[thirdparty/glibc.git] / elf / dl-cache.c

/* Support for reading /etc/ld.so.cache files written by Linux ldconfig.
   Copyright (C) 1996-2014 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 <assert.h>
#include <unistd.h>
#include <ldsodefs.h>
#include <sys/mman.h>
#include <dl-cache.h>
#include <dl-procinfo.h>
#include <stdint.h>
#include <_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 (__glibc_unlikely (cmpres == 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.  The cache is loaded if it was not already.  If loading
   the cache previously failed there will be no more attempts to load it.  */

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 (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS))
    _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;

#define _DL_HWCAP_TLS_MASK (1LL << 63)
      uint64_t hwcap_exclude = ~((GLRO(dl_hwcap) & GLRO(dl_hwcap_mask))
				 | _DL_HWCAP_PLATFORM | _DL_HWCAP_TLS_MASK);

      /* Only accept hwcap if it's for the right platform.  */
#define HWCAP_CHECK \
      if (lib->hwcap & hwcap_exclude)					      \
	continue;							      \
      if (GLRO(dl_osversion) && lib->osversion > GLRO(dl_osversion))	      \
	continue;							      \
      if (_DL_PLATFORMS_COUNT						      \
	  && (lib->hwcap & _DL_HWCAP_PLATFORM) != 0			      \
	  && (lib->hwcap & _DL_HWCAP_PLATFORM) != platform)		      \
	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
Commit	Line	Data
b6ab06ce	1	/* Support for reading /etc/ld.so.cache files written by Linux ldconfig.
d4697bc9	2	Copyright (C) 1996-2014 Free Software Foundation, Inc.
b6ab06ce UD	3	This file is part of the GNU C Library.
	4
	5	The GNU C Library is free software; you can redistribute it and/or
	6	modify it under the terms of the GNU Lesser General Public
	7	License as published by the Free Software Foundation; either
	8	version 2.1 of the License, or (at your option) any later version.
	9
	10	The GNU C Library is distributed in the hope that it will be useful,
	11	but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	13	Lesser General Public License for more details.
	14
	15	You should have received a copy of the GNU Lesser General Public
59ba27a6 PE	16	License along with the GNU C Library; if not, see
59ba27a6 PE	17	<http://www.gnu.org/licenses/>. */
b6ab06ce UD	18
	19	#include <assert.h>
	20	#include <unistd.h>
	21	#include <ldsodefs.h>
	22	#include <sys/mman.h>
	23	#include <dl-cache.h>
	24	#include <dl-procinfo.h>
e054f494	25	#include <stdint.h>
eb96ffb0	26	#include <_itoa.h>
b6ab06ce UD	27
	28	#ifndef _DL_PLATFORMS_COUNT
	29	# define _DL_PLATFORMS_COUNT 0
	30	#endif
	31
	32	/* This is the starting address and the size of the mmap()ed file. */
	33	static struct cache_file *cache;
	34	static struct cache_file_new *cache_new;
	35	static size_t cachesize;
	36
	37	/* 1 if cache_data + PTR points into the cache. */
	38	#define _dl_cache_verify_ptr(ptr) (ptr < cache_data_size)
	39
	40	#define SEARCH_CACHE(cache) \
	41	/* We use binary search since the table is sorted in the cache file. \
	42	The first matching entry in the table is returned. \
	43	It is important to use the same algorithm as used while generating \
	44	the cache file. */ \
	45	do \
	46	{ \
	47	left = 0; \
	48	right = cache->nlibs - 1; \
	49	\
	50	while (left <= right) \
	51	{ \
	52	__typeof__ (cache->libs[0].key) key; \
	53	\
	54	middle = (left + right) / 2; \
	55	\
	56	key = cache->libs[middle].key; \
	57	\
	58	/* Make sure string table indices are not bogus before using \
	59	them. */ \
	60	if (! _dl_cache_verify_ptr (key)) \
	61	{ \
	62	cmpres = 1; \
	63	break; \
	64	} \
	65	\
	66	/* Actually compare the entry with the key. */ \
	67	cmpres = _dl_cache_libcmp (name, cache_data + key); \
a1ffb40e	68	if (__glibc_unlikely (cmpres == 0)) \
b6ab06ce UD	69	{ \
	70	/* Found it. LEFT now marks the last entry for which we \
	71	know the name is correct. */ \
	72	left = middle; \
	73	\
	74	/* There might be entries with this name before the one we \
	75	found. So we have to find the beginning. */ \
	76	while (middle > 0) \
	77	{ \
	78	__typeof__ (cache->libs[0].key) key; \
	79	\
	80	key = cache->libs[middle - 1].key; \
	81	/* Make sure string table indices are not bogus before \
	82	using them. */ \
	83	if (! _dl_cache_verify_ptr (key) \
	84	/* Actually compare the entry. */ \
	85	\|\| _dl_cache_libcmp (name, cache_data + key) != 0) \
	86	break; \
	87	--middle; \
	88	} \
	89	\
	90	do \
	91	{ \
	92	int flags; \
	93	__typeof__ (cache->libs[0]) *lib = &cache->libs[middle]; \
	94	\
	95	/* Only perform the name test if necessary. */ \
	96	if (middle > left \
	97	/* We haven't seen this string so far. Test whether the \
	98	index is ok and whether the name matches. Otherwise \
	99	we are done. */ \
	100	&& (! _dl_cache_verify_ptr (lib->key) \
	101	\|\| (_dl_cache_libcmp (name, cache_data + lib->key) \
	102	!= 0))) \
	103	break; \
	104	\
	105	flags = lib->flags; \
	106	if (_dl_cache_check_flags (flags) \
	107	&& _dl_cache_verify_ptr (lib->value)) \
	108	{ \
	109	if (best == NULL \|\| flags == GLRO(dl_correct_cache_id)) \
	110	{ \
	111	HWCAP_CHECK; \
	112	best = cache_data + lib->value; \
	113	\
	114	if (flags == GLRO(dl_correct_cache_id)) \
	115	/* We've found an exact match for the shared \
	116	object and no general `ELF' release. Stop \
	117	searching. */ \
	118	break; \
	119	} \
	120	} \
	121	} \
	122	while (++middle <= right); \
	123	break; \
	124	} \
	125	\
	126	if (cmpres < 0) \
	127	left = middle + 1; \
	128	else \
	129	right = middle - 1; \
	130	} \
	131	} \
	132	while (0)
133
134
135	int
136	internal_function
137	_dl_cache_libcmp (const char p1, const char p2)
138	{
139	while (*p1 != '\0')
140	{
141	if (p1 >= '0' && p1 <= '9')
142	{
143	if (p2 >= '0' && p2 <= '9')
144	{
145	/* Must compare this numerically. */
146	int val1;
147	int val2;
148
149	val1 = *p1++ - '0';
150	val2 = *p2++ - '0';
151	while (p1 >= '0' && p1 <= '9')
152	val1 = val1 * 10 + *p1++ - '0';
153	while (p2 >= '0' && p2 <= '9')
154	val2 = val2 * 10 + *p2++ - '0';
155	if (val1 != val2)
156	return val1 - val2;
157	}
158	else
159	return 1;
160	}
161	else if (p2 >= '0' && p2 <= '9')
162	return -1;
163	else if (p1 != p2)
164	return p1 - p2;
165	else
166	{
167	++p1;
168	++p2;
169	}
170	}
171	return p1 - p2;
172	}
173
174
b2d3c3be CD	175	/* Look up NAME in ld.so.cache and return the file name stored there, or null
	176	if none is found. The cache is loaded if it was not already. If loading
	177	the cache previously failed there will be no more attempts to load it. */
b6ab06ce UD	178
	179	const char *
	180	internal_function
	181	_dl_load_cache_lookup (const char *name)
	182	{
	183	int left, right, middle;
	184	int cmpres;
	185	const char *cache_data;
	186	uint32_t cache_data_size;
	187	const char *best;
	188
	189	/* Print a message if the loading of libs is traced. */
a1ffb40e	190	if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS))
b6ab06ce UD	191	_dl_debug_printf (" search cache=%s\n", LD_SO_CACHE);
	192
	193	if (cache == NULL)
	194	{
	195	/* Read the contents of the file. */
	196	void *file = _dl_sysdep_read_whole_file (LD_SO_CACHE, &cachesize,
	197	PROT_READ);
