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glibc  2.9
Defines | Functions | Variables
dl-sysdep.c File Reference
#include <assert.h>
#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <libintl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <ldsodefs.h>
#include <stdio-common/_itoa.h>
#include <fpu_control.h>
#include <entry.h>
#include <dl-machine.h>
#include <dl-procinfo.h>
#include <dl-osinfo.h>
#include <hp-timing.h>
#include <tls.h>

Go to the source code of this file.

Defines

#define _DL_FIRST_EXTRA   _DL_HWCAP_COUNT
#define DL_FIND_ARG_COMPONENTS(cookie, argc, argv, envp, auxp)
#define DL_STACK_END(cookie)   ((void *) (cookie))
#define set_seen_secure()   (seen = -1)
#define M(type)   (1 << (type))
#define set_seen(tag)   seen |= M ((tag)->a_type)
#define SEE(UID, var, uid)   if ((seen & M (AT_##UID)) == 0) var ^= __get##uid ()
#define add(idx)   cp = __mempcpy (__mempcpy (cp, temp[idx].str, temp[idx].len), "/", 1);

Functions

void __libc_check_standard_fds (void)
 rtld_hidden_data_def (__libc_stack_end)
void internal_function _dl_sysdep_start_cleanup (void)
void internal_function _dl_show_auxv (void)
struct r_strlenpair
*internal_function 
_dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz, size_t *max_capstrlen)

Variables

char **_environ attribute_hidden
int __libc_enable_secure attribute_relro = 0
int __libc_multiple_libcs = 0

Define Documentation

Definition at line 45 of file dl-sysdep.c.

#define add (   idx)    cp = __mempcpy (__mempcpy (cp, temp[idx].str, temp[idx].len), "/", 1);
#define DL_FIND_ARG_COMPONENTS (   cookie,
  argc,
  argv,
  envp,
  auxp 
)
Value:
do {                                                                 \
    void **_tmp;                                                     \
    (argc) = *(long int *) cookie;                                   \
    (argv) = (char **) ((long int *) cookie + 1);                           \
    (envp) = (argv) + (argc) + 1;                                    \
    for (_tmp = (void **) (envp); *_tmp; ++_tmp)                     \
      continue;                                                             \
    (auxp) = (void *) ++_tmp;                                               \
  } while (0)
#define DL_STACK_END (   cookie)    ((void *) (cookie))
#define M (   type)    (1 << (type))
#define SEE (   UID,
  var,
  uid 
)    if ((seen & M (AT_##UID)) == 0) var ^= __get##uid ()
#define set_seen (   tag)    seen |= M ((tag)->a_type)
#define set_seen_secure ( )    (seen = -1)

Function Documentation

void __libc_check_standard_fds ( void  )

Definition at line 89 of file check_fds.c.

{
  /* This is really paranoid but some people actually are.  If /dev/null
     should happen to be a symlink to somewhere else and not the device
     commonly known as "/dev/null" we bail out.  We can detect this with
     the O_NOFOLLOW flag for open() but only on some system.  */
#ifndef O_NOFOLLOW
# define O_NOFOLLOW  0
#endif
  /* Check all three standard file descriptors.  */
  check_one_fd (STDIN_FILENO, O_WRONLY | O_NOFOLLOW);
  check_one_fd (STDOUT_FILENO, O_RDONLY | O_NOFOLLOW);
  check_one_fd (STDERR_FILENO, O_RDONLY | O_NOFOLLOW);
}
struct r_strlenpair* internal_function _dl_important_hwcaps ( const char *  platform,
size_t  platform_len,
size_t sz,
size_t max_capstrlen 
) [read]

Definition at line 345 of file dl-sysdep.c.

{
  /* Determine how many important bits are set.  */
  uint64_t masked = GLRO(dl_hwcap) & GLRO(dl_hwcap_mask);
  size_t cnt = platform != NULL;
  size_t n, m;
  size_t total;
  struct r_strlenpair *temp;
  struct r_strlenpair *result;
  struct r_strlenpair *rp;
  char *cp;

  /* Count the number of bits set in the masked value.  */
  for (n = 0; (~((1ULL << n) - 1) & masked) != 0; ++n)
    if ((masked & (1ULL << n)) != 0)
      ++cnt;

