[PATCH v5 6/8] kern/misc, kern/efi: Extract UTF-8 to UTF-16 code

[Oliver Steffen]

Create a new function for UTF-8 to UTF-16 conversion called
grub_utf8_to_utf16_alloc() in the grub-code/kern/misc.c and replace
charset conversion code used in some places in the EFI code. It is
modeled after the grub_utf8_to_ucs4_alloc() like functions in charset.h.
It can't live in charset.h, because it needs to be reachable from the
kern/efi code.

Add a check for integer overflow and remove redundant NUL-termination.

Signed-off-by: Oliver Steffen <osteffen@redhat.com>
---
 grub-core/kern/efi/efi.c | 21 ++++++---------------
 grub-core/kern/misc.c    | 32 ++++++++++++++++++++++++++++++++
 include/grub/misc.h      |  3 +++
 3 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/grub-core/kern/efi/efi.c b/grub-core/kern/efi/efi.c
index 8df861a59..8fc3edfae 100644
--- a/grub-core/kern/efi/efi.c
+++ b/grub-core/kern/efi/efi.c
@@ -207,15 +207,11 @@ grub_efi_set_variable_with_attributes (const char *var, 
const grub_guid_t *guid,
   grub_efi_status_t status;
   grub_efi_runtime_services_t *r;
   grub_efi_char16_t *var16;
-  grub_size_t len, len16;
 
-  len = grub_strlen (var);
-  len16 = len * GRUB_MAX_UTF16_PER_UTF8;
-  var16 = grub_calloc (len16 + 1, sizeof (var16[0]));
-  if (!var16)
+  grub_utf8_to_utf16_alloc (var, &var16, NULL);
+
+  if (var16 == NULL)
     return grub_errno;
-  len16 = grub_utf8_to_utf16 (var16, len16, (grub_uint8_t *) var, len, NULL);
-  var16[len16] = 0;
 
   r = grub_efi_system_table->runtime_services;
 
@@ -250,18 +246,13 @@ grub_efi_get_variable_with_attributes (const char *var,
   grub_efi_runtime_services_t *r;
   grub_efi_char16_t *var16;
   void *data;
-  grub_size_t len, len16;
 
   *data_out = NULL;
   *datasize_out = 0;
 
-  len = grub_strlen (var);
-  len16 = len * GRUB_MAX_UTF16_PER_UTF8;
-  var16 = grub_calloc (len16 + 1, sizeof (var16[0]));
-  if (!var16)
-    return GRUB_EFI_OUT_OF_RESOURCES;
-  len16 = grub_utf8_to_utf16 (var16, len16, (grub_uint8_t *) var, len, NULL);
-  var16[len16] = 0;
+  grub_utf8_to_utf16_alloc (var, &var16, NULL);
+  if (var16 == NULL)
+    return grub_errno;
 
   r = grub_efi_system_table->runtime_services;
 
diff --git a/grub-core/kern/misc.c b/grub-core/kern/misc.c
index 1a8aff543..b25a65863 100644
--- a/grub-core/kern/misc.c
+++ b/grub-core/kern/misc.c
@@ -25,6 +25,7 @@
 #include <grub/env.h>
 #include <grub/i18n.h>
 #include <grub/types.h>
+#include <grub/charset.h>
 
 union printf_arg
 {
@@ -1323,6 +1324,37 @@ grub_fatal (const char *fmt, ...)
   grub_abort ();
 }
 
+grub_ssize_t
+grub_utf8_to_utf16_alloc (const char *str8, grub_uint16_t **utf16_msg, 
grub_uint16_t **last_position)
+{
+  grub_size_t len;
+  grub_size_t len16;
+
+  len = grub_strlen (str8);
+
+  /* Check for integer overflow */
+  if (len > GRUB_SSIZE_MAX / GRUB_MAX_UTF16_PER_UTF8 - 1)
+    {
+      grub_error (GRUB_ERR_BAD_ARGUMENT, N_("string too large"));
+      *utf16_msg = NULL;
+      return -1;
+    }
+
+  len16 = len * GRUB_MAX_UTF16_PER_UTF8;
+
+  *utf16_msg = grub_calloc (len16 + 1, sizeof (*utf16_msg[0]));
+  if (*utf16_msg == NULL)
+    return -1;
+
+  len16 = grub_utf8_to_utf16 (*utf16_msg, len16, (grub_uint8_t *) str8, len, 
NULL);
+
+  if (last_position)
+    *last_position = *utf16_msg + len16;
+
+  return len16;
+}
+
+
 #if BOOT_TIME_STATS
 
 #include <grub/time.h>
diff --git a/include/grub/misc.h b/include/grub/misc.h
index 6c9d56de9..1b35a167f 100644
--- a/include/grub/misc.h
+++ b/include/grub/misc.h
@@ -529,4 +529,7 @@ void EXPORT_FUNC(grub_real_boot_time) (const char *file,
 
 #define grub_log2ull(n) (GRUB_TYPE_BITS (grub_uint64_t) - __builtin_clzll (n) 
- 1)
 
+grub_ssize_t
+EXPORT_FUNC(grub_utf8_to_utf16_alloc) (const char *str8, grub_uint16_t 
**utf16_msg, grub_uint16_t **last_position);
+
 #endif /* ! GRUB_MISC_HEADER */
-- 
2.39.2