/*

 * 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 <limits.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <errno.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <sys/ptrace.h>

#include <sys/param.h>

#include <sys/user.h>

#include <elf.h>

#include <sys/elf_common.h>

#include <sys/link_elf.h>

#include <libutil.h>

#include "libproc_impl.h"

#include "elfmacros.h"

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

// For core files, refer to ps_core.c

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) {

  int rslt;

  size_t i, words;

  uintptr_t end_addr = addr + size;

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

  if (aligned_addr != addr) {

    char *ptr = (char *)&rslt;

    errno = 0;

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

    if (errno) {

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

      return false;

    }

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

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

        aligned_addr++)

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

  }

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

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

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

    errno = 0;

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

    if (errno) {

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

      return false;

    }

    *(int *)buf = rslt;

    buf += sizeof(int);

    aligned_addr += sizeof(int);

  }

  if (aligned_addr != end_addr) {

    char *ptr = (char *)&rslt;

    errno = 0;

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

    if (errno) {

      print_debug("ptrace(PT_READ_D, ..) 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 reg

static bool process_get_lwp_regs(struct ps_prochandle* ph, pid_t pid, struct reg *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.

 if (ptrace(PT_GETREGS, pid, (caddr_t) user, 0) < 0) {

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

   return false;

 }

 return true;

}

// fill in ptrace_lwpinfo for lid

static bool process_get_lwp_info(struct ps_prochandle *ph, lwpid_t lwp_id, void *linfo) {

  errno = 0;

  ptrace(PT_LWPINFO, lwp_id, linfo, sizeof(struct ptrace_lwpinfo));

  return (errno == 0)? true: false;

}

static bool ptrace_continue(pid_t pid, int signal) {

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

  if (ptrace(PT_CONTINUE, 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 bool ptrace_waitpid(pid_t pid) {

  int ret;

  int status;

  do {

    // Wait for debuggee to stop.

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

    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 true;

        }

        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 false;

        }

      } else {

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

        return false;

      }

    } else {

      switch (errno) {

        case EINTR:

          continue;

          break;

        case ECHILD:

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

          break;

        case EINVAL:

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

          break;

        default:

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

      }

      return false;

    }

  } while(true);

}

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

static bool ptrace_attach(pid_t pid) {

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

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

    return false;

  } else {

    return ptrace_waitpid(pid);

  }

}

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

// functions for obtaining library information

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

// callback for read_thread_info

static bool add_new_thread(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) {

  return add_thread_info(ph, pthread_id, lwp_id) != NULL;

}

#if defined(__FreeBSD__) && __FreeBSD_version < 701000

/*

 * TEXT_START_ADDR from binutils/ld/emulparams/<arch_spec>.sh

 * Not the most robust but good enough.

 */

#if defined(amd64) || defined(x86_64)

#define TEXT_START_ADDR 0x400000

#elif defined(i386)

#define TEXT_START_ADDR 0x8048000

#else

#error TEXT_START_ADDR not defined

#endif

#define BUF_SIZE (PATH_MAX + NAME_MAX + 1)

uintptr_t linkmap_addr(struct ps_prochandle *ph) {

  uintptr_t ehdr_addr, phdr_addr, dyn_addr, dmap_addr, lmap_addr;

  ELF_EHDR ehdr;

  ELF_PHDR *phdrs, *phdr;

  ELF_DYN *dyns, *dyn;

  struct r_debug dmap;

  unsigned long hdrs_size;

  unsigned int i;

  /* read ELF_EHDR at TEXT_START_ADDR and validate */

  ehdr_addr = (uintptr_t)TEXT_START_ADDR;

  if (process_read_data(ph, ehdr_addr, (char *)&ehdr, sizeof(ehdr)) != true) {

    print_debug("process_read_data failed for ehdr_addr %p\n", ehdr_addr);

    return (0);

  }

  if (!IS_ELF(ehdr) ||

        ehdr.e_ident[EI_CLASS] != ELF_TARG_CLASS ||

        ehdr.e_ident[EI_DATA] != ELF_TARG_DATA ||

        ehdr.e_ident[EI_VERSION] != EV_CURRENT ||

        ehdr.e_phentsize != sizeof(ELF_PHDR) ||

        ehdr.e_version != ELF_TARG_VER ||

        ehdr.e_machine != ELF_TARG_MACH) {

    print_debug("not an ELF_EHDR at %p\n", ehdr_addr);

    return (0);

  }

  /* allocate space for all ELF_PHDR's and read */

  phdr_addr = ehdr_addr + ehdr.e_phoff;

  hdrs_size = ehdr.e_phnum * sizeof(ELF_PHDR);

  if ((phdrs = malloc(hdrs_size)) == NULL)

    return (0);

  if (process_read_data(ph, phdr_addr, (char *)phdrs, hdrs_size) != true) {

    print_debug("process_read_data failed for phdr_addr %p\n", phdr_addr);

    return (0);

