From 648b3243859cafa6588ab95785ae25ac80790299 Mon Sep 17 00:00:00 2001
From: Jonas 'Sortie' Termansen <sortie@maxsi.org>
Date: Mon, 26 Dec 2011 23:12:12 +0100
Subject: [PATCH] Added lseek(2).

---
 libmaxsi/c/decl/SEEK_END.h |  4 ++--
 libmaxsi/c/hsrc/unistd.h   |  2 +-
 libmaxsi/io.cpp            |  7 +++++++
 sortix/io.cpp              | 34 ++++++++++++++++++++++++++++++++++
 sortix/syscallnum.h        |  3 ++-
 5 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/libmaxsi/c/decl/SEEK_END.h b/libmaxsi/c/decl/SEEK_END.h
index dc64c8f0..13f1e0f7 100644
--- a/libmaxsi/c/decl/SEEK_END.h
+++ b/libmaxsi/c/decl/SEEK_END.h
@@ -1,3 +1,3 @@
-#ifndef SEEK_SET
-#define SEEK_SET 2 /* Seek from end of file.  */
+#ifndef SEEK_END
+#define SEEK_END 2 /* Seek from end of file.  */
 #endif
diff --git a/libmaxsi/c/hsrc/unistd.h b/libmaxsi/c/hsrc/unistd.h
index 08c164ab..4c8a6edd 100644
--- a/libmaxsi/c/hsrc/unistd.h
+++ b/libmaxsi/c/hsrc/unistd.h
@@ -120,7 +120,6 @@ int lchown(const char*, uid_t, gid_t);
 int link(const char*, const char*);
 int linkat(int, const char*, int, const char*, int);
 int lockf(int, int, off_t);
-off_t lseek(int, off_t, int);
 int nice(int);
 long pathconf(const char*, int);
 int pause(void);
@@ -166,6 +165,7 @@ char* getcwd(char*, size_t);
 pid_t getpid(void);
 pid_t getppid(void);
 int isatty(int);
+off_t lseek(int, off_t, int);
 int pipe(int [2]);
 ssize_t read(int, void*, size_t);
 unsigned sleep(unsigned);
diff --git a/libmaxsi/io.cpp b/libmaxsi/io.cpp
index b9e989dc..0dec9a8a 100644
--- a/libmaxsi/io.cpp
+++ b/libmaxsi/io.cpp
@@ -49,6 +49,7 @@ namespace Maxsi
 	DEFN_SYSCALL2(char*, SysGetCWD, SYSCALL_GETCWD, char*, size_t);
 	DEFN_SYSCALL1(int, SysUnlink, SYSCALL_UNLINK, const char*);
 	DEFN_SYSCALL1(int, SysIsATTY, SYSCALL_ISATTY, int);
+	DEFN_SYSCALL3_VOID(SysSeek, SYSCALL_SEEK, int, off_t*, int);
 
 	size_t Print(const char* string)
 	{
@@ -151,6 +152,12 @@ namespace Maxsi
 		return 0;
 	}
 
+	extern "C" off_t lseek(int fd, off_t offset, int whence)
+	{
+		SysSeek(fd, &offset, whence);
+		return offset;
+	}
+
 	extern "C" int pipe(int pipefd[2])
 	{
 		return SysPipe(pipefd);
diff --git a/sortix/io.cpp b/sortix/io.cpp
index c42d9521..e7ee34e1 100644
--- a/sortix/io.cpp
+++ b/sortix/io.cpp
@@ -117,6 +117,39 @@ namespace Sortix
 			return 0;		
 		}
 
+// TODO: Get these from unistd.h or something.
+#ifndef SEEK_SET
+#define SEEK_SET 0 /* Seek from beginning of file.  */
+#endif
+#ifndef SEEK_CUR
+#define SEEK_CUR 1 /* Seek from current position.  */
+#endif
+#ifndef SEEK_END
+#define SEEK_END 2 /* Seek from end of file.  */
+#endif
+
+		void SysSeek(int fd, off_t* offset, int whence)
+		{
+			// TODO: Validate that offset is a legal user-space off_t!
+			Process* process = CurrentProcess();
+			Device* dev = process->descriptors.Get(fd);
+			if ( !dev ) { Error::Set(EBADF); *offset = -1; return; }
+			if ( !dev->IsType(Device::BUFFER) ) { Error::Set(EBADF); *offset = -1; return; }
+			DevBuffer* buffer = (DevBuffer*) dev;
+			off_t origin;
+			switch ( whence )
+			{
+				case SEEK_SET: origin = 0; break;
+				case SEEK_CUR: origin = buffer->Position(); break;
+				case SEEK_END: origin = buffer->Size(); break;
+				default: Error::Set(EINVAL); *offset = -1; break;
+			}
+			off_t newposition = origin + *offset;
+			if ( newposition < 0 ) { Error::Set(EINVAL); *offset = -1; return; }
+			if ( !buffer->Seek(newposition) ) { *offset = -1; return; }
+			*offset = buffer->Position();
+		}
+
 		int SysClose(int fd)
 		{
 			Process* process = CurrentProcess();
@@ -150,6 +183,7 @@ namespace Sortix
 			Syscall::Register(SYSCALL_CLOSE, (void*) SysClose);
 			Syscall::Register(SYSCALL_DUP, (void*) SysDup);
 			Syscall::Register(SYSCALL_ISATTY, (void*) SysIsATTY);
+			Syscall::Register(SYSCALL_SEEK, (void*) SysSeek);
 		}
 	}
 }
diff --git a/sortix/syscallnum.h b/sortix/syscallnum.h
index 0a7a5179..8e71af3d 100644
--- a/sortix/syscallnum.h
+++ b/sortix/syscallnum.h
@@ -61,7 +61,8 @@
 #define SYSCALL_ISATTY 33
 #define SYSCALL_UPTIME 34
 #define SYSCALL_SBRK 35
-#define SYSCALL_MAX_NUM 36 /* index of highest constant + 1 */
+#define SYSCALL_SEEK 36
+#define SYSCALL_MAX_NUM 37 /* index of highest constant + 1 */
 
 #endif