glibc/elf/dl-load.c

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/* _dl_map_object -- Map in a shared object's segments from the file.
Copyright (C) 1995, 1996 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"
/* On some systems, no flag bits are given to specify file mapping. */
#ifndef MAP_FILE
#define MAP_FILE 0
#endif
/* The right way to map in the shared library files is MAP_COPY, which
makes a virtual copy of the data at the time of the mmap call; this
guarantees the mapped pages will be consistent even if the file is
overwritten. Some losing VM systems like Linux's lack MAP_COPY. All we
get is MAP_PRIVATE, which copies each page when it is modified; this
means if the file is overwritten, we may at some point get some pages
from the new version after starting with pages from the old version. */
#ifndef MAP_COPY
#define MAP_COPY MAP_PRIVATE
#endif
#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)
{
Thu Jun 8 02:50:26 1995 Roland McGrath <roland@churchy.gnu.ai.mit.edu> * elf/rtld.c [! NDEBUG] (__assert_perror_fail): New function. * hurd/hurdstartup.c (_hurd_startup): Fancier kludge to guess phdr and user entry point addresses. * elf/dl-load.c (open_path): Don't do strlen on DIRPATH if it's null. (_dl_map_object): DT_RPATH value is relative to DT_STRTAB value. * Makerules (install-lib.so): Don't include libc.so. [$(build-shared)=yes] (install): Depend on the installed libc.so file. [$(build-shared)=yes] (install-no-libc.a): Make this, rather than install, depend on the installed $(install-lib.so) files. [$(build-shared)=yes] (install-lib.so): Append libc.so after that rule. * sysdeps/mach/hurd/dl-sysdep.c (_dl_sysdep_start): Add kludge to allocate high addresses to avoid random mappings appearing there. (mmap): Comment out mask; always pass zero. Tue Jun 6 13:34:53 1995 Roland McGrath <roland@churchy.gnu.ai.mit.edu> * sysdeps/i386/dl-machine.h (ELF_MACHINE_USER_ADDRESS_MASK): New macro. * sysdeps/mach/hurd/dl-sysdep.c (mmap): Use it as mask in vm_map call. * elf/dl-error.c (_dl_catch_error): Clear *ERRSTRING and *OBJNAME when successful. * sysdeps/mach/hurd/dl-sysdep.c (threadvars): New static variable. (__hurd_threadvar_max, __hurd_threadvar_stack_offset): Define these variables, using the `threadvars' buffer. * elf/dl-reloc.c: Don't dereference L->l_prev when it's null. * sysdeps/i386/dl-runtime.c: Likewise. * elf/rtld.c (dl_main): Add missing NULL terminating argument in _dl_sysdep_fatal call. (__assert_fail): Likewise. * locale/Makefile (localedef-modules): Renamed ctype to locale-ctype so as not to conflict with the object file for ctype/ctype.c in the build directory. * sysdeps/i386/dl-machine.h (elf_machine_rel): If MAP->l_type is lt_interpreter, first undo relocation done during bootstrapping.
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char *buf;
const char *p;
int fd;
p = dirpath;
if (p == NULL || *p == '\0')
{
errno = ENOENT;
return -1;
}
Thu Jun 8 02:50:26 1995 Roland McGrath <roland@churchy.gnu.ai.mit.edu> * elf/rtld.c [! NDEBUG] (__assert_perror_fail): New function. * hurd/hurdstartup.c (_hurd_startup): Fancier kludge to guess phdr and user entry point addresses. * elf/dl-load.c (open_path): Don't do strlen on DIRPATH if it's null. (_dl_map_object): DT_RPATH value is relative to DT_STRTAB value. * Makerules (install-lib.so): Don't include libc.so. [$(build-shared)=yes] (install): Depend on the installed libc.so file. [$(build-shared)=yes] (install-no-libc.a): Make this, rather than install, depend on the installed $(install-lib.so) files. [$(build-shared)=yes] (install-lib.so): Append libc.so after that rule. * sysdeps/mach/hurd/dl-sysdep.c (_dl_sysdep_start): Add kludge to allocate high addresses to avoid random mappings appearing there. (mmap): Comment out mask; always pass zero. Tue Jun 6 13:34:53 1995 Roland McGrath <roland@churchy.gnu.ai.mit.edu> * sysdeps/i386/dl-machine.h (ELF_MACHINE_USER_ADDRESS_MASK): New macro. * sysdeps/mach/hurd/dl-sysdep.c (mmap): Use it as mask in vm_map call. * elf/dl-error.c (_dl_catch_error): Clear *ERRSTRING and *OBJNAME when successful. * sysdeps/mach/hurd/dl-sysdep.c (threadvars): New static variable. (__hurd_threadvar_max, __hurd_threadvar_stack_offset): Define these variables, using the `threadvars' buffer. * elf/dl-reloc.c: Don't dereference L->l_prev when it's null. * sysdeps/i386/dl-runtime.c: Likewise. * elf/rtld.c (dl_main): Add missing NULL terminating argument in _dl_sysdep_fatal call. (__assert_fail): Likewise. * locale/Makefile (localedef-modules): Renamed ctype to locale-ctype so as not to conflict with the object file for ctype/ctype.c in the build directory. * sysdeps/i386/dl-machine.h (elf_machine_rel): If MAP->l_type is lt_interpreter, first undo relocation done during bootstrapping.
