Merge branch 'cc/help'

* cc/help:
  Documentation/git-help: typofix
  help: warn if specified 'man.viewer' is unsupported, instead of erroring out
  Documentation: help: explain 'man.viewer' multiple values
  help: implement multi-valued "man.viewer" config option
  Documentation: help: describe 'man.viewer' config variable
  help: add "man.viewer" config var to use "woman" or "konqueror"

3 files changed, 168 insertions, 11 deletions

diff --git a/Documentation/config.txt b/Documentation/config.txt
index ed2cb832b9..0865f4e01a 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -757,6 +757,10 @@ log.showroot::
 	Tools like linkgit:git-log[1] or linkgit:git-whatchanged[1], which
 	normally hide the root commit will now show it. True by default.
 
+man.viewer::
+	Specify the programs that may be used to display help in the
+	'man' format. See linkgit:git-help[1].
+
 merge.summary::
 	Whether to include summaries of merged commits in newly created
 	merge commit messages. False by default.
diff --git a/Documentation/git-help.txt b/Documentation/git-help.txt
index 0926dc12ba..be2ae53b90 100644
--- a/Documentation/git-help.txt
+++ b/Documentation/git-help.txt
@@ -33,17 +33,21 @@ OPTIONS
 	option supersedes any other option.
 
 -i|--info::
-	Use the 'info' program to display the manual page, instead of
-	the 'man' program that is used by default.
+	Display manual page for the command in the 'info' format. The
+	'info' program will be used for that purpose.
 
 -m|--man::
-	Use the 'man' program to display the manual page. This may be
-	used to override a value set in the 'help.format'
-	configuration variable.
+	Display manual page for the command in the 'man' format. This
+	option may be used to override a value set in the
+	'help.format' configuration variable.
++
+By default the 'man' program will be used to display the manual page,
+but the 'man.viewer' configuration variable may be used to choose
+other display programs (see below).
 
 -w|--web::
-	Use a web browser to display the HTML manual page, instead of
-	the 'man' program that is used by default.
+	Display manual page for the command in the 'web' (HTML)
+	format. A web browser will be used for that purpose.
 +
 The web browser can be specified using the configuration variable
 'help.browser', or 'web.browser' if the former is not set. If none of
@@ -54,6 +58,9 @@ linkgit:git-web--browse[1] for more information about this.
 CONFIGURATION VARIABLES
 -----------------------
 
+help.format
+~~~~~~~~~~~
+
 If no command line option is passed, the 'help.format' configuration
 variable will be checked. The following values are supported for this
 variable; they make 'git-help' behave as their corresponding command
@@ -61,15 +68,47 @@ line option:
 
 * "man" corresponds to '-m|--man',
 * "info" corresponds to '-i|--info',
-* "web" or "html" correspond to '-w|--web',
+* "web" or "html" correspond to '-w|--web'.
+
+help.browser, web.browser and browser.<tool>.path
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 The 'help.browser', 'web.browser' and 'browser.<tool>.path' will also
 be checked if the 'web' format is chosen (either by command line
 option or configuration variable). See '-w|--web' in the OPTIONS
 section above and linkgit:git-web--browse[1].
 
-Note that these configuration variables should probably be set using
-the '--global' flag, for example like this:
+man.viewer
+~~~~~~~~~~
+
+The 'man.viewer' config variable will be checked if the 'man' format
+is chosen. Only the following values are currently supported:
+
+* "man": use the 'man' program as usual,
+* "woman": use 'emacsclient' to launch the "woman" mode in emacs
+(this only works starting with emacsclient versions 22),
+* "konqueror": use a man KIO slave in konqueror.
+
+Multiple values may be given to this configuration variable. Their
+corresponding programs will be tried in the order listed in the
+configuration file.
+
+For example, this configuration:
+
+	[man]
+		viewer = konqueror
+		viewer = woman
+
+will try to use konqueror first. But this may fail (for example if
+DISPLAY is not set) and in that case emacs' woman mode will be tried.
+
+If everything fails the 'man' program will be tried anyway.
+
+Note about git config --global
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Note that all these configuration variables should probably be set
+using the '--global' flag, for example like this:
 
 ------------------------------------------------
 $ git config --global help.format web
diff --git a/help.c b/help.c
index e57a50ed59..ecaca770d3 100644
--- a/help.c
+++ b/help.c
@@ -8,6 +8,12 @@
 #include "exec_cmd.h"
 #include "common-cmds.h"
 #include "parse-options.h"
+#include "run-command.h"
+
+static struct man_viewer_list {
+	void (*exec)(const char *);
+	struct man_viewer_list *next;
+} *man_viewer_list;
 
 enum help_format {
 	HELP_FORMAT_MAN,
@@ -42,6 +48,102 @@ static enum help_format parse_help_format(const char *format)
 	die("unrecognized help format '%s'", format);
 }
 
