[PATCH olang] cli: replace memory allocation malloc -> arena

[Johnny Richard <johnny@johnnyrichard.com>]

This code assumes that 1MB will be enough space to accommodate the
entire source code and the AST.  If the source code is greater than half
of the arena capacity, the program will crash.

Signed-off-by: Johnny Richard <johnny@johnnyrichard.com>
---
 src/0c.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/0c.c b/src/0c.c
index 978b770..f0ac974 100644
--- a/src/0c.c
+++ b/src/0c.c
@@ -14,15 +14,19 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
+#include <assert.h>
 #include <errno.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
+#include "arena.h"
 #include "lexer.h"
 #include "string_view.h"
 
+#define ARENA_CAPACITY (1024 * 1024)
+
 typedef struct cli_args
 {
     int argc;
@@ -45,7 +49,7 @@ static void
 print_token(char *file_path, token_t *token);
 
 string_view_t
-read_entire_file(char *file_path);
+read_entire_file(char *file_path, arena_t *arena);
 
 int
 main(int argc, char **argv)
@@ -73,7 +77,8 @@ main(int argc, char **argv)
         return EXIT_FAILURE;
     }
 
-    string_view_t file_content = read_entire_file(opts.file_path);
+    arena_t arena = arena_new(ARENA_CAPACITY);
+    string_view_t file_content = read_entire_file(opts.file_path, &arena);
 
     lexer_t lexer = { 0 };
     lexer_init(&lexer, file_content);
@@ -107,7 +112,7 @@ print_usage(FILE *stream, char *prog)
 }
 
 string_view_t
-read_entire_file(char *file_path)
+read_entire_file(char *file_path, arena_t *arena)
 {
     FILE *stream = fopen(file_path, "rb");
 
@@ -122,7 +127,9 @@ read_entire_file(char *file_path)
     file_content.size = ftell(stream);
     fseek(stream, 0, SEEK_SET);
 
-    file_content.chars = (char *)malloc(file_content.size);
+    assert(file_content.size * 2 < ARENA_CAPACITY);
+
+    file_content.chars = (char *)arena_alloc(arena, (size_t)file_content.size);
 
     if (file_content.chars == NULL) {
         fprintf(stderr, "Could not read file %s: %s\n", file_path, strerror(errno));
-- 
2.43.2