Improve error code formattingfixes

For text output, allocate exactly the right buffer size.

For JSON output, return error codes as an array, not just a
concatinated text string.

2 files changed, 95 insertions, 42 deletions

diff --git a/src/main.c b/src/main.c
index a66c6a6..4ab43f7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -285,7 +285,7 @@ for(int i = 0; i < img->height; ++i)
 				if (status.err_info_1 || status.err_info_2)
 					bail_out(&json_ctx,
 						 "Printer reported error(s): %s",
-						 ql_decode_errors(&status));
+						 ql_decode_errors_human(&status));
 			} while (status.status_type != QL_STATUS_TYPE_PRINTING_DONE);
 			alarm(0);
 
diff --git a/src/ql.c b/src/ql.c
index 3a94c03..02ac3cb 100644
--- a/src/ql.c
+++ b/src/ql.c
@@ -12,6 +12,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
+#include <assert.h>
 
 #define QL_XMIT_SIZE 4096
 #define QL_BUF_SIZE (QL_XMIT_SIZE * 2)
@@ -315,52 +316,105 @@ const char *ql_decode_mode(const ql_status_t *status)
 		return "no-auto-cut";
 }
 
-const char *ql_decode_errors(const ql_status_t *status)
-{
-	typedef struct {
-		uint16_t bit;
-		const char *str;
-	} strmap_t;
+typedef struct {
+	uint16_t bit;
+	const char *str;
+} strmap_t;
 
 #define ERR1(x) (x << 0)
 #define ERR2(x) (x << 8)
-	const strmap_t strmap[] = {
-		{ERR1(QL_ERR_1_NO_MEDIA), "no-media "},
-		{ERR1(QL_ERR_1_END_OF_MEDIA), "end-of-media "},
-		{ERR1(QL_ERR_1_CUTTER_JAM), "cutter-jam "},
-		{ERR1(QL_ERR_1_PRINTER_IN_USE), "printer-in-use "},
-		{ERR1(QL_ERR_1_PRINTER_TURNED_OFF), "printer-turned-off "},
-		{ERR1(QL_ERR_1_HIGH_VOLTAGE_ADAPTER), "high-voltage-adapter "},
-		{ERR1(QL_ERR_1_FAN_MOTOR_ERROR), "fan-motor-error "},
-
-		{ERR2(QL_ERR_2_REPLACE_MEDIA), "replace-media "},
-		{ERR2(QL_ERR_2_EXPANSION_BUFFER_FULL), "expansion-buffer-full "},
-		{ERR2(QL_ERR_2_COMMUNICATION_ERROR), "communication-error "},
-		{ERR2(QL_ERR_2_COMMUNICATION_BUFFER_FULL), "communication-buffer-full "},
-		{ERR2(QL_ERR_2_COVER_OPEN), "cover-open "},
-		{ERR2(QL_ERR_2_CANCEL_KEY), "cancel-key-pressed "},
-		{ERR2(QL_ERR_2_MEDIA_CANNOT_BE_FED), "media-cannot-be-fed "},
-		{ERR2(QL_ERR_2_SYSTEM_ERROR), "system-error "}
-	};
+static const strmap_t strmap[] = {
+	{ERR1(QL_ERR_1_NO_MEDIA), "no-media"},
+	{ERR1(QL_ERR_1_END_OF_MEDIA), "end-of-media"},
+	{ERR1(QL_ERR_1_CUTTER_JAM), "cutter-jam"},
+	{ERR1(QL_ERR_1_PRINTER_IN_USE), "printer-in-use"},
+	{ERR1(QL_ERR_1_PRINTER_TURNED_OFF), "printer-turned-off"},
+	{ERR1(QL_ERR_1_HIGH_VOLTAGE_ADAPTER), "high-voltage-adapter"},
+	{ERR1(QL_ERR_1_FAN_MOTOR_ERROR), "fan-motor-error"},
+
+	{ERR2(QL_ERR_2_REPLACE_MEDIA), "replace-media"},
+	{ERR2(QL_ERR_2_EXPANSION_BUFFER_FULL), "expansion-buffer-full"},
+	{ERR2(QL_ERR_2_COMMUNICATION_ERROR), "communication-error"},
+	{ERR2(QL_ERR_2_COMMUNICATION_BUFFER_FULL), "communication-buffer-full"},
+	{ERR2(QL_ERR_2_COVER_OPEN), "cover-open"},
+	{ERR2(QL_ERR_2_CANCEL_KEY), "cancel-key-pressed"},
+	{ERR2(QL_ERR_2_MEDIA_CANNOT_BE_FED), "media-cannot-be-fed"},
+	{ERR2(QL_ERR_2_SYSTEM_ERROR), "system-error"}
+};
+
+const char *ql_decode_errors_human(const ql_status_t *status)
+{
+	static char *buf = NULL;
+	unsigned int i;
+	uint16_t errs;
+	size_t len;
+
+	errs = ERR1(status->err_info_1) | ERR2(status->err_info_2);
+	if (!errs)
+		return "none";
 