	198
	199	/* We can handle three different cache file formats here:
	200	- the old libc5/glibc2.0/2.1 format
	201	- the old format with the new format in it
	202	- only the new format
	203	The following checks if the cache contains any of these formats. */
	204	if (file != MAP_FAILED && cachesize > sizeof *cache
	205	&& memcmp (file, CACHEMAGIC, sizeof CACHEMAGIC - 1) == 0)
	206	{
	207	size_t offset;
	208	/* Looks ok. */
	209	cache = file;
	210
	211	/* Check for new version. */
	212	offset = ALIGN_CACHE (sizeof (struct cache_file)
	213	+ cache->nlibs * sizeof (struct file_entry));
	214
	215	cache_new = (struct cache_file_new ) ((void ) cache + offset);
	216	if (cachesize < (offset + sizeof (struct cache_file_new))
	217	\|\| memcmp (cache_new->magic, CACHEMAGIC_VERSION_NEW,
	218	sizeof CACHEMAGIC_VERSION_NEW - 1) != 0)
	219	cache_new = (void *) -1;
	220	}
	221	else if (file != MAP_FAILED && cachesize > sizeof *cache_new
	222	&& memcmp (file, CACHEMAGIC_VERSION_NEW,
	223	sizeof CACHEMAGIC_VERSION_NEW - 1) == 0)
	224	{
	225	cache_new = file;
	226	cache = file;
	227	}
	228	else
	229	{
	230	if (file != MAP_FAILED)
	231	__munmap (file, cachesize);
	232	cache = (void *) -1;
	233	}
	234
	235	assert (cache != NULL);
	236	}
	237
	238	if (cache == (void *) -1)
	239	/* Previously looked for the cache file and didn't find it. */
	240	return NULL;
	241
	242	best = NULL;
	243
	244	if (cache_new != (void *) -1)
	245	{
	246	uint64_t platform;
	247
	248	/* This is where the strings start. */
	249	cache_data = (const char *) cache_new;
	250
	251	/* Now we can compute how large the string table is. */
	252	cache_data_size = (const char *) cache + cachesize - cache_data;
	253
	254	platform = _dl_string_platform (GLRO(dl_platform));
255	if (platform != (uint64_t) -1)
256	platform = 1ULL << platform;
257
11bf311e	258	#define _DL_HWCAP_TLS_MASK (1LL << 63)
7bfa311f RM	259	uint64_t hwcap_exclude = ~((GLRO(dl_hwcap) & GLRO(dl_hwcap_mask))
	260	\| _DL_HWCAP_PLATFORM \| _DL_HWCAP_TLS_MASK);
	261
	262	/* Only accept hwcap if it's for the right platform. */
b6ab06ce	263	#define HWCAP_CHECK \
7bfa311f RM	264	if (lib->hwcap & hwcap_exclude) \
7bfa311f RM	265	continue; \
b6ab06ce UD	266	if (GLRO(dl_osversion) && lib->osversion > GLRO(dl_osversion)) \
b6ab06ce UD	267	continue; \
33315ced	268	if (_DL_PLATFORMS_COUNT \
b6ab06ce UD	269	&& (lib->hwcap & _DL_HWCAP_PLATFORM) != 0 \
b6ab06ce UD	270	&& (lib->hwcap & _DL_HWCAP_PLATFORM) != platform) \
b6ab06ce UD	271	continue
	272	SEARCH_CACHE (cache_new);
	273	}
	274	else
	275	{
	276	/* This is where the strings start. */
	277	cache_data = (const char *) &cache->libs[cache->nlibs];
	278
	279	/* Now we can compute how large the string table is. */
	280	cache_data_size = (const char *) cache + cachesize - cache_data;
	281
	282	#undef HWCAP_CHECK
	283	#define HWCAP_CHECK do {} while (0)
	284	SEARCH_CACHE (cache);
	285	}
	286
	287	/* Print our result if wanted. */
	288	if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_LIBS, 0)
	289	&& best != NULL)
	290	_dl_debug_printf (" trying file=%s\n", best);
	291
	292	return best;
	293	}
	294
	295	#ifndef MAP_COPY
	296	/* If the system does not support MAP_COPY we cannot leave the file open
	297	all the time since this would create problems when the file is replaced.
	298	Therefore we provide this function to close the file and open it again
	299	once needed. */
	300	void
	301	_dl_unload_cache (void)
	302	{
	303	if (cache != NULL && cache != (struct cache_file *) -1)
	304	{
	305	__munmap (cache, cachesize);
	306	cache = NULL;
	307	}
	308	}
	309	#endif