1995-06-08 17:00:23 +08:00
buf = alloca (strlen (dirpath) + 1 + namelen);
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)
{
int fd;
char *realname;
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;
inline void trypath (const char *dirpath)
{
fd = open_path (name, namelen, dirpath, &realname);
}
fd = -1;
if (loader && loader->l_info[DT_RPATH])
trypath ((const char *) (loader->l_addr +
Thu Jun 8 02:50:26 1995 Roland McGrath <roland@churchy.gnu.ai.mit.edu> * elf/rtld.c [! NDEBUG] (__assert_perror_fail): New function. * hurd/hurdstartup.c (_hurd_startup): Fancier kludge to guess phdr and user entry point addresses. * elf/dl-load.c (open_path): Don't do strlen on DIRPATH if it's null. (_dl_map_object): DT_RPATH value is relative to DT_STRTAB value. * Makerules (install-lib.so): Don't include libc.so. [$(build-shared)=yes] (install): Depend on the installed libc.so file. [$(build-shared)=yes] (install-no-libc.a): Make this, rather than install, depend on the installed $(install-lib.so) files. [$(build-shared)=yes] (install-lib.so): Append libc.so after that rule. * sysdeps/mach/hurd/dl-sysdep.c (_dl_sysdep_start): Add kludge to allocate high addresses to avoid random mappings appearing there. (mmap): Comment out mask; always pass zero. Tue Jun 6 13:34:53 1995 Roland McGrath <roland@churchy.gnu.ai.mit.edu> * sysdeps/i386/dl-machine.h (ELF_MACHINE_USER_ADDRESS_MASK): New macro. * sysdeps/mach/hurd/dl-sysdep.c (mmap): Use it as mask in vm_map call. * elf/dl-error.c (_dl_catch_error): Clear *ERRSTRING and *OBJNAME when successful. * sysdeps/mach/hurd/dl-sysdep.c (threadvars): New static variable. (__hurd_threadvar_max, __hurd_threadvar_stack_offset): Define these variables, using the `threadvars' buffer. * elf/dl-reloc.c: Don't dereference L->l_prev when it's null. * sysdeps/i386/dl-runtime.c: Likewise. * elf/rtld.c (dl_main): Add missing NULL terminating argument in _dl_sysdep_fatal call. (__assert_fail): Likewise. * locale/Makefile (localedef-modules): Renamed ctype to locale-ctype so as not to conflict with the object file for ctype/ctype.c in the build directory. * sysdeps/i386/dl-machine.h (elf_machine_rel): If MAP->l_type is lt_interpreter, first undo relocation done during bootstrapping.
1995-06-08 17:00:23 +08:00
loader->l_info[DT_STRTAB]->d_un.d_ptr +
loader->l_info[DT_RPATH]->d_un.d_val));
if (fd == -1 && ! _dl_secure)
trypath (getenv ("LD_LIBRARY_PATH"));
if (fd == -1)
{
extern const char *_dl_rpath; /* Set in rtld.c. */
trypath (_dl_rpath);
}
}
else
{
fd = open (name, O_RDONLY);
if (fd != -1)
realname = strdup (name);
}
if (fd == -1)
_dl_signal_error (errno, name, "cannot open shared object file");
return _dl_map_object_from_fd (name, fd, realname);
}
/* Map in the shared object NAME, actually located in REALNAME, and already
opened on FD. */
struct link_map *
_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;
}