Add colors to error output and improve messages

include/patchelfcrc/reporting.h

@@ -21,14 +21,25 @@
 
 #include <stdbool.h>
 
-#define print_err(fmt, ...) fprintf(stderr, "[ERR] " fmt, ## __VA_ARGS__)
+/**
+ * @brief Setting for reporting to console.
+ */
+enum reporting_color_mode {
+    COLOR_MODE_DETECT, /**< @brief Automatically detect if tty. If tty, color is used */
+    COLOR_MODE_COLOR, /**< @brief Force color mode on stderr */
+    COLOR_MODE_COLOR_OFF, /**< @brief Force no color on stderr */
+};
 
-#define print_warn(fmt, ...) fprintf(stderr, "[WARN] " fmt, ## __VA_ARGS__)
+void print_err(const char *fmt, ...);
+
+void print_warn(const char *fmt, ...);
 
 void print_debug(const char *fmt, ...);
 
-void reporting_enable_verbose(void);
+void reporting_enable_verbose(bool state);
 
 bool reporting_get_verbosity(void);
 
+void reporting_init(enum reporting_color_mode mode);
+
 #endif /* _REPORTING_H_ */

man/patchelfcrc.1.md

@@ -84,6 +84,9 @@
 **--usage**
 : Print usage hints on command line options.
 
+**--no-color**
+: Force output on stdout and stderr to be pure text without color codes.
+
 # EXAMPLES
 
 **patchelfcrc** --list-crcs

src/elfpatch.c

@@ -470,12 +470,12 @@ elfpatch_handle_t *elf_patch_open(const char *path, bool readonly, bool expect_l
 		case 1:
 			print_debug("ELF Endianess: little\n");
 			if (!expect_little_endian)
-				print_err("Big endian format expected. File is little endian. Double check settings!\n");
+				print_warn("Big endian format expected. File is little endian. Double check settings!\n");
 			break;
 		case 2:
 			print_debug("ELF Endianess: big\n");
 			if (expect_little_endian)
-				print_err("Little endian format expected. File is big endian. Double check settings!\n");
+				print_warn("Little endian format expected. File is big endian. Double check settings!\n");
 			break;
 		default:
 			print_err("Cannot determine endianess of ELF file. EI_DATA is: %d\n", ident[5]);

src/main.c

@@ -40,8 +40,10 @@ const char *argp_program_bug_address = "<mario [dot] huettel [at] linux [dot] co
 #define ARG_KEY_IMPORT (6)
 #define ARG_KEY_USE_VMA (7)
 #define ARG_KEY_XSD (8)
+#define ARG_KEY_FORCE_NO_COLOR (9)
 
 struct command_line_options {
+	bool force_nocolor;
 	bool little_endian;
 	bool dry_run;
 	bool verbose;
@@ -104,6 +106,9 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state)
 	case ARG_KEY_USE_VMA:
 		args->use_vma = true;
 		break;
+	case ARG_KEY_FORCE_NO_COLOR:
+		args->force_nocolor = true;
+		break;
 	case 'p':
 		/* Polyniomial */
 		args->crc.polynomial = strtoull(arg, &endptr, 0);
@@ -195,6 +200,7 @@ static int parse_cmdline_options(int *argc, char ***argv, struct command_line_op
 		{"import", ARG_KEY_IMPORT, "XML", 0, "Do not caclulate CRCs but import them from file", 3},
 		{"xsd", ARG_KEY_XSD, 0, 0, "Print XSD to stdout", 0},
 		{"use-vma", ARG_KEY_USE_VMA, 0, 0, "Use the VMA instead of the LMA for struct output", 2},
+		{"no-color", ARG_KEY_FORCE_NO_COLOR, 0, 0, "Force the output to be text only without colors", 0},
 		/* Sentinel */
 		{NULL, 0, 0, 0, NULL, 0}
 	};
@@ -425,8 +431,11 @@ int main(int argc, char **argv)
 		goto free_cmds;
 	}
 
