threads / patch / 58195

patch, 2 partsgit-p4: fix two undefined variables

Subject: [PATCH 0/2] git-p4: fix two undefined variables

## tl;dr

11 messages between Jul 20, 2022 and Jul 20, 2022. Diffs are folded; open one to read it.

replies: 10people: 3as markdown or json

Moritz Baumann via GitGitGadget· Jul 20, 2022, 06:34 UTC · lore
Moritz Baumann (2):
  git-p4: fix typo in P4Submit.applyCommit()
  git-p4: fix error handling in P4Unshelve.renameBranch()
 git-p4.py | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)
base-commit: bbea4dcf42b28eb7ce64a6306cdde875ae5d09ca
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1297%2Fmbs-c%2Ffix-undefined-variables-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1297/mbs-c/fix-undefined-variables-v1
Pull-Request: https://github.com/git/git/pull/1297
-- 
gitgitgadget
Moritz Baumann via GitGitGadget· Jul 20, 2022, 06:34 UTC · re: Moritz Baumann via GitGitGadget · lore

[PATCH 1/2] git-p4: fix typo in P4Submit.applyCommit()

From: Moritz Baumann <moritz.baumann@sap.com>
Signed-off-by: Moritz Baumann <moritz.baumann@sap.com>
---
 git-p4.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
Show changes to git-p4.py +1 −1
diff --git a/git-p4.py b/git-p4.py
index 8fbf6eb1fe3..1de3d6f1cd4 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -2226,7 +2226,7 @@ class P4Submit(Command, P4UserMap):
                                 raw=True):
                             if regexp.search(line):
                                 if verbose:
-                                    print("got keyword match on %s in %s in %s" % (regex.pattern, line, file))
+                                    print("got keyword match on %s in %s in %s" % (regexp.pattern, line, file))
                                 kwfiles[file] = regexp
                                 break
 
-- 
gitgitgadget
Junio C Hamano· Jul 20, 2022, 16:09 UTC · re: Moritz Baumann via GitGitGadget · lore

Re: [PATCH 1/2] git-p4: fix typo in P4Submit.applyCommit()

"Moritz Baumann via GitGitGadget" <gitgitgadget@gmail.com> writes:
Show 17 quoted lines
> From: Moritz Baumann <moritz.baumann@sap.com>
>
> Signed-off-by: Moritz Baumann <moritz.baumann@sap.com>
> ---
>  git-p4.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/git-p4.py b/git-p4.py
> index 8fbf6eb1fe3..1de3d6f1cd4 100755
> --- a/git-p4.py
> +++ b/git-p4.py
> @@ -2226,7 +2226,7 @@ class P4Submit(Command, P4UserMap):
>                                  raw=True):
>                              if regexp.search(line):
>                                  if verbose:
> -                                    print("got keyword match on %s in %s in %s" % (regex.pattern, line, file))
> +                                    print("got keyword match on %s in %s in %s" % (regexp.pattern, line, file))
OK.  That's an obvious fix.
>                                  kwfiles[file] = regexp
>                                  break
Moritz Baumann via GitGitGadget· Jul 20, 2022, 06:34 UTC · re: Moritz Baumann via GitGitGadget · lore

[PATCH 2/2] git-p4: fix error handling in P4Unshelve.renameBranch()

From: Moritz Baumann <moritz.baumann@sap.com>

The error handling code referenced a variable that does not exist. Also, the condition could never evaluate to True.

Signed-off-by: Moritz Baumann <moritz.baumann@sap.com>
---
 git-p4.py | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)
Show changes to git-p4.py +2 −5
diff --git a/git-p4.py b/git-p4.py
index 1de3d6f1cd4..8f20d15f272 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -4369,19 +4369,16 @@ class P4Unshelve(Command):
     def renameBranch(self, branch_name):
         """Rename the existing branch to branch_name.N ."""
 
-        found = True
         for i in range(0, 1000):
             backup_branch_name = "{0}.{1}".format(branch_name, i)
             if not gitBranchExists(backup_branch_name):
                 # Copy ref to backup
                 gitUpdateRef(backup_branch_name, branch_name)
                 gitDeleteRef(branch_name)
-                found = True
                 print("renamed old unshelve branch to {0}".format(backup_branch_name))
                 break
-
-        if not found:
-            sys.exit("gave up trying to rename existing branch {0}".format(sync.branch))
+        else:
+            sys.exit("gave up trying to rename existing branch {0}".format(branch_name))
 
     def findLastP4Revision(self, starting_point):
         """Look back from starting_point for the first commit created by git-p4
-- 
gitgitgadget
Junio C Hamano· Jul 20, 2022, 16:18 UTC · re: Moritz Baumann via GitGitGadget · lore

Re: [PATCH 2/2] git-p4: fix error handling in P4Unshelve.renameBranch()

