memlib enhancements

Fix DMTF#1585.

Signed-off-by: Steven Bellock <[email protected]>

include/hal/library/memlib.h

@@ -15,76 +15,44 @@
 #ifndef BASE_MEMORY_LIB
 #define BASE_MEMORY_LIB
 
+#include "hal/base.h"
+
 /**
  * Copies bytes from a source buffer to a destination buffer.
  *
- * This function copies "src_len" bytes from "src_buf" to "dst_buf".
- *
- * Asserts and returns a non-zero value if any of the following are true:
- *   1) "src_buf" or "dst_buf" are NULL.
- *   2) "src_len" or "dst_len" is greater than (SIZE_MAX >> 1).
- *   3) "src_len" is greater than "dst_len".
- *   4) "src_buf" and "dst_buf" overlap.
- *
- * If any of these cases fail, a non-zero value is returned. Additionally if
- * "dst_buf" points to a non-NULL value and "dst_len" is valid, then "dst_len"
- * bytes of "dst_buf" are zeroed.
- *
- * This function follows the C11 cppreference description of memcpy_s.
- * https://en.cppreference.com/w/c/string/byte/memcpy
- * The cppreferece description does NOT allow the source or destination
- * buffers to be NULL.
- *
- * This function differs from the Microsoft and Safeclib memcpy_s implementations
- * in that the Microsoft and Safeclib implementations allow for NULL source and
- * destinations pointers when the number of bytes to copy (src_len) is zero.
- *
- * In addition the Microsoft and Safeclib memcpy_s functions return different
- * negative values on error. For best support, clients should generally check
- * against zero for success or failure.
+ * This function copies src_len bytes from src_buf to dst_buf. The following properties should
+ * hold by the caller:
+ * - dst_buf and src_buf are non-NULL.
+ * - src_len is less than or equal to dst_len.
+ * - The source and destination buffers do not overlap.
  *
+ * The implementer of this function is free to check that these properties hold and take action
+ * if they fail to do so.
+
  * @param    dst_buf   Destination buffer to copy to.
- * @param    dst_len   Maximum length in bytes of the destination buffer.
+ * @param    dst_len   Size, in bytes, of the destination buffer.
  * @param    src_buf   Source buffer to copy from.
  * @param    src_len   The number of bytes to copy from the source buffer.
- *
- * @return   0 on success. non-zero on error.
- *
  **/
-int libspdm_copy_mem(void *dst_buf, size_t dst_len,
-                     const void *src_buf, size_t src_len);
+void libspdm_copy_mem(void *dst_buf, size_t dst_len,
+                      const void *src_buf, size_t src_len);
 
 /**
- * Fills a target buffer with a byte value, and returns the target buffer.
- *
- * This function fills length bytes of buffer with value, and returns buffer.
- *
- * If length is greater than (MAX_ADDRESS - buffer + 1), then ASSERT().
+ * Fills a target buffer with a byte value.
  *
  * @param  buffer    The memory to set.
  * @param  length    The number of bytes to set.
  * @param  value     The value with which to fill length bytes of buffer.
- *
- * @return buffer.
- *
  **/
-void *libspdm_set_mem(void *buffer, size_t length, uint8_t value);
+void libspdm_set_mem(void *buffer, size_t length, uint8_t value);
 
 /**
- * Fills a target buffer with zeros, and returns the target buffer.
- *
- * This function fills length bytes of buffer with zeros, and returns buffer.
- *
- * If length > 0 and buffer is NULL, then ASSERT().
- * If length is greater than (MAX_ADDRESS - buffer + 1), then ASSERT().
+ * Fills a target buffer with zeros.
  *
  * @param  buffer      The pointer to the target buffer to fill with zeros.
  * @param  length      The number of bytes in buffer to fill with zeros.
- *
- * @return buffer.
- *
  **/
-void *libspdm_zero_mem(void *buffer, size_t length);
+void libspdm_zero_mem(void *buffer, size_t length);
 
 /**
  * Compares the contents of two buffers in constant time.

os_stub/memlib/copy_mem.c

@@ -4,92 +4,29 @@
  *  License: BSD 3-Clause License. For full text see link: https://github.com/DMTF/libspdm/blob/main/LICENSE.md
  **/
 
-/** @file
- * libspdm_copy_mem() implementation.
- **/
-
-#include "base.h"
 #include "library/debuglib.h"
 #include "hal/library/memlib.h"
 