-	static char *buf = 0;
-	if (!buf) {
-		int len = 0;
-		for (unsigned i = 0; i < (sizeof(strmap) / sizeof(strmap[0])); ++i)
-			len += strlen(strmap[i].str);
-		buf = malloc(len + 1);
-		if (!buf)
-			return "<host-out-of-memory>";
+	len = 0;
+	for (i = 0; i < (sizeof(strmap) / sizeof(strmap[0])); ++i)
+		if (errs & strmap[i].bit)
+			len += strlen(strmap[i].str) + 1; /* space or terminating NULL byte */
+	if (!len)
+		return "unknown-error";
+
+	buf = malloc(len);
+	if (!buf)
+		return "<host-out-of-memory>";
+
+	buf[0] = '\0';
+	for (i = 0; i < (sizeof(strmap) / sizeof(strmap[0])); ++i) {
+		if (errs & strmap[i].bit) {
+			if (buf[0])
+				strcat(buf, " ");
+			strcat(buf, strmap[i].str);
+		}
 	}
+	assert(strlen(buf) == len - 1);
+	return buf;
+}
+
+const char *ql_decode_errors_json(const ql_status_t *status)
+{
+	static char *buf = NULL;
+	unsigned int i;
+	uint16_t errs;
+	size_t len;
 
-	uint16_t errs = ERR1(status->err_info_1) | ERR2(status->err_info_2);
-	buf[0] = 0;
-	for (unsigned i = 0; i < (sizeof(strmap) / sizeof(strmap[0])); ++i) {
+	errs = ERR1(status->err_info_1) | ERR2(status->err_info_2);
+	if (!errs)
+		return "null";
+
+	len = 2; /* [] */
+	for (i = 0; i < (sizeof(strmap) / sizeof(strmap[0])); ++i)
 		if (errs & strmap[i].bit)
+			len += strlen(strmap[i].str) + 3; /* quotes + comma or terminating NULL byte */
+	if (!len)
+		return "\"unknown-error\"";
+
+	buf = malloc(len);
+	if (!buf)
+		return "\"<host-out-of-memory>\"";
+
+	buf[0] = '[';
+	buf[1] = '\0';
+	for (i = 0; i < (sizeof(strmap) / sizeof(strmap[0])); ++i) {
+		if (errs & strmap[i].bit) {
+			if (buf[1])
+				strcat(buf, ",");
+			strcat(buf, "\"");
 			strcat(buf, strmap[i].str);
+			strcat(buf, "\"");
+		}
 	}
-	return (buf[0] == 0) ? "none" : buf;
+	strcat(buf, "]");
+	assert(strlen(buf) == len - 1);
+	return buf;
 }
+#undef ERR1
+#undef ERR2
 
 const char *ql_decode_media_type(const ql_status_t *status)
 {
@@ -391,7 +445,7 @@ static void ql_decode_print_status_human(FILE *f, const ql_status_t *status, uns
 	if (flags & QL_DECODE_MODE)
 		fprintf(f, fmt_s, "Mode", ql_decode_mode(status));
 	if (flags & QL_DECODE_ERROR)
-		fprintf(f, fmt_s, "Errors", ql_decode_errors(status));
+		fprintf(f, fmt_s, "Errors", ql_decode_errors_human(status));
 	if (flags & QL_DECODE_MEDIA) {
 		fprintf(f, fmt_s, "Media type", ql_decode_media_type(status));
 		fprintf(f, fmt_u, "Media width (mm)", status->media_width_mm);
@@ -408,6 +462,7 @@ static void ql_decode_print_status_json(FILE *f, const ql_print_json_t *json_ctx
 
 	const char *fmt_s = "\t\"%s\": \"%s\",\n";
 	const char *fmt_u = "\t\"%s\": %u,\n";
+	const char *fmt_d = "\t\"%s\": %s,\n";
 	bool status_ok = true;
 	fprintf(f, "{\n");
 	fprintf(f, fmt_s, "printer", ql_json_escape(json_ctx->printer));
@@ -416,11 +471,9 @@ static void ql_decode_print_status_json(FILE *f, const ql_print_json_t *json_ctx
 	if (flags & QL_DECODE_MODE)
 		fprintf(f, fmt_s, "mode", ql_decode_mode(status));
 	if (flags & QL_DECODE_ERROR) {
-		const char *errors = ql_decode_errors(status);
-
-		if (strcmp(errors, "none") != 0)
+		if (status->err_info_1 || status->err_info_2)
 			status_ok = false;
-		fprintf(f, fmt_s, "errors", ql_decode_errors(status));
+		fprintf(f, fmt_d, "errors", ql_decode_errors_json(status));
 	}
 	if (flags & QL_DECODE_MEDIA) {
 		fprintf(f, fmt_s, "media_type", ql_decode_media_type(status));