"Moritz Baumann via GitGitGadget" <gitgitgadget@gmail.com> writes:
> From: Moritz Baumann <moritz.baumann@sap.com>
>
> The error handling code referenced a variable that does not exist.
> Also, the condition could never evaluate to True.
Show 15 quoted lines
>
> Signed-off-by: Moritz Baumann <moritz.baumann@sap.com>
> ---
>  git-p4.py | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/git-p4.py b/git-p4.py
> index 1de3d6f1cd4..8f20d15f272 100755
> --- a/git-p4.py
> +++ b/git-p4.py
> @@ -4369,19 +4369,16 @@ class P4Unshelve(Command):
>      def renameBranch(self, branch_name):
>          """Rename the existing branch to branch_name.N ."""
>  
> -        found = True
This has to be initialized to False, because ...
Show 8 quoted lines
>          for i in range(0, 1000):
>              backup_branch_name = "{0}.{1}".format(branch_name, i)
>              if not gitBranchExists(backup_branch_name):
>                  # Copy ref to backup
>                  gitUpdateRef(backup_branch_name, branch_name)
>                  gitDeleteRef(branch_name)
> -                found = True
>                  print("renamed old unshelve branch to {0}".format(backup_branch_name))

... we flip it to True when we find an available unused name and break out ...

>                  break
> -
> -        if not found:
> -            sys.exit("gave up trying to rename existing branch {0}".format(sync.branch))
... so that we can complain when we didn't find anything usable.

So a minimum fix would be to initialize found correctly, and rewriting the logic to use "for ... else" is an unrelated style change. The version using "for ... else" may be more idiomatic Python, and I do not think people would mind it, but it should be mentioned in the proposed log mesage, perhaps like:

    The code tries to see if there is an available name by setting
    the variable 'found' to true when it finds one and breaks out of
    the loop, but because the variable is incorrectly initialized to
    true (it should be initialized to false), the code after the
    loop cannot tell if it found an available name or not.
    It would be the minimal fix to initialize the variable to false,
    but in modern Python it is more idiomatic to add else: clause
    after a loop to write what happens when the loop did not break
    out, so let's do that instead.
    Also, fix the error message that refers to a wrong variable
    name.
or something.
Thanks.  Will queue.
Show 5 quoted lines
> +        else:
> +            sys.exit("gave up trying to rename existing branch {0}".format(branch_name))
>  
>      def findLastP4Revision(self, starting_point):
>          """Look back from starting_point for the first commit created by git-p4
Junio C Hamano· Jul 20, 2022, 16:21 UTC · re: Junio C Hamano · lore

Re: [PATCH 2/2] git-p4: fix error handling in P4Unshelve.renameBranch()

Junio C Hamano <gitster@pobox.com> writes:
Show 23 quoted lines
>>  
>> -        found = True
>
> This has to be initialized to False, because ...
>
>>          for i in range(0, 1000):
>>              backup_branch_name = "{0}.{1}".format(branch_name, i)
>>              if not gitBranchExists(backup_branch_name):
>>                  # Copy ref to backup
>>                  gitUpdateRef(backup_branch_name, branch_name)
>>                  gitDeleteRef(branch_name)
>> -                found = True
>>                  print("renamed old unshelve branch to {0}".format(backup_branch_name))
>
> ... we flip it to True when we find an available unused name and
> break out ...
>
>>                  break
>> -
>> -        if not found:
>> -            sys.exit("gave up trying to rename existing branch {0}".format(sync.branch))
>
> ... so that we can complain when we didn't find anything usable.

By the way, isn't this a typical time-of-check to time-of-use bug? Not the problem with the fix in the patch but in the original, but regardless of whose fault it is, it may be good to fix it (outside the topic of this patch).

Thanks.
Baumann, Moritz· Jul 20, 2022, 17:01 UTC · re: Junio C Hamano · lore

RE: [PATCH 2/2] git-p4: fix error handling in P4Unshelve.renameBranch()

Thank you for your criticism, I will keep it in mind and submit more detailed descriptions in the future.
> By the way, isn't this a typical time-of-check to time-of-use bug?
> Not the problem with the fix in the patch but in the original, but regardless of
> whose fault it is, it may be good to fix it (outside the topic of this patch).
Is concurrent use even meant to be supported in general? I have not done a thorough review, but judging from what I have seen so far, I highly doubt that the majority of git-p4.py was written with potential concurrency problems in mind.

