[PATCH v3 3/4] lib: efi_loader: efi_memory.c: add efi_realloc() for realloc memory

[Ying-Chun Liu (PaulLiu)]

From: "Ying-Chun Liu (PaulLiu)" <paul.liu at linaro.org>

Add efi_realloc() for realloc memory that previously alloc by efi_alloc().

Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu at linaro.org>
Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
Cc: Ilias Apalodimas <ilias.apalodimas at linaro.org>
Cc: Peter Robinson <pbrobinson at gmail.com>
---
 include/efi_loader.h        |  2 ++
 lib/efi_loader/efi_memory.c | 52 +++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/include/efi_loader.h b/include/efi_loader.h
index d0c72d0bc58..ff7ca5a0480 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -878,6 +878,8 @@ efi_status_t efi_next_variable_name(efi_uintn_t *size, u16 **buf,
 #define efi_size_in_pages(size) (((size) + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT)
 /* Allocate boot service data pool memory */
 void *efi_alloc(size_t len);
+/* Reallocate boot service data pool memory */
+void *efi_realloc(void *ptr, size_t len);
 /* Allocate pages on the specified alignment */
 void *efi_alloc_aligned_pages(u64 len, int memory_type, size_t align);
 /* More specific EFI memory allocator, called by EFI payloads */
diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index 0abb1f6159a..4c76df642dc 100644
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -666,6 +666,58 @@ void *efi_alloc(size_t size)
 	return buf;
 }
 
+/**
+ * efi_realloc() - reallocate boot services data pool memory
+ *
+ * Reallocate memory from pool for a new size and copy the data from old one.
+ *
+ * @ptr:	pointer to old buffer
+ * @size:	number of bytes to allocate
+ * Return:	pointer to allocated memory or NULL
+ */
+void *efi_realloc(void *ptr, size_t size)
+{
+	efi_status_t ret;
+	void *new_ptr;
+	struct efi_pool_allocation *alloc;
+	u64 num_pages = efi_size_in_pages(size +
+					  sizeof(struct efi_pool_allocation));
+	size_t old_size;
+
+	if (!ptr)
+		return efi_alloc(size);
+
+	ret = efi_check_allocated((uintptr_t)ptr, true);
+	if (ret != EFI_SUCCESS)
+		return ptr;
+
+	alloc = container_of(ptr, struct efi_pool_allocation, data);
+
+	/* Check that this memory was allocated by efi_allocate_pool() */
+	if (((uintptr_t)alloc & EFI_PAGE_MASK) ||
+	    alloc->checksum != checksum(alloc)) {
+		printf("%s: illegal realloc 0x%p\n", __func__, ptr);
+		return ptr;
+	}
+
+	/* Don't realloc. The actual size in pages is the same. */
+	if (alloc->num_pages == num_pages)
+		return ptr;
+
+	old_size = alloc->num_pages * EFI_PAGE_SIZE -
+		sizeof(struct efi_pool_allocation);
+
+	new_ptr = efi_alloc(size);
+
+	/* copy old data to new alloced buffer */
+	memcpy(new_ptr, ptr, min(size, old_size));
+
+	/* free the old buffer */
+	efi_free_pool(ptr);
+
+	return new_ptr;
+}
+
 /**
  * efi_free_pool() - free memory from pool
  *
-- 
2.39.5