/*

 * Copyright (c) 2003, 2019, 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 <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <signal.h>

#include <errno.h>

#include <elf.h>

#include <dirent.h>

#include <ctype.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <sys/ptrace.h>

#include <sys/uio.h>

#include "libproc_impl.h"

#if defined(x86_64) && !defined(amd64)

#define amd64 1

#endif

#ifndef __WALL

#define __WALL          0x40000000  // Copied from /usr/include/linux/wait.h

#endif

// This file has the libproc implementation specific to live process

// For core files, refer to ps_core.c

typedef enum {

  ATTACH_SUCCESS,

  ATTACH_FAIL,

  ATTACH_THREAD_DEAD

} attach_state_t;

static inline uintptr_t align(uintptr_t ptr, size_t size) {

  return (ptr & ~(size - 1));

}

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

// ptrace functions

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

// read "size" bytes of data from "addr" within the target process.

// unlike the standard ptrace() function, process_read_data() can handle

// unaligned address - alignment check, if required, should be done

// before calling process_read_data.

static bool process_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {

  long rslt;

  size_t i, words;

  uintptr_t end_addr = addr + size;

  uintptr_t aligned_addr = align(addr, sizeof(long));

  if (aligned_addr != addr) {

    char *ptr = (char *)&rslt;

    errno = 0;

    rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);

    if (errno) {

      print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);

      return false;

    }

    for (; aligned_addr != addr; aligned_addr++, ptr++);

    for (; ((intptr_t)aligned_addr % sizeof(long)) && aligned_addr < end_addr;

        aligned_addr++)

       *(buf++) = *(ptr++);

  }

  words = (end_addr - aligned_addr) / sizeof(long);

  // assert((intptr_t)aligned_addr % sizeof(long) == 0);

  for (i = 0; i < words; i++) {

    errno = 0;

    rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);

    if (errno) {

      print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);

      return false;

    }

    *(long *)buf = rslt;

    buf += sizeof(long);

    aligned_addr += sizeof(long);

  }

  if (aligned_addr != end_addr) {

    char *ptr = (char *)&rslt;

    errno = 0;

    rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);

    if (errno) {

      print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);

      return false;

    }

    for (; aligned_addr != end_addr; aligned_addr++)

       *(buf++) = *(ptr++);

  }

  return true;

}

// null implementation for write

static bool process_write_data(struct ps_prochandle* ph,

                             uintptr_t addr, const char *buf , size_t size) {

  return false;

}

// "user" should be a pointer to a user_regs_struct

static bool process_get_lwp_regs(struct ps_prochandle* ph, pid_t pid, struct user_regs_struct *user) {

  // we have already attached to all thread 'pid's, just use ptrace call

  // to get regset now. Note that we don't cache regset upfront for processes.

// Linux on x86 and sparc are different.  On x86 ptrace(PTRACE_GETREGS, ...)

// uses pointer from 4th argument and ignores 3rd argument.  On sparc it uses

// pointer from 3rd argument and ignores 4th argument

#if defined(sparc) || defined(sparcv9)

#define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, addr, data)

#else

#define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, data, addr)

#endif

#if defined(_LP64) && defined(PTRACE_GETREGS64)

#define PTRACE_GETREGS_REQ PTRACE_GETREGS64

#elif defined(PTRACE_GETREGS)

#define PTRACE_GETREGS_REQ PTRACE_GETREGS

#elif defined(PT_GETREGS)

#define PTRACE_GETREGS_REQ PT_GETREGS

#endif

#ifdef PTRACE_GETREGS_REQ

 if (ptrace_getregs(PTRACE_GETREGS_REQ, pid, user, NULL) < 0) {

   print_debug("ptrace(PTRACE_GETREGS, ...) failed for lwp %d\n", pid);

   return false;

 }

 return true;

