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authorRoland McGrath <roland@gnu.org>1995-05-02 06:35:55 +0000
committerRoland McGrath <roland@gnu.org>1995-05-02 06:35:55 +0000
commitd66e34cd423425c348bcc83df127dd19711b0b9a (patch)
tree97058e776d3b4fe06ef54bc4951596991652183f /elf/dl-load.c
parent08162fa888913a5153d2fcdc4e1a816b57b1fe56 (diff)
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* sysdeps/mach/i386/sysdep.h (SNARF_ARGS, CALL_WITH_SP): Rewritten.
* sysdeps/i386/dl-machine.h: New file. * sysdeps/stub/dl-machine.h: New file. * sysdeps/i386/dl-runtime.c: New file. * sysdeps/stub/dl-runtime.c: New file. * sysdeps/i386/elf/start.S: New file. * sysdeps/generic/dl-sysdep.c: New file. * sysdeps/mach/hurd/dl-sysdep.c: New file.
Diffstat (limited to 'elf/dl-load.c')
-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 0000000..0de7404
--- /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;
+}