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-rw-r--r--elf/dl-load.c377
1 files changed, 377 insertions, 0 deletions
diff --git a/elf/dl-load.c b/elf/dl-load.c
new file mode 100644
index 0000000000..0de7404a80
--- /dev/null
+++ b/elf/dl-load.c
@@ -0,0 +1,377 @@
+/* _dl_map_object -- Map in a shared object's segments from the file.
+Copyright (C) 1995 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 Library General Public License as
+published by the Free Software Foundation; either version 2 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <link.h>
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+#include "dynamic-link.h"
+
+
+#include <endian.h>
+#if BYTE_ORDER == BIG_ENDIAN
+#define byteorder ELFDATA2MSB
+#define byteorder_name "big-endian"
+#elif BYTE_ORDER == LITTLE_ENDIAN
+#define byteorder ELFDATA2LSB
+#define byteorder_name "little-endian"
+#else
+#error "Unknown BYTE_ORDER " BYTE_ORDER
+#define byteorder ELFDATANONE
+#endif
+
+#define STRING(x) #x
+
+int _dl_zerofd = -1;
+
+
+/* Try to open NAME in one of the directories in DIRPATH.
+   Return the fd, or -1.  If successful, fill in *REALNAME
+   with the malloc'd full directory name.  */
+
+static int
+open_path (const char *name, size_t namelen,
+	   const char *dirpath,
+	   char **realname)
+{
+  char buf[strlen (dirpath) + 1 + namelen];
+  const char *p;
+  int fd;
+
+  p = dirpath;
+  if (p == NULL || *p == '\0')
+    {
+      errno = ENOENT;
+      return -1;
+    }
+
+  do
+    {
+      dirpath = p;
+      p = strpbrk (dirpath, ":;");
+      if (p == NULL)
+	p = strchr (dirpath, '\0');
+
+      if (p == dirpath)
+	/* Two adjacent colons, or a colon at the beginning or the end of
+	   the path means to search the current directory.  */
+	(void) memcpy (buf, name, namelen);
+      else
+	{
+	  /* Construct the pathname to try.  */
+	  (void) memcpy (buf, dirpath, p - dirpath);
+	  buf[p - dirpath] = '/';
+	  (void) memcpy (&buf[(p - dirpath) + 1], name, namelen);
+	}
+
+      fd = open (buf, O_RDONLY);
+      if (fd != -1)
+	{
+	  *realname = strdup (buf);
+	  return fd;
+	}
+      if (errno != ENOENT && errno != EACCES)
+	/* The file exists and is readable, but something went wrong.  */
+	return -1;
+    }
+  while (*p++ != '\0');
+
+  return -1;
+}
+
+
+/* Map in the shared object file NAME.  */
+
+struct link_map *
+_dl_map_object (struct link_map *loader, const char *name,
+		Elf32_Addr *entry_point)
+{
+  int fd;
+  char *realname;
+  const size_t pagesize = getpagesize ();
+  void *file_mapping = NULL;
+  size_t mapping_size = 0;
+  /* 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)
+	    return NULL;
+	  file_mapping = result;
+	}
+      return file_mapping + location;
+    }
+
+  const Elf32_Ehdr *header;
+  struct link_map *l;
+
+  /* Look for this name among those already loaded.  */
+  for (l = _dl_loaded; l; l = l->l_next)
+    if (! strcmp (name, l->l_libname))
+      {
+	/* The object is already loaded.
+	   Just bump its reference count and return it.  */
+	++l->l_opencount;
+	return l;
+      }
+
+  if (strchr (name, '/') == NULL)
+    {
+      /* Search for NAME in several places.  */
+
+      size_t namelen = strlen (name) + 1;
+
+      void trypath (const char *dirpath)
+	{
+	  fd = open_path (name, namelen, dirpath, &realname);
+	}
+
+      if (loader && loader->l_info[DT_RPATH])
+	trypath ((const char *) (loader->l_addr +
+				 loader->l_info[DT_RPATH]->d_un.d_ptr));
+      if (fd == -1 && ! _dl_secure)
+	trypath (getenv ("LD_LIBRARY_PATH"));
+      if (fd == -1)
+	trypath ("/lib:/usr/lib");
+    }
+  else
+    {
+      fd = open (name, O_RDONLY);
+      if (fd != -1)
+	realname = strdup (name);
+    }
+
+  if (fd == -1)
+    return NULL;
+
+  /* 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);
+	++l->l_opencount;
+	return l;
+      }
+
+
+  /* Map in the first page to read the header.  */
+  header = map (0, sizeof *header);
+  if (! header)
+    {
+    lose:
+      (void) close (fd);
+      if (file_mapping)
+	munmap (file_mapping, mapping_size);
+      return NULL;
+    }
+
+#undef LOSE
+#define LOSE(s) _dl_signal_error (0, s)