#elif defined(PTRACE_GETREGSET)

 struct iovec iov;

 iov.iov_base = user;

 iov.iov_len = sizeof(*user);

 if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, (void*) &iov) < 0) {

   print_debug("ptrace(PTRACE_GETREGSET, ...) failed for lwp %d\n", pid);

   return false;

 }

 return true;

#else

 print_debug("ptrace(PTRACE_GETREGS, ...) not supported\n");

 return false;

#endif

}

static bool ptrace_continue(pid_t pid, int signal) {

  // pass the signal to the process so we don't swallow it

  if (ptrace(PTRACE_CONT, pid, NULL, signal) < 0) {

    print_debug("ptrace(PTRACE_CONT, ..) failed for %d\n", pid);

    return false;

  }

  return true;

}

// waits until the ATTACH has stopped the process

// by signal SIGSTOP

static attach_state_t ptrace_waitpid(pid_t pid) {

  int ret;

  int status;

  errno = 0;

  while (true) {

    // Wait for debuggee to stop.

    ret = waitpid(pid, &status, 0);

    if (ret == -1 && errno == ECHILD) {

      // try cloned process.

      ret = waitpid(pid, &status, __WALL);

    }

    if (ret >= 0) {

      if (WIFSTOPPED(status)) {

        // Any signal will stop the thread, make sure it is SIGSTOP. Otherwise SIGSTOP

        // will still be pending and delivered when the process is DETACHED and the process

        // will go to sleep.

        if (WSTOPSIG(status) == SIGSTOP) {

          // Debuggee stopped by SIGSTOP.

          return ATTACH_SUCCESS;

        }

        if (!ptrace_continue(pid, WSTOPSIG(status))) {

          print_error("Failed to correctly attach to VM. VM might HANG! [PTRACE_CONT failed, stopped by %d]\n", WSTOPSIG(status));

          return ATTACH_FAIL;

        }

      } else {

        print_debug("waitpid(): Child process %d exited/terminated (status = 0x%x)\n", pid, status);

        return ATTACH_THREAD_DEAD;

      }

    } else {

      switch (errno) {

        case EINTR:

          continue;

          break;

        case ECHILD:

          print_debug("waitpid() failed. Child process pid (%d) does not exist \n", pid);

          return ATTACH_THREAD_DEAD;

        case EINVAL:

          print_error("waitpid() failed. Invalid options argument.\n");

          return ATTACH_FAIL;

        default:

          print_error("waitpid() failed. Unexpected error %d\n", errno);

          return ATTACH_FAIL;

      }

    } // else

  } // while

}

// checks the state of the thread/process specified by "pid", by reading

// in the 'State:' value from the /proc/<pid>/status file. From the proc

// man page, "Current state of the process. One of "R (running)",

// "S (sleeping)", "D (disk sleep)", "T (stopped)", "T (tracing stop)",

// "Z (zombie)", or "X (dead)"." Assumes that the thread is dead if we

// don't find the status file or if the status is 'X' or 'Z'.

static bool process_doesnt_exist(pid_t pid) {

  char fname[32];

  char buf[30];

  FILE *fp = NULL;

  const char state_string[] = "State:";

  sprintf(fname, "/proc/%d/status", pid);

  fp = fopen(fname, "r");

  if (fp == NULL) {

    print_debug("can't open /proc/%d/status file\n", pid);

    // Assume the thread does not exist anymore.

    return true;

  }

  bool found_state = false;

  size_t state_len = strlen(state_string);

  while (fgets(buf, sizeof(buf), fp) != NULL) {

    char *state = NULL;

    if (strncmp (buf, state_string, state_len) == 0) {

      found_state = true;

      state = buf + state_len;

      // Skip the spaces

      while (isspace(*state)) {

        state++;

      }

      // A state value of 'X' indicates that the thread is dead. 'Z'

      // indicates that the thread is a zombie.

      if (*state == 'X' || *state == 'Z') {

        fclose (fp);

        return true;

      }

      break;

    }

  }

  // If the state value is not 'X' or 'Z', the thread exists.

  if (!found_state) {

    // We haven't found the line beginning with 'State:'.

