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From: SZEDER Gábor <szeder.dev@gmail.com>
To: Jeff Hostetler via GitGitGadget <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, gitster@pobox.com, peff@peff.net,
	jrnieder@gmail.com, steadmon@google.com, avarab@gmail.com,
	Jeff Hostetler <jeffhost@microsoft.com>
Subject: Re: [PATCH v4 06/10] trace2: use system/global config for default trace2 settings
Date: Sat, 27 Apr 2019 15:43:16 +0200
Message-ID: <20190427134316.GE8695@szeder.dev> (raw)
In-Reply-To: <550cad618923c6e5aa1bd5f901f2968791d7566b.1555360780.git.gitgitgadget@gmail.com>

On Mon, Apr 15, 2019 at 01:39:47PM -0700, Jeff Hostetler via GitGitGadget wrote:
> From: Jeff Hostetler <jeffhost@microsoft.com>
> 
> Teach git to read the system and global config files for
> default Trace2 settings.  This allows system-wide Trace2 settings to
> be installed and inherited to make it easier to manage a collection of
> systems.
> 
> The original GIT_TR2* environment variables are loaded afterwards and
> can be used to override the system settings.
> 
> Only the system and global config files are used.  Repo and worktree
> local config files are ignored.  Likewise, the "-c" command line
> arguments are also ignored.  These limits are for performance reasons.
> 
> (1) For users not using Trace2, there should be minimal overhead to
> detect that Trace2 is not enabled.  In particular, Trace2 should not
> allocate lots of otherwise unused data strucutres.
> 
> (2) For accurate performance measurements, Trace2 should be initialized
> as early in the git process as possible, and before most of the normal
> git process initialization (which involves discovering the .git directory
> and reading a hierarchy of config files).

Reading the configuration that early causes unexpected and undesired
behavior change:

  $ sudo chmod a-rwx /usr/local/etc/gitconfig
  $ ./BUILDS/v2.21.0/bin/git
  usage: git [--version] [--help] [-C <path>] [-c <name>=<value>]
  <... snip rest of usage ...>
  $ strace ./BUILDS/v2.21.0/bin/git 2>&1 |grep config -c
  0
  $ ./git
  fatal: unable to access '/usr/local/etc/gitconfig': Permission denied
  $ ./git --version
  fatal: unable to access '/usr/local/etc/gitconfig': Permission denied

I think at least 'git', 'git --help', and 'git --version' should Just
Work, no matter what.


This breaks the 32 bit Linux build job on Travis CI, because:

  - In the 32 bit Docker image we change UID from root to regular user
    while preserving the environment, including $HOME.
    
  - Since $HOME is the default build prefix, Git will look for the
    system-wide configuration under '/root/etc/gitconfig', which fails
    as a regular user.

  - Our test harness checks early (i.e. earlier than setting
    GIT_CONFIG_NOSYSTEM=1) whether Git has been built successfully by
    attempting to run '$GIT_BUILD_DIR}/git', which fails because of
    the inaccessible system-wide config file, and in turn the harness
    assumes that Git hasn't been built and aborts.

