sys: add userspace bootstrap program

sys/bootstrap/tar.c

@@ -0,0 +1,96 @@
+#include "tar.h"
+
+#include <mango/handle.h>
+#include <mango/vm.h>
+#include <string.h>
+
+size_t getsize(const char *in)
+{
+	size_t size = 0;
+	size_t j;
+	size_t count = 1;
+
+	for (j = 11; j > 0; j--, count *= 8) {
+		size += ((in[j - 1] - '0') * count);
+	}
+
+	return size;
+}
+
+int tar_init(struct tar *tar, uintptr_t base)
+{
+	memset(tar, 0x0, sizeof *tar);
+	tar->tar_entries = (struct tar_bin_header *)base;
+	return 0;
+}
+
+int tar_open(struct tar *tar, const char *path, struct tar_file *out)
+{
+	while (*path == '/') {
+		path++;
+	}
+
+	if (*path == '\0') {
+		return -1;
+	}
+
+	struct tar_bin_header *bin_header = tar->tar_entries;
+	struct tar_header header;
+	for (size_t i = 0;; i++) {
+		tar_header_decode(bin_header, &header);
+		if (bin_header->filename[0] == 0) {
+			break;
+		}
+
+		char *s = (char *)bin_header;
+		s += sizeof *bin_header;
+
+		if (!strcmp(bin_header->filename, path)) {
+			out->f_header = header;
+			out->f_data = s;
+			return 0;
+		}
+
+		s += header.size;
+		s += ((sizeof *bin_header)
+		      - ((uintptr_t)s % (sizeof *bin_header)));
+
+		bin_header = (struct tar_bin_header *)s;
+	}
+
+	return -1;
+}
+
+int tar_file_create_vm_object(const struct tar_file *file, kern_handle_t *out)
+{
+	const void *data = file->f_data;
+	size_t len = file->f_header.size;
+	kern_handle_t vmo = KERN_HANDLE_INVALID;
+
+	kern_status_t status = vm_object_create(
+		NULL,
+		0,
+		file->f_header.size,
+		VM_PROT_READ | VM_PROT_EXEC | VM_PROT_USER,
+		&vmo);
+	if (status != KERN_OK) {
+		return -1;
+	}
+
+	size_t nr_written = 0;
+	status = vm_object_write(vmo, data, 0, len, &nr_written);
+	if (status != KERN_OK || nr_written != len) {
+		kern_handle_close(vmo);
+		return -1;
+	}
+
+	*out = vmo;
+	return 0;
+}
+
+int tar_header_decode(const struct tar_bin_header *in, struct tar_header *out)
+{
+	memcpy(out->filename, in->filename, sizeof out->filename);
+	out->size = getsize(in->size);
+	return 0;
+}