[PATCH v2 3/8] Teach git var about GIT_EDITOR

[Jonathan Nieder <jrnieder@gmail.com>]

From: Johannes Sixt <j6t@kdbg.org>

Expose the command used by launch_editor() for scripts to use.
This should allow one to avoid searching for a proper editor
separately in each command.

If no satisfactory GIT_EDITOR could be chosen, let "git var -l"
output a warning.  This warning goes to stderr so as not to
confuse scripts.  Example:

	core.logallrefupdates=true

	*** Please tell me who you are.

	Run

	  git config --global user.email "you@example.com"
	  git config --global user.name "Your Name"

	to set your account's default identity.
	Omit --global to set the identity only in this repository.

	GIT_COMMITTER_IDENT=user <user@domain> 1256952739 -0500
	GIT_AUTHOR_IDENT=user <user@domain> 1256952739 -0500
	warning: GIT_EDITOR: terminal is dumb, but EDITOR unset

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---

 Documentation/git-var.txt |    8 ++++++++
 cache.h                   |    1 +
 editor.c                  |   14 ++++++++++++--
 var.c                     |   21 ++++++++++++++++++++-
 4 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-var.txt b/Documentation/git-var.txt
index e2f4c09..89e4b4f 100644
--- a/Documentation/git-var.txt
+++ b/Documentation/git-var.txt
@@ -36,6 +36,14 @@ GIT_AUTHOR_IDENT::
 GIT_COMMITTER_IDENT::
     The person who put a piece of code into git.
 
+GIT_EDITOR::
+    Text editor for use by git commands.  The value is meant to be
+    interpreted by the shell when it is used.  Examples: `~/bin/vi`,
+    `$SOME_ENVIRONMENT_VARIABLE`, `"C:\Program Files\Vim\gvim.exe"
+    --nofork`.  The order of preference is the `$GIT_EDITOR`
+    environment variable, then `core.editor` configuration, then
+    `$VISUAL`, then `$EDITOR`, and then finally 'vi'.
+
 Diagnostics
 -----------
 You don't exist. Go away!::
diff --git a/cache.h b/cache.h
index 96840c7..311cfe1 100644
--- a/cache.h
+++ b/cache.h
@@ -750,6 +750,7 @@ extern const char *git_author_info(int);
 extern const char *git_committer_info(int);
 extern const char *fmt_ident(const char *name, const char *email, const char *date_str, int);
 extern const char *fmt_name(const char *name, const char *email);
+extern const char *git_editor(void);
 
 struct checkout {
 	const char *base_dir;
diff --git a/editor.c b/editor.c
index 3f13751..4f98b72 100644
--- a/editor.c
+++ b/editor.c
@@ -2,7 +2,7 @@
 #include "strbuf.h"
 #include "run-command.h"
 
-int launch_editor(const char *path, struct strbuf *buffer, const char *const *env)
+const char *git_editor(void)
 {
 	const char *editor = getenv("GIT_EDITOR");
 	const char *terminal = getenv("TERM");
@@ -16,11 +16,21 @@ int launch_editor(const char *path, struct strbuf *buffer, const char *const *en
 		editor = getenv("EDITOR");
 
 	if (!editor && terminal_is_dumb)
-		return error("terminal is dumb, but EDITOR unset");
+		return NULL;
 
 	if (!editor)
 		editor = "vi";
 
+	return editor;
+}
+
+int launch_editor(const char *path, struct strbuf *buffer, const char *const *env)
+{
+	const char *editor = git_editor();
+
+	if (!editor)
+		return error("terminal is dumb, but EDITOR unset");
+
 	if (strcmp(editor, ":")) {
 		size_t len = strlen(editor);
 		int i = 0;
diff --git a/var.c b/var.c
index 125c0d1..399f409 100644
--- a/var.c
+++ b/var.c
@@ -8,6 +8,21 @@
 
 static const char var_usage[] = "git var [-l | <variable>]";
 
+static const char *editor(int flag)
+{
+	const char *pgm = git_editor();
+
+	if (!pgm) {
+		if (flag & IDENT_ERROR_ON_NO_NAME)
+			die("terminal is dumb, but EDITOR unset");
+		if (flag & IDENT_WARN_ON_NO_NAME)
+			warning("GIT_EDITOR: terminal is dumb, "
+				"but EDITOR unset");
+	}
+
+	return pgm;
+}
+
 struct git_var {
 	const char *name;
 	const char *(*read)(int);
@@ -15,14 +30,18 @@ struct git_var {
 static struct git_var git_vars[] = {
 	{ "GIT_COMMITTER_IDENT", git_committer_info },
 	{ "GIT_AUTHOR_IDENT",   git_author_info },
+	{ "GIT_EDITOR", editor },
 	{ "", NULL },
 };
 
 static void list_vars(void)
 {
 	struct git_var *ptr;
+	const char *val;
+
 	for (ptr = git_vars; ptr->read; ptr++)
-		printf("%s=%s\n", ptr->name, ptr->read(IDENT_WARN_ON_NO_NAME));
+		if ((val = ptr->read(IDENT_WARN_ON_NO_NAME)))
+			printf("%s=%s\n", ptr->name, val);
 }
 
 static const char *read_var(const char *var)
-- 
1.6.5.2