munmap (mapat + c->mapend, loadcmds[nloadcmds - 1].allocend - c->mapend);
mprotect (mapat + c->mapend, loadcmds[nloadcmds - 1].allocend - c->mapend, 0);
_dl_map_object_from_fd (const char *name, int fd, char *realname){  struct link_map *l = NULL;  const size_t pagesize = getpagesize ();  void *file_mapping = NULL;  size_t mapping_size = 0;#define LOSE(s) lose (0, (s))  void lose (int code, const char *msg)    {      (void) close (fd);      if (file_mapping)	munmap (file_mapping, mapping_size);      _dl_signal_error (code, l ? l->l_name : name, msg);    }  inline caddr_t map_segment (Elf32_Addr mapstart, size_t len,			      int prot, int fixed, off_t offset)    {      caddr_t mapat = mmap ((caddr_t) mapstart, len, prot,			    fixed|MAP_COPY|MAP_FILE,			    fd, offset);      if (mapat == (caddr_t) -1)	lose (errno, "failed to map segment from shared object");      return mapat;    }  /* Make sure LOCATION is mapped in.  */  void *map (off_t location, size_t size)    {      if ((off_t) mapping_size <= location + (off_t) size)	{	  void *result;	  if (file_mapping)	    munmap (file_mapping, mapping_size);	  mapping_size = (location + size + 1 + pagesize - 1);	  mapping_size &= ~(pagesize - 1);	  result = mmap (file_mapping, mapping_size, PROT_READ,			 MAP_COPY|MAP_FILE, fd, 0);	  if (result == (void *) -1)	    lose (errno, "cannot map file data");	  file_mapping = result;	}      return file_mapping + location;    }  const Elf32_Ehdr *header;  const Elf32_Phdr *phdr;  const Elf32_Phdr *ph;  int type;  /* Look again to see if the real name matched another already loaded.  */  for (l = _dl_loaded; l; l = l->l_next)    if (! strcmp (realname, l->l_name))      {	/* The object is already loaded.	   Just bump its reference count and return it.  */	close (fd);	free (realname);	++l->l_opencount;	return l;      }  /* Map in the first page to read the header.  */  header = map (0, sizeof *header);  /* Check the header for basic validity.  */  if (*(Elf32_Word *) &header->e_ident !=#if BYTE_ORDER == LITTLE_ENDIAN      ((ELFMAG0 << (EI_MAG0 * 8)) |       (ELFMAG1 << (EI_MAG1 * 8)) |       (ELFMAG2 << (EI_MAG2 * 8)) |       (ELFMAG3 << (EI_MAG3 * 8)))#else      ((ELFMAG0 << (EI_MAG3 * 8)) |       (ELFMAG1 << (EI_MAG2 * 8)) |       (ELFMAG2 << (EI_MAG1 * 8)) |       (ELFMAG3 << (EI_MAG0 * 8)))#endif      )    LOSE ("invalid ELF header");  if (header->e_ident[EI_CLASS] != ELFCLASS32)    LOSE ("ELF file class not 32-bit");  if (header->e_ident[EI_DATA] != byteorder)    LOSE ("ELF file data encoding not " byteorder_name);  if (header->e_ident[EI_VERSION] != EV_CURRENT)    LOSE ("ELF file version ident not " STRING(EV_CURRENT));  if (header->e_version != EV_CURRENT)    LOSE ("ELF file version not " STRING(EV_CURRENT));  if (! elf_machine_matches_host (header->e_machine))    LOSE ("ELF file machine architecture not " ELF_MACHINE_NAME);  if (header->e_phentsize != sizeof (Elf32_Phdr))    LOSE ("ELF file's phentsize not the expected size");  /* Enter the new object in the list of loaded objects.  */  l = _dl_new_object (realname, name, lt_loaded);  l->l_opencount = 1;  if (_dl_zerofd == -1)    {      _dl_zerofd = _dl_sysdep_open_zero_fill ();      if (_dl_zerofd == -1)	_dl_signal_error (errno, NULL, "cannot open zero fill device");    }  /* Extract the remaining details we need from the ELF header     and then map in the program header table.  */  l->l_entry = header->e_entry;  type = header->e_type;  l->l_phnum = header->e_phnum;  phdr = map (header->e_phoff, l->l_phnum * sizeof (Elf32_Phdr));  {    /* Scan the program header table, collecting its load commands.  */    struct loadcmd      {	Elf32_Addr mapstart, mapend, dataend, allocend;	off_t mapoff;	int prot;      } loadcmds[l->l_phnum], *c;    size_t nloadcmds = 0;    l->l_ld = 0;    l->l_phdr = 0;    l->l_addr = 0;    for (ph = phdr; ph < &phdr[l->l_phnum]; ++ph)      switch (ph->p_type)	{	  /* These entries tell us where to find things once the file's	     segments are mapped in.  We record the addresses it says	     verbatim, and later correct for the run-time load address.  */	case PT_DYNAMIC:	  l->l_ld = (void *) ph->p_vaddr;	  break;	case PT_PHDR:	  l->l_phdr = (void *) ph->p_vaddr;	  break;	case PT_LOAD:	  /* A load command tells us to map in part of the file.	     We record the load commands and process them all later.  */	  if (ph->p_align % pagesize != 0)	    LOSE ("ELF load command alignment not page-aligned");	  if ((ph->p_vaddr - ph->p_offset) % ph->p_align)	    LOSE ("ELF load command address/offset not properly aligned");	  {	    struct loadcmd *c = &loadcmds[nloadcmds++];	    c->mapstart = ph->p_vaddr & ~(ph->p_align - 1);	    c->mapend = ((ph->p_vaddr + ph->p_filesz + pagesize - 1)			 & ~(pagesize - 1));	    c->dataend = ph->p_vaddr + ph->p_filesz;	    c->allocend = ph->p_vaddr + ph->p_memsz;	    c->mapoff = ph->p_offset & ~(ph->p_align - 1);	    c->prot = 0;	    if (ph->p_flags & PF_R)	      c->prot |= PROT_READ;	    if (ph->p_flags & PF_W)	      c->prot |= PROT_WRITE;	    if (ph->p_flags & PF_X)	      c->prot |= PROT_EXEC;	    break;	  }	}    /* We are done reading the file's headers now.  Unmap them.  */    munmap (file_mapping, mapping_size);    /* Now process the load commands and map segments into memory.  */    c = loadcmds;    if (type == ET_DYN || type == ET_REL)      {	/* This is a position-independent shared object.  We can let the	   kernel map it anywhere it likes, but we must have space for all	   the segments in their specified positions relative to the first.	   So we map the first segment without MAP_FIXED, but with its	   extent increased to cover all the segments.  Then we unmap the	   excess portion, and there is known sufficient space there to map	   the later segments.  */ 	caddr_t mapat;	mapat = map_segment (c->mapstart,			     loadcmds[nloadcmds - 1].allocend - c->mapstart,			     c->prot, 0, c->mapoff);	l->l_addr = (Elf32_Addr) mapat - c->mapstart;	/* Unmap the excess portion, and then jump into the normal	   segment-mapping loop to handle the portion of the segment past	   the end of the file mapping.  */	munmap (mapat + c->mapend,		loadcmds[nloadcmds - 1].allocend - c->mapend);	goto postmap;      }    while (c < &loadcmds[nloadcmds])      {	if (c->mapend > c->mapstart)	  /* Map the segment contents from the file.  */	  map_segment (l->l_addr + c->mapstart, c->mapend - c->mapstart,		       c->prot, MAP_FIXED, c->mapoff);      postmap:	if (c->allocend > c->dataend)	  {	    /* Extra zero pages should appear at the end of this segment,	       after the data mapped from the file.   */	    Elf32_Addr zero, zeroend, zeropage;	    zero = l->l_addr + c->dataend;	    zeroend = l->l_addr + c->allocend;	    zeropage = (zero + pagesize - 1) & ~(pagesize - 1);	    if (zeroend < zeropage)	      /* All the extra data is in the last page of the segment.		 We can just zero it.  */	      zeropage = zeroend;	    if (zeropage > zero)	      {		/* Zero the final part of the last page of the segment.  */		if ((c->prot & PROT_WRITE) == 0)		  {		    /* Dag nab it.  */		    if (mprotect ((caddr_t) (zero & ~(pagesize - 1)),				  pagesize, c->prot|PROT_WRITE) < 0)		      lose (errno, "cannot change memory protections");		  }		memset ((void *) zero, 0, zeropage - zero);		if ((c->prot & PROT_WRITE) == 0)		  mprotect ((caddr_t) (zero & ~(pagesize - 1)),			    pagesize, c->prot);	      }	    if (zeroend > zeropage)	      {		/* Map the remaining zero pages in from the zero fill FD.  */		caddr_t mapat;		mapat = mmap ((caddr_t) zeropage, zeroend - zeropage, c->prot,			      MAP_ANON|MAP_PRIVATE|MAP_FIXED,			      _dl_zerofd, 0);		if (mapat == (caddr_t) -1)		  lose (errno, "cannot map zero-fill pages");	      }	  }	++c;      }  }  if (type == ET_EXEC)    l->l_type = lt_executable;  if (l->l_ld == 0)    {      if (type == ET_DYN)	LOSE ("object file has no dynamic section");    }  else    (Elf32_Addr) l->l_ld += l->l_addr;  if (l->l_phdr == 0)    l->l_phdr = (void *) ((const Elf32_Ehdr *) l->l_addr)->e_phoff;  (Elf32_Addr) l->l_phdr += l->l_addr;  elf_get_dynamic_info (l->l_ld, l->l_info);  if (l->l_info[DT_HASH])    _dl_setup_hash (l);  return l;}