flash: map existing file to memory to use as sandbox flash

source/drivers/sandbox_flash.c

@@ -4,6 +4,7 @@
 #include <string.h>
 
 #include <sys/mman.h>
+#include <sys/stat.h>
 
 #include <flash.h>
 #include <macros.h>
@@ -11,6 +12,7 @@
 #define CONFIG_FLASH_SIZE 4 * MIB
 
 struct stdio_flash_priv {
+	FILE *fp;
 	char *data;
 	size_t size;
 };
@@ -76,6 +78,7 @@ static int stdio_flash_erase(struct flash_dev *dev, uint32_t addr,
 
 struct flash_dev *flash_probe(void)
 {
+	struct stat st;
 	struct flash_dev *dev;
 	struct stdio_flash_priv *priv;
 
@@ -85,18 +88,25 @@ struct flash_dev *flash_probe(void)
 	if (!(priv = malloc(sizeof *priv)))
 		goto err_free_dev;
 
-	if (!(priv->data = mmap(NULL, CONFIG_FLASH_SIZE, PROT_READ | PROT_WRITE,
-		MAP_ANONYMOUS | MAP_PRIVATE, -1, 0)))
+	if (!(priv->fp = fopen("flash.img", "r+b")))
 		goto err_free_priv;
 
-	memset(priv->data, 0xFF, CONFIG_FLASH_SIZE);
-	priv->size = CONFIG_FLASH_SIZE;
+	if (fstat(fileno(priv->fp), &st) < 0)
+		goto err_close_fp;
+
+	priv->size = st.st_size;
+
+	if (!(priv->data = mmap(NULL, priv->size, PROT_READ | PROT_WRITE,
+		MAP_PRIVATE, fileno(priv->fp), 0)))
+		goto err_close_fp;
 
 	dev->priv = priv;
 	dev->ops = &stdio_flash_ops;
 
 	return dev;
 
+err_close_fp:
+	fclose(priv->fp);
 err_free_priv:
 	free(priv);
 err_free_dev: