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/* Sort array of link maps according to dependencies.
Copyright (C) 2017-2021 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 <ldsodefs.h>
/* Sort array MAPS according to dependencies of the contained objects.
Array USED, if non-NULL, is permutated along MAPS. If FOR_FINI this is
called for finishing an object. */
void
_dl_sort_maps (struct link_map **maps, unsigned int nmaps, char *used,
bool for_fini)
{
/* A list of one element need not be sorted. */
if (nmaps <= 1)
return;
unsigned int i = 0;
uint16_t seen[nmaps];
memset (seen, 0, nmaps * sizeof (seen[0]));
while (1)
{
/* Keep track of which object we looked at this round. */
++seen[i];
struct link_map *thisp = maps[i];
if (__glibc_unlikely (for_fini))
{
/* Do not handle ld.so in secondary namespaces and objects which
are not removed. */
if (thisp != thisp->l_real || thisp->l_idx == -1)
goto skip;
}
/* Find the last object in the list for which the current one is
a dependency and move the current object behind the object
with the dependency. */
unsigned int k = nmaps - 1;
while (k > i)
{
struct link_map **runp = maps[k]->l_initfini;
if (runp != NULL)
/* Look through the dependencies of the object. */
while (*runp != NULL)
if (__glibc_unlikely (*runp++ == thisp))
{
move:
/* Move the current object to the back past the last
object with it as the dependency. */
memmove (&maps[i], &maps[i + 1],
(k - i) * sizeof (maps[0]));
maps[k] = thisp;
if (used != NULL)
{
char here_used = used[i];
memmove (&used[i], &used[i + 1],
(k - i) * sizeof (used[0]));
used[k] = here_used;
}
if (seen[i + 1] > nmaps - i)
{
++i;
goto next_clear;
}
uint16_t this_seen = seen[i];
memmove (&seen[i], &seen[i + 1], (k - i) * sizeof (seen[0]));
seen[k] = this_seen;
goto next;
}
if (__glibc_unlikely (for_fini && maps[k]->l_reldeps != NULL))
{
unsigned int m = maps[k]->l_reldeps->act;
struct link_map **relmaps = &maps[k]->l_reldeps->list[0];
/* Look through the relocation dependencies of the object. */
while (m-- > 0)
if (__glibc_unlikely (relmaps[m] == thisp))
{
/* If a cycle exists with a link time dependency,
preserve the latter. */
struct link_map **runp = thisp->l_initfini;
if (runp != NULL)
while (*runp != NULL)
if (__glibc_unlikely (*runp++ == maps[k]))
goto ignore;
goto move;
}
ignore:;
}
--k;
}
skip:
if (++i == nmaps)
break;
next_clear:
memset (&seen[i], 0, (nmaps - i) * sizeof (seen[0]));
next:;
}
}
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