  https://travis-ci.org/git/git/jobs/524403682#L1258


  reply index

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-28 13:30 [PATCH 0/4] trace2: load trace2 settings from system config Jeff Hostetler via GitGitGadget
2019-03-28 13:30 ` [PATCH 1/4] trace2: refactor setting process starting time Jeff Hostetler via GitGitGadget
2019-03-28 13:31 ` [PATCH 2/4] trace2: add absolute elapsed time to start event Jeff Hostetler via GitGitGadget
2019-03-28 13:31 ` [PATCH 3/4] trace2: find exec-dir before trace2 initialization Jeff Hostetler via GitGitGadget
2019-03-28 13:31 ` [PATCH 4/4] trace2: use system config for default trace2 settings Jeff Hostetler via GitGitGadget
2019-03-28 14:36   ` Ævar Arnfjörð Bjarmason
2019-03-28 18:50     ` Jeff Hostetler
2019-03-28 21:28   ` Josh Steadmon
2019-03-29 17:04 ` [PATCH v2 0/7] trace2: load trace2 settings from system config Jeff Hostetler via GitGitGadget
2019-03-29 17:04   ` [PATCH v2 1/7] trace2: refactor setting process starting time Jeff Hostetler via GitGitGadget
2019-03-29 17:04   ` [PATCH v2 2/7] trace2: add absolute elapsed time to start event Jeff Hostetler via GitGitGadget
2019-03-29 17:04   ` [PATCH v2 3/7] trace2: find exec-dir before trace2 initialization Jeff Hostetler via GitGitGadget
2019-03-29 17:04   ` [PATCH v2 4/7] trace2: use system config for default trace2 settings Jeff Hostetler via GitGitGadget
2019-04-01 21:00     ` Josh Steadmon
2019-04-01 21:06       ` Jeff Hostetler
2019-04-03  0:01       ` Jonathan Nieder
2019-04-03  0:00     ` Jonathan Nieder
2019-04-09 15:58       ` Jeff Hostetler
2019-03-29 17:04   ` [PATCH v2 5/7] trace2: report peak memory usage of the process Jeff Hostetler via GitGitGadget
2019-03-29 22:16     ` Ævar Arnfjörð Bjarmason
2019-04-01 21:05       ` Jeff Hostetler
2019-03-29 17:04   ` [PATCH v2 6/7] trace2: clarify UTC datetime formatting Jeff Hostetler via GitGitGadget
2019-03-29 17:04   ` [PATCH v2 7/7] trace2: make SIDs more unique Jeff Hostetler via GitGitGadget
2019-03-29 22:12     ` Ævar Arnfjörð Bjarmason
2019-04-01 21:16       ` Jeff Hostetler
2019-04-01 21:02   ` [PATCH v2 0/7] trace2: load trace2 settings from system config Josh Steadmon
2019-04-11 15:18   ` [PATCH v3 00/10] " Jeff Hostetler via GitGitGadget
2019-04-11 15:18     ` [PATCH v3 01/10] config: initialize opts structure in repo_read_config() Jeff Hostetler via GitGitGadget
2019-04-12  3:52       ` Jonathan Nieder
2019-04-15 14:34         ` Johannes Schindelin
2019-04-11 15:18     ` [PATCH v3 03/10] trace2: add absolute elapsed time to start event Jeff Hostetler via GitGitGadget
2019-04-11 15:18     ` [PATCH v3 02/10] trace2: refactor setting process starting time Jeff Hostetler via GitGitGadget
2019-04-11 15:18     ` [PATCH v3 04/10] trace2: find exec-dir before trace2 initialization Jeff Hostetler via GitGitGadget
2019-04-11 15:18     ` [PATCH v3 05/10] config: add read_very_early_config() Jeff Hostetler via GitGitGadget
2019-04-11 15:18     ` [PATCH v3 06/10] trace2: use system/global config for default trace2 settings Jeff Hostetler via GitGitGadget
2019-04-11 15:18     ` [PATCH v3 07/10] trace2: report peak memory usage of the process Jeff Hostetler via GitGitGadget
2019-04-11 15:18     ` [PATCH v3 08/10] trace2: clarify UTC datetime formatting Jeff Hostetler via GitGitGadget
2019-04-11 15:18     ` [PATCH v3 10/10] trace2: update docs to describe system/global config settings Jeff Hostetler via GitGitGadget
2019-04-11 15:18     ` [PATCH v3 09/10] trace2: make SIDs more unique Jeff Hostetler via GitGitGadget
2019-04-12  2:29     ` [PATCH v3 00/10] trace2: load trace2 settings from system config Junio C Hamano
2019-04-12 13:47       ` Jeff Hostetler
2019-04-15 20:39     ` [PATCH v4 " Jeff Hostetler via GitGitGadget
2019-04-15 20:39       ` [PATCH v4 01/10] config: initialize opts structure in repo_read_config() Jeff Hostetler via GitGitGadget
2019-04-15 20:39       ` [PATCH v4 02/10] trace2: refactor setting process starting time Jeff Hostetler via GitGitGadget
2019-04-15 20:39       ` [PATCH v4 03/10] trace2: add absolute elapsed time to start event Jeff Hostetler via GitGitGadget
2019-04-15 20:39       ` [PATCH v4 04/10] trace2: find exec-dir before trace2 initialization Jeff Hostetler via GitGitGadget
2019-04-15 20:39       ` [PATCH v4 05/10] config: add read_very_early_config() Jeff Hostetler via GitGitGadget
2019-04-15 20:39       ` [PATCH v4 06/10] trace2: use system/global config for default trace2 settings Jeff Hostetler via GitGitGadget
2019-04-27 13:43         ` SZEDER Gábor [this message]
2019-04-29 19:03           ` Jeff Hostetler
2019-04-15 20:39       ` [PATCH v4 08/10] trace2: clarify UTC datetime formatting Jeff Hostetler via GitGitGadget
2019-04-15 20:39       ` [PATCH v4 07/10] trace2: report peak memory usage of the process Jeff Hostetler via GitGitGadget
2019-04-15 20:39       ` [PATCH v4 09/10] trace2: make SIDs more unique Jeff Hostetler via GitGitGadget
2019-04-15 20:39       ` [PATCH v4 10/10] trace2: update docs to describe system/global config settings Jeff Hostetler via GitGitGadget
2019-04-29 20:14       ` [PATCH v5 00/11] trace2: load trace2 settings from system config Jeff Hostetler via GitGitGadget
2019-04-29 20:14         ` [PATCH v5 02/11] trace2: refactor setting process starting time Jeff Hostetler via GitGitGadget
2019-04-29 20:14         ` [PATCH v5 01/11] config: initialize opts structure in repo_read_config() Jeff Hostetler via GitGitGadget
2019-04-29 20:14         ` [PATCH v5 03/11] trace2: add absolute elapsed time to start event Jeff Hostetler via GitGitGadget
2019-04-29 20:14         ` [PATCH v5 04/11] trace2: find exec-dir before trace2 initialization Jeff Hostetler via GitGitGadget
2019-04-29 20:14         ` [PATCH v5 05/11] config: add read_very_early_config() Jeff Hostetler via GitGitGadget
2019-04-29 20:14         ` [PATCH v5 06/11] trace2: use system/global config for default trace2 settings Jeff Hostetler via GitGitGadget
2019-04-29 20:14         ` [PATCH v5 07/11] trace2: report peak memory usage of the process Jeff Hostetler via GitGitGadget
2019-04-29 20:14         ` [PATCH v5 08/11] trace2: clarify UTC datetime formatting Jeff Hostetler via GitGitGadget
2019-04-29 20:14         ` [PATCH v5 09/11] trace2: make SIDs more unique Jeff Hostetler via GitGitGadget
2019-04-29 20:14         ` [PATCH v5 10/11] trace2: update docs to describe system/global config settings Jeff Hostetler via GitGitGadget
2019-04-29 20:14         ` [PATCH v5 11/11] trace2: fixup access problem on /etc/gitconfig in read_very_early_config Jeff Hostetler via GitGitGadget
2019-04-29 20:21         ` [PATCH v5 00/11] trace2: load trace2 settings from system config Jeff Hostetler
2019-05-07  1:18           ` Junio C Hamano

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