/*

 * Copyright (c) 2003, 2017, Oracle and/or its affiliates. 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 <stdarg.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <fcntl.h>

#include <thread_db.h>

#include "libproc_impl.h"

#define SA_ALTROOT "SA_ALTROOT"

int pathmap_open(const char* name) {

  static const char *alt_root = NULL;

  static int alt_root_initialized = 0;

  int fd;

  char alt_path[PATH_MAX + 1], *alt_path_end;

  const char *s;

  int free_space;

  if (!alt_root_initialized) {

    alt_root_initialized = -1;

    alt_root = getenv(SA_ALTROOT);

  }

  if (alt_root == NULL) {

    return open(name, O_RDONLY);

  }

  if (strlen(alt_root) + strlen(name) > PATH_MAX) {

    // Buffer too small.

    return -1;

  }

  strncpy(alt_path, alt_root, PATH_MAX);

  alt_path[PATH_MAX] = '\0';

  alt_path_end = alt_path + strlen(alt_path);

  free_space = PATH_MAX + 1 - (alt_path_end-alt_path);

  // Strip path items one by one and try to open file with alt_root prepended.

  s = name;

  while (1) {

    strncat(alt_path, s, free_space);

    s += 1;  // Skip /.

    fd = open(alt_path, O_RDONLY);

    if (fd >= 0) {

      print_debug("path %s substituted for %s\n", alt_path, name);

      return fd;

    }

    // Linker always put full path to solib to process, so we can rely

    // on presence of /. If slash is not present, it means, that SOlib doesn't

    // physically exist (e.g. linux-gate.so) and we fail opening it anyway

    if ((s = strchr(s, '/')) == NULL) {

      break;

    }

    // Cut off what we appended above.

    *alt_path_end = '\0';

  }

  return -1;

}

static bool _libsaproc_debug;

void print_debug(const char* format,...) {

   if (_libsaproc_debug) {

     va_list alist;

     va_start(alist, format);

     fputs("libsaproc DEBUG: ", stderr);

     vfprintf(stderr, format, alist);

     va_end(alist);

   }

}

void print_error(const char* format,...) {

  va_list alist;

  va_start(alist, format);

  fputs("ERROR: ", stderr);

  vfprintf(stderr, format, alist);

  va_end(alist);

}

bool is_debug() {

   return _libsaproc_debug;

}

// initialize libproc

bool init_libproc(bool debug) {

   // init debug mode

   _libsaproc_debug = debug;

   // initialize the thread_db library

   if (td_init() != TD_OK) {

     print_debug("libthread_db's td_init failed\n");

     return false;

   }

   return true;

}

static void destroy_lib_info(struct ps_prochandle* ph) {

   lib_info* lib = ph->libs;

   while (lib) {

     lib_info *next = lib->next;

     if (lib->symtab) {

        destroy_symtab(lib->symtab);

     }

     free(lib);

     lib = next;

   }

}

static void destroy_thread_info(struct ps_prochandle* ph) {

   thread_info* thr = ph->threads;

   while (thr) {

     thread_info *next = thr->next;

     free(thr);

     thr = next;

   }

}

// ps_prochandle cleanup

// ps_prochandle cleanup

void Prelease(struct ps_prochandle* ph) {

   // do the "derived class" clean-up first

   ph->ops->release(ph);

   destroy_lib_info(ph);

   destroy_thread_info(ph);

   free(ph);

}

lib_info* add_lib_info(struct ps_prochandle* ph, const char* libname, uintptr_t base) {

   return add_lib_info_fd(ph, libname, -1, base);

}

lib_info* add_lib_info_fd(struct ps_prochandle* ph, const char* libname, int fd, uintptr_t base) {

   lib_info* newlib;

   if ( (newlib = (lib_info*) calloc(1, sizeof(struct lib_info))) == NULL) {

      print_debug("can't allocate memory for lib_info\n");

      return NULL;

   }

   if (strlen(libname) >= sizeof(newlib->name)) {

     print_debug("libname %s too long\n", libname);

     free(newlib);

     return NULL;

   }

   strcpy(newlib->name, libname);

   newlib->base = base;

   if (fd == -1) {

      if ( (newlib->fd = pathmap_open(newlib->name)) < 0) {

         print_debug("can't open shared object %s\n", newlib->name);

         free(newlib);

         return NULL;

      }

   } else {

      newlib->fd = fd;

   }

   // check whether we have got an ELF file. /proc/<pid>/map

   // gives out all file mappings and not just shared objects

   if (is_elf_file(newlib->fd) == false) {

      close(newlib->fd);

      free(newlib);

      return NULL;

   }

   newlib->symtab = build_symtab(newlib->fd, libname);

   if (newlib->symtab == NULL) {

      print_debug("symbol table build failed for %s\n", newlib->name);

   }

   // even if symbol table building fails, we add the lib_info.

   // This is because we may need to read from the ELF file for core file

   // address read functionality. lookup_symbol checks for NULL symtab.

   if (ph->libs) {

      ph->lib_tail->next = newlib;

      ph->lib_tail = newlib;

   }  else {

      ph->libs = ph->lib_tail = newlib;

   }

   ph->num_libs++;

   return newlib;

}

// lookup for a specific symbol

uintptr_t lookup_symbol(struct ps_prochandle* ph,  const char* object_name,

                       const char* sym_name) {

   // ignore object_name. search in all libraries

   // FIXME: what should we do with object_name?? The library names are obtained

   // by parsing /proc/<pid>/maps, which may not be the same as object_name.

   // What we need is a utility to map object_name to real file name, something

   // dlopen() does by looking at LD_LIBRARY_PATH and /etc/ld.so.cache. For

   // now, we just ignore object_name and do a global search for the symbol.

   lib_info* lib = ph->libs;

   while (lib) {

      if (lib->symtab) {

         uintptr_t res = search_symbol(lib->symtab, lib->base, sym_name, NULL);

         if (res) return res;

      }

      lib = lib->next;

   }

   print_debug("lookup failed for symbol '%s' in obj '%s'\n",

                          sym_name, object_name);

   return (uintptr_t) NULL;

}

const char* symbol_for_pc(struct ps_prochandle* ph, uintptr_t addr, uintptr_t* poffset) {

   const char* res = NULL;

   lib_info* lib = ph->libs;

   while (lib) {

      if (lib->symtab && addr >= lib->base) {

         res = nearest_symbol(lib->symtab, addr - lib->base, poffset);

         if (res) return res;

      }

      lib = lib->next;

   }

   return NULL;

}

// add a thread to ps_prochandle

thread_info* add_thread_info(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) {

   thread_info* newthr;

   if ( (newthr = (thread_info*) calloc(1, sizeof(thread_info))) == NULL) {

      print_debug("can't allocate memory for thread_info\n");

      return NULL;

   }

   // initialize thread info

   newthr->pthread_id = pthread_id;

   newthr->lwp_id = lwp_id;

   // add new thread to the list

   newthr->next = ph->threads;

   ph->threads = newthr;

   ph->num_threads++;

   return newthr;

}

// struct used for client data from thread_db callback

struct thread_db_client_data {

   struct ps_prochandle* ph;

   thread_info_callback callback;

};

// callback function for libthread_db

static int thread_db_callback(const td_thrhandle_t *th_p, void *data) {

  struct thread_db_client_data* ptr = (struct thread_db_client_data*) data;

  td_thrinfo_t ti;

  td_err_e err;

  memset(&ti, 0, sizeof(ti));

  err = td_thr_get_info(th_p, &ti);

  if (err != TD_OK) {

    print_debug("libthread_db : td_thr_get_info failed, can't get thread info\n");

    return err;

  }

  print_debug("thread_db : pthread %d (lwp %d)\n", ti.ti_tid, ti.ti_lid);

  if (ptr->callback(ptr->ph, ti.ti_tid, ti.ti_lid) != true)

    return TD_ERR;

  return TD_OK;

}

// read thread_info using libthread_db

bool read_thread_info(struct ps_prochandle* ph, thread_info_callback cb) {

  struct thread_db_client_data mydata;

  td_thragent_t* thread_agent = NULL;

  if (td_ta_new(ph, &thread_agent) != TD_OK) {

     print_debug("can't create libthread_db agent\n");

     return false;

  }

  mydata.ph = ph;

  mydata.callback = cb;

  // we use libthread_db iterator to iterate thru list of threads.

  if (td_ta_thr_iter(thread_agent, thread_db_callback, &mydata,

                 TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,

                 TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS) != TD_OK) {

     td_ta_delete(thread_agent);

     return false;

  }

  // delete thread agent

  td_ta_delete(thread_agent);

  return true;

}

// get number of threads

int get_num_threads(struct ps_prochandle* ph) {

   return ph->num_threads;

}

// get lwp_id of n'th thread

lwpid_t get_lwp_id(struct ps_prochandle* ph, int index) {

   int count = 0;

   thread_info* thr = ph->threads;

   while (thr) {

      if (count == index) {

         return thr->lwp_id;

      }

      count++;

      thr = thr->next;

   }

   return -1;

}

// get regs for a given lwp

bool get_lwp_regs(struct ps_prochandle* ph, lwpid_t lwp_id, struct user_regs_struct* regs) {

  return ph->ops->get_lwp_regs(ph, lwp_id, regs);

}

// get number of shared objects

int get_num_libs(struct ps_prochandle* ph) {

   return ph->num_libs;

}

// get name of n'th solib

const char* get_lib_name(struct ps_prochandle* ph, int index) {

   int count = 0;

   lib_info* lib = ph->libs;

   while (lib) {

      if (count == index) {

         return lib->name;

      }

      count++;

      lib = lib->next;

   }

   return NULL;

}

// get base address of a lib

uintptr_t get_lib_base(struct ps_prochandle* ph, int index) {

   int count = 0;

   lib_info* lib = ph->libs;

   while (lib) {

      if (count == index) {

         return lib->base;

      }

      count++;

      lib = lib->next;

   }

   return (uintptr_t)NULL;

}

bool find_lib(struct ps_prochandle* ph, const char *lib_name) {

  lib_info *p = ph->libs;

  while (p) {

    if (strcmp(p->name, lib_name) == 0) {

      return true;

    }

    p = p->next;

  }

  return false;

}

//--------------------------------------------------------------------------

// proc service functions

// get process id

pid_t ps_getpid(struct ps_prochandle *ph) {

   return ph->pid;

}

// ps_pglobal_lookup() looks up the symbol sym_name in the symbol table

// of the load object object_name in the target process identified by ph.

// It returns the symbol's value as an address in the target process in

// *sym_addr.

ps_err_e ps_pglobal_lookup(struct ps_prochandle *ph, const char *object_name,

                    const char *sym_name, psaddr_t *sym_addr) {

  *sym_addr = (psaddr_t) lookup_symbol(ph, object_name, sym_name);

  return (*sym_addr ? PS_OK : PS_NOSYM);

}

// read "size" bytes info "buf" from address "addr"

ps_err_e ps_pdread(struct ps_prochandle *ph, psaddr_t  addr,

                   void *buf, size_t size) {

  return ph->ops->p_pread(ph, (uintptr_t) addr, buf, size)? PS_OK: PS_ERR;

}

// write "size" bytes of data to debuggee at address "addr"

ps_err_e ps_pdwrite(struct ps_prochandle *ph, psaddr_t addr,

                    const void *buf, size_t size) {

  return ph->ops->p_pwrite(ph, (uintptr_t)addr, buf, size)? PS_OK: PS_ERR;

}

// ------------------------------------------------------------------------

// Functions below this point are not yet implemented. They are here only

// to make the linker happy.

ps_err_e ps_lsetfpregs(struct ps_prochandle *ph, lwpid_t lid, const prfpregset_t *fpregs) {

  print_debug("ps_lsetfpregs not implemented\n");

  return PS_OK;

}

ps_err_e ps_lsetregs(struct ps_prochandle *ph, lwpid_t lid, const prgregset_t gregset) {

  print_debug("ps_lsetregs not implemented\n");

  return PS_OK;

}

ps_err_e  ps_lgetfpregs(struct  ps_prochandle  *ph,  lwpid_t lid, prfpregset_t *fpregs) {

  print_debug("ps_lgetfpregs not implemented\n");

  return PS_OK;

}

ps_err_e ps_lgetregs(struct ps_prochandle *ph, lwpid_t lid, prgregset_t gregset) {

  print_debug("ps_lgetfpregs not implemented\n");

  return PS_OK;

}

// new libthread_db of NPTL seem to require this symbol

ps_err_e ps_get_thread_area() {

  print_debug("ps_get_thread_area not implemented\n");

  return PS_OK;

}