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/* Fault-safe copy into or out of pager-backed memory. |
/* Fault-safe copy into or out of pager-backed memory. |
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Copyright (C) 1996,97,99,2000,2001 Free Software Foundation, Inc. |
Copyright (C) 1996,97,99, 2000,01,02 Free Software Foundation, Inc. |
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Written by Roland McGrath. |
Written by Roland McGrath. |
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This program is free software; you can redistribute it and/or |
This program is free software; you can redistribute it and/or |
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along with this program; if not, write to the Free Software |
along with this program; if not, write to the Free Software |
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ |
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ |
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#include "priv.h" |
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#include "pager.h" |
#include "pager.h" |
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#include <sys/mman.h> |
#include <sys/mman.h> |
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#include <hurd/sigpreempt.h> |
#include <hurd/sigpreempt.h> |
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#include <assert.h> |
#include <assert.h> |
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#include <string.h> |
#include <string.h> |
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/* Start using vm_copy over memcpy when we have at a page. (This |
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value *cannot* be less than vm_page_size.) */ |
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#define VMCOPY_BETTER_THAN_MEMCPY (vm_page_size) |
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/* Try to copy *SIZE bytes between the region OTHER points to |
/* Try to copy *SIZE bytes between the region OTHER points to |
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and the region at OFFSET in the pager indicated by PAGER and MEMOBJ. |
and the region at OFFSET in the pager indicated by PAGER and MEMOBJ. |
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If PROT is VM_PROT_READ, copying is from the pager to OTHER; |
If PROT is VM_PROT_READ, copying is from the pager to OTHER; |
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*SIZE is always filled in the actual number of bytes successfully copied. |
*SIZE is always filled in the actual number of bytes successfully copied. |
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Returns an error code if the pager-backed memory faults; |
Returns an error code if the pager-backed memory faults; |
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if there is no fault, returns 0 and *SIZE will be unchanged. */ |
if there is no fault, returns 0 and *SIZE will be unchanged. */ |
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error_t |
error_t |
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pager_memcpy (struct pager *pager, memory_object_t memobj, |
pager_memcpy (struct pager *pager, memory_object_t memobj, |
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vm_offset_t offset, void *other, size_t *size, |
vm_offset_t offset, void *other, size_t *size, |
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vm_prot_t prot) |
vm_prot_t prot) |
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{ |
{ |
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vm_address_t window = 0; |
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vm_size_t windowsize = 8 * vm_page_size; |
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size_t to_copy = *size; |
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error_t err; |
error_t err; |
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size_t n = *size; |
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error_t copy (struct hurd_signal_preemptor *preemptor) |
#define VMCOPY_WINDOW_DEFAULT_SIZE (16 * vm_page_size) |
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#define MEMCPY_WINDOW_DEFAULT_SIZE (8 * vm_page_size) |
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vm_address_t window; |
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vm_size_t window_size; |
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error_t do_vm_copy (void) |
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{ |
{ |
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while (to_copy > 0) |
assert ((offset & (vm_page_size - 1)) == 0); |
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{ |
assert (((vm_address_t) other & (vm_page_size - 1)) == 0); |
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size_t pageoff = offset & (vm_page_size - 1); |
assert (n >= vm_page_size); |
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if (window) |
do |
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/* Deallocate the old window. */ |
{ |
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munmap ((caddr_t) window, windowsize); |
window_size = |
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VMCOPY_WINDOW_DEFAULT_SIZE > n |
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/* Map in and copy a standard-sized window, unless that is |
? (n - (n & (vm_page_size - 1))) |
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more than the total left to be copied. */ |
: VMCOPY_WINDOW_DEFAULT_SIZE; |
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if (windowsize > pageoff + to_copy) |
assert (window_size >= VMCOPY_BETTER_THAN_MEMCPY); |
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windowsize = pageoff + to_copy; |
assert ((window_size & (vm_page_size - 1)) == 0); |
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window = 0; |
err = vm_map (mach_task_self (), &window, window_size, 0, 1, |
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err = vm_map (mach_task_self (), &window, windowsize, 0, 1, |
memobj, offset, 0, prot, prot, VM_INHERIT_NONE); |
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memobj, offset - pageoff, 0, |
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prot, prot, VM_INHERIT_NONE); |
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if (err) |
if (err) |
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return 0; |
return err; |
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/* Realign the fault preemptor for the new mapping window. */ |
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preemptor->first = window; |
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preemptor->last = window + windowsize; |
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if (prot == VM_PROT_READ) |
if (prot == VM_PROT_READ) |
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memcpy (other, (const void *) window + pageoff, |
err = vm_copy (mach_task_self (), window, window_size, |
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windowsize - pageoff); |
(vm_address_t) other); |
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else |
else |
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memcpy ((void *) window + pageoff, other, windowsize - pageoff); |
err = vm_copy (mach_task_self (), (vm_address_t) other, |
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window_size, window); |
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offset += windowsize - pageoff; |
vm_deallocate (mach_task_self (), window, window_size); |
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other += windowsize - pageoff; |
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to_copy -= windowsize - pageoff; |
if (err) |
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return err; |
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other += window_size; |
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offset += window_size; |
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n -= window_size; |
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} |
} |
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while (n >= VMCOPY_BETTER_THAN_MEMCPY); |
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return 0; |
return 0; |
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} |
} |
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error_t do_copy (struct hurd_signal_preemptor *preemptor) |
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{ |
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error_t do_memcpy (size_t to_copy) |
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{ |
