/*

 * Copyright 2012, 2013 SAP AG. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "asm/assembler.hpp"

#include "loadlib_aix.hpp"

#include "memory/allocation.hpp"

#include "memory/allocation.inline.hpp"

// For CritSect

#include "misc_aix.hpp"

#include "porting_aix.hpp"

#include "runtime/os.hpp"

#include "utilities/debug.hpp"

#include <demangle.h>

#include <sys/debug.h>

//////////////////////////////////

// Provide implementation for dladdr based on LoadedLibraries pool and

// traceback table scan (see getFuncName).

// Search traceback table in stack,

// return procedure name from trace back table.

#define MAX_FUNC_SEARCH_LEN 0x10000

// Any PC below this value is considered toast.

#define MINIMUM_VALUE_FOR_PC ((unsigned int*)0x1024)

#define PTRDIFF_BYTES(p1,p2) (((ptrdiff_t)p1) - ((ptrdiff_t)p2))

// Unfortunately, the interface of dladdr makes the implementator

// responsible for maintaining memory for function name/library

// name. I guess this is because most OS's keep those values as part

// of the mapped executable image ready to use. On AIX, this doesn't

// work, so I have to keep the returned strings. For now, I do this in

// a primitive string map. Should this turn out to be a performance

// problem, a better hashmap has to be used.

class fixed_strings {

  struct node : public CHeapObj<mtInternal> {

    char* v;

    node* next;

  };

  node* first;

  public:

  fixed_strings() : first(0) {}

  ~fixed_strings() {

    node* n = first;

    while (n) {

      node* p = n;

      n = n->next;

      os::free(p->v);

      delete p;

    }

  }

  char* intern(const char* s) {

    for (node* n = first; n; n = n->next) {

      if (strcmp(n->v, s) == 0) {

        return n->v;

      }

    }

    node* p = new node;

    p->v = os::strdup_check_oom(s);

    p->next = first;

    first = p;

    return p->v;

  }

};

static fixed_strings dladdr_fixed_strings;

// Given a code pointer, returns the function name and the displacement.

// Function looks for the traceback table at the end of the function.

extern "C" int getFuncName(

    codeptr_t pc,                    // [in] program counter

    char* p_name, size_t namelen,    // [out] optional: function name ("" if not available)

    int* p_displacement,             // [out] optional: displacement (-1 if not available)

    const struct tbtable** p_tb,     // [out] optional: ptr to traceback table to get further

                                     //                 information (NULL if not available)

    char* p_errmsg, size_t errmsglen,// [out] optional: user provided buffer for error messages

    bool demangle                    // [in] whether to demangle the name

  ) {

  struct tbtable* tb = 0;

  unsigned int searchcount = 0;

  // initialize output parameters

  if (p_name && namelen > 0) {

    *p_name = '\0';

  }

  if (p_errmsg && errmsglen > 0) {

    *p_errmsg = '\0';

  }

  if (p_displacement) {

    *p_displacement = -1;

  }

  if (p_tb) {

    *p_tb = NULL;

  }

  // weed out obvious bogus states

  if (pc < MINIMUM_VALUE_FOR_PC) {

    ERRBYE("invalid program counter");

  }

  // We see random but frequent crashes in this function since some months mainly on shutdown

  // (-XX:+DumpInfoAtExit). It appears the page we are reading is randomly disappearing while

  // we read it (?).

  // As the pc cannot be trusted to be anything sensible lets make all reads via SafeFetch. Also

  // bail if this is not a text address right now.

  if (!LoadedLibraries::find_for_text_address(pc, NULL)) {

    ERRBYE("not a text address");

  }

  // .. (Note that is_readable_pointer returns true if safefetch stubs are not there yet;

  // in that case I try reading the traceback table unsafe - I rather risk secondary crashes in

  // error files than not having a callstack.)

#define CHECK_POINTER_READABLE(p) \

  if (!MiscUtils::is_readable_pointer(p)) { \

    ERRBYE("pc not readable"); \

  }

  codeptr_t pc2 = pc;

  // Make sure the pointer is word aligned.

  pc2 = (codeptr_t) align_ptr_up((char*)pc2, 4);

  CHECK_POINTER_READABLE(pc2)

  // Find start of traceback table.

  // (starts after code, is marked by word-aligned (32bit) zeros)

  while ((*pc2 != NULL) && (searchcount++ < MAX_FUNC_SEARCH_LEN)) {

    CHECK_POINTER_READABLE(pc2)

    pc2++;

  }

  if (*pc2 != 0) {

    ERRBYE("no traceback table found");

  }

  //

  // Set up addressability to the traceback table

  //

  tb = (struct tbtable*) (pc2 + 1);

  // Is this really a traceback table? No way to be sure but

  // some indicators we can check.

  if (tb->tb.lang >= 0xf && tb->tb.lang <= 0xfb) {

    // Language specifiers, go from 0 (C) to 14 (Objective C).

    // According to spec, 0xf-0xfa reserved, 0xfb-0xff reserved for ibm.

    ERRBYE("no traceback table found");

  }

  // Existence of fields in the tbtable extension are contingent upon

  // specific fields in the base table.  Check for their existence so

  // that we can address the function name if it exists.

  pc2 = (codeptr_t) tb +

    sizeof(struct tbtable_short)/sizeof(int);

  if (tb->tb.fixedparms != 0 || tb->tb.floatparms != 0)

    pc2++;

  CHECK_POINTER_READABLE(pc2)

  if (tb->tb.has_tboff == TRUE) {

    // I want to know the displacement

    const unsigned int tb_offset = *pc2;

    codeptr_t start_of_procedure =

    (codeptr_t)(((char*)tb) - 4 - tb_offset);  // (-4 to omit leading 0000)

    // Weed out the cases where we did find the wrong traceback table.

    if (pc < start_of_procedure) {

      ERRBYE("no traceback table found");

    }

    // return the displacement

    if (p_displacement) {

      (*p_displacement) = (int) PTRDIFF_BYTES(pc, start_of_procedure);

    }

    pc2++;

  } else {

    // return -1 for displacement

    if (p_displacement) {

      (*p_displacement) = -1;

    }

  }

  if (tb->tb.int_hndl == TRUE)

    pc2++;

  if (tb->tb.has_ctl == TRUE)

    pc2 += (*pc2) + 1; // don't care

  CHECK_POINTER_READABLE(pc2)

  //

  // return function name if it exists.

  //

  if (p_name && namelen > 0) {

    if (tb->tb.name_present) {

      // Copy name from text because it may not be zero terminated.

      // 256 is good enough for most cases; do not use large buffers here.

      char buf[256];

      const short l = MIN2<short>(*((short*)pc2), sizeof(buf) - 1);

      // Be very careful.

      int i = 0; char* const p = (char*)pc2 + sizeof(short);

      while (i < l && MiscUtils::is_readable_pointer(p + i)) {

        buf[i] = p[i];

        i++;

      }

      buf[i] = '\0';

      p_name[0] = '\0';

      // If it is a C++ name, try and demangle it using the Demangle interface (see demangle.h).

      if (demangle) {

        char* rest;

        Name* const name = Demangle(buf, rest);

        if (name) {

          const char* const demangled_name = name->Text();

          if (demangled_name) {

            strncpy(p_name, demangled_name, namelen-1);

            p_name[namelen-1] = '\0';

          }

          delete name;

        }

      }

      // Fallback: if demangling did not work, just provide the unmangled name.

      if (p_name[0] == '\0') {

        strncpy(p_name, buf, namelen-1);

        p_name[namelen-1] = '\0';

      }

    } else {

      strncpy(p_name, "<nameless function>", namelen-1);

      p_name[namelen-1] = '\0';

    }

  }

  // Return traceback table, if user wants it.

  if (p_tb) {

    (*p_tb) = tb;

  }

  return 0;

}

// Special implementation of dladdr for Aix based on LoadedLibraries

// Note: dladdr returns non-zero for ok, 0 for error!

// Note: dladdr is not posix, but a non-standard GNU extension. So this tries to

//   fulfill the contract of dladdr on Linux (see http://linux.die.net/man/3/dladdr)

// Note: addr may be both an AIX function descriptor or a real code pointer

//   to the entry of a function.

extern "C"

int dladdr(void* addr, Dl_info* info) {

  if (!addr) {

    return 0;

  }

  assert(info, "");

  int rc = 0;

  const char* const ZEROSTRING = "";

  // Always return a string, even if a "" one. Linux dladdr manpage

  // does not say anything about returning NULL

  info->dli_fname = ZEROSTRING;

  info->dli_sname = ZEROSTRING;

  info->dli_saddr = NULL;

  address p = (address) addr;

  loaded_module_t lm;

  bool found = false;

  enum { noclue, code, data } type = noclue;

  trcVerbose("dladdr(%p)...", p);

  // Note: input address may be a function. I accept both a pointer to

  // the entry of a function and a pointer to the function decriptor.

  // (see ppc64 ABI)

  found = LoadedLibraries::find_for_text_address(p, &lm);

  if (found) {

    type = code;

  }

  if (!found) {

    // Not a pointer into any text segment. Is it a function descriptor?

    const FunctionDescriptor* const pfd = (const FunctionDescriptor*) p;

    p = pfd->entry();

    if (p) {

      found = LoadedLibraries::find_for_text_address(p, &lm);

      if (found) {

        type = code;

      }

    }

  }

  if (!found) {

    // Neither direct code pointer nor function descriptor. A data ptr?

    p = (address)addr;

    found = LoadedLibraries::find_for_data_address(p, &lm);

    if (found) {

      type = data;

    }

  }

  // If we did find the shared library this address belongs to (either

  // code or data segment) resolve library path and, if possible, the

  // symbol name.

  if (found) {

    // No need to intern the libpath, that one is already interned one layer below.

    info->dli_fname = lm.path;

    if (type == code) {

      // For code symbols resolve function name and displacement. Use

      // displacement to calc start of function.

      char funcname[256] = "";

      int displacement = 0;

      if (getFuncName((codeptr_t) p, funcname, sizeof(funcname), &displacement,

                      NULL, NULL, 0, false) == 0) {

        if (funcname[0] != '\0') {

          const char* const interned = dladdr_fixed_strings.intern(funcname);

          info->dli_sname = interned;

          trcVerbose("... function name: %s ...", interned);

        }

        // From the displacement calculate the start of the function.

        if (displacement != -1) {

          info->dli_saddr = p - displacement;

        } else {

          info->dli_saddr = p;

        }

      } else {

        // No traceback table found. Just assume the pointer is it.

        info->dli_saddr = p;

      }

    } else if (type == data) {

      // For data symbols.

      info->dli_saddr = p;

    } else {

      ShouldNotReachHere();

    }

    rc = 1; // success: return 1 [sic]

  }

  // sanity checks.

  if (rc) {

    assert(info->dli_fname, "");

    assert(info->dli_sname, "");

    assert(info->dli_saddr, "");

  }

  return rc; // error: return 0 [sic]

}