#if (defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO) && defined SHARED
  /* The system-supplied DSO can contain a note of type 2, vendor "GNU".
     This gives us a list of names to treat as fake hwcap bits.  */

  const char *dsocaps = NULL;
  size_t dsocapslen = 0;
  if (GLRO(dl_sysinfo_map) != NULL)
    {
      const ElfW(Phdr) *const phdr = GLRO(dl_sysinfo_map)->l_phdr;
      const ElfW(Word) phnum = GLRO(dl_sysinfo_map)->l_phnum;
      for (uint_fast16_t i = 0; i < phnum; ++i)
       if (phdr[i].p_type == PT_NOTE)
         {
           const ElfW(Addr) start = (phdr[i].p_vaddr
                                  + GLRO(dl_sysinfo_map)->l_addr);
           const struct
           {
             ElfW(Word) vendorlen;
             ElfW(Word) datalen;
             ElfW(Word) type;
           } *note = (const void *) start;
           while ((ElfW(Addr)) (note + 1) - start < phdr[i].p_memsz)
             {
#define ROUND(len) (((len) + sizeof (ElfW(Word)) - 1) & -sizeof (ElfW(Word)))
              if (note->type == 2
                  && note->vendorlen == sizeof "GNU"
                  && !memcmp ((note + 1), "GNU", sizeof "GNU")
                  && note->datalen > 2 * sizeof (ElfW(Word)) + 2)
                {
                  const ElfW(Word) *p = ((const void *) (note + 1)
                                      + ROUND (sizeof "GNU"));
                  cnt += *p++;
                  ++p;      /* Skip mask word.  */
                  dsocaps = (const char *) p;
                  dsocapslen = note->datalen - sizeof *p * 2;
                  break;
                }
              note = ((const void *) (note + 1)
                     + ROUND (note->vendorlen) + ROUND (note->datalen));
#undef ROUND
             }
           if (dsocaps != NULL)
             break;
         }
    }
#endif

  /* For TLS enabled builds always add 'tls'.  */
  ++cnt;

  /* Create temporary data structure to generate result table.  */
  temp = (struct r_strlenpair *) alloca (cnt * sizeof (*temp));
  m = 0;
#if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
  if (dsocaps != NULL)
    {
      const ElfW(Word) mask = ((const ElfW(Word) *) dsocaps)[-1];
      GLRO(dl_hwcap) |= (uint64_t) mask << _DL_FIRST_EXTRA;
      size_t len;
      for (const char *p = dsocaps; p < dsocaps + dsocapslen; p += len + 1)
       {
         uint_fast8_t bit = *p++;
         len = strlen (p);

         /* Skip entries that are not enabled in the mask word.  */
         if (__builtin_expect (mask & ((ElfW(Word)) 1 << bit), 1))
           {
             temp[m].str = p;
             temp[m].len = len;
             ++m;
           }
         else
           --cnt;
       }
    }
#endif
  for (n = 0; masked != 0; ++n)
    if ((masked & (1ULL << n)) != 0)
      {
       temp[m].str = _dl_hwcap_string (n);
       temp[m].len = strlen (temp[m].str);
       masked ^= 1ULL << n;
       ++m;
      }
  if (platform != NULL)
    {
      temp[m].str = platform;
      temp[m].len = platform_len;
      ++m;
    }

  temp[m].str = "tls";
  temp[m].len = 3;
  ++m;

  assert (m == cnt);

  /* Determine the total size of all strings together.  */
  if (cnt == 1)
    total = temp[0].len + 1;
  else
    {
      total = temp[0].len + temp[cnt - 1].len + 2;
      if (cnt > 2)
       {
         total <<= 1;
         for (n = 1; n + 1 < cnt; ++n)
           total += temp[n].len + 1;
         if (cnt > 3
             && (cnt >= sizeof (size_t) * 8
                || total + (sizeof (*result) << 3)
                   >= (1UL << (sizeof (size_t) * 8 - cnt + 3))))
           _dl_signal_error (ENOMEM, NULL, NULL,
                           N_("cannot create capability list"));

         total <<= cnt - 3;
       }
    }

  /* The result structure: we use a very compressed way to store the
     various combinations of capability names.  */
  *sz = 1 << cnt;
  result = (struct r_strlenpair *) malloc (*sz * sizeof (*result) + total);
  if (result == NULL)
    _dl_signal_error (ENOMEM, NULL, NULL,
                    N_("cannot create capability list"));

  if (cnt == 1)
    {
      result[0].str = (char *) (result + *sz);
      result[0].len = temp[0].len + 1;
      result[1].str = (char *) (result + *sz);
      result[1].len = 0;
      cp = __mempcpy ((char *) (result + *sz), temp[0].str, temp[0].len);
      *cp = '/';
      *sz = 2;
      *max_capstrlen = result[0].len;

