shell: simplify prompt()

source/shell/cmd.c

@@ -5,6 +5,7 @@
 #include <shell.h>
 
 static int should_exit = 0;
+static char buf[128];
 static void do_exit(const char *s);
 
 struct cmd main_cmds[] = {
@@ -25,35 +26,21 @@ static void do_exit(const char *s)
 
 static char *prompt(const char *prefix)
 {
-	char *alloc, *line;
+	size_t len;
-	size_t nbytes = 0, nalloc_bytes = 16;
-	char c;
 
 	printf(prefix);
 
-	if (!(line = malloc(nalloc_bytes)))
+	if (!fgets(buf, 128, stdin))
 		return NULL;
 
-	while ((c = getchar()) && c != '\n') {
+	len = strlen(buf);
-		if (nbytes + 1 >= nalloc_bytes) {
-			nalloc_bytes *= 2;
 
-			if (!(alloc = realloc(line, nalloc_bytes)))
+	if (len > 0 && buf[len - 1] == '\n')
-				goto err_free_line;
+		buf[len - 1] = '\0';
 
-			line = alloc;
+	putchar('\n');
-		}
-
-		line[nbytes++] = c;
-	}
 
-	line[nbytes] = '\0';
+	return buf;
-
-	return line;
-
-err_free_line:
-	free(line);
-	return NULL;
 }
 
 void cmd_exec(struct cmd *cmds, const char *line)
@@ -88,6 +75,5 @@ void cmd_loop(const char *show)
 	while (!should_exit) {
 		line = prompt(show);
 		cmd_exec(main_cmds, line);
-		free(line);
 	}
 }