Add a StatefulMemcpy which can be used to safely and iteratively copy blocks of memory.
Review URL: http://codereview.chromium.org/572024
diff --git a/common/utility_stub.c b/common/utility_stub.c
index 14a5910..ca12fa6 100644
--- a/common/utility_stub.c
+++ b/common/utility_stub.c
@@ -10,7 +10,6 @@
#include <stdio.h>
#include <stdlib.h>
-#include <string.h>
void* Malloc(size_t size) {
void* p = malloc(size);
@@ -29,6 +28,13 @@
return memcpy(dest, src, n);
}
+void* Memset(void* dest, const uint8_t c, size_t n) {
+ while (n--) {
+ *((uint8_t*)dest) = c;
+ }
+ return dest;
+}
+
int SafeMemcmp(const void* s1, const void* s2, size_t n) {
int match = 1;
const unsigned char* us1 = s1;
@@ -42,3 +48,16 @@
return match;
}
+
+void* StatefulMemcpy(MemcpyState* state, void* dst, int len) {
+ void* saved_ptr;
+ if (len > state->remaining_len) {
+ state->remaining_len = -1;
+ return NULL;
+ }
+ saved_ptr = state->remaining_buf;
+ Memcpy(dst, saved_ptr, len);
+ state->remaining_buf += len;
+ state->remaining_len -= len;
+ return dst;
+}
diff --git a/include/utility.h b/include/utility.h
index ddb1dc0..87d17ea 100644
--- a/include/utility.h
+++ b/include/utility.h
@@ -10,6 +10,7 @@
#ifndef VBOOT_REFERENCE_UTILITY_H_
#define VBOOT_REFERENCE_UTILITY_H_
+#include <inttypes.h>
#include <string.h>
/* Allocate [size] bytes and return a pointer to the allocated memory. Abort
@@ -23,10 +24,30 @@
/* Copy [n] bytes from [src] to [dest]. */
void* Memcpy(void* dest, const void* src, size_t n);
+/* Set [n] bytes starting at [s] to [c]. */
+void* Memset(void *dest, const uint8_t c, size_t n);
+
/* Compare [n] bytes starting at [s1] with [s2] and return 1 if they match,
* 0 if they don't. Time taken to perform the comparison is only dependent on
* [n] and not on the relationship of the match between [s1] and [s2].
*/
int SafeMemcmp(const void* s1, const void* s2, size_t n);
+/* Track remaining data to be read in a buffer. */
+typedef struct MemcpyState {
+ void* remaining_buf;
+ int remaining_len;
+} MemcpyState;
+
+/* Copy [len] bytes into [dst] only if there's enough data to read according
+ * to [state].
+ * On success, return [dst] and update [state]..
+ * On failure, return NULL, set remaining len in state to -1.
+ *
+ * Useful for iterating through a binary blob to populate a struct. After the
+ * first failure (buffer overrun), successive calls will always fail.
+ */
+void* StatefulMemcpy(MemcpyState* state, void* dst, int len);
+
+
#endif /* VBOOT_REFERENCE_UTILITY_H_ */
diff --git a/utils/Makefile b/utils/Makefile
index e7ebc7e..8573583 100644
--- a/utils/Makefile
+++ b/utils/Makefile
@@ -8,6 +8,5 @@
dumpRSAPublicKey: dumpRSAPublicKey.c
$(CC) $(CFLAGS) $(LIBS) $< -o $@
-
clean:
rm -f dumpRSAPublicKey