      return result;
    }

  /* Fill in the information.  This follows the following scheme
     (indeces from TEMP for four strings):
       entry #0: 0, 1, 2, 3 binary: 1111
             #1: 0, 1, 3            1101
             #2: 0, 2, 3            1011
             #3: 0, 3                      1001
     This allows the representation of all possible combinations of
     capability names in the string.  First generate the strings.  */
  result[1].str = result[0].str = cp = (char *) (result + *sz);
#define add(idx) \
      cp = __mempcpy (__mempcpy (cp, temp[idx].str, temp[idx].len), "/", 1);
  if (cnt == 2)
    {
      add (1);
      add (0);
    }
  else
    {
      n = 1 << (cnt - 1);
      do
       {
         n -= 2;

         /* We always add the last string.  */
         add (cnt - 1);

         /* Add the strings which have the bit set in N.  */
         for (m = cnt - 2; m > 0; --m)
           if ((n & (1 << m)) != 0)
             add (m);

         /* Always add the first string.  */
         add (0);
       }
      while (n != 0);
    }
#undef add

  /* Now we are ready to install the string pointers and length.  */
  for (n = 0; n < (1UL << cnt); ++n)
    result[n].len = 0;
  n = cnt;
  do
    {
      size_t mask = 1 << --n;

      rp = result;
      for (m = 1 << cnt; m > 0; ++rp)
       if ((--m & mask) != 0)
         rp->len += temp[n].len + 1;
    }
  while (n != 0);

  /* The first half of the strings all include the first string.  */
  n = (1 << cnt) - 2;
  rp = &result[2];
  while (n != (1UL << (cnt - 1)))
    {
      if ((--n & 1) != 0)
       rp[0].str = rp[-2].str + rp[-2].len;
      else
       rp[0].str = rp[-1].str;
      ++rp;
    }

  /* The second half starts right after the first part of the string of
     the corresponding entry in the first half.  */
  do
    {
      rp[0].str = rp[-(1 << (cnt - 1))].str + temp[cnt - 1].len + 1;
      ++rp;
    }
  while (--n != 0);

  /* The maximum string length.  */
  *max_capstrlen = result[0].len;

  return result;
}

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Definition at line 251 of file dl-sysdep.c.

{
  char buf[64];
  ElfW(auxv_t) *av;

  /* Terminate string.  */
  buf[63] = '\0';

  /* The following code assumes that the AT_* values are encoded
     starting from 0 with AT_NULL, 1 for AT_IGNORE, and all other values
     close by (otherwise the array will be too large).  In case we have
     to support a platform where these requirements are not fulfilled
     some alternative implementation has to be used.  */
  for (av = _dl_auxv; av->a_type != AT_NULL; ++av)
    {
      static const struct
      {
       const char label[20];
       enum { unknown = 0, dec, hex, str, ignore } form;
      } auxvars[] =
       {
         [AT_EXECFD - 2] =         { "AT_EXECFD:       ", dec },
         [AT_EXECFN - 2] =         { "AT_EXECFN:       ", str },
         [AT_PHDR - 2] =           { "AT_PHDR:         0x", hex },
         [AT_PHENT - 2] =          { "AT_PHENT:        ", dec },
         [AT_PHNUM - 2] =          { "AT_PHNUM:        ", dec },
         [AT_PAGESZ - 2] =         { "AT_PAGESZ:       ", dec },
         [AT_BASE - 2] =           { "AT_BASE:         0x", hex },
         [AT_FLAGS - 2] =          { "AT_FLAGS:        0x", hex },
         [AT_ENTRY - 2] =          { "AT_ENTRY:        0x", hex },
         [AT_NOTELF - 2] =         { "AT_NOTELF:       ", hex },
         [AT_UID - 2] =            { "AT_UID:          ", dec },
         [AT_EUID - 2] =           { "AT_EUID:         ", dec },
         [AT_GID - 2] =            { "AT_GID:          ", dec },
         [AT_EGID - 2] =           { "AT_EGID:         ", dec },
         [AT_PLATFORM - 2] =              { "AT_PLATFORM:     ", str },
         [AT_HWCAP - 2] =          { "AT_HWCAP:        ", hex },
         [AT_CLKTCK - 2] =         { "AT_CLKTCK:       ", dec },
         [AT_FPUCW - 2] =          { "AT_FPUCW:        ", hex },
         [AT_DCACHEBSIZE - 2] =    { "AT_DCACHEBSIZE:  0x", hex },
         [AT_ICACHEBSIZE - 2] =    { "AT_ICACHEBSIZE:  0x", hex },
         [AT_UCACHEBSIZE - 2] =    { "AT_UCACHEBSIZE:  0x", hex },
         [AT_IGNOREPPC - 2] =             { "AT_IGNOREPPC", ignore },
         [AT_SECURE - 2] =         { "AT_SECURE:       ", dec },
         [AT_SYSINFO - 2] =        { "AT_SYSINFO:      0x", hex },
         [AT_SYSINFO_EHDR - 2] =   { "AT_SYSINFO_EHDR: 0x", hex },
       };
      unsigned int idx = (unsigned int) (av->a_type - 2);

