[PATCH 1/4] color.h: document and modernize header

[Stefan Beller <sbeller@xxxxxxxxxx>]

Add documentation explaining the functions in color.h.
While at it, mark them extern.

Signed-off-by: Stefan Beller <sbeller@xxxxxxxxxx>
---
 color.c |  2 --
 color.h | 48 +++++++++++++++++++++++++++++++++++-------------
 2 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/color.c b/color.c
index d48dd947c9..c4dc1cb989 100644
--- a/color.c
+++ b/color.c
@@ -399,8 +399,6 @@ static int color_vfprintf(FILE *fp, const char *color, const char *fmt,
 	return r;
 }
 
-
-
 int color_fprintf(FILE *fp, const char *color, const char *fmt, ...)
 {
 	va_list args;
diff --git a/color.h b/color.h
index fd2b688dfb..6cd632c0d8 100644
--- a/color.h
+++ b/color.h
@@ -72,26 +72,48 @@ extern int color_stdout_is_tty;
  * Use the first one if you need only color config; the second is a convenience
  * if you are just going to change to git_default_config, too.
  */
-int git_color_config(const char *var, const char *value, void *cb);
-int git_color_default_config(const char *var, const char *value, void *cb);
+extern int git_color_config(const char *var, const char *value, void *cb);
+extern int git_color_default_config(const char *var, const char *value, void *cb);
 
 /*
- * Set the color buffer (which must be COLOR_MAXLEN bytes)
- * to the raw color bytes; this is useful for initializing
+ * Set the color buffer `dst` (which must be COLOR_MAXLEN bytes)
+ * to the raw color bytes `color_bytes`; this is useful for initializing
  * default color variables.
  */
-void color_set(char *dst, const char *color_bytes);
+extern void color_set(char *dst, const char *color_bytes);
 
-int git_config_colorbool(const char *var, const char *value);
-int want_color(int var);
-int color_parse(const char *value, char *dst);
-int color_parse_mem(const char *value, int len, char *dst);
+/*
+ * Parses a config option, which can be a boolean or one of
+ * "never", "auto", "always". Returns the constant for the given setting.
+ */
+extern int git_config_colorbool(const char *var, const char *value);
+
+/* Is the output supposed to be colored? Resolve and cache the 'auto' setting */
+extern int want_color(int var);
+
+/*
+ * Translate the human readable color string from `value` and into
+ * terminal color codes and store them in `dst`
+ */
+extern int color_parse(const char *value, char *dst);
+extern int color_parse_mem(const char *value, int len, char *dst);
+
+/*
+ * Print the format string `fmt`, encapsulated by setting and resetting the
+ * color. Omits the color encapsulation if `color` is NULL.
+ * The `color_fprintf_ln` prints a new line after resetting the color.
+ * The `color_print_strbuf` prints the given pre-formatted strbuf instead.
+ */
 __attribute__((format (printf, 3, 4)))
-int color_fprintf(FILE *fp, const char *color, const char *fmt, ...);
+extern int color_fprintf(FILE *fp, const char *color, const char *fmt, ...);
 __attribute__((format (printf, 3, 4)))
-int color_fprintf_ln(FILE *fp, const char *color, const char *fmt, ...);
-void color_print_strbuf(FILE *fp, const char *color, const struct strbuf *sb);
+extern int color_fprintf_ln(FILE *fp, const char *color, const char *fmt, ...);
+extern void color_print_strbuf(FILE *fp, const char *color, const struct strbuf *sb);
 
-int color_is_nil(const char *color);
+/*
+ * Check if the given color is GIT_COLOR_NIL that means "no color selected".
+ * The application needs to replace the color with the actual desired color.
+ */
+extern int color_is_nil(const char *color);
 
 #endif /* COLOR_H */
-- 
2.15.1.620.gb9897f4670-goog