+	/* Initialize console output */
+	reporting_init(cmd_opts.force_nocolor ? COLOR_MODE_COLOR_OFF : COLOR_MODE_DETECT);
+
 	if (cmd_opts.verbose || cmd_opts.dry_run)
-		reporting_enable_verbose();
+		reporting_enable_verbose(true);
 
 	print_verbose_start_info(&cmd_opts);
 
@@ -450,7 +459,7 @@ int main(int argc, char **argv)
 		print_warn("--use-vma option only has an effect when exporting as struct output.\n");
 
 	if (!cmd_opts.output_section && cmd_opts.export_xml == NULL)
-		print_err("No output section / XML export specified. Will continue but not create any output\n");
+		print_warn("No output section / XML export specified. Will continue but not create any output\n");
 
 	/* Prepare libelf for use with the latest ELF version */
 	elf_version(EV_CURRENT);

src/reporting.c

@@ -19,9 +19,66 @@
 #include <patchelfcrc/reporting.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
 
 static bool global_verbosity_state = false;
+static bool reporting_use_color = false;
+
+#define COLOR_RESET "\e[0m"
+
+#define COLOR_BOLD_RED "\e[31;1m"
+#define COLOR_RED "\e[31m"
+
+#define COLOR_BOLD_YELLOW "\e[33;1m"
+#define COLOR_YELLOW "\e[33m"
+
+
+void print_err(const char *fmt, ...)
+{
+	va_list va;
+	va_start(va, fmt);
+
+	/* Set color */
+	if (reporting_use_color)
+		fprintf(stderr, COLOR_BOLD_RED "[ERR]" COLOR_RESET " " COLOR_RED);
+	else
+		fprintf(stderr, "[ERR] ");
+
+
+	vfprintf(stderr, fmt, va);
+
+	/* Reset color */
+	if (reporting_use_color) {
+		fprintf(stderr, COLOR_RESET);
+	}
+
+	va_end(va);
+}
+
+void print_warn(const char *fmt, ...)
+{
+	va_list va;
+	va_start(va, fmt);
+
+	/* Set color */
+	if (reporting_use_color)
+		fprintf(stderr, COLOR_BOLD_YELLOW "[WARN]" COLOR_RESET " " COLOR_YELLOW);
+	else
+		fprintf(stderr, "[WARN] ");
+
+
+	vfprintf(stderr, fmt, va);
+
+	/* Reset color */
+	if (reporting_use_color) {
+		fprintf(stderr, COLOR_RESET);
+	}
+
+	va_end(va);
+}
 
 void print_debug(const char *fmt, ...)
 {
@@ -34,12 +91,52 @@ void print_debug(const char *fmt, ...)
 	}
 }
 
-void reporting_enable_verbose(void)
+void reporting_enable_verbose(bool state)
 {
-	global_verbosity_state = true;
+	global_verbosity_state = state;
 }
 
 bool reporting_get_verbosity(void)
 {
 	return global_verbosity_state;
 }
+
+/**
+ * @brief Check whether stderr supports colors.
+ * @note This function checks for a tty and the TERM environment variable. It has to contain "xterm".
+ * @return true if colors are supported
+ * @return false if no colors should be used
+ */
+static bool stderr_supports_colors(void)
+{
+	const char *env_var;
+	const char *tmp;
+
+	if (isatty(2) != 1)
+		return false;
+
+	env_var = getenv("TERM");
+	if (!env_var)
+		return false;
+
+	tmp = strstr(env_var, "xterm");
+	if (!tmp)
+		return false;
+
+	return true;
+}
+
+void reporting_init(enum reporting_color_mode mode)
+{
+	switch (mode) {
+	case COLOR_MODE_COLOR:
+		reporting_use_color = true;
+		break;
+	case COLOR_MODE_COLOR_OFF:
+		reporting_use_color = false;
+		break;
+	default: /* Auto detect case and invalid settings */
+		reporting_use_color = stderr_supports_colors();
+		break;
+	}
+}