grub.c

#include "bootloader.h"
#include "grub.h"

static int grubenv_open(struct grubenv_t *grubenv)
{
	FILE *fp = NULL;
	size_t size;
	int ret = 0;
	char *buf = NULL, *key = NULL, *value = NULL;

	fp = fopen(GRUBENV_PATH, "rb");
	if (!fp) {
		ERROR("Failed to open grubenv file: %s", GRUBENV_PATH);
		ret = -1;
		goto cleanup;
	}

	if (fseek(fp, 0, SEEK_END)) {
		ERROR("Failed to seek end grubenv file: %s", GRUBENV_PATH);
		ret = -1;
		goto cleanup;
	}

	size = (size_t)ftell(fp);

	if (size != GRUBENV_SIZE) {
		ERROR("Invalid grubenv file size: %d", (int)size);
		ret = -1;
		goto cleanup;
	}

	if (fseek(fp, 0, SEEK_SET)) {
		ERROR("Failed to seek set grubenv file: %s", GRUBENV_PATH);
		ret = -1;
		goto cleanup;
	}

	buf = calloc(1, size + 1);
	if (!buf) {
		ERROR("Not enough memory for environment");
		ret = -ENOMEM;
		goto cleanup;
	}

	if (fread(buf, 1, size, fp) != size) {
		ERROR("Failed to read file %s", GRUBENV_PATH);
		ret = 1;
		goto cleanup;
	}

	if (memcmp(buf, GRUBENV_HEADER, strlen(GRUBENV_HEADER) -1)) {
		ERROR("Invalid grubenv header");
		ret = -1;
		goto cleanup;
	}
    
	char *entry = buf;
	char *p_char = buf;
	while(*p_char != '\0') {
		if (*p_char != '\n') {
			p_char++;
			continue;
		}
        
		if (*entry == '#') {
			entry = p_char + 1;
			p_char++;
			continue;
		}