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* [PATCH v2] help: colorize man pages
@ 2021-05-18 13:20 Felipe Contreras
  2021-05-18 14:50 ` Junio C Hamano
  0 siblings, 1 reply; 3+ messages in thread
From: Felipe Contreras @ 2021-05-18 13:20 UTC (permalink / raw)
  To: git
  Cc: Jeff King, Ævar Arnfjörð Bjarmason,
	Junio C Hamano, Randall S. Becker, Felipe Contreras

Our man pages don't contain many useful colors (just blue links),
moreover, many people have groff SGR disabled, so they don't see any
colors with man pages.

We can set LESS_TERMCAP variables to render bold and underlined text
with colors in the pager; a common trick[1].

Bold is rendered as red, underlined as blue, and standout (messages and
highlighted search) as inverse magenta.

This only works when the pager is less.

If the user already has LESS_TERMCAP variables set in his/her
environment, those are respected and not overwritten.

A new color configuration is added: `color.man`, otherwise `color.ui` is
respected, and in addition color.pager needs to turned on.

Normally check_auto_color() would check the value of `color.pager`, but
in this particular case it's not git the one executing the pager, but
man. Therefore we need to check pager_use_color ourselves.

[1] https://unix.stackexchange.com/questions/119/colors-in-man-pages/147

Suggested-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Comments-by: Jeff King <peff@peff.net>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
---
Range-diff against v1:
1:  a943dedab8 ! 1:  9e34a49fa9 help: colorize man pages
    @@ Commit message
         Bold is rendered as red, underlined as blue, and standout (messages and
         highlighted search) as inverse magenta.
     
    -    This only works when the pager is less, and the color.pager
    -    configuration is enabled, as well as color.ui.
    +    This only works when the pager is less.
    +
    +    If the user already has LESS_TERMCAP variables set in his/her
    +    environment, those are respected and not overwritten.
    +
    +    A new color configuration is added: `color.man`, otherwise `color.ui` is
    +    respected, and in addition color.pager needs to turned on.
    +
    +    Normally check_auto_color() would check the value of `color.pager`, but
    +    in this particular case it's not git the one executing the pager, but
    +    man. Therefore we need to check pager_use_color ourselves.
     
         [1] https://unix.stackexchange.com/questions/119/colors-in-man-pages/147
     
    +    Suggested-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
    +    Comments-by: Jeff King <peff@peff.net>
         Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
     
    + ## Documentation/config/color.txt ##
    +@@ Documentation/config/color.txt: color.interactive.<slot>::
    + 	or `error`, for four distinct types of normal output from
    + 	interactive commands.
    + 
    ++color.man::
    ++	When set to `always`, always colorize the man pages. When `false`
    ++	(or `never`), never.  When set to `true` or `auto`, use color only
    ++	when the output is written to the terminal. If unset, then the
    ++	value of `color.ui` is used (`auto` by default).
    ++
    + color.pager::
    + 	A boolean to enable/disable colored output when the pager is in
    + 	use (default is true).
    +
      ## builtin/help.c ##
     @@
      #include "config-list.h"
    @@ builtin/help.c
      
      #ifndef DEFAULT_HELP_FORMAT
      #define DEFAULT_HELP_FORMAT "man"
    +@@ builtin/help.c: static int verbose = 1;
    + static unsigned int colopts;
    + static enum help_format help_format = HELP_FORMAT_NONE;
    + static int exclude_guides;
    ++static int man_color = GIT_COLOR_UNKNOWN;
    + static struct option builtin_help_options[] = {
    + 	OPT_BOOL('a', "all", &show_all, N_("print all available commands")),
    + 	OPT_HIDDEN_BOOL(0, "exclude-guides", &exclude_guides, N_("exclude guides")),
     @@ builtin/help.c: static void exec_man_konqueror(const char *path, const char *page)
      	}
      }
      
     +static void colorize_man(void)
     +{
    -+	if (!pager_use_color || !want_color(GIT_COLOR_UNKNOWN))
    ++	if (!want_color(man_color) || !pager_use_color)
     +		return;
     +
     +	/* Disable groff colors */
    @@ builtin/help.c: static void exec_man_man(const char *path, const char *page)
      	execl(SHELL_PATH, SHELL_PATH, "-c", shell_cmd.buf, (char *)NULL);
      	warning(_("failed to exec '%s'"), cmd);
     @@ builtin/help.c: static int git_help_config(const char *var, const char *value, void *cb)
    + 	}
      	if (starts_with(var, "man."))
      		return add_man_viewer_info(var, value);
    ++	if (!strcmp(var, "color.man")) {
    ++		man_color = git_config_colorbool(var, value);
    ++		return 0;
    ++	}
      
     -	return git_default_config(var, value, cb);
     +	return git_color_default_config(var, value, cb);

 Documentation/config/color.txt |  6 ++++++
 builtin/help.c                 | 32 +++++++++++++++++++++++++++++++-
 color.h                        |  1 +
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/Documentation/config/color.txt b/Documentation/config/color.txt
index d5daacb13a..02019a612c 100644
--- a/Documentation/config/color.txt
+++ b/Documentation/config/color.txt
@@ -126,6 +126,12 @@ color.interactive.<slot>::
 	or `error`, for four distinct types of normal output from
 	interactive commands.
 