+static int check_emacsclient_version(void)
+{
+	struct strbuf buffer = STRBUF_INIT;
+	struct child_process ec_process;
+	const char *argv_ec[] = { "emacsclient", "--version", NULL };
+	int version;
+
+	/* emacsclient prints its version number on stderr */
+	memset(&ec_process, 0, sizeof(ec_process));
+	ec_process.argv = argv_ec;
+	ec_process.err = -1;
+	ec_process.stdout_to_stderr = 1;
+	if (start_command(&ec_process)) {
+		fprintf(stderr, "Failed to start emacsclient.\n");
+		return -1;
+	}
+	strbuf_read(&buffer, ec_process.err, 20);
+	close(ec_process.err);
+
+	/*
+	 * Don't bother checking return value, because "emacsclient --version"
+	 * seems to always exits with code 1.
+	 */
+	finish_command(&ec_process);
+
+	if (prefixcmp(buffer.buf, "emacsclient")) {
+		fprintf(stderr, "Failed to parse emacsclient version.\n");
+		strbuf_release(&buffer);
+		return -1;
+	}
+
+	strbuf_remove(&buffer, 0, strlen("emacsclient"));
+	version = atoi(buffer.buf);
+
+	if (version < 22) {
+		fprintf(stderr,
+			"emacsclient version '%d' too old (< 22).\n",
+			version);
+		strbuf_release(&buffer);
+		return -1;
+	}
+
+	strbuf_release(&buffer);
+	return 0;
+}
+
+static void exec_woman_emacs(const char *page)
+{
+	if (!check_emacsclient_version()) {
+		/* This works only with emacsclient version >= 22. */
+		struct strbuf man_page = STRBUF_INIT;
+		strbuf_addf(&man_page, "(woman \"%s\")", page);
+		execlp("emacsclient", "emacsclient", "-e", man_page.buf, NULL);
+	}
+}
+
+static void exec_man_konqueror(const char *page)
+{
+	const char *display = getenv("DISPLAY");
+	if (display && *display) {
+		struct strbuf man_page = STRBUF_INIT;
+		strbuf_addf(&man_page, "man:%s(1)", page);
+		execlp("kfmclient", "kfmclient", "newTab", man_page.buf, NULL);
+	}
+}
+
+static void exec_man_man(const char *page)
+{
+	execlp("man", "man", page, NULL);
+}
+
+static void do_add_man_viewer(void (*exec)(const char *))
+{
+	struct man_viewer_list **p = &man_viewer_list;
+
+	while (*p)
+		p = &((*p)->next);
+	*p = xmalloc(sizeof(**p));
+	(*p)->next = NULL;
+	(*p)->exec = exec;
+}
+
+static int add_man_viewer(const char *value)
+{
+	if (!strcasecmp(value, "man"))
+		do_add_man_viewer(exec_man_man);
+	else if (!strcasecmp(value, "woman"))
+		do_add_man_viewer(exec_woman_emacs);
+	else if (!strcasecmp(value, "konqueror"))
+		do_add_man_viewer(exec_man_konqueror);
+	else
+		warning("'%s': unsupported man viewer.", value);
+
+	return 0;
+}
+
 static int git_help_config(const char *var, const char *value)
 {
 	if (!strcmp(var, "help.format")) {
@@ -50,6 +152,11 @@ static int git_help_config(const char *var, const char *value)
 		help_format = parse_help_format(value);
 		return 0;
 	}
+	if (!strcmp(var, "man.viewer")) {
+		if (!value)
+			return config_error_nonbool(var);
+		return add_man_viewer(value);
+	}
 	return git_default_config(var, value);
 }
 
@@ -347,9 +454,16 @@ static void setup_man_path(void)
 
 static void show_man_page(const char *git_cmd)
 {
+	struct man_viewer_list *viewer;
 	const char *page = cmd_to_page(git_cmd);
+
 	setup_man_path();
-	execlp("man", "man", page, NULL);
+	for (viewer = man_viewer_list; viewer; viewer = viewer->next)
+	{
+		viewer->exec(page); /* will return when unable */
+	}
+	exec_man_man(page);
+	die("no man viewer handled the request");
 }
 
 static void show_info_page(const char *git_cmd)