[PATCH iproute2 v2] allow overriding color option in environment

[Stephen Hemminger <stephen@networkplumber.org>]

For ip, tc, and bridge command introduce IPROUTE_COLORS to enable
automatic colorization via environment variable.
Similar to how grep handles color flag.

Example:
  $ IPROUTE_COLORS=auto ip -br addr

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 bridge/bridge.c   |  2 +-
 include/color.h   |  1 +
 ip/ip.c           |  2 +-
 lib/color.c       | 36 +++++++++++++++++++++++++++---------
 man/man8/bridge.8 |  8 ++++++--
 man/man8/ip.8     | 14 ++++++++------
 man/man8/tc.8     |  8 ++++++--
 tc/tc.c           |  2 +-
 8 files changed, 51 insertions(+), 22 deletions(-)

diff --git a/bridge/bridge.c b/bridge/bridge.c
index 339101a874b1..d506f75ebc46 100644
--- a/bridge/bridge.c
+++ b/bridge/bridge.c
@@ -102,7 +102,7 @@ static int batch(const char *name)
 int
 main(int argc, char **argv)
 {
-	int color = CONF_COLOR;
+	int color = default_color();
 
 	while (argc > 1) {
 		const char *opt = argv[1];
diff --git a/include/color.h b/include/color.h
index 17ec56f3d7b4..1ddd1bda5797 100644
--- a/include/color.h
+++ b/include/color.h
@@ -20,6 +20,7 @@ enum color_opt {
 	COLOR_OPT_ALWAYS = 2
 };
 
+int default_color(void);
 bool check_enable_color(int color, int json);
 bool matches_color(const char *arg, int *val);
 int color_fprintf(FILE *fp, enum color_attr attr, const char *fmt, ...);
diff --git a/ip/ip.c b/ip/ip.c
index 860ff957c3b3..0befe14e3d66 100644
--- a/ip/ip.c
+++ b/ip/ip.c
@@ -168,7 +168,7 @@ int main(int argc, char **argv)
 	const char *libbpf_version;
 	char *batch_file = NULL;
 	char *basename;
-	int color = CONF_COLOR;
+	int color = default_color();
 
 	/* to run vrf exec without root, capabilities might be set, drop them
 	 * if not needed as the first thing.
diff --git a/lib/color.c b/lib/color.c
index 59976847295c..e2ffefaf75a8 100644
--- a/lib/color.c
+++ b/lib/color.c
@@ -93,6 +93,32 @@ bool check_enable_color(int color, int json)
 	return false;
 }
 
+static bool match_color_value(const char *arg, int *val)
+{
+	if (*arg == '\0' || !strcmp(arg, "always"))
+		*val = COLOR_OPT_ALWAYS;
+	else if (!strcmp(arg, "auto"))
+		*val = COLOR_OPT_AUTO;
+	else if (!strcmp(arg, "never"))
+		*val = COLOR_OPT_NEVER;
+	else
+		return false;
+	return true;
+}
+
+int default_color(void)
+{
+	const char *name;
+	int val;
+
+	name = getenv("IPROUTE_COLORS");
+	if (name && *name && match_color_value(name, &val))
+		return val;
+
+	/* default is from config */
+	return CONF_COLOR;
+}
+
 bool matches_color(const char *arg, int *val)
 {
 	char *dup, *p;
@@ -108,15 +134,7 @@ bool matches_color(const char *arg, int *val)
 	if (matches(dup, "-color"))
 		return false;
 
-	if (*p == '\0' || !strcmp(p, "always"))
-		*val = COLOR_OPT_ALWAYS;
-	else if (!strcmp(p, "auto"))
-		*val = COLOR_OPT_AUTO;
-	else if (!strcmp(p, "never"))
-		*val = COLOR_OPT_NEVER;
-	else
-		return false;
-	return true;
+	return match_color_value(p, val);
 }
 
 static void set_color_palette(void)
diff --git a/man/man8/bridge.8 b/man/man8/bridge.8
index c52c9331e2c2..6ad34e4d704a 100644
--- a/man/man8/bridge.8
+++ b/man/man8/bridge.8
@@ -315,10 +315,14 @@ color output is enabled regardless of stdout state. If parameter is
 stdout is checked to be a terminal before enabling color output. If parameter is
 .BR never ,
 color output is disabled. If specified multiple times, the last one takes
-precedence. This flag is ignored if
+precedence.
+The default color setting is
+.B never
+but can be overridden by the
+.B IPROUTE_COLORS
+environment variable. This flag is ignored if
 .B \-json
 is also given.
-
 .TP
 .BR "\-j", " \-json"
 Output results in JavaScript Object Notation (JSON).
diff --git a/man/man8/ip.8 b/man/man8/ip.8
index 72227d44fd30..63858edc318d 100644
--- a/man/man8/ip.8
+++ b/man/man8/ip.8
@@ -193,15 +193,17 @@ stdout is checked to be a terminal before enabling color output. If
 parameter is
 .BR never ,
 color output is disabled. If specified multiple times, the last one takes
-precedence. This flag is ignored if
+precedence.The default color setting is
+.B never
+but can be overridden by the
+.B IPROUTE_COLORS
+environment variable. This flag is ignored if
 .B \-json
 is also given.
 
-Used color palette can be influenced by
-.BR COLORFGBG
-environment variable
-(see
-.BR ENVIRONMENT ).
+The color palette used can be adjusted with
+.B COLORFGBG
+environment variable.
 
 .TP
 .BR "\-t" , " \-timestamp"
diff --git a/man/man8/tc.8 b/man/man8/tc.8
index d436d46472af..e47817704e4c 100644
--- a/man/man8/tc.8
+++ b/man/man8/tc.8
@@ -801,10 +801,14 @@ color output is enabled regardless of stdout state. If parameter is
 stdout is checked to be a terminal before enabling color output. If parameter is
 .BR never ,
 color output is disabled. If specified multiple times, the last one takes
-precedence. This flag is ignored if
+precedence.
+The default color setting is
+.B never
+but can be overridden by the
+.B IPROUTE_COLORS
+environment variable. This flag is ignored if
 .B \-json
 is also given.
-
 .TP
 .BR "\-j", " \-json"
 Display results in JSON format.
diff --git a/tc/tc.c b/tc/tc.c
index 082c6677d34a..e8b214802d1f 100644
--- a/tc/tc.c
+++ b/tc/tc.c
@@ -253,7 +253,7 @@ int main(int argc, char **argv)
 {
 	const char *libbpf_version;
 	char *batch_file = NULL;
-	int color = CONF_COLOR;
+	int color = default_color();
 	int ret;
 
 	while (argc > 1) {
-- 
2.39.2