+color.man::
+	When set to `always`, always colorize the man pages. When `false`
+	(or `never`), never.  When set to `true` or `auto`, use color only
+	when the output is written to the terminal. If unset, then the
+	value of `color.ui` is used (`auto` by default).
+
 color.pager::
 	A boolean to enable/disable colored output when the pager is in
 	use (default is true).
diff --git a/builtin/help.c b/builtin/help.c
index bb339f0fc8..05c758ca1b 100644
--- a/builtin/help.c
+++ b/builtin/help.c
@@ -11,6 +11,7 @@
 #include "config-list.h"
 #include "help.h"
 #include "alias.h"
+#include "color.h"
 
 #ifndef DEFAULT_HELP_FORMAT
 #define DEFAULT_HELP_FORMAT "man"
@@ -43,6 +44,7 @@ static int verbose = 1;
 static unsigned int colopts;
 static enum help_format help_format = HELP_FORMAT_NONE;
 static int exclude_guides;
+static int man_color = GIT_COLOR_UNKNOWN;
 static struct option builtin_help_options[] = {
 	OPT_BOOL('a', "all", &show_all, N_("print all available commands")),
 	OPT_HIDDEN_BOOL(0, "exclude-guides", &exclude_guides, N_("exclude guides")),
@@ -253,10 +255,33 @@ static void exec_man_konqueror(const char *path, const char *page)
 	}
 }
 
+static void colorize_man(void)
+{
+	if (!want_color(man_color) || !pager_use_color)
+		return;
+
+	/* Disable groff colors */
+	setenv("GROFF_NO_SGR", "1", 0);
+
+	/* Bold */
+	setenv("LESS_TERMCAP_md", GIT_COLOR_BOLD_RED, 0);
+	setenv("LESS_TERMCAP_me", GIT_COLOR_RESET, 0);
+
+	/* Underline */
+	setenv("LESS_TERMCAP_us", GIT_COLOR_BLUE GIT_COLOR_UNDERLINE, 0);
+	setenv("LESS_TERMCAP_ue", GIT_COLOR_RESET, 0);
+
+	/* Standout */
+	setenv("LESS_TERMCAP_so", GIT_COLOR_MAGENTA GIT_COLOR_REVERSE, 0);
+	setenv("LESS_TERMCAP_se", GIT_COLOR_RESET, 0);
+}
+
 static void exec_man_man(const char *path, const char *page)
 {
 	if (!path)
 		path = "man";
+
+	colorize_man();
 	execlp(path, "man", page, (char *)NULL);
 	warning_errno(_("failed to exec '%s'"), path);
 }
@@ -264,6 +289,7 @@ static void exec_man_man(const char *path, const char *page)
 static void exec_man_cmd(const char *cmd, const char *page)
 {
 	struct strbuf shell_cmd = STRBUF_INIT;
+	colorize_man();
 	strbuf_addf(&shell_cmd, "%s %s", cmd, page);
 	execl(SHELL_PATH, SHELL_PATH, "-c", shell_cmd.buf, (char *)NULL);
 	warning(_("failed to exec '%s'"), cmd);
@@ -371,8 +397,12 @@ static int git_help_config(const char *var, const char *value, void *cb)
 	}
 	if (starts_with(var, "man."))
 		return add_man_viewer_info(var, value);
+	if (!strcmp(var, "color.man")) {
+		man_color = git_config_colorbool(var, value);
+		return 0;
+	}
 
-	return git_default_config(var, value, cb);
+	return git_color_default_config(var, value, cb);
 }
 
 static struct cmdnames main_cmds, other_cmds;
diff --git a/color.h b/color.h
index 98894d6a17..d012add4e8 100644
--- a/color.h
+++ b/color.h
@@ -51,6 +51,7 @@ struct strbuf;
 #define GIT_COLOR_FAINT		"\033[2m"
 #define GIT_COLOR_FAINT_ITALIC	"\033[2;3m"
 #define GIT_COLOR_REVERSE	"\033[7m"
+#define GIT_COLOR_UNDERLINE	"\033[4m"
 
 /* A special value meaning "no color selected" */
 #define GIT_COLOR_NIL "NIL"
-- 
2.31.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH v2] help: colorize man pages
  2021-05-18 13:20 [PATCH v2] help: colorize man pages Felipe Contreras
@ 2021-05-18 14:50 ` Junio C Hamano
  2021-05-18 20:53   ` Felipe Contreras
  0 siblings, 1 reply; 3+ messages in thread
From: Junio C Hamano @ 2021-05-18 14:50 UTC (permalink / raw)
  To: Felipe Contreras
  Cc: git, Jeff King, Ævar Arnfjörð Bjarmason,
	Randall S. Becker

Felipe Contreras <felipe.contreras@gmail.com> writes:

> +color.man::
> +	When set to `always`, always colorize the man pages. When `false`
> +	(or `never`), never.  When set to `true` or `auto`, use color only
> +	when the output is written to the terminal. If unset, then the
> +	value of `color.ui` is used (`auto` by default).