      if ((unsigned int) av->a_type < 2u || auxvars[idx].form == ignore)
       continue;

      assert (AT_NULL == 0);
      assert (AT_IGNORE == 1);

      if (av->a_type == AT_HWCAP)
       {
         /* This is handled special.  */
         if (_dl_procinfo (av->a_un.a_val) == 0)
           continue;
       }

      if (idx < sizeof (auxvars) / sizeof (auxvars[0])
         && auxvars[idx].form != unknown)
       {
         const char *val = (char *) av->a_un.a_val;

         if (__builtin_expect (auxvars[idx].form, dec) == dec)
           val = _itoa ((unsigned long int) av->a_un.a_val,
                      buf + sizeof buf - 1, 10, 0);
         else if (__builtin_expect (auxvars[idx].form, hex) == hex)
           val = _itoa ((unsigned long int) av->a_un.a_val,
                      buf + sizeof buf - 1, 16, 0);

         _dl_printf ("%s%s\n", auxvars[idx].label, val);

         continue;
       }

      /* Unknown value: print a generic line.  */
      char buf2[17];
      buf[sizeof (buf2) - 1] = '\0';
      const char *val2 = _itoa ((unsigned long int) av->a_un.a_val,
                            buf2 + sizeof buf2 - 1, 16, 0);
      const char *val =  _itoa ((unsigned long int) av->a_type,
                            buf + sizeof buf - 1, 16, 0);
      _dl_printf ("AT_??? (0x%s): 0x%s\n", val, val2);
    }
}

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Definition at line 245 of file dl-sysdep.c.

{
}

Definition at line 63 of file dl-sysdep.c.

     {                                                               \
    void **_tmp;                                                     \
    (argc) = *(long int *) cookie;                                   \
    (argv) = (char **) ((long int *) cookie + 1);                           \
    (envp) = (argv) + (argc) + 1;                                    \
    for (_tmp = (void **) (envp); *_tmp; ++_tmp)                     \
      continue;                                                             \
    (auxp) = (void *) ++_tmp;                                               \
  } while (0)
#endif

#ifndef DL_STACK_END
# define DL_STACK_END(cookie) ((void *) (cookie))
#endif

ElfW(Addr)
_dl_sysdep_start (void **start_argptr,
                void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
                               ElfW(Addr) *user_entry))
{
  const ElfW(Phdr) *phdr = NULL;
  ElfW(Word) phnum = 0;
  ElfW(Addr) user_entry;
  ElfW(auxv_t) *av;
#ifdef HAVE_AUX_SECURE
# define set_seen(tag) (tag)       /* Evaluate for the side effects.  */
# define set_seen_secure() ((void) 0)
#else
  uid_t uid = 0;
  gid_t gid = 0;
  unsigned int seen = 0;
# define set_seen_secure() (seen = -1)
# ifdef HAVE_AUX_XID
#  define set_seen(tag) (tag)      /* Evaluate for the side effects.  */
# else
#  define M(type) (1 << (type))
#  define set_seen(tag) seen |= M ((tag)->a_type)
# endif
#endif
#ifdef NEED_DL_SYSINFO
  uintptr_t new_sysinfo = 0;
#endif