Best regards, Moritz

Moritz Baumann via GitGitGadget· Jul 20, 2022, 18:55 UTC · re: Moritz Baumann via GitGitGadget · lore

[PATCH v2 0/2] git-p4: fix two undefined variables

Moritz Baumann (2):
  git-p4: fix typo in P4Submit.applyCommit()
  git-p4: fix error handling in P4Unshelve.renameBranch()
 git-p4.py | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)
base-commit: bbea4dcf42b28eb7ce64a6306cdde875ae5d09ca
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1297%2Fmbs-c%2Ffix-undefined-variables-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1297/mbs-c/fix-undefined-variables-v2
Pull-Request: https://github.com/git/git/pull/1297
Range-diff vs v1:
 1:  1484eee8961 = 1:  1484eee8961 git-p4: fix typo in P4Submit.applyCommit()
 2:  69c9fd5fbec ! 2:  f7566dd5fc3 git-p4: fix error handling in P4Unshelve.renameBranch()
     @@ Metadata
       ## Commit message ##
          git-p4: fix error handling in P4Unshelve.renameBranch()
      
     -    The error handling code referenced a variable that does not exist.
     -    Also, the condition could never evaluate to True.
     +    The error handling code path is meant to be triggered when the loop does
     +    not exit early via "break". This fails, as the boolean variable "found",
     +    which is used to track whether the loop was exited early, is initialized
     +    incorrectly.
     +
     +    It would be possible to fix this issue by correcting the initialization,
     +    but Python supports a for:-else: control flow construct for this exact
     +    use case (executing code if a loop does not exit early), so it is more
     +    idiomatic to remove the tracking variable entirely.
     +
     +    In addition, the error message no longer refers to a variable that does
     +    not exist.
      
          Signed-off-by: Moritz Baumann <moritz.baumann@sap.com>
      
-- 
gitgitgadget
Moritz Baumann via GitGitGadget· Jul 20, 2022, 18:55 UTC · re: Moritz Baumann via GitGitGadget · lore

[PATCH v2 1/2] git-p4: fix typo in P4Submit.applyCommit()

From: Moritz Baumann <moritz.baumann@sap.com>
Signed-off-by: Moritz Baumann <moritz.baumann@sap.com>
---
 git-p4.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
Show changes to git-p4.py +1 −1
diff --git a/git-p4.py b/git-p4.py
index 8fbf6eb1fe3..1de3d6f1cd4 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -2226,7 +2226,7 @@ class P4Submit(Command, P4UserMap):
                                 raw=True):
                             if regexp.search(line):
                                 if verbose:
-                                    print("got keyword match on %s in %s in %s" % (regex.pattern, line, file))
+                                    print("got keyword match on %s in %s in %s" % (regexp.pattern, line, file))
                                 kwfiles[file] = regexp
                                 break
 
-- 
gitgitgadget
Moritz Baumann via GitGitGadget· Jul 20, 2022, 18:55 UTC · re: Moritz Baumann via GitGitGadget · lore

[PATCH v2 2/2] git-p4: fix error handling in P4Unshelve.renameBranch()

From: Moritz Baumann <moritz.baumann@sap.com>

The error handling code path is meant to be triggered when the loop does not exit early via "break". This fails, as the boolean variable "found", which is used to track whether the loop was exited early, is initialized incorrectly.

It would be possible to fix this issue by correcting the initialization, but Python supports a for:-else: control flow construct for this exact use case (executing code if a loop does not exit early), so it is more idiomatic to remove the tracking variable entirely.

In addition, the error message no longer refers to a variable that does not exist.

Signed-off-by: Moritz Baumann <moritz.baumann@sap.com>
---
 git-p4.py | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)
Show changes to git-p4.py +2 −5
diff --git a/git-p4.py b/git-p4.py
index 1de3d6f1cd4..8f20d15f272 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -4369,19 +4369,16 @@ class P4Unshelve(Command):
     def renameBranch(self, branch_name):
         """Rename the existing branch to branch_name.N ."""
 
-        found = True
         for i in range(0, 1000):
             backup_branch_name = "{0}.{1}".format(branch_name, i)
             if not gitBranchExists(backup_branch_name):
                 # Copy ref to backup
                 gitUpdateRef(backup_branch_name, branch_name)
                 gitDeleteRef(branch_name)
-                found = True
                 print("renamed old unshelve branch to {0}".format(backup_branch_name))
                 break
-
-        if not found:
-            sys.exit("gave up trying to rename existing branch {0}".format(sync.branch))
+        else:
+            sys.exit("gave up trying to rename existing branch {0}".format(branch_name))
 
     def findLastP4Revision(self, starting_point):
         """Look back from starting_point for the first commit created by git-p4
-- 
gitgitgadget
Junio C Hamano· Jul 20, 2022, 20:54 UTC · re: Moritz Baumann via GitGitGadget · lore

Re: [PATCH v2 0/2] git-p4: fix two undefined variables

"Moritz Baumann via GitGitGadget" <gitgitgadget@gmail.com> writes:
Show 6 quoted lines
> Moritz Baumann (2):
>   git-p4: fix typo in P4Submit.applyCommit()
>   git-p4: fix error handling in P4Unshelve.renameBranch()
>
>  git-p4.py | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
Perfect.  Thanks.

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