Avoid using strcat and small realloc

For performance reasons with large strings, we don't want to
call strlen multiple times or to realloc one byte at a time.

2 files changed, 20 insertions, 9 deletions

diff --git a/src/execute.c b/src/execute.c
index e56526f1..c36f6416 100644
--- a/src/execute.c
+++ b/src/execute.c
@@ -358,11 +358,17 @@ format_command(char **argv)
 		len += strlen(argv[i]);
 	}
 	len += 1;
-	char *buf = x_calloc(1, len + 1);
+	char *buf = x_malloc(len + 1);
+	char *p = buf;
 	for (int i = 0; argv[i]; i++) {
-		strcat(buf, (i == 0) ? "" : " ");
-		strcat(buf, argv[i]);
+		if (i != 0) {
+			*p++ = ' ';
+		}
+		for (char *q = argv[i]; *q != '\0'; q++) {
+			*p++ = *q;
+		}
 	}
-	strcat(buf, "\n");
+	*p++ = '\n';
+	*p++ = '\0';
 	return buf;
 }
diff --git a/src/util.c b/src/util.c
index d9143cea..40e553ea 100644
--- a/src/util.c
+++ b/src/util.c
@@ -35,8 +35,11 @@
 
 static FILE *logfile;
 static char *logbuffer;
+static size_t logbufsize;
 static size_t logsize;
 
+#define LOGBUFSIZ 1024
+
 static bool
 init_log(void)
 {
@@ -47,7 +50,8 @@ init_log(void)
 	}
 	assert(conf);
 	if (conf->debug) {
-		logbuffer = x_calloc(1, 1);
+		logbufsize = LOGBUFSIZ;
+		logbuffer = x_malloc(logbufsize);
 		logsize = 0;
 	}
 	if (str_eq(conf->log_file, "")) {
@@ -68,11 +72,12 @@ static void
 append_log(const char *s, size_t len)
 {
 	assert(logbuffer);
-	if (logsize + len > logsize) {
-		logbuffer = x_realloc(logbuffer, logsize + len + 1);
-		logsize = logsize + len;
+	if (logsize + len + 1 > logbufsize) {
+		logbufsize = logbufsize + len + 1 + LOGBUFSIZ;
+		logbuffer = x_realloc(logbuffer, logbufsize);
 	}
-	strncat(logbuffer, s, len);
+	strncpy(logbuffer + logsize, s, len);
+	logsize += len;
 }
 
 static void