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/* Copyright (C) 2020-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <sys/types.h>
#include <sys/mman.h>
#include <errno.h>
#include <stdarg.h>
#include <hurd.h>
#include <stdio.h>
/* Remap pages mapped by the range [ADDR,ADDR+OLD_LEN) to new length
NEW_LEN. If MREMAP_MAYMOVE is set in FLAGS the returned address
may differ from ADDR. If MREMAP_FIXED is set in FLAGS the function
takes another parameter which is a fixed address at which the block
resides after a successful call. */
void *
__mremap (void *addr, size_t old_len, size_t new_len, int flags, ...)
{
error_t err;
vm_address_t vm_addr = (vm_address_t) addr;
vm_offset_t new_vm_addr = 0;
vm_address_t begin = vm_addr;
vm_address_t end;
vm_size_t len;
vm_prot_t prot;
vm_prot_t max_prot;
vm_inherit_t inherit;
boolean_t shared;
memory_object_name_t obj;
vm_offset_t offset;
if ((flags & ~(MREMAP_MAYMOVE | MREMAP_FIXED)) ||
((flags & MREMAP_FIXED) && !(flags & MREMAP_MAYMOVE)) ||
(old_len == 0 && !(flags & MREMAP_MAYMOVE)))
return (void *) (long int) __hurd_fail (EINVAL);
if (flags & MREMAP_FIXED)
{
va_list arg;
va_start (arg, flags);
new_vm_addr = (vm_offset_t) va_arg (arg, void *);
va_end (arg);
}
err = __vm_region (__mach_task_self (),
&begin, &len, &prot, &max_prot, &inherit,
&shared, &obj, &offset);
if (err)
return (void *) (uintptr_t) __hurd_fail (err);
if (begin > vm_addr)
{
err = EFAULT;
goto out;
}
if (begin < vm_addr || (old_len != 0 && old_len != len))
{
err = EINVAL;
goto out;
}
end = begin + len;
if ((flags & MREMAP_FIXED) &&
((new_vm_addr + new_len > vm_addr && new_vm_addr < end)))
{
/* Overlapping is not supported, like in Linux. */
err = EINVAL;
goto out;
}
/* FIXME: locked memory. */
if (old_len != 0 && !(flags & MREMAP_FIXED))
{
/* A mere change of the existing map. */
if (new_len == len)
{
new_vm_addr = vm_addr;
goto out;
}
if (new_len < len)
{
/* Shrink. */
__mach_port_deallocate (__mach_task_self (), obj);
err = __vm_deallocate (__mach_task_self (),
begin + new_len, len - new_len);
new_vm_addr = vm_addr;
goto out;
}
/* Try to expand. */
err = __vm_map (__mach_task_self (),
&end, new_len - len, 0, 0,
obj, offset + len, 0, prot, max_prot, inherit);
if (!err)
{
/* Ok, that worked. Now coalesce them. */
new_vm_addr = vm_addr;
/* XXX this is not atomic as it is in unix! */
err = __vm_deallocate (__mach_task_self (), begin, new_len);
if (err)
{
__vm_deallocate (__mach_task_self (), end, new_len - len);
goto out;
}
err = __vm_map (__mach_task_self (),
&begin, new_len, 0, 0,
obj, offset, 0, prot, max_prot, inherit);
if (err)
{
/* Oops, try to remap before reporting. */
__vm_map (__mach_task_self (),
&begin, len, 0, 0,
obj, offset, 0, prot, max_prot, inherit);
}
goto out;
}
}
if (!(flags & MREMAP_MAYMOVE))
{
/* Can not map here */
err = ENOMEM;
goto out;
}
err = __vm_map (__mach_task_self (),
&new_vm_addr, new_len, 0,
new_vm_addr == 0, obj, offset,
old_len == 0, prot, max_prot, inherit);
if (err == KERN_NO_SPACE && (flags & MREMAP_FIXED))
{
/* XXX this is not atomic as it is in unix! */
/* The region is already allocated; deallocate it first. */
err = __vm_deallocate (__mach_task_self (), new_vm_addr, new_len);
if (! err)
err = __vm_map (__mach_task_self (),
&new_vm_addr, new_len, 0,
0, obj, offset,
old_len == 0, prot, max_prot, inherit);
}
if (!err)
/* Alright, can remove old mapping. */
__vm_deallocate (__mach_task_self (), begin, len);
out:
__mach_port_deallocate (__mach_task_self (), obj);
if (err)
return (void *) (uintptr_t) __hurd_fail (err);
return (void *) new_vm_addr;
}
libc_hidden_def (__mremap)
weak_alias (__mremap, mremap)
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