[libunwind] Remove the remote unwinding support

[phosek]

Summary

This is unfinished, unused and incomplete. This could be brought back in
the future if there's a desire to build a more complete implementation,
but at the moment it's just bitrotting.

[ldionne]

I'm in favour of the removal -- apparently the presence of this incomplete API has confused some people in the past, too, so that's yet another reason to remove it.

[ldionne]

libunwind/include/libunwind.h

138

Consider leaving part of this comment so that people searching for API functions that were removed can find that we've removed them. Just a suggestion -- I don't know how likely it is that someone will be confused by this API "disappearing".

[phosek]

libunwind/include/libunwind.h

138

Ack, though this documentation is also incomplete so I'd prefer to remove it as well to avoid confusion.

libunwind/include/libunwind.h

 extern int unw_get_proc_info(unw_cursor_t *, unw_proc_info_t *) LIBUNWIND_AVAIL;
 extern int unw_is_fpreg(unw_cursor_t *, unw_regnum_t) LIBUNWIND_AVAIL;
 extern int unw_is_signal_frame(unw_cursor_t *) LIBUNWIND_AVAIL;
 extern int unw_get_proc_name(unw_cursor_t *, char *, size_t, unw_word_t *) LIBUNWIND_AVAIL;
 //extern int       unw_get_save_loc(unw_cursor_t*, int, unw_save_loc_t*);
 
 extern unw_addr_space_t unw_local_addr_space;
 
-#ifdef UNW_REMOTE
-/*
- * Mac OS X "remote" API for unwinding other processes on same machine
- *
- */
-extern unw_addr_space_t unw_create_addr_space_for_task(task_t);
-extern void unw_destroy_addr_space(unw_addr_space_t);
-extern int unw_init_remote_thread(unw_cursor_t *, unw_addr_space_t, thread_t *);
-#endif /* UNW_REMOTE */
-
-/*
- * traditional libunwind "remote" API
- *   NOT IMPLEMENTED on Mac OS X
- *
- * extern int               unw_init_remote(unw_cursor_t*, unw_addr_space_t,
- *                                          thread_t*);
- * extern unw_accessors_t   unw_get_accessors(unw_addr_space_t);
- * extern unw_addr_space_t  unw_create_addr_space(unw_accessors_t, int);
- * extern void              unw_flush_cache(unw_addr_space_t, unw_word_t,
- *                                          unw_word_t);
- * extern int               unw_set_caching_policy(unw_addr_space_t,
- *                                                 unw_caching_policy_t);
- * extern void              _U_dyn_register(unw_dyn_info_t*);
- * extern void              _U_dyn_cancel(unw_dyn_info_t*);
- */
-
 #ifdef __cplusplus
 }
 #endif
 
 // architecture independent register numbers
 enum {
   UNW_REG_IP = -1, // instruction pointer
   UNW_REG_SP = -2, // stack pointer

libunwind/src/AddressSpace.hpp

#else
   (void)addr;
   (void)buf;
   (void)bufLen;
   (void)offset;
 #endif
   return false;
 }
 