    // Assuming the thread exists.

    print_error("Could not find the 'State:' string in the /proc/%d/status file\n", pid);

  }

  fclose (fp);

  return false;

}

// attach to a process/thread specified by "pid"

static attach_state_t ptrace_attach(pid_t pid, char* err_buf, size_t err_buf_len) {

  errno = 0;

  if (ptrace(PTRACE_ATTACH, pid, NULL, NULL) < 0) {

    if (errno == EPERM || errno == ESRCH) {

      // Check if the process/thread is exiting or is a zombie

      if (process_doesnt_exist(pid)) {

        print_debug("Thread with pid %d does not exist\n", pid);

        return ATTACH_THREAD_DEAD;

      }

    }

    char buf[200];

    char* msg = strerror_r(errno, buf, sizeof(buf));

    snprintf(err_buf, err_buf_len, "ptrace(PTRACE_ATTACH, ..) failed for %d: %s", pid, msg);

    print_error("%s\n", err_buf);

    return ATTACH_FAIL;

  } else {

    attach_state_t wait_ret = ptrace_waitpid(pid);

    if (wait_ret == ATTACH_THREAD_DEAD) {

      print_debug("Thread with pid %d does not exist\n", pid);

    }

    return wait_ret;

  }

}

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

// functions for obtaining library information

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

/*

 * splits a string _str_ into substrings with delimiter _delim_ by replacing old * delimiters with _new_delim_ (ideally, '\0'). the address of each substring

 * is stored in array _ptrs_ as the return value. the maximum capacity of _ptrs_ * array is specified by parameter _n_.

 * RETURN VALUE: total number of substrings (always <= _n_)

 * NOTE: string _str_ is modified if _delim_!=_new_delim_

 */

static int split_n_str(char * str, int n, char ** ptrs, char delim, char new_delim)

{

   int i;

   for(i = 0; i < n; i++) ptrs[i] = NULL;

   if (str == NULL || n < 1 ) return 0;

   i = 0;

   // skipping leading blanks

   while(*str&&*str==delim) str++;

   while(*str&&i<n){

     ptrs[i++] = str;

     while(*str&&*str!=delim) str++;

     while(*str&&*str==delim) *(str++) = new_delim;

   }

   return i;

}

/*

 * fgets without storing '\n' at the end of the string

 */

static char * fgets_no_cr(char * buf, int n, FILE *fp)

{

   char * rslt = fgets(buf, n, fp);

   if (rslt && buf && *buf){

       char *p = strchr(buf, '\0');

       if (*--p=='\n') *p='\0';

   }

   return rslt;

}

static bool read_lib_info(struct ps_prochandle* ph) {

  char fname[32];

  char buf[PATH_MAX];

  FILE *fp = NULL;

  sprintf(fname, "/proc/%d/maps", ph->pid);

  fp = fopen(fname, "r");

  if (fp == NULL) {

    print_debug("can't open /proc/%d/maps file\n", ph->pid);

    return false;

  }

  while(fgets_no_cr(buf, PATH_MAX, fp)){

    char * word[7];

    int nwords = split_n_str(buf, 7, word, ' ', '\0');

    if (nwords < 6) {

      // not a shared library entry. ignore.

      continue;

    }

    // SA does not handle the lines with patterns:

    //   "[stack]", "[heap]", "[vdso]", "[vsyscall]", etc.

    if (word[5][0] == '[') {

        // not a shared library entry. ignore.

        continue;

    }

    if (nwords > 6) {

      // prelink altered mapfile when the program is running.

      // Entries like one below have to be skipped

      //  /lib64/libc-2.15.so (deleted)

      // SO name in entries like one below have to be stripped.

