From c63c3bffe6a373bb8c4b7ca0bf646a46444ca4e1 Mon Sep 17 00:00:00 2001
From: LoRd_MuldeR <mulder2@gmx.de>
Date: Tue, 8 Feb 2022 22:46:33 +0100
Subject: [PATCH] Make sure that the requested number of random bytes is fully
 read, even if a single read() invocation returned fewer than "count" bytes.

---
 libslunkcrypt/src/compiler.h |  2 +-
 libslunkcrypt/src/junk.c     | 50 ++++++++++++++++++++++++++----------
 libslunkcrypt/src/version.h  |  2 +-
 3 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/libslunkcrypt/src/compiler.h b/libslunkcrypt/src/compiler.h
index ad2e215..49c9093 100644
--- a/libslunkcrypt/src/compiler.h
+++ b/libslunkcrypt/src/compiler.h
@@ -8,7 +8,7 @@
 
 /* Intel(R) oneAPI DPC++/C++ Compiler */
 #if defined(__INTEL_LLVM_COMPILER) && (!defined(__GNUC__))
-#	define __GNUC__ 9
+#	define __GNUC__ 10
 #endif
 
 /* Compiler compatibility */
diff --git a/libslunkcrypt/src/junk.c b/libslunkcrypt/src/junk.c
index e593eb9..4cb46e6 100644
--- a/libslunkcrypt/src/junk.c
+++ b/libslunkcrypt/src/junk.c
@@ -28,6 +28,7 @@ static INLINE size_t MIN_SIZE(const size_t a, const size_t b) { return (a > b) ?
 
 #ifdef _WIN32
 #	include <Windows.h>
+#	include <io.h>
 #else
 #	include <unistd.h>
 #	include <pthread.h>
@@ -88,12 +89,14 @@ static void win32_call_once(CALL_ONCE_TYPE *const control, void (*init_routine)(
 // Random bytes
 // ==========================================================================
 
+#define MAX_COUNT 1048576U
+
 /* Global state */
 static CALL_ONCE_TYPE s_random_is_initialized = CALL_ONCE_INIT;
 #if defined(_WIN32)
-typedef BOOLEAN(WINAPI *rtlgenrandom_t)(void *buffer, ULONG length);
+typedef BOOLEAN(WINAPI *ptr_genrandom_t)(void *buffer, ULONG length);
 static HMODULE s_advapi32 = NULL;
-static rtlgenrandom_t s_rtlgenrandom = NULL;
+static ptr_genrandom_t s_genrandom = NULL;
 #else
 static const char *const DEV_RANDOM[] = { "/dev/urandom", "/dev/arandom", "/dev/random", NULL };
 static int s_random_fd = -1;
@@ -102,8 +105,11 @@ static int s_random_fd = -1;
 /* De-initialize CSRNG */
 static void exit_random_source(void)
 {
-#if defined(_WIN32)
-	s_rtlgenrandom = NULL;
+#ifdef _WIN32
+	if (s_genrandom)
+	{
+		s_genrandom = NULL;
+	}
 	if (s_advapi32)
 	{
 		FreeLibrary(s_advapi32);
@@ -121,10 +127,10 @@ static void exit_random_source(void)
 /* Initialize CSRNG */
 static void init_random_source(void)
 {
-#if defined(_WIN32)
+#ifdef _WIN32
 	if ((s_advapi32 = LoadLibraryW(L"advapi32.dll")))
 	{
-		s_rtlgenrandom = (rtlgenrandom_t) GetProcAddress(s_advapi32, "SystemFunction036");
+		s_genrandom = (ptr_genrandom_t) GetProcAddress(s_advapi32, "SystemFunction036");
 	}
 #else
 #if defined(GETENTROPY)
@@ -151,27 +157,43 @@ init_completed: ;
 /* Generate random bytes */
 size_t slunkcrypt_random_bytes(uint8_t* const buffer, const size_t length)
 {
+	size_t offset;
 	CALL_ONCE(&s_random_is_initialized, init_random_source);
-#if defined(_WIN32)
-	if (s_rtlgenrandom)
+#ifdef _WIN32
+	if (s_genrandom)
 	{
-		const ULONG count = (ULONG) MIN_SIZE(length, ULONG_MAX);
-		return s_rtlgenrandom(buffer, count) ? count : 0U;
+		ULONG count;
+		for (offset = 0U; offset < length; offset += count)
+		{
+			count = (ULONG) MIN_SIZE(length - offset, MAX_COUNT);
+			if (!s_genrandom(buffer + offset, count))
+			{
+				break; /*failed*/
+			}
+		}
+		return offset;
 	}
 	return 0U;
 #else
 	if (s_random_fd >= 0)
 	{
-		const ssize_t result = read(s_random_fd, buffer, length);
-		return (result < 0) ? 0U : ((size_t)result);
+		ssize_t count;
+		for (offset = 0; offset < length; offset += (size_t)count)
+		{
+			if (!((count = read(s_random_fd, buffer + offset, MIN_SIZE(length - offset, MAX_COUNT))) > 0))
+			{
+				break; /*failed*/
+			}
+		}
+		return offset;
 	}
 #if defined(GETENTROPY)
 	else
 	{
-		size_t offset, count;
+		size_t count;
 		for (offset = 0U; offset < length; offset += count)
 		{
-			count = MIN_SIZE(length - offset, 256U);
+			count = MIN_SIZE(length - offset, 256U); /*the maximum permitted value is 256*/
 			if (GETENTROPY(buffer + offset, count) < 0)
 			{
 				break; /*failed*/
diff --git a/libslunkcrypt/src/version.h b/libslunkcrypt/src/version.h
index 33e8e0c..097c508 100644
--- a/libslunkcrypt/src/version.h
+++ b/libslunkcrypt/src/version.h
@@ -8,6 +8,6 @@
 
 #define LIB_VERSION_MAJOR 1
 #define LIB_VERSION_MINOR 1
-#define LIB_VERSION_PATCH 1
+#define LIB_VERSION_PATCH 2
 
 #endif