path: root/exec/elfcore.c

#include <hurd.h>
#include <elf.h>
#include <link.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/utsname.h>


#define ELF_MACHINE	EM_386	/* XXX */

#define ELF_CLASS	PASTE (ELFCLASS, __ELF_NATIVE_CLASS)
#define PASTE(a, b)	PASTE_1 (a, b)
#define PASTE_1(a, b)	a##b

#include <endian.h>
#if BYTE_ORDER == BIG_ENDIAN
#define ELF_DATA ELFDATA2MSB
#elif BYTE_ORDER == LITTLE_ENDIAN
#define ELF_DATA ELFDATA2LSB
#endif


error_t
dump_core (task_t task, file_t file, off_t corelimit,
	   int signo, long int sigcode, int sigerror)
{
  error_t err;
  ElfW(Phdr) *phdrs, *ph;
  ElfW(Ehdr) hdr =		/* ELF header for the core file.  */
  {
    e_ident:
    {
      [EI_MAG0] = ELFMAG0,
      [EI_MAG1] = ELFMAG1,
      [EI_MAG2] = ELFMAG2,
      [EI_MAG3] = ELFMAG3,
      [EI_CLASS] = ELF_CLASS,
      [EI_DATA] = ELF_DATA,
      [EI_VERSION] = EV_CURRENT,
      [EI_OSABI] = ELFOSABI_SYSV,
      [EI_ABIVERSION] = 0
    },
    e_type: ET_CORE,
    e_version: EV_CURRENT,
    e_machine: ELF_MACHINE,
    e_ehsize: sizeof hdr,
    e_phentsize: sizeof phdrs[0],
    e_phoff: sizeof hdr,	/* Fill in e_phnum later.  */
  };
  off_t offset;
  size_t wrote;

  thread_t *threads;
  size_t nthreads, i;
  off_t notestart;

  /* Helper macros for writing notes.  */
#define DEFINE_NOTE(typename) struct { struct note_header hdr; typename data; }
#define WRITE_NOTE(type, var) ({ 					      \
  (var).hdr = NOTE_HEADER ((type), sizeof (var).data);			      \
  write_note (&(var).hdr);						      \
})
  struct note_header
  {
    ElfW(Nhdr) note;
    char name[4];
  };
#define NOTE_HEADER(type, size) \
  ((struct note_header) { { 4, (size), (type) }, "CORE" })
  inline error_t write_note (struct note_header *hdr)
    {
      error_t err = 0;
      char *data = (char *) hdr;
      size_t size = sizeof *hdr + hdr->note.n_descsz;
      if (corelimit >= 0 && offset + size > corelimit)
	size = corelimit - offset;
      while (size > 0)
	{
	  err = io_write (file, data, size, offset, &wrote);
	  if (err)
	    return err;
	  offset = (offset + wrote + 3) &~ 3; /* Pad it to word alignment.  */
	  if (wrote > size)
	    break;
	  data += wrote;
	  size -= wrote;
	}
      return err;
    }

  struct vm_region_list
  {
    struct vm_region_list *next;
    vm_prot_t protection;
    vm_address_t start;
    vm_size_t length;
  };
  struct vm_region_list *regions = NULL, **tailp = &regions, *r;
  unsigned int nregions = 0;

  if (corelimit >= 0 && corelimit < sizeof hdr)
    return EFBIG;

  {
    /* Examine the task and record the locations of contiguous memory
       segments that we will dump into the core file.  */

    vm_address_t region_address, last_region_address, last_region_end;
    vm_prot_t last_protection;
#define RECORD_LAST_REGION do {						      \
    if (last_region_end > last_region_address				      \
	&& last_protection != VM_PROT_NONE)				      \
      record_last_region (alloca (sizeof (struct vm_region_list))); } while (0)
    inline void record_last_region (struct vm_region_list *region)
      {
	*tailp = region;
	tailp = &region->next;
	region->next = NULL;
	region->start = last_region_address;
	region->length = last_region_end - last_region_address;
	region->protection = last_protection;
	++nregions;
      }

    region_address = last_region_address = last_region_end = VM_MIN_ADDRESS;
    last_protection = VM_PROT_NONE;
    while (region_address < VM_MAX_ADDRESS)
      {
	vm_prot_t protection;
	vm_prot_t max_protection;
	vm_inherit_t inheritance;
	boolean_t shared;
	mach_port_t object_name;
	vm_offset_t offset;
	vm_size_t region_length = VM_MAX_ADDRESS - region_address;

	err = vm_region (task,
			 &region_address,
			 &region_length,
			 &protection,
			 &max_protection,
			 &inheritance,
			 &shared,
			 &object_name,
			 &offset);
	if (err == KERN_NO_SPACE)
	  break;
	if (err != KERN_SUCCESS)
	  return err;

	if (protection == last_protection && region_address == last_region_end)
	  /* This region is contiguous with and indistinguishable from
	     the previous one, so we just extend that one.  */
	  last_region_end = region_address += region_length;
	else
	  {
	    /* This region is distinct from the last one we saw,
	       so record that previous one.  */
	    RECORD_LAST_REGION;
	    last_region_address = region_address;
	    last_region_end = region_address += region_length;
	    last_protection = protection;
	  }
      }
    /* Record the final region.  */
    RECORD_LAST_REGION;
  }

  /* Now we start laying out the file.  */
  offset = round_page (sizeof hdr + ((nregions + 1) * sizeof *phdrs));

  /* Final check for tiny core limit.  From now on, we will simply truncate
     the file at CORELIMIT but not change the contents of what we write.  */
  if (corelimit >= 0 && corelimit < offset)
    return EFBIG;