      //  /lib64/libpthread-2.15.so.#prelink#.EECVts

      char *s = strstr(word[5],".#prelink#");

      if (s == NULL) {

        // No prelink keyword. skip deleted library

        print_debug("skip shared object %s deleted by prelink\n", word[5]);

        continue;

      }

      // Fall through

      print_debug("rectifying shared object name %s changed by prelink\n", word[5]);

      *s = 0;

    }

    if (find_lib(ph, word[5]) == false) {

       intptr_t base;

       lib_info* lib;

#ifdef _LP64

       sscanf(word[0], "%lx", &base);

#else

       sscanf(word[0], "%x", &base);

#endif

       if ((lib = add_lib_info(ph, word[5], (uintptr_t)base)) == NULL)

          continue; // ignore, add_lib_info prints error

       // we don't need to keep the library open, symtab is already

       // built. Only for core dump we need to keep the fd open.

       close(lib->fd);

       lib->fd = -1;

    }

  }

  fclose(fp);

  return true;

}

// detach a given pid

static bool ptrace_detach(pid_t pid) {

  if (pid && ptrace(PTRACE_DETACH, pid, NULL, NULL) < 0) {

    print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid);

    return false;

  } else {

    return true;

  }

}

// detach all pids of a ps_prochandle

static void detach_all_pids(struct ps_prochandle* ph) {

  thread_info* thr = ph->threads;

  while (thr) {

     ptrace_detach(thr->lwp_id);

     thr = thr->next;

  }

}

static void process_cleanup(struct ps_prochandle* ph) {

  detach_all_pids(ph);

}

static ps_prochandle_ops process_ops = {

  .release=  process_cleanup,

  .p_pread=  process_read_data,

  .p_pwrite= process_write_data,

  .get_lwp_regs= process_get_lwp_regs

};

// attach to the process. One and only one exposed stuff

JNIEXPORT struct ps_prochandle* JNICALL

Pgrab(pid_t pid, char* err_buf, size_t err_buf_len) {

  struct ps_prochandle* ph = NULL;

  thread_info* thr = NULL;

  attach_state_t attach_status = ATTACH_SUCCESS;

  if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) {

    snprintf(err_buf, err_buf_len, "can't allocate memory for ps_prochandle");

    print_debug("%s\n", err_buf);

    return NULL;

  }

  if ((attach_status = ptrace_attach(pid, err_buf, err_buf_len)) != ATTACH_SUCCESS) {

    if (attach_status == ATTACH_THREAD_DEAD) {

       print_error("The process with pid %d does not exist.\n", pid);

    }

    free(ph);

    return NULL;

  }

  // initialize ps_prochandle

  ph->pid = pid;

  add_thread_info(ph, ph->pid);

  // initialize vtable

  ph->ops = &process_ops;

  // read library info and symbol tables, must do this before attaching threads,

  // as the symbols in the pthread library will be used to figure out

  // the list of threads within the same process.

  read_lib_info(ph);

  /*

   * Read thread info.

   * SA scans all tasks in /proc/<PID>/task to read all threads info.

   */

  char taskpath[PATH_MAX];

  DIR *dirp;

  struct dirent *entry;

  snprintf(taskpath, PATH_MAX, "/proc/%d/task", ph->pid);

  dirp = opendir(taskpath);

  int lwp_id;

  while ((entry = readdir(dirp)) != NULL) {

    if (*entry->d_name == '.') {

      continue;

    }

    lwp_id = atoi(entry->d_name);

    if (lwp_id == ph->pid) {

      continue;

    }

    if (!process_doesnt_exist(lwp_id)) {

      add_thread_info(ph, lwp_id);

    }

  }

  closedir(dirp);

  // attach to the threads

  thr = ph->threads;

  while (thr) {

    thread_info* current_thr = thr;

    thr = thr->next;

    // don't attach to the main thread again

    if (ph->pid != current_thr->lwp_id) {

      if ((attach_status = ptrace_attach(current_thr->lwp_id, err_buf, err_buf_len)) != ATTACH_SUCCESS) {

        if (attach_status == ATTACH_THREAD_DEAD) {

          // Remove this thread from the threads list