Properly setup colorized printing functions

Previously, non-colorized and colorized printing made use of the same
pw_*print family of functions.

Since we do most of the setup after we parse the user supplied arguments,
the user may supply the "--debug" option. This will cause a segmentation
fault as the color struct has not been initialized but a NULL string in it
is printed.

The pw_safe_*print family of functions is introduced to solve this.
Now, the pw_*print family of functions are just function pointers to the
pw_safe_*print family of functions until we confirm whether the output is
colorized. If so, then we call color_print_setup() to switch the pw_*print
function pointers to pw_c*print family of functions to support colorized
output.

Otherwise, the pw_*print family of functions will still point to the original
pw_safe_*print family of functions.

When we destroy the color struct, color_print_restore() is invoked to switch
the pw_*print pointers to the pw_safe_*print functions.

Signed-off-by: Pang Yan Han <pangyanhan@gmail.com>

environment.c

@@ -57,6 +57,10 @@ static void colors_setup(void)
 		color.nocolor = xstrdup(NOCOLOR);
 		color.bold    = xstrdup(BOLD);
 		color.votecol = xstrdup(VOTECOL);
+
+		/* Setup colorized print functions */
+		color_print_setup();
+
 	} else {
 		color.black   = xstrdup("");
 		color.red     = xstrdup("");
@@ -77,6 +81,9 @@ static void colors_setup(void)
 		color.nocolor = xstrdup("");
 		color.bold    = xstrdup("");
 		color.votecol = xstrdup("");
+
+		/* Restore non-colorized print functions */
+		color_print_restore;
 	}
 }
 

util.c

@@ -19,7 +19,69 @@
 #include "powaur.h"
 #include "util.h"
 
-int pw_printf(enum pwloglevel_t lvl, const char *fmt, ...)
+/* Safe family of print functions for use when color struct isnt initialized */
+static int pw_safe_vfprintf(enum pwloglevel_t lvl, FILE *stream, const char *fmt,
+							va_list ap)
+{
+	int ret = 0;
+	va_list copy_list;
+
+	if (!config || !(config->loglvl & lvl)) {
+		return ret;
+	}
+
+	va_copy(copy_list, ap);
+
+	switch (lvl) {
+	case PW_LOG_WARNING:
+		fprintf(stream, "WARNING: ");
+		break;
+	case PW_LOG_ERROR:
+		fprintf(stream, "error: ");
+		break;
+	case PW_LOG_INFO:
+		fprintf(stream, "==> ");
+		break;
+	case PW_LOG_DEBUG:
+		fprintf(stream, "debug: ");
+		break;
+	}
+
+	ret = vfprintf(stream, fmt, ap);
+	return ret;
+}
+
+static int pw_safe_printf(enum pwloglevel_t lvl, const char *fmt, ...)
+{
+	int ret;
+	va_list ap;
+
+	va_start(ap, fmt);
+	ret = pw_safe_vfprintf(lvl, stdout, fmt, ap);
+	va_end(ap);
+
+	return ret;
+}
+
+static int pw_safe_fprintf(enum pwloglevel_t lvl, FILE *stream,
+						   const char *fmt, ...)
+{
+	int ret;
+	va_list ap;
+
+	va_start(ap, fmt);
+	ret = pw_safe_vfprintf(lvl, stderr, fmt, ap);
+	va_end(ap);
+
+	return ret;
+}
+
+int (*pw_printf)(enum pwloglevel_t lvl, const char *fmt, ...) = pw_safe_printf;
+int (*pw_fprintf)(enum pwloglevel_t lvl, FILE *stream, const char *fmt, ...) = pw_safe_fprintf;
+int (*pw_vfprintf)(enum pwloglevel_t lvl, FILE *stream, const char *fmt, va_list ap) = pw_safe_vfprintf;
+
+/* Colorized output printing functions */
+static int pw_cprintf(enum pwloglevel_t lvl, const char *fmt, ...)
 {
 	int ret;
 	va_list ap;
@@ -31,7 +93,7 @@ int pw_printf(enum pwloglevel_t lvl, const char *fmt, ...)
 	return ret;
 }
 
-int pw_fprintf(enum pwloglevel_t lvl, FILE *stream, const char *fmt, ...)
+static int pw_cfprintf(enum pwloglevel_t lvl, FILE *stream, const char *fmt, ...)
 {
 	int ret;
 	va_list ap;
@@ -43,7 +105,7 @@ int pw_fprintf(enum pwloglevel_t lvl, FILE *stream, const char *fmt, ...)
 	return ret;
 }
 
-int pw_vfprintf(enum pwloglevel_t lvl, FILE *stream, const char *fmt, va_list ap)
+static int pw_cvfprintf(enum pwloglevel_t lvl, FILE *stream, const char *fmt, va_list ap)
 {
 	int ret = 0;
 	va_list copy_list;
@@ -74,6 +136,22 @@ int pw_vfprintf(enum pwloglevel_t lvl, FILE *stream, const char *fmt, va_list ap
 	return ret;
 }
 
+void color_print_setup(void)
+{
+	if (config->color) {
+		pw_printf   = pw_cprintf;
+		pw_fprintf  = pw_cfprintf;
+		pw_vfprintf = pw_cvfprintf;
+	}
+}
+
+void color_print_restore(void)
+{
+	pw_printf   = pw_safe_printf;
+	pw_fprintf  = pw_safe_fprintf;
+	pw_vfprintf = pw_safe_vfprintf;
+}
+
 /* Extracts the downloaded archive and removes it upon success.
  * Assumed to be in destination directory before calling this.
  * Returns -1 on fatal errors, > 0 on extraction errors, 0 on success.

util.h

@@ -15,15 +15,21 @@
 
 int powaur_backup(alpm_list_t *targets);
 
-int pw_printf(enum pwloglevel_t lvl, const char *fmt, ...)
+extern int (*pw_printf)(enum pwloglevel_t lvl, const char *fmt, ...)
 __attribute__((format (printf, 2, 3)));
 
-int pw_fprintf(enum pwloglevel_t lvl, FILE *stream, const char *fmt, ...)
+extern int (*pw_fprintf)(enum pwloglevel_t lvl, FILE *stream, const char *fmt, ...)
 __attribute__((format (printf, 3, 4)));
 
-int pw_vfprintf(enum pwloglevel_t lvl, FILE *stream, const char *fmt, va_list ap)
+extern int (*pw_vfprintf)(enum pwloglevel_t lvl, FILE *stream, const char *fmt, va_list ap)
 __attribute__((format (printf, 3, 0)));
 
+/* Setup color printing functions */
+void color_print_setup(void);
+
+/* Restore color printing functions to non-colorized versions */
+void color_print_restore(void);
+
 int extract_file(const char *filename);
 int getcols(void);
 char *strtrim(char *line);