#!/usr/bin/awk

# Scan a patch for correctness, according to XFS/iomap rules.
#
# Pass the commit id as the variable "commit_id" and the git log --oneline
# output as "oneline" for report generation.

function getval(key) {
	realkey = sprintf("%s: ", key)
	keylen = length(realkey)

	if (substr($0, 0, keylen) != realkey)
		return 0
	return substr($0, keylen + 1)
}

function is_me(val, my_signature, dead_signature)
{
	if (val == my_signature)
		return 1
	if (dead_signature != 0 && val == dead_signature)
		return 1
	return 0
}

function commit_error(why)
{
	if (!commit_errored)
		printf("%s\n", oneline) > "/dev/stderr"

	printf(" - %s\n", why) > "/dev/stderr"
	commit_errored = 1
}

function commit_error_end(why)
{
	if (commit_errored)
		printf("\n") > "/dev/stderr"
}

function prog_error(why)
{
	printf("%s: %s\n", commit_id, why) > "/dev/stderr"
}

BEGIN {
	ret = 0
	commit_errored = 0

	if (length(commit_id) == 0) {
		printf("Commit id not supplied.") > "/dev/stderr"
		ret = 2
		exit
	}

	if (length(oneline) == 0) {
		prog_error("Commit oneline not supplied.")
		ret = 2
		exit
	}

	if (("git config user.name" | getline name) < 0) {
		prog_error("%s: Can't get git user.name.")
		ret = 2
		exit
	}

	if (("git config user.email" | getline email) < 0) {
		prog_error("%s: Can't get git user.email.")
		ret = 2
		exit
	}

	if (("git config core.abbrev" | getline abbrev_len) < 0) {
		prog_error("%s: Can't get git core.abbrev.")
		ret = 2
		exit
	}

	if (abbrev_len <= 0)
		abbrev_len = 12

	("git config user.deadname" | getline dead_name)
	("git config user.deademail" | getline dead_email)

	if (length(dead_name) > 0 && length(dead_email) == 0) {
		dead_email = email
	}
	if (length(dead_email) > 0 && length(dead_name) == 0) {
		dead_name = name
	}

	if (("git config --type bool user.devtree" | getline dev_tree) < 0) {
		dev_tree = "false"
	}
	dev_tree = (dev_tree == "true")

	my_signature = sprintf("%s <%s>", name, email)
	if (length(dead_email) > 0)
		dead_signature = sprintf("%s <%s>", dead_name, dead_email)
	else
		dead_signature = 0;
	you_are_author = 0
	has_other_review = 0
	has_self_review = 0
	has_self_signoff = 0
	has_committer_signoff = 0
	bad_commit = 0
	in_header = 1
	in_body = 0
	subject = 0
	committer_signature = 0
	committer_name = 0
	author_signature = 0
	author_name = 0
	merge = 0
}

{
	# Trim leading and trailing whitespace so that we can pick up tags that
	# are in the commit message.
	gsub(/^[[:space:]]+|[[:space:]]+$/, "", $0)

	if (debug)
		printf(":%s:%s:%s:\n", in_header, $1, $0)

	if (in_header && $0 == "") {
		in_header = 0
		in_body = 1
	} else if (in_body && subject == 0) {
		# Pick up the subject line for error reporting
		subject = $0
		if (debug)
			printf("subj:%s:%s:\n", $0, subject)
	} else if ((val = getval("Merge")) != 0) {
		# We don't process merge commits
		merge = 1
		if (debug)
			printf("Merge:%s:%s:\n", $0, val);
		nextfile
	} else if ((val = getval("Author")) != 0) {
		# Pick up the author header
		author_signature = val
		author_name = gensub(/^[[:space:]]*(.+) <.*$/, "\\1", "g",
							author_signature);
		if (debug)
			printf("author:%s:%s:\n", val, author_signature);
		if (is_me(val, my_signature, dead_signature))
			you_are_author = 1
	} else if ((val = getval("Commit")) != 0) {
		# Pick up the committer header
		committer_signature = val;
		committer_name = gensub(/^[[:space:]]*(.+) <.*$/, "\\1", "g",
							committer_signature);
		if (debug)
			printf("committer:%s:%s:\n", val, committer_name);
	} else if ((val = getval("Signed-off-by")) != 0) {
		# Pick up signoffs
		sob_name = gensub(/^[[:space:]]*(.+) <.*$/, "\\1", "g", val);
		if (is_me(val, my_signature, dead_signature))
			has_self_signoff = 1
		if (val == author_signature || sob_name == author_name)
			has_author_signoff = 1
		if (val == committer_signature || sob_name == committer_name)
			has_committer_signoff = 1
	} else if ((val = getval("Reviewed-by")) != 0) {
		# Pick up reviews
		if (is_me(val, my_signature, dead_signature))
			has_self_review = 1
		else
			has_other_review = 1
	} else if ((val = getval("Fixes")) != 0) {
		# Fixes tags must be of a certain length and exist in the git
		# history.
		split(val, cols)
		fixes_id = cols[1]
		if (debug)
			printf("fixes:%s:\n", fixes_id)
		if (length(fixes_id) < abbrev_len) {
			msg = sprintf("Fixes tag commit \"%s\" needs to be longer.", fixes_id)
			commit_error(msg)
			bad_commit = 1
		}

		cmd = sprintf("git log -n 1 \"%s\" >/dev/null 2>&1", fixes_id)
		if (system(cmd) != 0) {
			msg = sprintf("Fixes tag commit \"%s\" does not exist.", fixes_id)
			commit_error(msg)
			bad_commit = 1
		}
	} else if ($0 ~ /scanned for virus detection/) {
		commit_error("Email virus scanner garbage in commit message.")
		bad_commit = 1
	}
}
END {
	if (ret != 0 || merge != 0)
		exit ret

	if (subject == 0) {
		commit_error("Patch subject not found.")
		ret = 1
	}

	if (bad_commit)
		ret = 1

	if (you_are_author) {
		# If you wrote the patch, you must have your own signoff and a
		# review by someone else (if this isn't your development tree).
		# You can't review your own patches.
		if (!has_self_signoff) {
			commit_error("Your patch needs your signoff.")
			ret = 1
		}
		if (!has_other_review && !dev_tree) {
			commit_error("Your patch needs review by someone else.")
			ret = 1
		}
		if (has_self_review) {
			commit_error("You cannot review your own patch.")
			ret = 1
		}
	} else {
		# If you did not write the patch, it must have a signoff from
		# the author, a review by you, and a signoff by you unless the
		# author is the committer.
		if (!has_author_signoff) {
			commit_error("Patch needs to be signed off by the author.")
			ret = 1
		}
		if (!has_self_review) {
			commit_error("Patch needs your review.")
			ret = 1
		}
		if (!has_committer_signoff && !has_self_signoff) {
			commit_error("Patch needs your (or the committer's) signoff.")
			has_committer_signoff = 1
			ret = 1
		}
	}

	# All commits must have a signoff from the committer.
	if (!has_committer_signoff) {
		commit_error("This patch needs to be signed off by the committer.")
		ret = 1
	}

	commit_error_end()
	exit ret
}