2005-12-13 Ulrich Drepper <drepper@redhat.com>

1 files changed, 311 insertions, 0 deletions

diff --git a/elf/dl-cache.c b/elf/dl-cache.c
new file mode 100644
index 0000000..29886e1
--- /dev/null
+++ b/elf/dl-cache.c
@@ -0,0 +1,311 @@
+/* Support for reading /etc/ld.so.cache files written by Linux ldconfig.
+   Copyright (C) 1996-2002, 2003, 2004 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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <assert.h>
+#include <unistd.h>
+#include <ldsodefs.h>
+#include <sys/mman.h>
+#include <dl-cache.h>
+#include <dl-procinfo.h>
+
+#include <stdio-common/_itoa.h>
+
+#ifndef _DL_PLATFORMS_COUNT
+# define _DL_PLATFORMS_COUNT 0
+#endif
+
+/* This is the starting address and the size of the mmap()ed file.  */
+static struct cache_file *cache;
+static struct cache_file_new *cache_new;
+static size_t cachesize;
+
+/* 1 if cache_data + PTR points into the cache.  */
+#define _dl_cache_verify_ptr(ptr) (ptr < cache_data_size)
+
+#define SEARCH_CACHE(cache) \
+/* We use binary search since the table is sorted in the cache file.	      \
+   The first matching entry in the table is returned.			      \
+   It is important to use the same algorithm as used while generating	      \
+   the cache file.  */							      \
+do									      \
+  {									      \
+    left = 0;								      \
+    right = cache->nlibs - 1;						      \
+									      \
+    while (left <= right)						      \
+      {									      \
+	__typeof__ (cache->libs[0].key) key;				      \
+									      \
+	middle = (left + right) / 2;					      \
+									      \
+	key = cache->libs[middle].key;					      \
+									      \
+	/* Make sure string table indices are not bogus before using	      \
+	   them.  */							      \
+	if (! _dl_cache_verify_ptr (key))				      \
+	  {								      \
+	    cmpres = 1;							      \
+	    break;							      \
+	  }								      \
+									      \
+	/* Actually compare the entry with the key.  */			      \
+	cmpres = _dl_cache_libcmp (name, cache_data + key);		      \
+	if (__builtin_expect (cmpres == 0, 0))				      \
+	  {								      \
+	    /* Found it.  LEFT now marks the last entry for which we	      \
+	       know the name is correct.  */				      \
+	    left = middle;						      \
+									      \
+	    /* There might be entries with this name before the one we	      \
+	       found.  So we have to find the beginning.  */		      \
+	    while (middle > 0)						      \
+	      {								      \
+		__typeof__ (cache->libs[0].key) key;			      \
+									      \
+		key = cache->libs[middle - 1].key;			      \
+		/* Make sure string table indices are not bogus before	      \
+		   using them.  */					      \
+		if (! _dl_cache_verify_ptr (key)			      \
+		    /* Actually compare the entry.  */			      \
+		    || _dl_cache_libcmp (name, cache_data + key) != 0)	      \
+		  break;						      \
+		--middle;						      \
+	      }								      \
+									      \
+	    do								      \
+	      {								      \
+		int flags;						      \
+		__typeof__ (cache->libs[0]) *lib = &cache->libs[middle];      \
+									      \
+		/* Only perform the name test if necessary.  */		      \
+		if (middle > left					      \
+		    /* We haven't seen this string so far.  Test whether the  \
+		       index is ok and whether the name matches.  Otherwise   \
+		       we are done.  */					      \
+		    && (! _dl_cache_verify_ptr (lib->key)		      \
+			|| (_dl_cache_libcmp (name, cache_data + lib->key)    \
+			    != 0)))					      \
+		  break;						      \
+									      \
+		flags = lib->flags;					      \
+		if (_dl_cache_check_flags (flags)			      \
+		    && _dl_cache_verify_ptr (lib->value))		      \
+		  {							      \
+		    if (best == NULL || flags == GLRO(dl_correct_cache_id))   \
+		      {							      \
+			HWCAP_CHECK;					      \
+			best = cache_data + lib->value;			      \
+									      \
+			if (flags == GLRO(dl_correct_cache_id))		      \
+			  /* We've found an exact match for the shared	      \
+			     object and no general `ELF' release.  Stop	      \
+			     searching.  */				      \
+			  break;					      \
+		      }							      \
+		  }							      \
+	      }								      \
+	    while (++middle <= right);					      \
+	    break;							      \
+	}								      \
+									      \
+	if (cmpres < 0)							      \
+	  left = middle + 1;						      \
+	else								      \
+	  right = middle - 1;						      \
+      }									      \
+  }									      \
+while (0)
+
+
+int
+internal_function
+_dl_cache_libcmp (const char *p1, const char *p2)
+{
+  while (*p1 != '\0')
+    {
+      if (*p1 >= '0' && *p1 <= '9')
+        {
+          if (*p2 >= '0' && *p2 <= '9')