-/**
- * Copies bytes from a source buffer to a destination buffer.
- *
- * This function copies "src_len" bytes from "src_buf" to "dst_buf".
- *
- * Asserts and returns a non-zero value if any of the following are true:
- *   1) "src_buf" or "dst_buf" are NULL.
- *   2) "src_len" or "dst_len" is greater than (SIZE_MAX >> 1).
- *   3) "src_len" is greater than "dst_len".
- *   4) "src_buf" and "dst_buf" overlap.
- *
- * If any of these cases fail, a non-zero value is returned. Additionally if
- * "dst_buf" points to a non-NULL value and "dst_len" is valid, then "dst_len"
- * bytes of "dst_buf" are zeroed.
- *
- * This function follows the C11 cppreference description of memcpy_s.
- * https://en.cppreference.com/w/c/string/byte/memcpy
- * The cppreferece description does NOT allow the source or destination
- * buffers to be NULL.
- *
- * This function differs from the Microsoft and Safeclib memcpy_s implementations
- * in that the Microsoft and Safeclib implementations allow for NULL source and
- * destinations pointers when the number of bytes to copy (src_len) is zero.
- *
- * In addition the Microsoft and Safeclib memcpy_s functions return different
- * negative values on error. For best support, clients should generally check
- * against zero for success or failure.
- *
- * @param    dst_buf   Destination buffer to copy to.
- * @param    dst_len   Maximum length in bytes of the destination buffer.
- * @param    src_buf   Source buffer to copy from.
- * @param    src_len   The number of bytes to copy from the source buffer.
- *
- * @return   0 on success. non-zero on error.
- *
- **/
-int libspdm_copy_mem(void *dst_buf, size_t dst_len,
-                     const void *src_buf, size_t src_len)
+void libspdm_copy_mem(void *dst_buf, size_t dst_len,
+                      const void *src_buf, size_t src_len)
 {
     volatile uint8_t* dst;
     const volatile uint8_t* src;
 
     dst = (volatile uint8_t*) dst_buf;
     src = (const volatile uint8_t*) src_buf;
 
-    /* Check for case where "dst" or "dst_len" may be invalid.
-     * Do not zero "dst" in this case. */
-    if (dst == NULL || dst_len > (SIZE_MAX >> 1)) {
+    if ((dst == NULL) || (src == NULL)) {
         LIBSPDM_ASSERT(0);
-        return -1;
     }
-
-    /* Gaurd against invalid source. Zero "dst" in this case. */
-    if (src == NULL) {
-        libspdm_zero_mem(dst_buf, dst_len);
+    if (((src < dst) && ((src + src_len) > dst)) || ((dst < src) && ((dst + src_len) > src))) {
         LIBSPDM_ASSERT(0);
-        return -1;
     }
-
-    /* Guard against overlap case. Zero "dst" in these cases. */
-    if ((src < dst && src + src_len > dst) || (dst < src && dst + src_len > src)) {
-        libspdm_zero_mem(dst_buf, dst_len);
+    if (src_len > dst_len) {
         LIBSPDM_ASSERT(0);
-        return -1;
-    }
-
-    /* Guard against invalid lengths. Zero "dst" in these cases. */
-    if (src_len > dst_len ||
-        src_len > (SIZE_MAX >> 1)) {
-
-        libspdm_zero_mem(dst_buf, dst_len);
-        LIBSPDM_ASSERT(0);
-        return -1;
     }
 
     while (src_len-- != 0) {
         *(dst++) = *(src++);
     }
-
-    return 0;
 }

os_stub/memlib/set_mem.c

@@ -4,30 +4,14 @@
  *  License: BSD 3-Clause License. For full text see link: https://github.com/DMTF/libspdm/blob/main/LICENSE.md
  **/
 
-#include "base.h"
+#include "hal/library/memlib.h"
 
-/**
- * Fills a target buffer with a byte value, and returns the target buffer.
- *
- * This function fills length bytes of buffer with value, and returns buffer.
- *
- * If length is greater than (MAX_ADDRESS - buffer + 1), then LIBSPDM_ASSERT().
- *
- * @param  buffer    The memory to set.
- * @param  length    The number of bytes to set.
- * @param  value     The value with which to fill length bytes of buffer.
- *
- * @return buffer.
- *
- **/
-void *libspdm_set_mem(void *buffer, size_t length, uint8_t value)
+void libspdm_set_mem(void *buffer, size_t length, uint8_t value)
 {
     volatile uint8_t *pointer;
 
     pointer = (uint8_t *)buffer;
     while (length-- != 0) {
         *(pointer++) = value;
     }
-
-    return buffer;
 }

os_stub/memlib/zero_mem.c

@@ -4,34 +4,14 @@
  *  License: BSD 3-Clause License. For full text see link: https://github.com/DMTF/libspdm/blob/main/LICENSE.md
  **/
 
-/** @file
- * libspdm_zero_mem() implementation.
- **/
-
-#include "base.h"
+#include "hal/library/memlib.h"
 
-/**
- * Fills a target buffer with zeros, and returns the target buffer.
- *
- * This function fills length bytes of buffer with zeros, and returns buffer.
- *
- * If length > 0 and buffer is NULL, then LIBSPDM_ASSERT().
- * If length is greater than (MAX_ADDRESS - buffer + 1), then LIBSPDM_ASSERT().
- *
- * @param  buffer      The pointer to the target buffer to fill with zeros.
- * @param  length      The number of bytes in buffer to fill with zeros.
- *
- * @return buffer.
- *
- **/
-void *libspdm_zero_mem(void *buffer, size_t length)
+void libspdm_zero_mem(void *buffer, size_t length)
 {
     volatile uint8_t *pointer;
 
     pointer = (uint8_t *)buffer;
     while (length-- != 0) {
         *(pointer++) = 0;
     }
-
-    return buffer;
 }