From c9e4ccda71c3f81b8b927275c76e5437528447ba Mon Sep 17 00:00:00 2001
From: Jonas Fonseca <jonas.fonseca@gmail.com>
Date: Sat, 19 May 2018 19:25:20 -0400
Subject: [PATCH] Fix #763: Handle GIT_PREFIX by setting GIT_WORK_TREE and
 changing directory

---
 NEWS.adoc                |  1 +
 src/tig.c                | 25 ++++++++++++++++++
 test/main/git-alias-test | 56 ++++++++++++++++++++++++++++++++++++++++
 test/tools/libtest.sh    |  2 +-
 4 files changed, 83 insertions(+), 1 deletion(-)
 create mode 100755 test/main/git-alias-test

diff --git a/NEWS.adoc b/NEWS.adoc
index 66b9aeef9..deb0681fb 100644
--- a/NEWS.adoc
+++ b/NEWS.adoc
@@ -11,6 +11,7 @@ Improvements:
  - Build against netbsd-curses. (GH #789)
  - Change the blame view to render more like `git blame`. (GH #812)
  - Improve worktree and submodule support. (GH #459, #781, #783)
+ - Support running Tig via a Git alias. (GH #763)
 
 Bug fixes:
 
diff --git a/src/tig.c b/src/tig.c
index 92718100e..aeefee390 100644
--- a/src/tig.c
+++ b/src/tig.c
@@ -738,6 +738,30 @@ die_if_failed(enum status_code code, const char *msg)
 		die("%s: %s", msg, get_status_message(code));
 }
 
+static inline enum status_code
+handle_git_prefix(void)
+{
+	const char *prefix = getenv("GIT_PREFIX");
+	char cwd[4096];
+
+	if (!prefix || !*prefix)
+		return SUCCESS;
+
+	/*
+	 * GIT_PREFIX is set when tig is invoked as a git alias.
+	 * Tig expects to run from the subdirectory so clear the prefix
+	 * and set GIT_WORK_TREE accordinglyt.
+	 */
+	if (!getcwd(cwd, sizeof(cwd)))
+		return error("Failed to read CWD");
+	if (setenv("GIT_WORK_TREE", cwd, 1))
+		return error("Failed to set GIT_WORK_TREE");
+	if (setenv("GIT_PREFIX", "", 1))
+		return error("Failed to clear GIT_PREFIX");
+
+	return chdir(prefix) ? error("Failed to change directory to %s", prefix) : SUCCESS;
+}
+
 int
 main(int argc, const char *argv[])
 {
@@ -761,6 +785,7 @@ main(int argc, const char *argv[])
 		codeset = nl_langinfo(CODESET);
 	}
 
+	die_if_failed(handle_git_prefix(), "Failed to handle GIT_PREFIX");
 	die_if_failed(load_repo_info(), "Failed to load repo info.");
 	die_if_failed(load_options(), "Failed to load user config.");
 	die_if_failed(load_git_config(), "Failed to load repo config.");
diff --git a/test/main/git-alias-test b/test/main/git-alias-test
new file mode 100755
index 000000000..ac909fc5f
--- /dev/null
+++ b/test/main/git-alias-test
@@ -0,0 +1,56 @@
+#!/bin/sh
+
+. libtest.sh
+. libgit.sh
+
+export LINES=5
+
+benchmarks_git="$output_dir/benchmarks.git"
+benchmarks_dir="$output_dir/$work_dir"
+
+tigrc <<EOF
+set line-graphics = ascii
+EOF
+
+steps '
+	:save-display main.screen
+'
+
+executable alias-vars <<EOF
+{
+	echo "PWD=\$(pwd)"
+	env | grep GIT_
+} | sed 's,$output_dir,ROOT,' >> "$output_dir/alias-vars"
+EOF
+
+test_setup_work_dir()
+{
+	mkdir -p "$output_dir/base"
+	cd "$output_dir/base"
+	create_repo_from_tgz "$base_dir/files/scala-js-benchmarks.tgz"
+	git branch work-branch ee912870202200a0b9cf4fd86ba57243212d341e
+	git worktree add "$output_dir/$work_dir" work-branch
+	git config --global alias.tig !tig
+	git config --global alias.alias-vars !alias-vars
+}
+
+test_exec_work_dir test_setup_work_dir
+
+runner=git
+
+work_dir="$work_dir/deltablue"
+test_tig -- src/main/scala
+in_work_dir git alias-vars
+
+assert_equals 'alias-vars' <<EOF
+PWD=ROOT/work dir
+GIT_DIR=ROOT/base/.git/worktrees/work dir
+GIT_PREFIX=deltablue/
+EOF
+
+assert_equals 'main.screen' <<EOF
+2014-03-01 17:26 Jonas Fonseca * [work-branch] [master] WIP: Upgrade to 0.4-SNAP
+2014-01-16 22:51 Jonas Fonseca I Move classes under org.scalajs.benchmark packag
+
+[main] ee912870202200a0b9cf4fd86ba57243212d341e - commit 1 of 2             100%
+EOF
\ No newline at end of file
diff --git a/test/tools/libtest.sh b/test/tools/libtest.sh
index 4b6a4373a..25ceb3075 100644
--- a/test/tools/libtest.sh
+++ b/test/tools/libtest.sh
@@ -240,6 +240,7 @@ diff_color_arg=
 indent='            '
 verbose=
 debugger=
+runner=exec
 trace=
 todos=
 valgrind=
@@ -599,7 +600,6 @@ test_tig()
 			"$debugger" tig "$@"
 		else
 			set +e
-			runner=exec
 			if [ "$expected_status_code" = 0 ] && [ -n "$valgrind" ]; then
 				runner=valgrind_exec
 				if [ "$timeout" -gt 0 ]; then