1 files changed, 62 insertions, 0 deletions
diff --git a/lib/src/syscalls.c b/lib/src/syscalls.c
new file mode 100644
index 0000000..074fced
--- /dev/null
+++ b/lib/src/syscalls.c
@@ -0,0 +1,62 @@
+// Copyright (c) 2021 Johannes Stoelp
+
+#include <asm/unistd.h>  // __NR_*
+#include <syscall.h>
+#include <syscalls.h>
+
+// Storage for `dynld_errno`.
+int dynld_errno;
+
+// Convert return value to errno/ret.
+static long syscall_ret(unsigned long ret) {
+    if (ret > (unsigned long)-4096ul) {
+        dynld_errno = -ret;
+        return -1;
+    }
+    return ret;
+}
+
+int open(const char* path, int flags) {
+    long ret = syscall2(__NR_open, path, flags);
+    return syscall_ret(ret);
+}
+
+int close(int fd) {
+    long ret = syscall1(__NR_close, fd);
+    return syscall_ret(ret);
+}
+
+int access(const char* path, int mode) {
+    long ret = syscall2(__NR_access, path, mode);
+    return syscall_ret(ret);
+}
+
+ssize_t write(int fd, const void* buf, size_t count) {
+    long ret = syscall3(__NR_write, fd, buf, count);
+    return syscall_ret(ret);
+}
+
+ssize_t read(int fd, void* buf, size_t count) {
+    long ret = syscall3(__NR_read, fd, buf, count);
+    return syscall_ret(ret);
+}
+
+ssize_t pread(int fd, void* buf, size_t count, off_t offset) {
+    long ret = syscall4(__NR_read, fd, buf, count, offset);
+    return syscall_ret(ret);
+}
+
+void* mmap(void* addr, size_t length, int prot, int flags, int fd, off_t offset) {
+    long ret = syscall6(__NR_mmap, addr, length, prot, flags, fd, offset);
+    return (void*)syscall_ret(ret);
+}
+
+int munmap(void* addr, size_t length) {
+    long ret = syscall2(__NR_munmap, addr, length);
+    return syscall_ret(ret);
+}
+
+void _exit(int status) {
+    syscall1(__NR_exit, status);
+    __builtin_unreachable();
+}