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-rw-r--r--elf/dl-sort-maps.c122
1 files changed, 122 insertions, 0 deletions
diff --git a/elf/dl-sort-maps.c b/elf/dl-sort-maps.c
new file mode 100644
index 0000000000..b2a01ede62
--- /dev/null
+++ b/elf/dl-sort-maps.c
@@ -0,0 +1,122 @@
+/* Sort array of link maps according to dependencies.
+ Copyright (C) 2017-2018 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
+ <http://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:;
+ }
+}