Consolidate link map sorting

Combine the four places where link maps are sorted into a single function. This also moves the logic to skip the first map (representing the main binary) to the callers.
2025-07-07 12:21:14 +03:00 · 2017-11-07 15:24:19 +01:00
parent de61465c04
commit c2c299fd24
8 changed files with 153 additions and 215 deletions
--- a/elf/dl-sort-maps.c
+++ b/elf/dl-sort-maps.c
@ -0,0 +1,122 @@
+/* Sort array of link maps according to dependencies.
+   Copyright (C) 2017 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:;
+    }
+}