1/*
2 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26#include "jni.h"
27#include "jni_util.h"
28#include "java_lang_ProcessHandleImpl.h"
29#include "java_lang_ProcessHandleImpl_Info.h"
30
31#include "ProcessHandleImpl_unix.h"
32
33
34#include <fcntl.h>
35#include <limits.h>
36#include <stdlib.h>
37#include <unistd.h>
38#include <sys/types.h>
39#include <sys/stat.h>
40
41#include <string.h>
42#include <ctype.h>
43
44/*
45 * Implementation of native ProcessHandleImpl functions for Linux.
46 * See ProcessHandleImpl_unix.c for more details.
47 */
48
49/* Signatures for internal OS specific functions. */
50static long long getBoottime(JNIEnv *env);
51
52/* A static offset in milliseconds since boot. */
53static long long bootTime_ms;
54static long clock_ticks_per_second;
55static int pageSize;
56
57void os_initNative(JNIEnv *env, jclass clazz) {
58    bootTime_ms = getBoottime(env);
59    clock_ticks_per_second = sysconf(_SC_CLK_TCK);
60    pageSize = sysconf(_SC_PAGESIZE);
61}
62
63jint os_getChildren(JNIEnv *env, jlong jpid, jlongArray jarray,
64                    jlongArray jparentArray, jlongArray jstimesArray) {
65    return unix_getChildren(env, jpid, jarray, jparentArray, jstimesArray);
66}
67
68/**
69 * Read /proc/<pid>/stat and return the ppid, total cputime and start time.
70 * -1 is fail;  >=  0 is parent pid
71 * 'total' will contain the running time of 'pid' in nanoseconds.
72 * 'start' will contain the start time of 'pid' in milliseconds since epoch.
73 */
74pid_t os_getParentPidAndTimings(JNIEnv *env, pid_t pid,
75                                jlong *totalTime, jlong* startTime) {
76    FILE* fp;
77    char buffer[2048];
78    int statlen;
79    char fn[32];
80    char* s;
81    int parentPid;
82    long unsigned int utime = 0;      // clock tics
83    long unsigned int stime = 0;      // clock tics
84    long long unsigned int start = 0; // microseconds
85
86    /*
87     * Try to stat and then open /proc/%d/stat
88     */
89    snprintf(fn, sizeof fn, "/proc/%d/stat", pid);
90
91    fp = fopen(fn, "r");
92    if (fp == NULL) {
93        return -1;              // fail, no such /proc/pid/stat
94    }
95
96    /*
97     * The format is: pid (command) state ppid ...
98     * As the command could be anything we must find the right most
99     * ")" and then skip the white spaces that follow it.
100     */
101    statlen = fread(buffer, 1, (sizeof buffer - 1), fp);
102    fclose(fp);
103    if (statlen < 0) {
104        return -1;               // parent pid is not available
105    }
106
107    buffer[statlen] = '\0';
108    s = strchr(buffer, '(');
109    if (s == NULL) {
110        return -1;               // parent pid is not available
111    }
112    // Found start of command, skip to end
113    s++;
114    s = strrchr(s, ')');
115    if (s == NULL) {
116        return -1;               // parent pid is not available
117    }
118    s++;
119
120    // Scan the needed fields from status, retaining only ppid(4),
121    // utime (14), stime(15), starttime(22)
122    if (4 != sscanf(s, " %*c %d %*d %*d %*d %*d %*d %*u %*u %*u %*u %lu %lu %*d %*d %*d %*d %*d %*d %llu",
123            &parentPid, &utime, &stime, &start)) {
124        return 0;              // not all values parsed; return error
125    }
126
127    *totalTime = (utime + stime) * (jlong)(1000000000 / clock_ticks_per_second);
128
129    *startTime = bootTime_ms + ((start * 1000) / clock_ticks_per_second);
130
131    return parentPid;
132}
133
134void os_getCmdlineAndUserInfo(JNIEnv *env, jobject jinfo, pid_t pid) {
135    int fd;
136    int cmdlen = 0;
137    char *cmdline = NULL, *cmdEnd = NULL; // used for command line args and exe
138    char *args = NULL;
139    jstring cmdexe = NULL;
140    char fn[32];
141    struct stat stat_buf;
142
143    /*
144     * Stat /proc/<pid> to get the user id
145     */
146    snprintf(fn, sizeof fn, "/proc/%d", pid);
147    if (stat(fn, &stat_buf) == 0) {
148        unix_getUserInfo(env, jinfo, stat_buf.st_uid);
149        JNU_CHECK_EXCEPTION(env);
150    }
151
152    /*
153     * Try to open /proc/<pid>/cmdline
154     */
155    strncat(fn, "/cmdline", sizeof fn - strnlen(fn, sizeof fn) - 1);
156    if ((fd = open(fn, O_RDONLY)) < 0) {
157        return;
158    }
159
160    do {                // Block to break out of on errors
161        int i, truncated = 0;
162        int count;
163        char *s;
164
165        /*
166         * The path name read by readlink() is limited to PATH_MAX characters.
