make_upstream_revert_noop.sh

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#!/bin/bash

# This script takes the current base sha, the next base sha, and the sha

# of the commit that reverts the next base as determined by

# detect_upstream_revert.sh and "inserts" two commits at the bottom of the

# moz_libwebrtc GitHub patch stack.  The two commits are exact copies of

# the upcoming commit and its corresponding revert commit, with commit

# messages indicating they are temporary commits.  Additionally, 2 files

# are written that act as markers for the fast-forward script and contain

# supplemental commit message text.

# When the fast-forward script runs, it will rebase onto the next base

# sha.  Since we have a corresponding, identical temp commit at the bottom

# of our patch stack, the temp commit will be absorbed as unnecessary.

# Since the patch stack now has the temp revert commit at the bottom, this

# results in a “no-op” commit.  The marker file indicates that specially

# handling should occur in the fast-forward-libwebrtc.sh and loop-ff.sh

# scripts.  This special handling includes adding the supplemental commit

# text that explains why the commit is a no-op (or empty) commit and

# skipping the verification of the number of files changed between our

# mercurial repository and the GitHub repository.

function show_error_msg()

  echo "*** ERROR *** $? line $1 $0 did not complete successfully!"

  echo "$ERROR_HELP"

ERROR_HELP=""

# Print an Error message if `set -eE` causes the script to exit due to a failed command

trap 'show_error_msg $LINENO' ERR

source dom/media/webrtc/third_party_build/use_config_env.sh

# If DEBUG_GEN is set all commands should be printed as they are executed

if [ ! "x$DEBUG_GEN" = "x" ]; then

  set -x

fi

if [ "x$MOZ_LIBWEBRTC_SRC" = "x" ]; then

  echo "MOZ_LIBWEBRTC_SRC is not defined, see README.md"

  exit

fi

if [ -d $MOZ_LIBWEBRTC_SRC ]; then

  echo "MOZ_LIBWEBRTC_SRC is $MOZ_LIBWEBRTC_SRC"

else

  echo "Path $MOZ_LIBWEBRTC_SRC is not found, see README.md"

  exit

fi

if [ "x$MOZ_LIBWEBRTC_BRANCH" = "x" ]; then

  echo "MOZ_LIBWEBRTC_BRANCH is not defined, see README.md"

  exit

fi

# After this point:

# * eE: All commands should succeed.

# * u: All variables should be defined before use.

# * o pipefail: All stages of all pipes should succeed.

set -eEuo pipefail

find_base_commit

find_next_commit

echo "MOZ_LIBWEBRTC_BASE: $MOZ_LIBWEBRTC_BASE"

echo "MOZ_LIBWEBRTC_NEXT_BASE: $MOZ_LIBWEBRTC_NEXT_BASE"

echo "MOZ_LIBWEBRTC_REVERT_SHA: $MOZ_LIBWEBRTC_REVERT_SHA"

# These files serve dual purposes:

# 1) They serve as marker/indicator files to loop-ff.sh to

#    know to process the commit differently, accounting for

#    the no-op nature of the commit and it's corresponding

#    revert commit.

# 2) The contain supplemental commit message text to explain

#    why the commits are essentially empty.

# They are written first on the off chance that the rebase

# operation below fails and requires manual intervention,

# thus avoiding the operator of these scripts to remember to

# generate these two files.

echo $"Essentially a no-op since we're going to see this change

reverted when we vendor in $MOZ_LIBWEBRTC_REVERT_SHA." \

> $STATE_DIR/$MOZ_LIBWEBRTC_NEXT_BASE.no-op-cherry-pick-msg

echo "We already cherry-picked this when we vendored $MOZ_LIBWEBRTC_NEXT_BASE." \

> $STATE_DIR/$MOZ_LIBWEBRTC_REVERT_SHA.no-op-cherry-pick-msg

cd $MOZ_LIBWEBRTC_SRC

git checkout -b moz-cherry-pick $MOZ_LIBWEBRTC_BASE

COMMIT_MSG_FILE=$TMP_DIR/commit.msg

# build commit message with annotated summary

git show --format='%s%n%n%b' --no-patch $MOZ_LIBWEBRTC_NEXT_BASE > $COMMIT_MSG_FILE

ed -s $COMMIT_MSG_FILE <<EOF

1,s/^\(.*\)$/(tmp-cherry-pick) & ($MOZ_LIBWEBRTC_NEXT_BASE)/

EOF

git cherry-pick --no-commit $MOZ_LIBWEBRTC_NEXT_BASE

git commit --file $COMMIT_MSG_FILE

# build commit message with annotated summary

git show --format='%s%n%n%b' --no-patch $MOZ_LIBWEBRTC_REVERT_SHA > $COMMIT_MSG_FILE

ed -s $COMMIT_MSG_FILE <<EOF

1,s/^\(.*\)$/(tmp-cherry-pick) & ($MOZ_LIBWEBRTC_REVERT_SHA)/

EOF

git cherry-pick --no-commit $MOZ_LIBWEBRTC_REVERT_SHA

git commit --file $COMMIT_MSG_FILE

git checkout $MOZ_LIBWEBRTC_BRANCH

git rebase moz-cherry-pick

git branch -d moz-cherry-pick