simple_file: Use second variable to create filesystem entries

If HandleProtocol or OpenVolume fails, the entries array will become
non-contiguous, i.e. will have NULL pointers between valid volume
names in the array. Because of that count_lines may return a lower
number of entries than expected. As a result one may not browse all
valid filesystems in the file explorer.

Add a second index variable that will increment only on successfully
created filesystem entries. As a result, count_lines should return
proper length and there won't be any lost partitions or accesses to
invalid entries.

Signed-off-by: Michał Żygowski <[email protected]>

lib/simple_file.c

@@ -170,7 +170,7 @@ simple_file_write_all(EFI_FILE *file, UINTN size, void *buffer)
 EFI_STATUS
 simple_volume_selector(CHAR16 **title, CHAR16 **selected, EFI_HANDLE *h)
 {
-	UINTN count, i;
+	UINTN count, i, j;
 	EFI_HANDLE *vol_handles = NULL;
 	EFI_STATUS efi_status;
 	CHAR16 **entries;
@@ -188,7 +188,7 @@ simple_volume_selector(CHAR16 **title, CHAR16 **selected, EFI_HANDLE *h)
 	if (!entries)
 		return EFI_OUT_OF_RESOURCES;
 
-	for (i = 0; i < count; i++) {
+	for (i = 0, j = 0; i < count; i++) {
 		char buf[4096];
 		UINTN size = sizeof(buf);
 		EFI_FILE_SYSTEM_INFO *fi = (void *)buf;
@@ -218,12 +218,12 @@ simple_volume_selector(CHAR16 **title, CHAR16 **selected, EFI_HANDLE *h)
 		if (!name || StrLen(name) == 0 || StrCmp(name, L" ") == 0)
 			name = DevicePathToStr(DevicePathFromHandle(vol_handles[i]));
 
-		entries[i] = AllocatePool((StrLen(name) + 2) * sizeof(CHAR16));
-		if (!entries[i])
+		entries[j] = AllocatePool((StrLen(name) + 2) * sizeof(CHAR16));
+		if (!entries[j])
 			break;
-		StrCpy(entries[i], name);
+		StrCpy(entries[j++], name);
 	}
-	entries[i] = NULL;
+	entries[j] = NULL;
 
 	val = console_select(title, entries, 0);