From 5bde040295f3c50da86fbe18d61bacc71d8e436a Mon Sep 17 00:00:00 2001
From: Jonas 'Sortie' Termansen <sortie@maxsi.org>
Date: Thu, 17 Nov 2011 13:11:09 +0100
Subject: [PATCH 1/2] Fixed randomness-related crash in snake.

---
 games/snake.cpp     | 10 ++++++----
 libmaxsi/random.cpp |  4 ++--
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/games/snake.cpp b/games/snake.cpp
index c1ac17e1..bea1690e 100644
--- a/games/snake.cpp
+++ b/games/snake.cpp
@@ -56,8 +56,8 @@ void Reset()
 		case 3: velx = 0; vely = -1; break;
 	}
 
-	animalx = 2 + (rand() % width-4);
-	animaly = 2 + (rand() % height-4);
+	animalx = 2 + (rand() % (width-4));
+	animaly = 2 + (rand() % (height-4));
 
 	taillen = 0;
 	tailmax = 3;
@@ -141,8 +141,10 @@ void Update()
 	if ( newx == animalx && newy == animaly )
 	{
 		tailmax++;
-		animalx = 2 + (rand() % width-4);
-		animaly = 2 + (rand() % height-4);
+		animalx = 2 + (rand() % (width-4));
+		animaly = 2 + (rand() % (height-4));
+		ASSERT(0 <= animalx && animalx < width);
+		ASSERT(0 <= animaly && animaly < height);
 		if ( maxspeed < speed ) { speed += speedincrease; }
 	}
 
diff --git a/libmaxsi/random.cpp b/libmaxsi/random.cpp
index 63daa8a4..9bbef8de 100644
--- a/libmaxsi/random.cpp
+++ b/libmaxsi/random.cpp
@@ -28,11 +28,11 @@ namespace Maxsi
 {
 	namespace Random
 	{
-		int random_seed=1337;
+		unsigned random_seed = 1337;
 		extern "C" int rand() 
 		{
 			random_seed = random_seed + 37 * 1103515245 + 12345;
-			return random_seed / 65536; 
+			return random_seed >> 16; 
 		}
 	}
 }

From 05196f49b25d704b27e5e97b3af978e945c43d7f Mon Sep 17 00:00:00 2001
From: Jonas 'Sortie' Termansen <sortie@maxsi.org>
Date: Thu, 17 Nov 2011 20:34:04 +0100
Subject: [PATCH 2/2] Added dup(2).

---
 libmaxsi/c/hsrc/unistd.h | 2 +-
 libmaxsi/io.cpp          | 5 +++++
 sortix/io.cpp            | 9 +++++++++
 sortix/syscallnum.h      | 3 ++-
 4 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/libmaxsi/c/hsrc/unistd.h b/libmaxsi/c/hsrc/unistd.h
index f150ce2b..25e3b506 100644
--- a/libmaxsi/c/hsrc/unistd.h
+++ b/libmaxsi/c/hsrc/unistd.h
@@ -84,7 +84,6 @@ int close(int);
 size_t confstr(int, char*, size_t);
 char* crypt(const char*, const char*);
 char* ctermid(char*);
-int dup(int);
 int dup2(int, int);
 void encrypt(char [64], int);
 int execl(const char*, const char*, ...);
@@ -159,6 +158,7 @@ extern char* optarg;
 extern int opterr, optind, optopt;
 #endif
 
+int dup(int);
 void _exit(int);
 pid_t fork(void);
 pid_t getpid(void);
diff --git a/libmaxsi/io.cpp b/libmaxsi/io.cpp
index 6217652c..0e6126cc 100644
--- a/libmaxsi/io.cpp
+++ b/libmaxsi/io.cpp
@@ -33,6 +33,7 @@ namespace Maxsi
 	DEFN_SYSCALL3(ssize_t, SysRead, 18, int, void*, size_t);
 	DEFN_SYSCALL3(ssize_t, SysWrite, 19, int, const void*, size_t);
 	DEFN_SYSCALL1(int, SysPipe, 20, int*);
+	DEFN_SYSCALL1(int, SysDup, 21, int);
 
 	size_t Print(const char* Message)
 	{
@@ -78,6 +79,10 @@ namespace Maxsi
 		return SysPipe(pipefd);
 	}
 
+	extern "C" int dup(int fd)
+	{
+		return SysDup(fd);
+	}
 #endif
 
 }
diff --git a/sortix/io.cpp b/sortix/io.cpp
index 75bba0f4..f0f7b0be 100644
--- a/sortix/io.cpp
+++ b/sortix/io.cpp
@@ -117,10 +117,19 @@ namespace Sortix
 			return 0;		
 		}
 
+		int SysDup(int fd)
+		{
+			Process* process = CurrentProcess();
+			Device* dev = process->descriptors.Get(fd);
+			if ( !dev ) { return -1; /* TODO: EBADF */ }
+			return process->descriptors.Allocate(dev);
+		}
+
 		void Init()
 		{
 			Syscall::Register(SYSCALL_WRITE, (void*) SysWrite);
 			Syscall::Register(SYSCALL_READ, (void*) SysRead);
+			Syscall::Register(SYSCALL_DUP, (void*) SysDup);
 		}
 	}
 }
diff --git a/sortix/syscallnum.h b/sortix/syscallnum.h
index c420ea7f..73b7708d 100644
--- a/sortix/syscallnum.h
+++ b/sortix/syscallnum.h
@@ -46,7 +46,8 @@
 #define SYSCALL_READ 18
 #define SYSCALL_WRITE 19
 #define SYSCALL_PIPE 20
-#define SYSCALL_MAX_NUM 21 /* index of highest constant + 1 */
+#define SYSCALL_DUP 21
+#define SYSCALL_MAX_NUM 22 /* index of highest constant + 1 */
 
 #endif