+            {
+	      /* Must compare this numerically.  */
+	      int val1;
+	      int val2;
+
+	      val1 = *p1++ - '0';
+	      val2 = *p2++ - '0';
+	      while (*p1 >= '0' && *p1 <= '9')
+	        val1 = val1 * 10 + *p1++ - '0';
+	      while (*p2 >= '0' && *p2 <= '9')
+	        val2 = val2 * 10 + *p2++ - '0';
+	      if (val1 != val2)
+		return val1 - val2;
+	    }
+	  else
+            return 1;
+        }
+      else if (*p2 >= '0' && *p2 <= '9')
+        return -1;
+      else if (*p1 != *p2)
+        return *p1 - *p2;
+      else
+	{
+	  ++p1;
+	  ++p2;
+	}
+    }
+  return *p1 - *p2;
+}
+
+
+/* Look up NAME in ld.so.cache and return the file name stored there,
+   or null if none is found.  */
+
+const char *
+internal_function
+_dl_load_cache_lookup (const char *name)
+{
+  int left, right, middle;
+  int cmpres;
+  const char *cache_data;
+  uint32_t cache_data_size;
+  const char *best;
+
+  /* Print a message if the loading of libs is traced.  */
+  if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_LIBS, 0))
+    _dl_debug_printf (" search cache=%s\n", LD_SO_CACHE);
+
+  if (cache == NULL)
+    {
+      /* Read the contents of the file.  */
+      void *file = _dl_sysdep_read_whole_file (LD_SO_CACHE, &cachesize,
+					       PROT_READ);
+
+      /* We can handle three different cache file formats here:
+	 - the old libc5/glibc2.0/2.1 format
+	 - the old format with the new format in it
+	 - only the new format
+	 The following checks if the cache contains any of these formats.  */
+      if (file != MAP_FAILED && cachesize > sizeof *cache
+	  && memcmp (file, CACHEMAGIC, sizeof CACHEMAGIC - 1) == 0)
+	{
+	  size_t offset;
+	  /* Looks ok.  */
+	  cache = file;
+
+	  /* Check for new version.  */
+	  offset = ALIGN_CACHE (sizeof (struct cache_file)
+				+ cache->nlibs * sizeof (struct file_entry));
+
+	  cache_new = (struct cache_file_new *) ((void *) cache + offset);
+	  if (cachesize < (offset + sizeof (struct cache_file_new))
+	      || memcmp (cache_new->magic, CACHEMAGIC_VERSION_NEW,
+			 sizeof CACHEMAGIC_VERSION_NEW - 1) != 0)
+	    cache_new = (void *) -1;
+	}
+      else if (file != MAP_FAILED && cachesize > sizeof *cache_new
+	       && memcmp (file, CACHEMAGIC_VERSION_NEW,
+			  sizeof CACHEMAGIC_VERSION_NEW - 1) == 0)
+	{
+	  cache_new = file;
+	  cache = file;
+	}
+      else
+	{
+	  if (file != MAP_FAILED)
+	    __munmap (file, cachesize);
+	  cache = (void *) -1;
+	}
+
+      assert (cache != NULL);
+    }
+
+  if (cache == (void *) -1)
+    /* Previously looked for the cache file and didn't find it.  */
+    return NULL;
+
+  best = NULL;
+
+  if (cache_new != (void *) -1)
+    {
+      uint64_t platform;
+
+      /* This is where the strings start.  */
+      cache_data = (const char *) cache_new;
+
+      /* Now we can compute how large the string table is.  */
+      cache_data_size = (const char *) cache + cachesize - cache_data;
+
+      platform = _dl_string_platform (GLRO(dl_platform));
+      if (platform != (uint64_t) -1)
+	platform = 1ULL << platform;
+
+      /* Only accept hwcap if it's for the right platform.  */
+#ifdef USE_TLS
+# define _DL_HWCAP_TLS_MASK (1LL << 63)
+#else
+# define _DL_HWCAP_TLS_MASK 0
+#endif
+#define HWCAP_CHECK \
+      if (GLRO(dl_osversion) && lib->osversion > GLRO(dl_osversion))	      \
+	continue;							      \
+      if (_DL_PLATFORMS_COUNT && platform != -1				      \
+	  && (lib->hwcap & _DL_HWCAP_PLATFORM) != 0			      \
+	  && (lib->hwcap & _DL_HWCAP_PLATFORM) != platform)		      \
+	continue;							      \
+      if (lib->hwcap							      \
+	  & ~(GLRO(dl_hwcap) | _DL_HWCAP_PLATFORM | _DL_HWCAP_TLS_MASK))      \
+	continue
+      SEARCH_CACHE (cache_new);
+    }
+  else
+    {
+      /* This is where the strings start.  */
+      cache_data = (const char *) &cache->libs[cache->nlibs];
+
+      /* Now we can compute how large the string table is.  */
+      cache_data_size = (const char *) cache + cachesize - cache_data;
+
+#undef HWCAP_CHECK
+#define HWCAP_CHECK do {} while (0)
+      SEARCH_CACHE (cache);
+    }
+
+  /* Print our result if wanted.  */
+  if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_LIBS, 0)
+      && best != NULL)
+    _dl_debug_printf ("  trying file=%s\n", best);
+
+  return best;
+}
+
+#ifndef MAP_COPY
+/* If the system does not support MAP_COPY we cannot leave the file open
+   all the time since this would create problems when the file is replaced.
+   Therefore we provide this function to close the file and open it again
+   once needed.  */
+void
+_dl_unload_cache (void)
+{
+  if (cache != NULL && cache != (struct cache_file *) -1)
+    {
+      __munmap (cache, cachesize);
+      cache = NULL;
+    }
+}
+#endif