Merge pull request #2191 from ghaerr/sigcb

[libc] Fix longstanding signal handling bug with improperly set DS register
ghaerr · Jan 20, 2025 · 678dd4e · 678dd4e
2 parents 7898cc9 + 0533753
commit 678dd4e
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diff --git a/libc/system/signalcb.S b/libc/system/signalcb.S
@@ -20,7 +20,10 @@ _signal_cbhandler:
 	push %dx
 	push %si
 	push %di
+	push %ds
 	push %es
+	mov %ss,%ax
+	mov %ax,%ds
 
 	mov 6(%bp),%bx
 #ifndef __IA16_CALLCVT_REGPARMCALL
@@ -43,6 +46,7 @@ _signal_cbhandler:
 #endif
 
 	pop %es
+	pop %ds
 	pop %di
 	pop %si
 	pop %dx

diff --git a/libc/watcom/asm/signalcb.asm b/libc/watcom/asm/signalcb.asm
@@ -20,6 +20,8 @@ __signal_cbhandler proc far
         push di
         push ds
         push es
+        mov ax,ss                   ; ensure valid DS (=SS)
+        mov ds,ax
 
         mov ax,6[bp]                ; get signal #
         callf _signal_wchandler_    ; call user function from C