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 /*

  * 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 <stdio.h>

 #include <stdlib.h>

 #include <string.h>

 #include <signal.h>

 #include <errno.h>

 #include <elf.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;

 }

 // 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;

 }

 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

 struct ps_prochandle* 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;

   // 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

   read_thread_info(ph, add_new_thread);

   // 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

           delete_thread_info(ph, current_thr);

         }

         else {

           Prelease(ph);

           return NULL;

         } // ATTACH_THREAD_DEAD

       } // !ATTACH_SUCCESS

     }

   }

   return ph;

 }