From 08a9d7442e333cb25dbcc2ee4e539ac6ff93c041 Mon Sep 17 00:00:00 2001
From: Mathieu Maret <mathieu.maret@gmail.com>
Date: Mon, 8 Nov 2021 22:33:15 +0100
Subject: [PATCH] Add user file size before the file

As a quick fix before FS support
---
 Makefile    |  3 ++-
 core/main.c | 28 +++++++++++++++++++++++++---
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 5d88075..7d472df 100644
--- a/Makefile
+++ b/Makefile
@@ -45,7 +45,8 @@ disk.img: disk.sfdisk userspace
 	sfdisk $@ < $<
 	# Before having filesystem support, just dump the user prog into the first partition
 	strip userspace/user -o userspace/user.strip
-	dd if=userspace/user.strip of=disk.img seek=2048 bs=512
+	$(eval file_size:=$(shell du -b userspace/user.strip|awk '{print $$1}' | xargs printf "%016d" )) \
+	sed '1s/^/$(file_size)/' userspace/user.strip | dd  of=disk.img seek=2048 bs=512
 
 # NASM without preprocessing
 %.o:%.asm
diff --git a/core/main.c b/core/main.c
index e90fa95..d296eaa 100644
--- a/core/main.c
+++ b/core/main.c
@@ -215,6 +215,8 @@ static uaddr_t loadElfProg(const char *prog)
     return elf_hdr->e_entry;
 }
 
+#define FILE_HEADER_SIZE   16
+#define FILE_MAX_SIZE   64
 void loadUserSpace()
 {
     struct ata_partition *part = ATAGetPartition(0);
@@ -224,13 +226,33 @@ void loadUserSpace()
         return;
     }
 
-    char *buf = malloc(26 * 512);
+    char *buf = malloc(FILE_MAX_SIZE * 512);
     if (buf == NULL) {
         printf("ENOMEM\n");
         return;
     }
 
-    if (ATAReadPartitionSector(part, 0, 26, buf)) {
+    if (ATAReadPartitionSector(part, 0, 1, buf)) {
+        printf("Fail to read from disk\n");
+        return;
+    }
+
+    int sectorToRead;
+    {
+        char size[FILE_HEADER_SIZE + 1];
+        memcpy(size, buf, FILE_HEADER_SIZE);
+        size[FILE_HEADER_SIZE] = '\0';
+        int sizeInt            = atoi(size);
+        sectorToRead           = DIV_ROUND_UP(sizeInt, DISK_SECTOR_SIZE) - 1;
+    }
+
+    if (sectorToRead > FILE_MAX_SIZE - 1) {
+        printf("File too long");
+        return;
+    }
+
+    if (ATAReadPartitionSector(part, 1, sectorToRead,
+                               buf + DISK_SECTOR_SIZE)) {
         printf("Fail to read from disk\n");
         return;
     }
@@ -238,7 +260,7 @@ void loadUserSpace()
     struct process *proc = processCreate("UserSpace");
 
     threadChangeCurrentContext(processGetMMUContext(proc));
-    uaddr_t prog = loadElfProg(buf);
+    uaddr_t prog = loadElfProg(buf + FILE_HEADER_SIZE);
     if (prog == (uaddr_t)NULL) {
         free(buf);
         return;