From c95a82da158dadef07f3ed49a88b09c87b0552c1 Mon Sep 17 00:00:00 2001
From: Stas Sergeev <stsp@users.sourceforge.net>
Date: Thu, 12 Sep 2024 00:44:41 +0300
Subject: [PATCH] plt: add API versioning

---
 src/libc/dj64/plt.S    | 13 ++++++++++++-
 src/libc/dj64/plt.h    |  1 +
 src/libc/dj64/thunks.c |  8 ++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/libc/dj64/plt.S b/src/libc/dj64/plt.S
index 5fda4eb0..459058c0 100644
--- a/src/libc/dj64/plt.S
+++ b/src/libc/dj64/plt.S
@@ -249,6 +249,7 @@ plt_init:
     movl %fs:STUBINFO_SELF_SIZE, %ecx
     movl %fs:STUBINFO_MEM_BASE, %edx
     call ctrl
+    jc 2f
     /* free mem */
     movl $0x502, %eax
     movw handle, %di
@@ -275,17 +276,27 @@ plt_init:
     movl $0, %ecx
     movl %fs:STUBINFO_MEM_BASE, %edx
     call ctrl
+    jc 2b
     jmp 11b
 
 ctrl:
     pushal
     movl %esp, %edx
     movl __plt_handle, %eax
-    movl $AUX_CORE, %ebx
+    movl $0, %ebx
+    movb $AUX_CORE, %bl
+    movb $DL_API_VER, %bh
     movl $DL_SET_SYMTAB, %ecx
     movl %cs, %esi
     lcalll *__plt_ctrl
+    testl %eax, %eax
+    jnz 1f
+    popal
+    clc
+    ret
+1:
     popal
+    stc
     ret
 
 .global plt_done
diff --git a/src/libc/dj64/plt.h b/src/libc/dj64/plt.h
index 82a4fd12..5689299c 100644
--- a/src/libc/dj64/plt.h
+++ b/src/libc/dj64/plt.h
@@ -1 +1,2 @@
 #define DL_SET_SYMTAB 0
+#define DL_API_VER 1
diff --git a/src/libc/dj64/thunks.c b/src/libc/dj64/thunks.c
index 3d93ee19..d49abe97 100644
--- a/src/libc/dj64/thunks.c
+++ b/src/libc/dj64/thunks.c
@@ -247,7 +247,15 @@ static void do_early_init(int handle)
 static int dj64_ctrl(int handle, int libid, int fn, unsigned esi, uint8_t *sp)
 {
     dpmi_regs *regs = (dpmi_regs *)sp;
+    int ver = libid >> 8;
     assert(handle < MAX_HANDLES);
+    if (ver != DL_API_VER) {
+        djloudprintf("dj64: API version mismatch, got %i want %i\n",
+                     ver, DL_API_VER);
+        if (ver == 0)  // this doesn't even handle errors, so terminate
+            dj64api->exit(1);
+        return -1;
+    }
     switch (fn) {
     case DL_SET_SYMTAB: {
         struct udisp *u = &udisps[handle];