  __libc_stack_end = DL_STACK_END (start_argptr);
  DL_FIND_ARG_COMPONENTS (start_argptr, _dl_argc, INTUSE(_dl_argv), _environ,
                       _dl_auxv);

  user_entry = (ElfW(Addr)) ENTRY_POINT;
  GLRO(dl_platform) = NULL; /* Default to nothing known about the platform.  */

  for (av = _dl_auxv; av->a_type != AT_NULL; set_seen (av++))
    switch (av->a_type)
      {
      case AT_PHDR:
       phdr = (void *) av->a_un.a_val;
       break;
      case AT_PHNUM:
       phnum = av->a_un.a_val;
       break;
      case AT_PAGESZ:
       GLRO(dl_pagesize) = av->a_un.a_val;
       break;
      case AT_ENTRY:
       user_entry = av->a_un.a_val;
       break;
#ifdef NEED_DL_BASE_ADDR
      case AT_BASE:
       _dl_base_addr = av->a_un.a_val;
       break;
#endif
#ifndef HAVE_AUX_SECURE
      case AT_UID:
      case AT_EUID:
       uid ^= av->a_un.a_val;
       break;
      case AT_GID:
      case AT_EGID:
       gid ^= av->a_un.a_val;
       break;
#endif
      case AT_SECURE:
#ifndef HAVE_AUX_SECURE
       seen = -1;
#endif
       INTUSE(__libc_enable_secure) = av->a_un.a_val;
       break;
      case AT_PLATFORM:
       GLRO(dl_platform) = (void *) av->a_un.a_val;
       break;
      case AT_HWCAP:
       GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
       break;
      case AT_CLKTCK:
       GLRO(dl_clktck) = av->a_un.a_val;
       break;
      case AT_FPUCW:
       GLRO(dl_fpu_control) = av->a_un.a_val;
       break;
#ifdef NEED_DL_SYSINFO
      case AT_SYSINFO:
       new_sysinfo = av->a_un.a_val;
       break;
#endif
#if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
      case AT_SYSINFO_EHDR:
       GLRO(dl_sysinfo_dso) = (void *) av->a_un.a_val;
       break;
#endif
#ifdef DL_PLATFORM_AUXV
      DL_PLATFORM_AUXV
#endif
      }

#ifndef HAVE_AUX_SECURE
  if (seen != -1)
    {
      /* Fill in the values we have not gotten from the kernel through the
        auxiliary vector.  */
# ifndef HAVE_AUX_XID
#  define SEE(UID, var, uid) \
   if ((seen & M (AT_##UID)) == 0) var ^= __get##uid ()
      SEE (UID, uid, uid);
      SEE (EUID, uid, euid);
      SEE (GID, gid, gid);
      SEE (EGID, gid, egid);
# endif

      /* If one of the two pairs of IDs does not match this is a setuid
        or setgid run.  */
      INTUSE(__libc_enable_secure) = uid | gid;
    }
#endif

#ifndef HAVE_AUX_PAGESIZE
  if (GLRO(dl_pagesize) == 0)
    GLRO(dl_pagesize) = __getpagesize ();
#endif

#if defined NEED_DL_SYSINFO
  /* Only set the sysinfo value if we also have the vsyscall DSO.  */
  if (GLRO(dl_sysinfo_dso) != 0 && new_sysinfo)
    GLRO(dl_sysinfo) = new_sysinfo;
#endif

#ifdef DL_SYSDEP_INIT
  DL_SYSDEP_INIT;
#endif

#ifdef DL_PLATFORM_INIT
  DL_PLATFORM_INIT;
#endif

  /* Determine the length of the platform name.  */
  if (GLRO(dl_platform) != NULL)
    GLRO(dl_platformlen) = strlen (GLRO(dl_platform));

  if (__sbrk (0) == &_end)
    /* The dynamic linker was run as a program, and so the initial break
       starts just after our bss, at &_end.  The malloc in dl-minimal.c
       will consume the rest of this page, so tell the kernel to move the
       break up that far.  When the user program examines its break, it
       will see this new value and not clobber our data.  */
    __sbrk (GLRO(dl_pagesize)
           - ((&_end - (void *) 0) & (GLRO(dl_pagesize) - 1)));

  /* If this is a SUID program we make sure that FDs 0, 1, and 2 are
     allocated.  If necessary we are doing it ourself.  If it is not
     possible we stop the program.  */
  if (__builtin_expect (INTUSE(__libc_enable_secure), 0))
    __libc_check_standard_fds ();

  (*dl_main) (phdr, phnum, &user_entry);
  return user_entry;
}

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Variable Documentation

Definition at line 59 of file dl-sysdep.c.

void _end attribute_hidden

Definition at line 49 of file dl-sysdep.c.

Definition at line 57 of file dl-sysdep.c.