  }

  /* find PT_DYNAMIC section */

  for (i = 0, phdr = phdrs; i < ehdr.e_phnum; i++, phdr++) {

    if (phdr->p_type == PT_DYNAMIC)

      break;

  }

  if (i >= ehdr.e_phnum) {

    print_debug("PT_DYNAMIC section not found!\n");

    free(phdrs);

    return (0);

  }

  /* allocate space and read in ELF_DYN headers */

  dyn_addr = phdr->p_vaddr;

  hdrs_size = phdr->p_memsz;

  free(phdrs);

  if ((dyns = malloc(hdrs_size)) == NULL)

    return (0);

  if (process_read_data(ph, dyn_addr, (char *)dyns, hdrs_size) != true) {

    print_debug("process_read_data failed for dyn_addr %p\n", dyn_addr);

    free(dyns);

    return (0);

  }

  /* find DT_DEBUG */

  dyn = dyns;

  while (dyn->d_tag != DT_DEBUG && dyn->d_tag != DT_NULL) {

    dyn++;

  }

  if (dyn->d_tag != DT_DEBUG) {

    print_debug("failed to find DT_DEBUG\n");

    free(dyns);

    return (0);

  }

  /* read struct r_debug into dmap */

  dmap_addr = (uintptr_t)dyn->d_un.d_ptr;

  free(dyns);

  if (process_read_data(ph, dmap_addr, (char *)&dmap, sizeof(dmap)) != true) {

    print_debug("process_read_data failed for dmap_addr %p\n", dmap_addr);

    return (0);

  }

  lmap_addr = (uintptr_t)dmap.r_map;

  return (lmap_addr);

}

#endif // __FreeBSD__ && __FreeBSD_version < 701000

static bool read_lib_info(struct ps_prochandle* ph) {

#if defined(__FreeBSD__) && __FreeBSD_version >= 701000

  struct kinfo_vmentry *freep, *kve;

  int i, cnt;

  freep = kinfo_getvmmap(ph->pid, &cnt);

  if (freep == NULL) {

      print_debug("can't get vm map for pid\n", ph->pid);

      return false;

  }

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

    kve = &freep[i];

    if ((kve->kve_flags & KVME_FLAG_COW) &&

        kve->kve_path != NULL &&

        strlen(kve->kve_path) > 0) {

      if (find_lib(ph, kve->kve_path) == false) {

        lib_info* lib;

        if ((lib = add_lib_info(ph, kve->kve_path,

                                (uintptr_t) kve->kve_start)) == 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;

      }

    }

  }

  free(freep);

  return true;

#else

  char *l_name;

  struct link_map *lmap;

  uintptr_t lmap_addr;

  if ((l_name = malloc(BUF_SIZE)) == NULL)

    return false;

  if ((lmap = malloc(sizeof(*lmap))) == NULL) {

    free(l_name);

    return false;

  }

  lmap_addr = linkmap_addr(ph);

  if (lmap_addr == 0) {

    free(l_name);

    free(lmap);

    return false;

  }

  do {

    if (process_read_data(ph, lmap_addr, (char *)lmap, sizeof(*lmap)) != true) {

      print_debug("process_read_data failed for lmap_addr %p\n", lmap_addr);

      free (l_name);

      free (lmap);

      return false;

    }

    if (process_read_data(ph, (uintptr_t)lmap->l_name, l_name,

        BUF_SIZE) != true) {

      print_debug("process_read_data failed for lmap->l_name %p\n",

          lmap->l_name);

      free (l_name);

      free (lmap);

      return false;

    }

    if (find_lib(ph, l_name) == false) {

      lib_info* lib;

      if ((lib = add_lib_info(ph, l_name,

                              (uintptr_t) lmap->l_addr)) == 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;

    }

    lmap_addr = (uintptr_t)lmap->l_next;

  } while (lmap->l_next != NULL);

  free (l_name);

  free (lmap);

  return true;

#endif

}

// detach a given pid

static bool ptrace_detach(pid_t pid) {

  if (pid && ptrace(PT_DETACH, pid, (caddr_t)1, 0) < 0) {

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

    return false;

  } else {

    return true;

  }

}

static void process_cleanup(struct ps_prochandle* ph) {

  ptrace_detach(ph->pid);

}

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,

  .get_lwp_info= process_get_lwp_info

};

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

struct ps_prochandle* Pgrab(pid_t pid) {

  struct ps_prochandle* ph = NULL;

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

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

     return NULL;

  }

  if (ptrace_attach(pid) != true) {

     free(ph);

     return NULL;

  }

  // initialize ps_prochandle

  ph->pid = 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.

  if (read_lib_info(ph) != true) {

     ptrace_detach(pid);

     free(ph);

     return NULL;

  }

  // read thread info

  read_thread_info(ph, add_new_thread);

  return ph;

}