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window_size = MEMCPY_WINDOW_DEFAULT_SIZE; |
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do |
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{ |
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size_t pageoff = offset & (vm_page_size - 1); |
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size_t copy_count = window_size - pageoff; |
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/* Map in and copy a standard-sized window, unless that is |
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more than the total left to be copied. */ |
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if (window_size >= round_page (pageoff + to_copy)) |
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{ |
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copy_count = to_copy; |
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window_size = round_page (pageoff + to_copy); |
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} |
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err = vm_map (mach_task_self (), &window, window_size, 0, 1, |
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memobj, offset - pageoff, 0, |
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prot, prot, VM_INHERIT_NONE); |
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if (err) |
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return err; |
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/* Realign the fault preemptor for the new mapping window. */ |
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preemptor->first = window; |
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preemptor->last = window + window_size; |
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if (prot == VM_PROT_READ) |
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memcpy (other, (const void *) window + pageoff, copy_count); |
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else |
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memcpy ((void *) window + pageoff, other, copy_count); |
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vm_deallocate (mach_task_self (), window, window_size); |
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offset += copy_count; |
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other += copy_count; |
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to_copy -= copy_count; |
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n -= copy_count; |
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assert (n >= 0); |
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assert (to_copy >= 0); |
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} |
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while (to_copy > 0); |
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return 0; |
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} |
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/* Can we use vm_copy? */ |
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if ((((vm_address_t) other & (vm_page_size - 1)) |
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== (offset & (vm_page_size - 1))) |
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&& (n >= (VMCOPY_BETTER_THAN_MEMCPY + vm_page_size |
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- ((vm_address_t) other & (vm_page_size - 1))))) |
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/* 1) other and offset are aligned with repect to each other; |
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and 2) we have at least VMCOPY_BETTER_THAN_MEMCPY fully |
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aligned pages. */ |
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{ |
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err = do_memcpy (vm_page_size |
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- ((vm_address_t) other & (vm_page_size - 1))); |
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if (err) |
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return err; |
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assert (n >= VMCOPY_BETTER_THAN_MEMCPY); |
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err = do_vm_copy (); |
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if (err || n == 0) |
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/* We failed or we finished. */ |
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return err; |
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assert (n < VMCOPY_BETTER_THAN_MEMCPY); |
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} |
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return do_memcpy (n); |
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} |
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jmp_buf buf; |
jmp_buf buf; |
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void fault (int signo, long int sigcode, struct sigcontext *scp) |
void fault (int signo, long int sigcode, struct sigcontext *scp) |
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{ |
{ |
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assert (scp->sc_error == EKERN_MEMORY_ERROR); |
assert (scp->sc_error == EKERN_MEMORY_ERROR); |
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err = pager_get_error (pager, sigcode - window + offset); |
err = pager_get_error (pager, |
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to_copy -= sigcode - window; |
(sigcode - window + offset) / vm_page_size); |
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n -= sigcode - window; |
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vm_deallocate (mach_task_self (), window, window_size); |
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longjmp (buf, 1); |
longjmp (buf, 1); |
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} |
} |
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if (to_copy == 0) |
if (n == 0) |
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/* Short-circuit return if nothing to do. |
/* Nothing to do. */ |
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ERR would not be initialized by the copy loop in this case. */ |
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return 0; |
return 0; |
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if (((vm_address_t) other & (vm_page_size - 1)) == 0 |
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&& (offset & (vm_page_size - 1)) == 0 |
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&& n >= VMCOPY_BETTER_THAN_MEMCPY) |
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/* 1) the start address is page aligned; 2) the offset is page |
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aligned; and 3) we have more than VMCOPY_BETTER_THAN_MEMCPY |
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pages. */ |
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{ |
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err = do_vm_copy (); |
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if (err || n == 0) |
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/* We failed or we finished. */ |
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{ |
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*size -= n; |
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return err; |
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} |
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assert (n < VMCOPY_BETTER_THAN_MEMCPY); |
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} |
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/* Need to do it the hard way. */ |
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window = 0; |
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window_size = 0; |
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if (setjmp (buf) == 0) |
if (setjmp (buf) == 0) |
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hurd_catch_signal (sigmask (SIGSEGV) | sigmask (SIGBUS), |
hurd_catch_signal (sigmask (SIGSEGV) | sigmask (SIGBUS), |
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window, window + windowsize, |
window, window + window_size, |
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©, (sighandler_t) &fault); |
&do_copy, (sighandler_t) &fault); |
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if (window) |
if (! err) |
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munmap ((caddr_t) window, windowsize); |
assert (n == 0); |
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*size -= to_copy; |
*size -= n; |
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return err; |
return err; |
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} |
} |