Makes sense and is more in line with the rest of the system to have
subcommand specific color.* variable.

There are two things that make me wonder in the above description,
though.

> +static void colorize_man(void)
> +{
> +	if (!want_color(man_color) || !pager_use_color)
> +		return;
> +
> +	/* Disable groff colors */
> +	setenv("GROFF_NO_SGR", "1", 0);
> +
> +	/* Bold */
> +	setenv("LESS_TERMCAP_md", GIT_COLOR_BOLD_RED, 0);
> +	setenv("LESS_TERMCAP_me", GIT_COLOR_RESET, 0);
> +
> +	/* Underline */
> +	setenv("LESS_TERMCAP_us", GIT_COLOR_BLUE GIT_COLOR_UNDERLINE, 0);
> +	setenv("LESS_TERMCAP_ue", GIT_COLOR_RESET, 0);
> +
> +	/* Standout */
> +	setenv("LESS_TERMCAP_so", GIT_COLOR_MAGENTA GIT_COLOR_REVERSE, 0);
> +	setenv("LESS_TERMCAP_se", GIT_COLOR_RESET, 0);
> +}

This seems very specific to use of "less" and hopefully does not do
anything (bad) when a different pager is used by "man".

 - Would it help readers to somehow tell that color.man does not
   apply at all to those whose "man" does not "less" in the
   documentation?

 - What does it mean to set this variable to "always"?  For commands
   that we control how the various pieces of output are colored (or
   not), e.g.

   $ git -c color.ui=always log -1 -p >git-log-output.txt

   it is obvious what "always" means, but given the implementation
   that tweaks how "less" should behave, a similar command (below)
   would not colorize its output like the "git log" example above
   does, would it?

   $ git -c color.man=always help -m git >git-help-text.txt

I am just wondering if we are better off not to mention "always" in
the documentation patch above.  It seems more like that the
configuration variable is to answer this question and nothing else:

    when 'git help' shows manual pages and internally uses 'less' as
    its pager, do we tell it to colorize the output?

for which sensible answers are 'true' or 'false'.  For that matter,
it is not clear what "auto" ought to mean, either.

Thanks.

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH v2] help: colorize man pages
  2021-05-18 14:50 ` Junio C Hamano
@ 2021-05-18 20:53   ` Felipe Contreras
  0 siblings, 0 replies; 3+ messages in thread
From: Felipe Contreras @ 2021-05-18 20:53 UTC (permalink / raw)
  To: Junio C Hamano, Felipe Contreras
  Cc: git, Jeff King, Ævar Arnfjörð Bjarmason,
	Randall S. Becker

Junio C Hamano wrote:
> This seems very specific to use of "less" and hopefully does not do
> anything (bad) when a different pager is used by "man".
> 
>  - Would it help readers to somehow tell that color.man does not
>    apply at all to those whose "man" does not "less" in the
>    documentation?

Indeed it would. Done.

>  - What does it mean to set this variable to "always"?  For commands
>    that we control how the various pieces of output are colored (or
>    not), e.g.
> 
>    $ git -c color.ui=always log -1 -p >git-log-output.txt
> 
>    it is obvious what "always" means, but given the implementation
>    that tweaks how "less" should behave, a similar command (below)
>    would not colorize its output like the "git log" example above
>    does, would it?
> 
>    $ git -c color.man=always help -m git >git-help-text.txt
> 
> I am just wondering if we are better off not to mention "always" in
> the documentation patch above.  It seems more like that the
> configuration variable is to answer this question and nothing else:
> 
>     when 'git help' shows manual pages and internally uses 'less' as
>     its pager, do we tell it to colorize the output?
> 
> for which sensible answers are 'true' or 'false'.  For that matter,
> it is not clear what "auto" ought to mean, either.

True. The user most likely is not going to run 'git help $x > output'.

Initially I was making color.man a boolean, but stopped when I found
color.pager. Since Jeff said to use want_color() in the same way all the
other color.* configurations, I forgot, and used a colorbool.

I've returned back to a bool, and updated the documentation.

color.ui=auto is still respected (if stdout is a tty color is disabled),
but it doesn't really matter because less seems to be smart and disable
color anyway.

v3 sent.

Cheers.

-- 
Felipe Contreras

^ permalink raw reply	[flat|nested] 3+ messages in thread

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