167         * The content of /proc/<pid>/cmdline is limited to PAGE_SIZE characters.
168         */
169        cmdline = (char*)malloc((PATH_MAX > pageSize ? PATH_MAX : pageSize) + 1);
170        if (cmdline == NULL) {
171            break;
172        }
173
174        /*
175         * On Linux, the full path to the executable command is the link in
176         * /proc/<pid>/exe. But it is only readable for processes we own.
177         */
178        snprintf(fn, sizeof fn, "/proc/%d/exe", pid);
179        if ((cmdlen = readlink(fn, cmdline, PATH_MAX)) > 0) {
180            // null terminate and create String to store for command
181            cmdline[cmdlen] = '\0';
182            cmdexe = JNU_NewStringPlatform(env, cmdline);
183            (*env)->ExceptionClear(env);        // unconditionally clear any exception
184        }
185
186        /*
187         * The command-line arguments appear as a set of strings separated by
188         * null bytes ('\0'), with a further null byte after the last
189         * string. The last string is only null terminated if the whole command
190         * line is not exceeding (PAGE_SIZE - 1) characters.
191         */
192        cmdlen = 0;
193        s = cmdline;
194        while ((count = read(fd, s, pageSize - cmdlen)) > 0) {
195            cmdlen += count;
196            s += count;
197        }
198        if (count < 0) {
199            break;
200        }
201        // We have to null-terminate because the process may have changed argv[]
202        // or because the content in /proc/<pid>/cmdline is truncated.
203        cmdline[cmdlen] = '\0';
204        if (cmdlen == pageSize && cmdline[pageSize - 1] != '\0') {
205            truncated = 1;
206        } else if (cmdlen == 0) {
207            // /proc/<pid>/cmdline was empty. This usually happens for kernel processes
208            // like '[kthreadd]'. We could try to read /proc/<pid>/comm in the future.
209        }
210        if (cmdlen > 0 && (cmdexe == NULL || truncated)) {
211            // We have no exact command or the arguments are truncated.
212            // In this case we save the command line from /proc/<pid>/cmdline.
213            args = (char*)malloc(pageSize + 1);
214            if (args != NULL) {
215                memcpy(args, cmdline, cmdlen + 1);
216                for (i = 0; i < cmdlen; i++) {
217                    if (args[i] == '\0') {
218                        args[i] = ' ';
219                    }
220                }
221            }
222        }
223        i = 0;
224        if (!truncated) {
225            // Count the arguments
226            cmdEnd = &cmdline[cmdlen];
227            for (s = cmdline; *s != '\0' && (s < cmdEnd); i++) {
228                s += strnlen(s, (cmdEnd - s)) + 1;
229            }
230        }
231        unix_fillArgArray(env, jinfo, i, cmdline, cmdEnd, cmdexe, args);
232    } while (0);
233
234    if (cmdline != NULL) {
235        free(cmdline);
236    }
237    if (args != NULL) {
238        free(args);
239    }
240    if (fd >= 0) {
241        close(fd);
242    }
243}
244
245/**
246 * Read the boottime from /proc/stat.
247 */
248static long long getBoottime(JNIEnv *env) {
249    FILE *fp;
250    char *line = NULL;
251    size_t len = 0;
252    long long bootTime = 0;
253
254    fp = fopen("/proc/stat", "r");
255    if (fp == NULL) {
256        return -1;
257    }
258
259    while (getline(&line, &len, fp) != -1) {
260        if (sscanf(line, "btime %llu", &bootTime) == 1) {
261            break;
262        }
263    }
264    free(line);
265
266    if (fp != 0) {
267        fclose(fp);
268    }
269
270    return bootTime * 1000;
271}
272