Re: Git Gui: Branch->create currently fails...

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Hi Pratyush,
On 13/10/2019 19:50, Pratyush Yadav wrote:
I've tried both parts and seen that this looks like some form of buffer
overrun or size limit
Looks like it, but I'm not sure if that is on our end.
with the mods I ran:
$ git gui > branch_create.txt

which produced the 'same' error missing ", but with a slightly different
fragment.

The branch_create.txt file is size 1.43 MB (1,502,103 bytes) (from the
windows explorer file properties dialog..)
opening in Notepad++ it's 4900 lines long with the final line trucated at
col 188 (shorter than other lines). There is an empty line 4901 (CRLF)
Yeah, that's a lot of refs! On my git.git clone, I get 1299 lines, and I
have git.git, my fork of git.git, and gitster in my remotes.
the last two lines are:
list "refs/heads/branch-patterns" [list "commit"
"b2453cea29b58f2ec57f9627b2456b41568ba5da" [concat "" "Philip Oakley"]
[reformat_date [concat "" "Tue May 28 20:22:09 2019 +0100"]] "squash! doc
branch: provide examples for listing remote tracking branches"] [list "" ""
"" [reformat_date ""] ""]
list "refs/heads/MSVC-README" [list "commit"
"056fb95c8e983ec07e9f5f8baa0b119bf3d13fed" [concat "" "Philip Oakley"]
[reformat_date [concat "" "Sun May 19 22:33:37 2019 +0100"]] "compat/vc

the file starts with 1018 lines of refs/tags before listing the refs/remotes
and finally the refs/heads.

The repo is my local Git repo with multiple remotes (git.git, G-f-W, ggg,
junio, gitster, dscho, t-b, tboeg, me), so plenty of refs there!

So it does look to be specific to repos with a large number of refs/tags,
refs/remotes, and refs/heads.

something for the back-burner?
I'm not sure why or where a buffer overflow would occur. We don't store
the whole output directly in a variable. Instead, we store each line
from the pipe coming in from `git for-each-ref` in $line, so that's a
few hundred characters at most. The rest of the data stays in the pipe,
which the OS should handle, and I don't think a few MBs should cause
trouble.

If I had to guess, I'd suspect either an internal Tcl limit, or
something with Tcl pipes.

Just to be sure it is a git-gui/Tcl issue and not an upstream git.git
issue, can you run:

   fmt='list %(refname) [list %(objecttype) %(objectname) [concat %(taggername) %(authorname)] [reformat_date [concat %(taggerdate) %(authordate)]] %(subject)] [list %(*objecttype) %(*objectname) %(*authorname) [reformat_date %(*authordate)] %(*subject)]'
git for-each-ref --tcl --format="$fmt" --sort=-taggerdate refs/heads refs/remotes refs/tags

and see if the output contains that truncated line? If it does, then
that means the bug is in git-for-each-ref. Note that this is bash
syntax, and I did a test run on Linux. Do adjust it for Windows and your
shell if needed.

ran that bit of code (as distinct commands), and got (last two lines):

[list "" "" "" [reformat_date ""] ""]
list "refs/heads/branch-patterns-v2" [list "commit" "d5a799d8833b0ae195915eefd5365f3fc4c7c0a4" [concat "" "Philip Oakley"] [reformat_date [concat "" "Sat Jun 8 22:50:06 2019 +0100"]] "t3203-branch-output: test -a & -r pattern options"] [list "" "" "" [reformat_date ""] ""] list "refs/heads/branch-patterns" [list "commit" "b2453cea29b58f2ec57f9627b2456b41568ba5da" [concat "" "Philip Oakley"] [reformat_date [concat "" "Tue May 28 20:22:09 2019 +0100"]] "squash! doc branch: provide examples for listing remote tracking branches"] [list "" "" "" [reformat_date ""] ""] list "refs/heads/MSVC-README" [list "commit" "056fb95c8e983ec07e9f5f8baa0b119bf3d13fed" [concat "" "Philip Oakley"] [reformat_date [concat "" "Sun May 19 22:33:37 2019 +0100"]] "compat/vcSegmentation fault


Not exactly the same, but almost. Ends the same place, with as similar short line. This is run inside the bash that is started directly by the git-for-windows sdk start icon. (Target: C:\git-sdk-64\git-bash.exe   Stat in: C:/git-sdk-64/)

so looks to be MSYS2/bash related.

--
Philip



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