install/devshell: Introduce git intercept script due to fakeroot issues

In a devshell, recent versions of git will complain if the repo is owned
by someone other than the current UID - consider this example:

 ------
  bitbake -c devshell linux-yocto

  [...]

  kernel-source#git branch
  fatal: unsafe repository ('/home/paul/poky/build-qemuarm64/tmp/work-shared/qemuarm64/kernel-source' is owned by someone else)
  To add an exception for this directory, call:

        git config --global --add safe.directory /home/paul/poky/build-qemuarm64/tmp/work-shared/qemuarm64/kernel-source
  kernel-source#
 ------

Of course the devshell has UID zero and the "real" UID is for "paul" in
this case.  And so recent git versions complain.

As the whole purpose of the devshell is to invoke a shell where development
can take place, having a non-functional git is clearly unacceptable.

Richard suggested we could use PSEUDO_UNLOAD=1 to evade this issue, and I
suggested we probably will see other similar instances like this and should
make use of PATH to intercept via devshell wrappers - conveniently we already
have examples of this.

Here, we copy the existing "ar" example and tune it to the needs of git to
combine Richard's suggestion and mine.

As such we now also can store commit logs and use send-email with our user
specific settings, instead of "root", so in additon to fixing basic
commands like "git branch" it should also increase general usefulness.

RP: Tweaked the patch so the PATH change only applies to the devshell task
and is a generic git intercept rather than devshell specific.

RP: Also apply the PATH change to do_install tasks since that also runs under
fakeroot and several software projects inject "git describe" output into
their binaries (systemd, iputils, llvm, ipt-gpu-tools at least) causing
reproducibility issues from systems with different git versions.

(From OE-Core rev: 3266c327dfa186791e0f1e2ad63c6f5d39714814)

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

3 files changed, 22 insertions, 0 deletions

diff --git a/meta/classes/base.bbclass b/meta/classes/base.bbclass
index 3515720bf9..b54b56d624 100644
--- a/meta/classes/base.bbclass
+++ b/meta/classes/base.bbclass
@@ -367,6 +367,7 @@ addtask install after do_compile
 do_install[dirs] = "${B}"
 # Remove and re-create ${D} so that is it guaranteed to be empty
 do_install[cleandirs] = "${D}"
+PATH:prepend:task-install = "${COREBASE}/scripts/git-intercept:"
 
 base_do_install() {
         :
diff --git a/meta/classes/devshell.bbclass b/meta/classes/devshell.bbclass
index 62dc958d9a..75604d0c07 100644
--- a/meta/classes/devshell.bbclass
+++ b/meta/classes/devshell.bbclass
@@ -2,6 +2,8 @@ inherit terminal
 
 DEVSHELL = "${SHELL}"
 
+PATH:prepend:task-devshell = "${COREBASE}/scripts/git-intercept:"
+
 python do_devshell () {
     if d.getVarFlag("do_devshell", "manualfakeroot"):
        d.prependVar("DEVSHELL", "pseudo ")
diff --git a/scripts/git-intercept/git b/scripts/git-intercept/git
new file mode 100755
index 0000000000..8adf5c9ecb
--- /dev/null
+++ b/scripts/git-intercept/git
@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+#
+# Wrapper around 'git' that doesn't think we are root
+
+import os
+import shutil
+import sys
+
+os.environ['PSEUDO_UNLOAD'] = '1'
+
+# calculate path to the real 'git'
+path = os.environ['PATH']
+path = path.replace(os.path.dirname(sys.argv[0]), '')
+real_git = shutil.which('git', path=path)
+
+if len(sys.argv) == 1:
+    os.execl(real_git, 'git')
+
+os.execv(real_git, sys.argv)