Emit long string values without truncation

There are few long options (`bin_shards` and `slab_sizes` for example)
when they are specified and we emit statistics value gets truncated.

Moved emitting logic for strings into separate `emitter_emit_str`
function. It will try to emit string same way as before and if value is
too long will fallback emiting rest partially with chunks of `BUF_SIZE`.

Justification for long strings (longer than `BUF_SIZE`) is not
supported.

include/jemalloc/internal/emitter.h

@@ -118,6 +118,37 @@ emitter_gen_fmt(char *out_fmt, size_t out_size, const char *fmt_specifier,
 	return out_fmt;
 }
 
+static inline void
+emitter_emit_str(emitter_t *emitter, emitter_justify_t justify, int width,
+    char *fmt, size_t fmt_size, const char *str) {
+#define BUF_SIZE 256
+	char buf[BUF_SIZE];
+	size_t str_written = malloc_snprintf(buf, BUF_SIZE, "\"%s\"", str);
+	emitter_printf(emitter,
+	    emitter_gen_fmt(fmt, fmt_size, "%s", justify, width), buf);
+	if (str_written < BUF_SIZE) {
+		return;
+	}
+	/*
+	 * There is no support for long string justification at the moment as
+	 * we output them partially with multiple malloc_snprintf calls and
+	 * justufication will work correctly only withing one call.
+	 * Fortunately this is not a big concern as we don't use justufication
+	 * with long strings right now.
+	 *
+	 * We emitted leading quotation mark and trailing '\0', hence need to
+	 * exclude extra characters from str shift.
+	 */
+	str += BUF_SIZE - 2;
+	do {
+		str_written = malloc_snprintf(buf, BUF_SIZE, "%s\"", str);
+		str += str_written >= BUF_SIZE ? BUF_SIZE - 1 : str_written;
+		emitter_printf(emitter,
+		    emitter_gen_fmt(fmt, fmt_size, "%s", justify, width), buf);
+	} while (str_written >= BUF_SIZE);
+#undef BUF_SIZE
+}
+
 /*
  * Internal.  Emit the given value type in the relevant encoding (so that the
  * bool true gets mapped to json "true", but the string "true" gets mapped to
@@ -128,8 +159,6 @@ emitter_gen_fmt(char *out_fmt, size_t out_size, const char *fmt_specifier,
 static inline void
 emitter_print_value(emitter_t *emitter, emitter_justify_t justify, int width,
     emitter_type_t value_type, const void *value) {
-	size_t str_written;
-#define BUF_SIZE 256
 #define FMT_SIZE 10
 	/*
 	 * We dynamically generate a format string to emit, to let us use the
@@ -138,7 +167,6 @@ emitter_print_value(emitter_t *emitter, emitter_justify_t justify, int width,
 	 * cases.
 	 */
 	char fmt[FMT_SIZE];
-	char buf[BUF_SIZE];
 
 #define EMIT_SIMPLE(type, format)					\
 	emitter_printf(emitter,						\
@@ -167,15 +195,8 @@ emitter_print_value(emitter_t *emitter, emitter_justify_t justify, int width,
 		EMIT_SIMPLE(size_t, "%zu")
 		break;
 	case emitter_type_string:
-		str_written = malloc_snprintf(buf, BUF_SIZE, "\"%s\"",
+		emitter_emit_str(emitter, justify, width, fmt, FMT_SIZE,
 		    *(const char *const *)value);
-		/*
-		 * We control the strings we output; we shouldn't get anything
-		 * anywhere near the fmt size.
-		 */
-		assert(str_written < BUF_SIZE);
-		emitter_printf(emitter,
-		    emitter_gen_fmt(fmt, FMT_SIZE, "%s", justify, width), buf);
 		break;
 	case emitter_type_uint32:
 		EMIT_SIMPLE(uint32_t, "%" FMTu32)
@@ -189,7 +210,6 @@ emitter_print_value(emitter_t *emitter, emitter_justify_t justify, int width,
 	default:
 		unreachable();
 	}
-#undef BUF_SIZE
 #undef FMT_SIZE
 }
 

test/unit/emitter.c

@@ -222,6 +222,17 @@ emit_types(emitter_t *emitter) {
 	ssize_t zd = -456;
 	size_t zu = 456;
 	const char *str = "string";
+	const char *long_str =
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz";
 	uint32_t u32 = 789;
 	uint64_t u64 = 10000000000ULL;
 
@@ -232,8 +243,9 @@ emit_types(emitter_t *emitter) {
 	emitter_kv(emitter, "k4", "K4", emitter_type_ssize, &zd);
 	emitter_kv(emitter, "k5", "K5", emitter_type_size, &zu);
 	emitter_kv(emitter, "k6", "K6", emitter_type_string, &str);
-	emitter_kv(emitter, "k7", "K7", emitter_type_uint32, &u32);
+	emitter_kv(emitter, "k7", "K7", emitter_type_string, &long_str);
-	emitter_kv(emitter, "k8", "K8", emitter_type_uint64, &u64);
+	emitter_kv(emitter, "k8", "K8", emitter_type_uint32, &u32);
+	emitter_kv(emitter, "k9", "K9", emitter_type_uint64, &u64);
 	/*
 	 * We don't test the title type, since it's only used for tables.  It's
 	 * tested in the emitter_table_row tests.
@@ -249,8 +261,18 @@ static const char *types_json =
 "\t\"k4\": -456,\n"
 "\t\"k5\": 456,\n"
 "\t\"k6\": \"string\",\n"
-"\t\"k7\": 789,\n"
+"\t\"k7\": \"abcdefghijklmnopqrstuvwxyz "
-"\t\"k8\": 10000000000\n"
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz\",\n"
+"\t\"k8\": 789,\n"
+"\t\"k9\": 10000000000\n"
 "}\n";
 static const char *types_json_compact =
 "{"
@@ -260,8 +282,18 @@ static const char *types_json_compact =
 	"\"k4\":-456,"
 	"\"k5\":456,"
 	"\"k6\":\"string\","
-	"\"k7\":789,"
+	"\"k7\":\"abcdefghijklmnopqrstuvwxyz "
-	"\"k8\":10000000000"
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz "
+	    "abcdefghijklmnopqrstuvwxyz\","
+	"\"k8\":789,"
+	"\"k9\":10000000000"
 "}";
 static const char *types_table =
 "K1: false\n"
@@ -270,8 +302,18 @@ static const char *types_table =
 "K4: -456\n"
 "K5: 456\n"
 "K6: \"string\"\n"
-"K7: 789\n"
+"K7: \"abcdefghijklmnopqrstuvwxyz "
-"K8: 10000000000\n";
+    "abcdefghijklmnopqrstuvwxyz "
+    "abcdefghijklmnopqrstuvwxyz "
+    "abcdefghijklmnopqrstuvwxyz "
+    "abcdefghijklmnopqrstuvwxyz "
+    "abcdefghijklmnopqrstuvwxyz "
+    "abcdefghijklmnopqrstuvwxyz "
+    "abcdefghijklmnopqrstuvwxyz "
+    "abcdefghijklmnopqrstuvwxyz "
+    "abcdefghijklmnopqrstuvwxyz\"\n"
+"K8: 789\n"
+"K9: 10000000000\n";
 
 static void
 emit_modal(emitter_t *emitter) {