-
-
-#ifdef UNW_REMOTE
-
-/// RemoteAddressSpace is used as a template parameter to UnwindCursor when
-/// unwinding a thread in the another process.  The other process can be a
-/// different endianness and a different pointer size which is handled by
-/// the P template parameter.
-template <typename P>
-class RemoteAddressSpace {
-public:
-  RemoteAddressSpace(task_t task) : fTask(task) {}
-
-  typedef typename P::uint_t pint_t;
-
-  uint8_t   get8(pint_t addr);
-  uint16_t  get16(pint_t addr);
-  uint32_t  get32(pint_t addr);
-  uint64_t  get64(pint_t addr);
-  pint_t    getP(pint_t addr);
-  uint64_t  getRegister(pint_t addr);
-  uint64_t  getULEB128(pint_t &addr, pint_t end);
-  int64_t   getSLEB128(pint_t &addr, pint_t end);
-  pint_t    getEncodedP(pint_t &addr, pint_t end, uint8_t encoding,
-                        pint_t datarelBase = 0);
-  bool      findFunctionName(pint_t addr, char *buf, size_t bufLen,
-                        unw_word_t *offset);
-  bool      findUnwindSections(pint_t targetAddr, UnwindInfoSections &info);
-  bool      findOtherFDE(pint_t targetAddr, pint_t &fde);
-private:
-  void *localCopy(pint_t addr);
-
-  task_t fTask;
-};
-
-template <typename P> uint8_t RemoteAddressSpace<P>::get8(pint_t addr) {
-  return *((uint8_t *)localCopy(addr));
-}
-
-template <typename P> uint16_t RemoteAddressSpace<P>::get16(pint_t addr) {
-  return P::E::get16(*(uint16_t *)localCopy(addr));
-}
-
-template <typename P> uint32_t RemoteAddressSpace<P>::get32(pint_t addr) {
-  return P::E::get32(*(uint32_t *)localCopy(addr));
-}
-
-template <typename P> uint64_t RemoteAddressSpace<P>::get64(pint_t addr) {
-  return P::E::get64(*(uint64_t *)localCopy(addr));
-}
-
-template <typename P>
-typename P::uint_t RemoteAddressSpace<P>::getP(pint_t addr) {
-  return P::getP(*(uint64_t *)localCopy(addr));
-}
-
-template <typename P>
-typename P::uint_t OtherAddressSpace<P>::getRegister(pint_t addr) {
-  return P::getRegister(*(uint64_t *)localCopy(addr));
-}
-
-template <typename P>
-uint64_t OtherAddressSpace<P>::getULEB128(pint_t &addr, pint_t end) {
-  uintptr_t size = (end - addr);
-  LocalAddressSpace::pint_t laddr = (LocalAddressSpace::pint_t) localCopy(addr);
-  LocalAddressSpace::pint_t sladdr = laddr;
-  uint64_t result = LocalAddressSpace::getULEB128(laddr, laddr + size);
-  addr += (laddr - sladdr);
-  return result;
-}
-
-template <typename P>
-int64_t RemoteAddressSpace<P>::getSLEB128(pint_t &addr, pint_t end) {
-  uintptr_t size = (end - addr);
-  LocalAddressSpace::pint_t laddr = (LocalAddressSpace::pint_t) localCopy(addr);
-  LocalAddressSpace::pint_t sladdr = laddr;
-  uint64_t result = LocalAddressSpace::getSLEB128(laddr, laddr + size);
-  addr += (laddr - sladdr);
-  return result;
-}
-
-template <typename P> void *RemoteAddressSpace<P>::localCopy(pint_t addr) {
-  // FIX ME
-}
-
-template <typename P>
-bool RemoteAddressSpace<P>::findFunctionName(pint_t addr, char *buf,
-                                             size_t bufLen,
-                                             unw_word_t *offset) {
-  // FIX ME
-}
-
-/// unw_addr_space is the base class that abstract unw_addr_space_t type in
-/// libunwind.h points to.
-struct unw_addr_space {
-  cpu_type_t cpuType;
-  task_t taskPort;
-};
-
-/// unw_addr_space_i386 is the concrete instance that a unw_addr_space_t points
-/// to when examining
-/// a 32-bit intel process.
-struct unw_addr_space_i386 : public unw_addr_space {
-  unw_addr_space_i386(task_t task) : oas(task) {}
-  RemoteAddressSpace<Pointer32<LittleEndian>> oas;
-};
-
-/// unw_addr_space_x86_64 is the concrete instance that a unw_addr_space_t
-/// points to when examining
-/// a 64-bit intel process.
-struct unw_addr_space_x86_64 : public unw_addr_space {
-  unw_addr_space_x86_64(task_t task) : oas(task) {}
-  RemoteAddressSpace<Pointer64<LittleEndian>> oas;
-};
-
-/// unw_addr_space_ppc is the concrete instance that a unw_addr_space_t points
-/// to when examining
-/// a 32-bit PowerPC process.
-struct unw_addr_space_ppc : public unw_addr_space {
-  unw_addr_space_ppc(task_t task) : oas(task) {}
-  RemoteAddressSpace<Pointer32<BigEndian>> oas;
-};
-
-/// unw_addr_space_ppc is the concrete instance that a unw_addr_space_t points
-/// to when examining a 64-bit PowerPC process.
-struct unw_addr_space_ppc64 : public unw_addr_space {
-  unw_addr_space_ppc64(task_t task) : oas(task) {}
-  RemoteAddressSpace<Pointer64<LittleEndian>> oas;
-};
-
-#endif // UNW_REMOTE
-
 } // namespace libunwind
 
 #endif // __ADDRESSSPACE_HPP__

libunwind/src/libunwind.cpp

new ((void *)cursor) UnwindCursor<LocalAddressSpace, REGISTER_KIND>(
                                  context, LocalAddressSpace::sThisAddressSpace);
 #undef REGISTER_KIND
   AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
   co->setInfoBasedOnIPRegister();
 
   return UNW_ESUCCESS;
 }
 
-#ifdef UNW_REMOTE
-/// Create a cursor into a thread in another process.
-_LIBUNWIND_EXPORT int unw_init_remote_thread(unw_cursor_t *cursor,
-                                             unw_addr_space_t as,
-                                             void *arg) {
-  // special case: unw_init_remote(xx, unw_local_addr_space, xx)
-  if (as == (unw_addr_space_t)&LocalAddressSpace::sThisAddressSpace)
-    return unw_init_local(cursor, NULL); //FIXME
-
-  // use "placement new" to allocate UnwindCursor in the cursor buffer
-  switch (as->cpuType) {
-  case CPU_TYPE_I386:
-    new ((void *)cursor)
-        UnwindCursor<RemoteAddressSpace<Pointer32<LittleEndian>>,
-                     Registers_x86>(((unw_addr_space_i386 *)as)->oas, arg);
-    break;
-  case CPU_TYPE_X86_64:
-    new ((void *)cursor)
-        UnwindCursor<RemoteAddressSpace<Pointer64<LittleEndian>>,
-                     Registers_x86_64>(((unw_addr_space_x86_64 *)as)->oas, arg);
-    break;
-  case CPU_TYPE_POWERPC:
-    new ((void *)cursor)
-        UnwindCursor<RemoteAddressSpace<Pointer32<BigEndian>>,
-                     Registers_ppc>(((unw_addr_space_ppc *)as)->oas, arg);
-    break;
-  default:
-    return UNW_EUNSPEC;
-  }
-  return UNW_ESUCCESS;
-}
-
-
-static bool is64bit(task_t task) {
-  return false; // FIXME
-}
-
-/// Create an address_space object for use in examining another task.
-_LIBUNWIND_EXPORT unw_addr_space_t unw_create_addr_space_for_task(task_t task) {
-#if __i386__
-  if (is64bit(task)) {
-    unw_addr_space_x86_64 *as = malloc(sizeof(unw_addr_space_x86_64));
-    new (as) unw_addr_space_x86_64(task);
-    as->taskPort = task;
-    as->cpuType = CPU_TYPE_X86_64;
-    //as->oas
-  } else {
-    unw_addr_space_i386 *as = malloc(sizeof(unw_addr_space_i386));
-    new (as) unw_addr_space_i386(task);
-    as->taskPort = task;
-    as->cpuType = CPU_TYPE_I386;
-    //as->oas
-  }
-#else
-// FIXME
-#endif
-}
-
-
-/// Delete an address_space object.
-_LIBUNWIND_EXPORT void unw_destroy_addr_space(unw_addr_space_t asp) {
-  switch (asp->cpuType) {
-#if __i386__ || __x86_64__
-  case CPU_TYPE_I386: {
-    unw_addr_space_i386 *as = (unw_addr_space_i386 *)asp;
-    as->~unw_addr_space_i386();
-    free(as);
-  }
-  break;
-  case CPU_TYPE_X86_64: {
-    unw_addr_space_x86_64 *as = (unw_addr_space_x86_64 *)asp;
-    as->~unw_addr_space_x86_64();
-    free(as);
-  }
-  break;
-#endif
-  case CPU_TYPE_POWERPC: {
-    unw_addr_space_ppc *as = (unw_addr_space_ppc *)asp;
-    as->~unw_addr_space_ppc();
-    free(as);
-  }
-  break;
-  }
-}
-#endif // UNW_REMOTE
-
-
 /// Get value of specified register at cursor position in stack frame.
 _LIBUNWIND_EXPORT int unw_get_reg(unw_cursor_t *cursor, unw_regnum_t regNum,
                                   unw_word_t *value) {
   _LIBUNWIND_TRACE_API("unw_get_reg(cursor=%p, regNum=%d, &value=%p)",
                        static_cast<void *>(cursor), regNum,
                        static_cast<void *>(value));
   AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
   if (co->validReg(regNum)) {