Simplify and fix reading and writing so they seem to work.

plat/msdos/libsys/read.c

@@ -5,6 +5,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdbool.h>
 #include <string.h>
 #include <errno.h>
 #include <unistd.h>
@@ -16,9 +17,7 @@ ssize_t read(int fd, void* buffer, size_t count)
 	ssize_t r, tot;
 	size_t left;
 	int eof = 0;
-
-	if (!count || _sys_getmode(fd) == O_BINARY)
-		return _sys_rawread(fd, buffer, count);
+	bool text = _sys_getmode(fd) == O_TEXT;
 
 	if (_sys_iseof(fd))
 		return 0;
@@ -47,6 +46,8 @@ ssize_t read(int fd, void* buffer, size_t count)
 		if (r <= 0)
 			return tot ? tot : r;
 
+		if (text)
+		{
 			q = memchr(p, 0x1a, (size_t)r);
 			if (q)
 			{
@@ -75,6 +76,7 @@ ssize_t read(int fd, void* buffer, size_t count)
 				}
 				--left;
 			}
+		}
 	} while (tot < count && !eof && _sys_isreadyr(fd));
 
 	return tot;

plat/msdos/libsys/write.c

@@ -20,13 +20,25 @@ ssize_t write(int fd, void* buffer, size_t count)
 	if (!count)
 		return 0;
 
-	if (_sys_getmode(fd) == O_BINARY)
-		return _sys_rawwrite(fd, buffer, count);
-
-	/* If the file descriptor is an O_TEXT fd, translate LFs to CRLFs. */
 	p = buffer;
 	left = count;
 	tot = 0;
+
+	if (_sys_getmode(fd) == O_BINARY)
+	{
+		while (left)
+		{
+			r = _sys_rawwrite(fd, p, left);
+			if (r <= 0)
+				return tot ? tot : r;
+			tot += r;
+			p += r;
+			left -= r;
+		}
+	}
+	else
+	{
+		/* If the file descriptor is an O_TEXT fd, translate LFs to CRLFs. */
 		while (left)
 		{
 			q = memchr(p, '\n', left);
@@ -57,5 +69,6 @@ ssize_t write(int fd, void* buffer, size_t count)
 			++p;
 			--left;
 		}
+	}
 	return tot;
 }

plat/msdos386/boot.s

@@ -166,7 +166,7 @@ empty_environment:
 
     ! argc, argv, and envp are now at the stack top.  Now go.
     call __m_a_i_n
-    add sp, 6
+    add sp, 3*4
     push ax
     call _exit
 

plat/msdos386/libsys/sys_rawread.s

@@ -26,19 +26,12 @@
 
 .define __sys_rawread
 __sys_rawread:
-	enter 4, 0
-amount_transferred = -1*4
+	enter 0, 0
 file_handle = 2*4
 write_buffer = 3*4
 amount_to_read = 4*4
 
-	mov amount_transferred(ebp), 0
-
-mainloop:
 	mov eax, amount_to_read(ebp)
-	test eax, eax
-	jz exit
-
 	mov ecx, 32*1024
 	cmp eax, ecx
 	jge 2f
@@ -53,33 +46,31 @@ mainloop:
 	mov ecx, 0x80
 	or ebx, 0x210000
 	callf (interrupt_ptr)
-	jc exit
-	test eax, eax
-	jz exit
+	jnc success
+
+	! Process errors.
+
+	push eax
+	call __sys_seterrno
+	leave
+	ret
+success:
 
 	! Copy eax bytes out of the transfer buffer.
 
-	mov ecx, eax
 	push eax
+	mov ecx, eax
 	movzx esi, (transfer_buffer_ptr)
 	mov edi, write_buffer(ebp)
 	mov es, (pmode_ds)
 	cld
 1:
-	eseg lods
+	eseg lodsb
 	movb (edi), al
-	add edi, 4
+	inc edi
 	loop 1b
 	pop eax
 
-	add write_buffer(ebp), eax
-	add amount_transferred(ebp), eax
-	sub amount_to_read(ebp), eax
-	jmp mainloop
-
-exit:
-	mov eax, amount_transferred(ebp)
 	leave
 	ret
 
-

plat/msdos386/libsys/sys_rawwrite.s

@@ -26,20 +26,13 @@
 
 .define __sys_rawwrite
 __sys_rawwrite:
-	enter 4, 0
-amount_transferred = -1*4
+    enter 0, 0
 file_handle = 2*4
 read_buffer = 3*4
 amount_to_write = 4*4
 
-	mov amount_transferred(ebp), 0
-
-mainloop:
     mov eax, amount_to_write(ebp)
-	test eax, eax
-	jz exit
-
-	mov ecx, 32*1024
+    mov ecx, 32*1024        ! size of transfer buffer
     cmp eax, ecx
     jge 2f
     mov ecx, eax
@@ -62,17 +55,13 @@ mainloop:
     o16 mov bx, file_handle(ebp)
     or ebx, 0x210000
     callf (interrupt_ptr)
-	jc exit
-
-	! Update counters and go again.
-
-	add read_buffer(ebp), eax
-	add amount_transferred(ebp), eax
-	sub amount_to_write(ebp), eax
-	jmp mainloop
+    jnc exit
 
+    push eax
+    call __sys_seterrno
 exit:
-	mov eax, amount_transferred(ebp)
     leave
     ret
 
+! vim: sw=4 ts=4 et
+

plat/msdos386/stub.s

@@ -116,7 +116,7 @@ exe_start:
     callf (pmode_switch)
     jc bad_dpmi
 
-    ! We're now in protected mode. (ae)
+    ! We're now in protected mode.
 
     mov (psegcs), cs
     mov (psegds), ds
@@ -222,10 +222,6 @@ exe_start:
     push 0
     retf ! 19b
 
-    ! ALL CODE ABOVE THIS POINT DISCARDED ON ENTRY TO 32-BIT CODE
-    ! (it's reused as the 16-bit stack)
-stack16:
-
     ! Helper routine which reallocates the linear block that the 32-bit code
     ! is running from. This can't happen from inside the 32-bit code itself
     ! because it might move.
@@ -238,7 +234,7 @@ realloc:
     o32 mov (dpmi_ebp), esp     ! yes, saving esp into the ebp field
     mov (dpmi_ss), ss
     mov ss, (psegds)
-    mov sp, stack16
+    mov sp, dosstack
     sti
     pusha
 
@@ -323,10 +319,10 @@ interrupt:
     mov (dpmi_edi), di
     mov ax, (rseg)
     mov (dpmi_ds), ax
+    mov (dpmi_ss), ax
     push es
     push ds
-    xor ax, ax
-    mov (dpmi_ss), ax           ! zero stack: DPMI host allocates one.
+    mov ax, dosstack            ! auto stack is too small
     mov (dpmi_sp), ax
     push ds
     pop es
@@ -401,8 +397,10 @@ pmemhandle:     .space 4 ! protected mode linear memory handle
 pmemlen:        .space 4 ! protected mode linear memory length
 fh:             .space 2
 
-    .space 128
+    .space 512
 stack:
+    .space 512
+dosstack:
 
 TRANSFER_BUFFER_SIZE = 32*1024
 transfer_buffer: