/*

 * Copyright (c) 2003, 2013, 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 "libproc_impl.h"

static const char* alt_root = NULL;

static int alt_root_len = -1;

#define SA_ALTROOT "SA_ALTROOT"

off_t ltell(int fd) {

  return lseek(fd, 0, SEEK_CUR);

}

static void init_alt_root() {

  if (alt_root_len == -1) {

    alt_root = getenv(SA_ALTROOT);

    if (alt_root) {

      alt_root_len = strlen(alt_root);

    } else {

      alt_root_len = 0;

    }

  }

}

int pathmap_open(const char* name) {

  int fd;

  char alt_path[PATH_MAX + 1];

  init_alt_root();

  if (alt_root_len > 0) {

    strcpy(alt_path, alt_root);

    strcat(alt_path, name);

    fd = open(alt_path, O_RDONLY);

    if (fd >= 0) {

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

      return fd;

    }

    if (strrchr(name, '/')) {

      strcpy(alt_path, alt_root);

      strcat(alt_path, strrchr(name, '/'));

      fd = open(alt_path, O_RDONLY);

      if (fd >= 0) {

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

        return fd;

      }

    }

  } else {

    fd = open(name, O_RDONLY);

    if (fd >= 0) {

      return fd;

    }

  }

  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;

}

#ifdef __APPLE__

// get arch offset in file

bool get_arch_off(int fd, cpu_type_t cputype, off_t *offset) {

  struct fat_header fatheader;

  struct fat_arch fatarch;

  off_t img_start = 0;

  off_t pos = ltell(fd);

  if (read(fd, (void *)&fatheader, sizeof(struct fat_header)) != sizeof(struct fat_header)) {

    return false;

  }

  if (fatheader.magic == FAT_CIGAM) {

    int i;

    for (i = 0; i < ntohl(fatheader.nfat_arch); i++) {

      if (read(fd, (void *)&fatarch, sizeof(struct fat_arch)) != sizeof(struct fat_arch)) {

        return false;

      }

      if (ntohl(fatarch.cputype) == cputype) {

        print_debug("fat offset=%x\n", ntohl(fatarch.offset));

        img_start = ntohl(fatarch.offset);

        break;

      }

    }

    if (img_start == 0) {

      return false;

    }

  }

  lseek(fd, pos, SEEK_SET);

  *offset = img_start;

  return true;

}

bool is_macho_file(int fd) {

  mach_header_64 fhdr;

  off_t x86_64_off;

  if (fd < 0) {

    print_debug("Invalid file handle passed to is_macho_file\n");

    return false;

  }

  off_t pos = ltell(fd);

  // check fat header

  if (!get_arch_off(fd, CPU_TYPE_X86_64, &x86_64_off)) {

    print_debug("failed to get fat header\n");

    return false;

  }

  lseek(fd, x86_64_off, SEEK_SET);

  if (read(fd, (void *)&fhdr, sizeof(mach_header_64)) != sizeof(mach_header_64)) {

     return false;

  }

  lseek(fd, pos, SEEK_SET);               // restore

  print_debug("fhdr.magic %x\n", fhdr.magic);

  return (fhdr.magic == MH_MAGIC_64 || fhdr.magic == MH_CIGAM_64);

}

#endif //__APPLE__

// initialize libproc

bool init_libproc(bool debug) {

   _libsaproc_debug = debug;

#ifndef __APPLE__

   // initialize the thread_db library

   if (td_init() != TD_OK) {

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

     return false;

   }

#endif // __APPLE__

   return true;

}

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;

  }

}

void destroy_thread_info(struct ps_prochandle* ph) {

  sa_thread_info* thr = ph->threads;

  while (thr) {

    sa_thread_info* n = thr->next;

    free(thr);

    thr = n;

  }

}

// 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;

  print_debug("add_lib_info_fd %s\n", libname);

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

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

    return NULL;

  }

  strncpy(newlib->name, libname, sizeof(newlib->name));

  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;

  }

#ifdef __APPLE__

  // check whether we have got an Macho file.

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

    close(newlib->fd);

    free(newlib);

    print_debug("not a mach-o file\n");

    return NULL;

  }

#else

  // 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;

  }

#endif // __APPLE__

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

  if (newlib->symtab == NULL) {

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

  } else {

    print_debug("built symbol table 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 or MachO 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

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

  sa_thread_info* newthr;

  if ( (newthr = (sa_thread_info*) calloc(1, sizeof(sa_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;

}

#ifndef __APPLE__

// 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, (pthread_t)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;

}

#endif // __APPLE__

// 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;

  sa_thread_info* thr = ph->threads;

  while (thr) {

    if (count == index) {

      return thr->lwp_id;

    }

    count++;

    thr = thr->next;

  }

  return 0;

}

#ifdef __APPLE__

// set lwp_id of n'th thread

bool set_lwp_id(struct ps_prochandle* ph, int index, lwpid_t lwpid) {

  int count = 0;

  sa_thread_info* thr = ph->threads;

  while (thr) {

    if (count == index) {

      thr->lwp_id = lwpid;

      return true;

    }

    count++;

    thr = thr->next;

  }

  return false;

}

// get regs of n-th thread, only used in fillThreads the first time called

bool get_nth_lwp_regs(struct ps_prochandle* ph, int index, struct reg* regs) {

  int count = 0;

  sa_thread_info* thr = ph->threads;

  while (thr) {

    if (count == index) {

      break;

    }

    count++;

    thr = thr->next;

  }

  if (thr != NULL) {

    memcpy(regs, &thr->regs, sizeof(struct reg));

    return true;

  }

  return false;

}

#endif // __APPLE__

// get regs for a given lwp

bool get_lwp_regs(struct ps_prochandle* ph, lwpid_t lwp_id, struct reg* 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

// 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_pread(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;

}