Date: Sat, 13 Apr 2024 14:01:09 +0200
From: Pali <pali@pali.im>
Cc: dj@delorie.com, sezeroz@gmail.com, djgpp@delorie.com

On Saturday 13 April 2024 14:51:17 Eli Zaretskii wrote:

Date: Sat, 13 Apr 2024 12:37:41 +0200
From: Pali <pali@pali.im>
Cc: djgpp@delorie.com

Hello, I have there a change for __djgpp_set_page_attributes() function which sets more sane errno value on different failures. Could you look
at it if it is useful?

Thanks. I think this can be useful, but I'd prefer to keep the style
of having just one exit point in this function. So could you please rewrite the patch so that the various conditions only set errno, and
still "goto fail"?

Ok. Something like this?

--- src/libc/dpmi/helper/setattr.c
+++ src/libc/dpmi/helper/setattr.c
@@ -28,7 +28,7 @@ __djgpp_set_page_attributes (void *_our_addr, unsigned long _num_bytes,
|| ((_attributes & 0x3) == 2))
{
errno = EINVAL;
- return -1;
+ goto fail;
}

/* Set up an array of page attribute information. */
@@ -50,7 +50,17 @@ __djgpp_set_page_attributes (void *_our_addr, unsigned long _num_bytes,
/* Find the memory handle corresponding to the first byte. */
d = __djgpp_memory_handle (p);
if (d == NULL)
- goto fail;
+ {
+ errno = EFAULT;
+ goto fail;
+ }
+
+ /* Base address of the memory handle must be page aligned too. */
+ if (d->address & 0xfff)
+ {
+ errno = EFAULT;
+ goto fail;
+ }

/* Find the last byte in the range that's also in the same
* memory handle as our current starting byte. We start with
@@ -68,7 +78,10 @@ __djgpp_set_page_attributes (void *_our_addr, unsigned long _num_bytes,
/* Find the memory handle corresponding to this test byte. */
d2 = __djgpp_memory_handle (handle_end_addr);
if (d2 == NULL)
- goto fail;
+ {
+ errno = EFAULT;
+ goto fail;
+ }

/* Is this test byte in the same handle as the first byte? */
if (d2->handle == d->handle)
@@ -81,9 +94,35 @@ __djgpp_set_page_attributes (void *_our_addr, unsigned long _num_bytes,
meminfo.handle = d->handle;
meminfo.size = num_pages2;
meminfo.address = p - d->address;
- if (__dpmi_set_page_attributes (&meminfo, attr)
- || meminfo.size != num_pages2)
- goto fail;
+ if (__dpmi_set_page_attributes (&meminfo, attr))
+ {
+ switch (__dpmi_error)
+ {
+ case 0x0507: /* Unsupported function (returned by DPMI 0.9 host, error number is same as DPMI function number) */
+ case 0x8001: /* Unsupported function (returned by DPMI 1.0 host) */
+ errno = ENOSYS;
+ break;
+ case 0x8002: /* Invalid state (page in wrong state for request) */
+ errno = EFAULT;
+ break;
+ case 0x8010: /* Resource unavailable (DPMI host cannot allocate internal resources to complete an operation) */
+ case 0x8013: /* Physical memory unavailable */
+ case 0x8014: /* Backing store unavailable */
+ errno = ENOMEM;
+ break;
+ case 0x8021: /* Invalid value (illegal request in bits 0-2 of one or more page attribute words) */
+ errno = EINVAL;
+ break;
+ case 0x8023: /* Invalid handle (in ESI) */
+ case 0x8025: /* Invalid linear address (specified range is not within specified block) */
+ errno = EFAULT;
+ break;
+ default: /* Other unspecified error */
+ errno = EIO;
+ break;