kernel: read syscall

kernel-src/arch/x86-64/syscall.asm

@@ -2,12 +2,13 @@ section .rodata
 extern syscall_print
 extern syscall_mmap
 extern syscall_openat
+extern syscall_read
 syscalltab:
 dq syscall_print
 dq syscall_mmap
 dq syscall_openat
-
-syscallcount equ 3
+dq syscall_read
+syscallcount equ 4
 section .text
 global arch_syscall_entry
 ; on entry:

kernel-src/sys/syscalls/read.c

@@ -0,0 +1,43 @@
+#include <kernel/syscalls.h>
+#include <kernel/vfs.h>
+#include <kernel/file.h>
+#include <errno.h>
+
+syscallret_t syscall_read(context_t *context, int fd, void *buffer, size_t size) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	void *kernelbuff = vmm_map(NULL, size, VMM_FLAGS_ALLOCATE, ARCH_MMU_FLAGS_READ | ARCH_MMU_FLAGS_WRITE | ARCH_MMU_FLAGS_NOEXEC, NULL);
+	if (kernelbuff == NULL) {
+		ret.errno = ENOMEM;
+		return ret;
+	}
+
+	file_t *file = fd_get(fd);
+
+	if (file == NULL || (file->flags & FILE_READ) == 0) {
+		ret.errno = EBADF;
+		goto cleanup;
+	}
+
+	// TODO pass flags
+	size_t bytesread;
+	ret.errno = vfs_read(file->vnode, kernelbuff, size, file->offset, &bytesread, 0);
+
+	if (ret.errno)
+		goto cleanup;
+
+	ret.ret = bytesread;
+	ret.errno = 0;
+
+	// TODO safe memcpy
+	memcpy(buffer, kernelbuff, bytesread);
+
+cleanup:
+	if (file)
+		fd_release(file);
+
+	vmm_unmap(kernelbuff, size, 0);
+	return ret;
+}

patches/mlibc/jinx-working-patch.patch

@@ -113,10 +113,10 @@ index 0000000..e5b087a
 +
 diff --git mlibc-workdir/sysdeps/astral/generic/generic.cpp mlibc-workdir/sysdeps/astral/generic/generic.cpp
 new file mode 100644
-index 0000000..6715503
+index 0000000..80a5884
 --- /dev/null
 +++ mlibc-workdir/sysdeps/astral/generic/generic.cpp
-@@ -0,0 +1,143 @@
+@@ -0,0 +1,148 @@
 +#include <bits/ensure.h>
 +#include <mlibc/debug.hpp>
 +#include <mlibc/all-sysdeps.hpp>
@@ -225,9 +225,14 @@ index 0000000..6715503
 +		*fd = ret;
 +		return 0;
 +	};
++
 +	int sys_read(int fd, void *buff, size_t count, ssize_t *bytes_read) {
-+		return ENOSYS;
++		long readc;
++		long error = syscall(SYSCALL_READ, &readc, fd, (uint64_t)buff, count);
++		*bytes_read = readc;
++		return error;
 +	}
++
 +	int sys_write(int fd, const void *buff, size_t count, ssize_t *bytes_written) {
 +		return ENOSYS;
 +	}
@@ -279,16 +284,17 @@ index 0000000..990eca0
 +#endif
 diff --git mlibc-workdir/sysdeps/astral/include/astral/syscall.h mlibc-workdir/sysdeps/astral/include/astral/syscall.h
 new file mode 100644
-index 0000000..6ef92cd
+index 0000000..17c0045
 --- /dev/null
 +++ mlibc-workdir/sysdeps/astral/include/astral/syscall.h
-@@ -0,0 +1,26 @@
+@@ -0,0 +1,27 @@
 +#ifndef _SYSCALL_H_INCLUDE
 +#define _SYSCALL_H_INCLUDE
 +
 +#define SYSCALL_PRINT 0
 +#define SYSCALL_MMAP 1
 +#define SYSCALL_OPENAT 2
++#define SYSCALL_READ 3
 +
 +#include <stddef.h>
 +#include <stdint.h>