLD)) {
 - hashclr(new_sha1);
 - have_old = 0;
 - } else {
 - hashcpy(new_sha1, old_sha1);
 - have_old = 1;
 - }
 + PARSE_SHA1_OLD))
 + hashclr(old_sha1);
 +
 + hashcpy(new_sha1, old_sha1);
  
   if (*next != line_termination)
   die(verify %s: extra input: %s, refname, next);
  
   if (ref_transaction_update(transaction, refname, new_sha1, old_sha1,
 -update_flags, have_old, msg, err))
 +update_flags, 1, msg, err))
   die(%s, err.buf);
  
   update_flags = 0;
 diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
 index 6a3cdd1..6805b9e 100755
 --- a/t/t1400-update-ref.sh
 +++ b/t/t1400-update-ref.sh
 @@ -655,7 +655,7 @@ test_expect_success 'stdin verify fails for mistaken null 
 value' '
   test_cmp expect actual
  '
  
 -test_expect_failure 'stdin verify fails for mistaken empty value' '
 +test_expect_success 'stdin verify fails for mistaken empty value' '
   M=$(git rev-parse $m) 
   test_when_finished git update-ref $m $M 
   git rev-parse $m expect 
 @@ -1020,7 +1020,7 @@ test_expect_success 'stdin -z verify fails for mistaken 
 null value' '
   test_cmp expect actual
  '
  
 -test_expect_failure 'stdin -z verify fails for mistaken empty value' '
 +test_expect_success 'stdin -z verify fails for mistaken empty value' '
   M=$(git rev-parse $m) 
   test_when_finished git update-ref $m $M 
   git rev-parse $m expect 
 -- 
 2.1.3
 
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