Save ESP filename

Signed-off-by: Javier Tia <javier.tia@linaro.org>

src/lib.c

@@ -16,9 +16,9 @@
 
 #include "efivar.h"
 
-#define EFI_VARTOFILE	 "b2ac5fc9-92b7-4acd-aeac-11e818c3130c-VarToFile"
+#define VAR2FILE	"/sys/firmware/efi/efivars/VarToFile-b2ac5fc9-92b7-4acd-aeac-11e818c3130c"
 #define EFI_RTSTORAGEVOLATILE	 "b2ac5fc9-92b7-4acd-aeac-11e818c3130c-RTStorageVolatile"
-#define PATH_SIZE 4096
+#define PATH_SIZE	4096
 
 static const char *esp_paths[] = {
 	"/boot",
@@ -345,8 +345,6 @@ get_esp_filename(char **esp_filename)
 			fprintf(stderr, "efivar: Error %d getting filename from RTStorageVolatile\n", rc);
 			return rc;
 		}
-
-		printf("efivar: RSTStorageVolatile found with %s\n", (char *)filename);
 	}
 
 	*esp_filename = (char *)filename;
@@ -373,6 +371,49 @@ search_esp_filename(const char *filename, char *esp_filename)
 	esp_filename[0] = '\0';
 }
 
+static
+void save_esp_filename(const char *esp_filename) {
+    FILE *var2file = NULL;
+    FILE *output_file = NULL;
+    unsigned char buffer[1024];
+    size_t bytes_read, bytes_written;
+	bool fail = false;
+
+    var2file = fopen(VAR2FILE, "rb");
+    if (var2file == NULL) {
+        fprintf(stderr, "Error: Could not open input file '%s'\n", VAR2FILE);
+        exit(1);
+    }
+
+    output_file = fopen(esp_filename, "wb");
+    if (output_file == NULL) {
+        fprintf(stderr, "Error: Could not open output file '%s'\n", esp_filename);
+        fclose(var2file);
+        exit(1);
+    }
+
+    if (fread(buffer, 1, 4, var2file) < 4) {
+        fprintf(stderr, "Error: Could not skip first 4 bytes or file is too small\n");
+        fail = true;
+        goto clean;
+    }
+
+    while ((bytes_read = fread(buffer, 1, sizeof(buffer), var2file)) > 0) {
+        bytes_written = fwrite(buffer, 1, bytes_read, output_file);
+        if (bytes_written != bytes_read) {
+            fprintf(stderr, "Error: Could not write data to output file\n");
+            fail = true;
+            goto clean;
+        }
+    }
+
+clean:
+    fclose(var2file);
+    fclose(output_file);
+	if (fail)
+		exit(1);
+}
+
 void PUBLIC
 efi_save_esp_filename(void)
 {
@@ -387,7 +428,7 @@ efi_save_esp_filename(void)
 
 	search_esp_filename(esp_filename, esp_filename_path);
 	if (esp_filename_path[0] != '\0') {
-		printf("efivar: VarToFile content saved at %s\n", esp_filename_path);
+		save_esp_filename(esp_filename_path);
 	}
 	else {
 		fprintf(stderr, "efivar: no found file in ESP part to save VarToFile\n");