From 10d9b72da19676f7169adee11cebcf18ac212844 Mon Sep 17 00:00:00 2001
From: Bananymous <bananymousosq@gmail.com>
Date: Sun, 7 May 2023 01:51:39 +0300
Subject: [PATCH] LibC: syscall() now returns -1 on error and updates errno

---
 libc/include/errno.h |  1 +
 libc/stdio.cpp       | 19 ++++++-------------
 libc/stdlib.cpp      |  9 +++------
 libc/string.cpp      |  3 +++
 libc/unistd.cpp      | 11 ++++++++++-
 5 files changed, 23 insertions(+), 20 deletions(-)

diff --git a/libc/include/errno.h b/libc/include/errno.h
index cf66b0c8..d616783a 100644
--- a/libc/include/errno.h
+++ b/libc/include/errno.h
@@ -17,6 +17,7 @@
 #define ENOTTY 13
 #define ENOTBLK 14
 #define EMFILE 15
+#define ENOSYS 16
 
 #define errno errno
 
diff --git a/libc/stdio.cpp b/libc/stdio.cpp
index a0ecbd87..aa7dee24 100644
--- a/libc/stdio.cpp
+++ b/libc/stdio.cpp
@@ -43,11 +43,8 @@ char* ctermid(char* buffer)
 
 int fclose(FILE* file)
 {
-	if (int ret = syscall(SYS_CLOSE, file->fd) < 0)
-	{
-		errno = -ret;
+	if (syscall(SYS_CLOSE, file->fd) < 0)
 		return EOF;
-	}
 	file->fd = -1;
 	return 0;
 }
@@ -79,9 +76,8 @@ int fflush(FILE* file)
 	if (file->buffer_index == 0)
 		return 0;
 	
-	if (long ret = syscall(SYS_WRITE, file->fd, file->buffer, file->buffer_index); ret < 0)
+	if (syscall(SYS_WRITE, file->fd, file->buffer, file->buffer_index) < 0)
 	{
-		errno = -ret;
 		file->error = true;
 		return EOF;
 	}
@@ -100,10 +96,11 @@ int fgetc(FILE* file)
 
 	if (ret < 0)
 	{
-		errno = -ret;
+		file->error = true;
 		return EOF;
 	}
-	else if (ret == 0)
+	
+	if (ret == 0)
 	{
 		file->eof = true;
 		return EOF;
@@ -241,7 +238,6 @@ size_t fread(void* buffer, size_t size, size_t nitems, FILE* file)
 	long ret = syscall(SYS_READ, file->fd, buffer, size * nitems);
 	if (ret < 0)
 	{
-		errno = -ret;
 		file->error = true;
 		return 0;
 	}
@@ -286,11 +282,8 @@ int fseeko(FILE* file, off_t offset, int whence)
 		return -1;
 	}
 
-	if (long ret = syscall(SYS_SEEK, file->fd, file->offset); ret < 0)
-	{
-		errno = -ret;
+	if (syscall(SYS_SEEK, file->fd, file->offset))
 		return -1;
-	}
 
 	file->eof = false;
 
diff --git a/libc/stdlib.cpp b/libc/stdlib.cpp
index 329dc167..7e9cd271 100644
--- a/libc/stdlib.cpp
+++ b/libc/stdlib.cpp
@@ -59,13 +59,10 @@ char* getenv(const char*)
 
 void* malloc(size_t bytes)
 {
-	long ret = syscall(SYS_ALLOC, bytes);
-	if (ret < 0)
-	{
-		errno = -ret;
+	long res = syscall(SYS_ALLOC, bytes);
+	if (res == -1)
 		return nullptr;
-	}
-	return (void*)ret;
+	return (void*)res;
 }
 
 void* calloc(size_t nmemb, size_t size)
diff --git a/libc/string.cpp b/libc/string.cpp
index d551b59b..49e84484 100644
--- a/libc/string.cpp
+++ b/libc/string.cpp
@@ -128,6 +128,9 @@ char* strerror(int error)
 	case EMFILE:
 		strcpy(buffer, "File descriptor value too large");
 		break;
+	case ENOSYS:
+		strcpy(buffer, "Function not implemented");
+		break;
 	default:
 		{
 			// FIXME: sprintf
diff --git a/libc/unistd.cpp b/libc/unistd.cpp
index 3d43839b..2ebb167d 100644
--- a/libc/unistd.cpp
+++ b/libc/unistd.cpp
@@ -1,4 +1,5 @@
 #include <BAN/Assert.h>
+#include <errno.h>
 #include <stdarg.h>
 #include <stddef.h>
 #include <stdio.h>
@@ -45,7 +46,7 @@ long syscall(long syscall, ...)
 		case SYS_TERMID:
 		{
 			char* buffer = va_arg(args, char*);
-			Kernel::syscall(SYS_TERMID, buffer);
+			ret = Kernel::syscall(SYS_TERMID, buffer);
 			break;
 		}
 		case SYS_CLOSE:
@@ -82,10 +83,18 @@ long syscall(long syscall, ...)
 		}
 		default:
 			puts("LibC: Unhandeled syscall");
+			ret = -ENOSYS;
+			break;
 	}
 
 	va_end(args);
 	
+	if (ret < 0)
+	{
+		errno = -ret;
+		return -1;
+	}
+
 	return ret;
 }