The right implementation of CGPT label conversion between UTF8 and UTF16.

cgpt/cgpt.h

 // Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef VBOOT_REFERENCE_UTILITY_CGPT_CGPT_H_
 #define VBOOT_REFERENCE_UTILITY_CGPT_CGPT_H_
 
 #define _GNU_SOURCE
 #define _FILE_OFFSET_BITS 64
 #include <features.h>
@@ skipping 63 matching lines @@
 void GuidToStr(const Guid *guid, char *str, unsigned int buflen);
 int IsZero(const Guid *guid);
 
 
 int ReadPMBR(struct drive *drive);
 int WritePMBR(struct drive *drive);
 
 
 /* Convert possibly unterminated UTF16 string to UTF8.
  * Caller must prepare enough space for UTF8, which could be up to
- * twice the number of UTF16 chars plus the terminating '\0'.
+ * twice the byte length of UTF16 string plus the terminating '\0'.
+ *
+ * Return: CGPT_OK --- all character are converted successfully.
+ *         CGPT_FAILED --- convert error, i.e. output buffer is too short.
  */
-void UTF16ToUTF8(const uint16_t *utf16, unsigned int maxinput,
-                 uint8_t *utf8, unsigned int maxoutput);
+int UTF16ToUTF8(const uint16_t *utf16, unsigned int maxinput,
+                uint8_t *utf8, unsigned int maxoutput);
+
 /* Convert null-terminated UTF8 string to UTF16.
- * Caller must prepare enough space for UTF16, including a terminating 0x0000
+ * Caller must prepare enough space for UTF16, which is the byte length of UTF8
+ * plus the terminating 0x0000.
+ *
+ * Return: CGPT_OK --- all character are converted successfully.
+ *         CGPT_FAILED --- convert error, i.e. output buffer is too short.
  */
-void UTF8ToUTF16(const uint8_t *utf8, uint16_t *utf16, unsigned int maxoutput);
+int UTF8ToUTF16(const uint8_t *utf8, uint16_t *utf16, unsigned int maxoutput);
 
 /* Helper functions for supported GPT types. */
 int ResolveType(const Guid *type, char *buf);
 int SupportedType(const char *name, Guid *type);
 void PrintTypes(void);
 void EntryDetails(GptEntry *entry, uint32_t index, int raw);
 
 uint32_t GetNumberOfEntries(const GptData *gpt);
 GptEntry *GetEntry(GptData *gpt, int secondary, uint32_t entry_index);
 void SetPriority(GptData *gpt, int secondary, uint32_t entry_index,
@@ skipping 33 matching lines @@
 /* The standard "assert" macro goes away when NDEBUG is defined. This doesn't.
  */
 #define require(A) do { \
   if (!(A)) { \
     fprintf(stderr, "condition (%s) failed at %s:%d\n", \
             #A, __FILE__, __LINE__); \
     exit(1); } \
   } while (0)
 
 #endif  // VBOOT_REFERENCE_UTILITY_CGPT_CGPT_H_