From 6350621f7dfc28ee1e9c1096727c4d3df2cb934e Mon Sep 17 00:00:00 2001
From: Matheus <matheusuky@gmail.com>
Date: Fri, 19 Aug 2022 20:04:01 -0300
Subject: [PATCH] read syscall

---
 src/arch/x86_64/syscall.asm |  4 ++-
 src/sys/syscalls/read.c     | 62 +++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+), 1 deletion(-)
 create mode 100644 src/sys/syscalls/read.c

diff --git a/src/arch/x86_64/syscall.asm b/src/arch/x86_64/syscall.asm
index f18d27ff..12bba1cc 100644
--- a/src/arch/x86_64/syscall.asm
+++ b/src/arch/x86_64/syscall.asm
@@ -6,7 +6,8 @@ extern syscall_mmap
 extern syscall_arch_ctl
 extern syscall_gettid
 extern syscall_open
-func_count equ 5
+extern syscall_read
+func_count equ 6
 
 
 func_table:
@@ -15,6 +16,7 @@ func_table:
 	dq syscall_arch_ctl
 	dq syscall_gettid
 	dq syscall_open
+	dq syscall_read
 section .text
 global asm_syscall_entry
 
diff --git a/src/sys/syscalls/read.c b/src/sys/syscalls/read.c
new file mode 100644
index 00000000..15600d67
--- /dev/null
+++ b/src/sys/syscalls/read.c
@@ -0,0 +1,62 @@
+#include <kernel/syscalls.h>
+#include <kernel/fd.h>
+#include <kernel/alloc.h>
+#include <kernel/vfs.h>
+#include <arch/cls.h>
+#include <kernel/sched.h>
+#include <arch/spinlock.h>
+#include <kernel/vmm.h>
+
+syscallret syscall_read(int ifd, void* buff, size_t count){
+	
+	syscallret retv;
+	retv.ret = -1;
+
+	if(buff > USER_SPACE_END){
+		retv.errno = EFAULT;
+		return retv;
+	}
+
+	proc_t* proc = arch_getcls()->thread->proc;
+
+	fd_t* fd = proc->fds + ifd;
+
+	spinlock_acquire(&proc->fdlock);
+
+	if(proc->fdcount <= ifd || fd->node == NULL || (fd->flags & FD_FLAGS_READ) == 0){
+		spinlock_release(&proc->fdlock);
+		retv.errno = EBADF;
+		return retv;
+	}
+
+	spinlock_acquire(&fd->lock);
+	spinlock_release(&proc->fdlock);
+
+	void* kbuff = alloc(count);
+
+	if(!kbuff){
+		spinlock_release(&fd->lock);
+		retv.errno = ENOMEM;
+		return retv;
+	}
+
+	int err;
+	size_t readc = vfs_read(&err, fd->node, kbuff, count, fd->offset);
+	
+	spinlock_release(&fd->lock);
+
+
+	if(err){
+		free(kbuff);
+		retv.errno = err;
+		return retv;
+	}
+
+	memcpy(buff, kbuff, count); // XXX user version for safety
+
+
+	retv.errno = 0;
+	retv.ret = readc;
+	
+	return retv;
+}