  /* Now we can complete the file header and write it.  */
  hdr.e_phnum = nregions + 1;
  err = io_write (file, (char *) &hdr, sizeof hdr, 0, &wrote);
  if (err)
    return err;
  if (wrote < sizeof hdr)
    return EGRATUITOUS;		/* XXX */

  /* Now we can write the various notes.  */
  notestart = offset;

  /* First a dull note containing the results of `uname', a la Solaris.  */
  {
    DEFINE_NOTE (struct utsname) note;
    if (uname (&note.data) == 0) /* XXX Use proc_uname on task's proc port?  */
      err = WRITE_NOTE (NT_UTSNAME, note);
  }
  if (err || (corelimit >= 0 && corelimit <= offset))
    return err;

#if 0
  /* The pstatus_t note should contain the death info and some process-global
     info we should get from the proc server, but no thread-specific info
     like register state.  We need to define this type.  */
  {
    DEFINE_NOTE (pstatus_t) note;
    note.data.pr_info.si_signo = signo;
    note.data.pr_info.si_code = sigcode;
    note.data.pr_info.si_errno = sigerror;
    err = WRITE_NOTE (NT_PSTATUS, note);
  }
  if (err || (corelimit >= 0 && corelimit <= offset))
    return err;
#endif

  /* Now examine all the threads in the task.
     For each thread we produce one or more notes.  */
  err = task_threads (task, &threads, &nthreads);
  if (err)
    return err;
  for (i = 0; i < nthreads; ++i)
    {
      {
	/* lwpinfo_t a la Solaris gives thread's CPU time and such.  */
	DEFINE_NOTE (struct thread_basic_info) note;
	mach_msg_type_number_t count = THREAD_BASIC_INFO_COUNT;
	err = thread_info (threads[i], THREAD_BASIC_INFO,
			   (thread_info_t)&note.data, &count);
	if (err == 0)
	  err = WRITE_NOTE (NT_LWPSINFO, note);
	else			/* Just skip it if we can't get the info.  */
	  err = 0;
      }
      if (err || (corelimit >= 0 && corelimit <= offset))
	break;

#ifdef WRITE_THREAD_NOTES
      /* XXX Here would go the note flavors for machine thread states.  */
      err = WRITE_THREAD_NOTES (i, threads[i]);
#endif
      if (err || (corelimit >= 0 && corelimit <= offset))
	break;
      mach_port_deallocate (mach_task_self (), threads[i]);
    }
  while (i < nthreads)
    mach_port_deallocate (mach_task_self (), threads[i++]);
  munmap (threads, nthreads * sizeof *threads);
  if (err || (corelimit >= 0 && corelimit <= offset))
    return err;

  /* Make an array of program headers and fill them in.
     The first one describes the note segment.  */
  ph = phdrs = alloca ((nregions + 1) * sizeof *phdrs);

  memset (ph, 0, sizeof *ph);
  ph->p_type = PT_NOTE;
  ph->p_offset = notestart;
  ph->p_filesz = offset - notestart;
  ++ph;

  /* Now make ELF program headers for each of the record memory regions.
     Consistent with the Linux kernel, we create PT_LOAD headers with
     p_filesz = 0 for the read-only segments that we are not dumping
     into the file.  */
  for (r = regions; r != NULL; r = r->next)
    {
      memset (ph, 0, sizeof *ph);
      ph->p_type = PT_LOAD;
      ph->p_align = vm_page_size;
      ph->p_flags = (((r->protection & VM_PROT_READ) ? PF_R : 0)
		     | ((r->protection & VM_PROT_WRITE) ? PF_W : 0)
		     | ((r->protection & VM_PROT_EXECUTE) ? PF_X : 0));
      ph->p_vaddr = r->start;
      ph->p_memsz = r->length;
      ph->p_filesz = (r->protection & VM_PROT_WRITE) ? ph->p_memsz : 0;
      ph->p_offset = offset;
      offset += ph->p_filesz;
      ++ph;
    }

  /* Now write the memory segment data.  */
  for (ph = &phdrs[1]; ph < &phdrs[nregions + 1]; ++ph)
    if (ph->p_filesz > 0)
      {
	vm_address_t va = ph->p_vaddr;
	vm_size_t sz = ph->p_memsz;
	off_t ofs = ph->p_offset;
	int wrote_any = 0;
	do
	  {
	    pointer_t copied;
	    int copy_count;
	    err = vm_read (task, va, sz, &copied, &copy_count);
	    if (err == 0)
	      {
		char *data = (void *) copied;
		size_t left = copy_count, wrote;

		va += copy_count;
		sz -= copy_count;

		do
		  {
		    if (corelimit >= 0 && ofs + left > corelimit)
		      left = corelimit - ofs;
		    err = io_write (file, data, left, ofs, &wrote);
		    if (err)
		      break;
		    ofs += wrote;
		    data += wrote;
		    left -= wrote;
		    if (ofs >= corelimit)
		      break;
		  } while (left > 0);

		munmap ((void *) copied, copy_count);

		if (left < copy_count)
		  wrote_any = 1;
	      }
	    else
	      {
		/* Leave a hole in the file for pages we can't read.  */
		va += vm_page_size;
		sz -= vm_page_size;
		ofs += vm_page_size;
	      }
	  } while (sz > 0 && (corelimit < 0 || ofs < corelimit));

	if (! wrote_any)
	  /* If we failed to write any contents at all,
	     don't claim the big hole as the contents.  */
	  ph->p_filesz = 0;
      }

  /* Finally, we go back and write the program headers.  */
  err = io_write (file, (char *) phdrs, (nregions + 1) * sizeof phdrs[0],
		  sizeof hdr, &wrote);

  return err;
}