+  /* Check the header for basic validity.  */
+  if (*(Elf32_Word *) &header->e_ident != ((ELFMAG0 << (EI_MAG0 * 8)) |
+					   (ELFMAG1 << (EI_MAG1 * 8)) |
+					   (ELFMAG2 << (EI_MAG2 * 8)) |
+					   (ELFMAG3 << (EI_MAG3 * 8))))
+    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, "cannot open zero fill device");
+    }
+
+  {
+    /* Copy the program header table into stack space so we can then unmap
+       the headers.  */
+    Elf32_Phdr phdr[header->e_phnum];
+    const Elf32_Phdr *ph;
+    int anywhere;
+
+    ph = map (header->e_phoff, header->e_phnum * sizeof (Elf32_Phdr));
+    if (! ph)
+      goto lose;
+    memcpy (phdr, ph, sizeof phdr);
+    l->l_phnum = header->e_phnum;
+
+    anywhere = header->e_type == ET_DYN || header->e_type == ET_REL;
+
+    if (entry_point)
+      *entry_point = header->e_entry;
+
+    /* We are done reading the file's headers now.  Unmap them.  */
+    munmap (file_mapping, mapping_size);
+
+    /* Scan the program header table, processing its load commands.  */
+    l->l_addr = 0;
+    l->l_ld = 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.  */
+	  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");
+	  {
+	    Elf32_Addr mapstart = ph->p_vaddr & ~(ph->p_align - 1);
+	    Elf32_Addr mapend = ((ph->p_vaddr + ph->p_filesz + ph->p_align - 1)
+				 & ~(ph->p_align - 1));
+	    off_t mapoff = ph->p_offset & ~(ph->p_align - 1);
+	    caddr_t mapat;
+	    int prot = 0;
+	    if (ph->p_flags & PF_R)
+	      prot |= PROT_READ;
+	    if (ph->p_flags & PF_W)
+	      prot |= PROT_WRITE;
+	    if (ph->p_flags & PF_X)
+	      prot |= PROT_EXEC;
+
+	    if (anywhere)
+	      {
+		/* XXX this loses if the first segment mmap call puts
+		   it someplace where the later segments cannot fit.  */
+		mapat = mmap ((caddr_t) l->l_addr + mapstart, mapend - mapstart,
+			      prot, MAP_COPY|MAP_FILE|MAP_INHERIT |
+			      /* Let the system choose any convenient
+				 location if this is the first segment.
+				 Following segments must be contiguous in
+				 virtual space with the first.  */
+			      (l->l_addr == 0 ? 0 : MAP_FIXED),
+			      fd, mapoff);
+		if (l->l_addr == 0)
+		  /* This was the first segment mapped, so MAPAT is
+		     the address the system chose for us.  Record it.  */
+		  l->l_addr = (Elf32_Addr) mapat - mapstart;
+	      }
+	    else
+	      {
+		mapat = mmap ((caddr_t) mapstart, mapend - mapstart,
+			      prot, MAP_COPY|MAP_FILE|MAP_INHERIT|MAP_FIXED,
+			      fd, mapoff);
+		/* This file refers to absolute addresses.  So consider its
+		   "load base" to be zero, since that is what we add to the
+		   file's addresses to find them in our memory.  */
+		l->l_addr = 0;
+	      }
+	    if (mapat == (caddr_t) -1)
+	      _dl_signal_error (errno,
+				"failed to map region from shared object");
+
+	    if (ph->p_memsz > ph->p_filesz)
+	      {
+		/* Extra zero pages should appear at the end of this segment,
+		   after the data mapped from the file.  Adjust MAPEND to map
+		   only the data from the file.  We will later allocate zero
+		   pages following the data mapping.  */
+		caddr_t zero = mapat - mapstart + ph->p_filesz;
+		caddr_t zeroend = mapat - mapstart + ph->p_memsz;
+		caddr_t zeropage
+		  = (caddr_t) ((Elf32_Addr) (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 ((prot & PROT_WRITE) == 0)
+		      {
+			/* Dag nab it.  */
+			if (mprotect ((caddr_t) ((Elf32_Addr) zero
+						 & ~(pagesize - 1)),
+				      pagesize,
+				      prot|PROT_WRITE) < 0)
+			  _dl_signal_error (errno,
+					    "cannot change protections");
+		      }
+		    memset (zero, 0, zeroend - zero);
+		    if ((prot & PROT_WRITE) == 0)
+		      mprotect ((caddr_t) ((Elf32_Addr) zero
+					   & ~(pagesize - 1)),
+				pagesize, prot);
+		  }
+
+		if (zeroend > zeropage)
+		  /* Map the remaining zero pages in from the zero fill FD.  */
+		  mapat = mmap (zeropage, zeroend - zeropage,
+				prot, MAP_ANON|MAP_PRIVATE|MAP_FIXED,
+				_dl_zerofd, 0);
+	      }
+	  }
+	}
+
+    if (l->l_ld == 0)
+      LOSE ("object file has no dynamic section");
+    (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;
+}