JDK14/Java14源码在线阅读
/*
* 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) {
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