API for process arguments and environment (#1654)

CHANGELOG.md

@@ -1,4 +1,7 @@
-# 5.7.6 (in progress)
+# 5.8.0 (in progress)
+
+##### New Features
+* [#1654](https://github.com/oshi/oshi/pull/1654): API for process arguments and environment - [@basil](https://github.com/basil) and [@dbwiddis](https://github.com/dbwiddis).
 
 ##### Bug fixes / Improvements
 * [#1673](https://github.com/oshi/oshi/pull/1673): Fix FreeBSD ps command arguments for context switches - [@basil](https://github.com/basil).

oshi-core/src/main/java/oshi/driver/unix/aix/PsInfo.java

@@ -0,0 +1,321 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2010 - 2021 The OSHI Project Contributors: https://github.com/oshi/oshi/graphs/contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package oshi.driver.unix.aix;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.util.ArrayList;
+import java.util.EnumMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.sun.jna.Memory; // NOSONAR squid:S1191
+import com.sun.jna.Native;
+import com.sun.jna.NativeLong;
+import com.sun.jna.platform.unix.LibCAPI.size_t;
+import com.sun.jna.platform.unix.LibCAPI.ssize_t;
+
+import oshi.annotation.concurrent.ThreadSafe;
+import oshi.jna.platform.unix.aix.AixLibc;
+import oshi.util.tuples.Pair;
+import oshi.util.tuples.Triplet;
+
+/**
+ * Utility to query /proc/psinfo
+ */
+@ThreadSafe
+public final class PsInfo {
+    private static final Logger LOG = LoggerFactory.getLogger(PsInfo.class);
+
+    private static final AixLibc LIBC = AixLibc.INSTANCE;
+
+    // AIX has multiple page size units, but for purposes of "pages" in perfstat,
+    // the docs specify 4KB pages so we hardcode this
+    private static final long PAGE_SIZE = 4096L;
+
+    enum LwpsInfoT {
+        PR_LWPID(8), // thread id
+        PR_ADDR(8), // internal address of thread
+        PR_WCHAN(8), // wait addr for sleeping thread
+        PR_FLAG(4), // thread flags
+        PR_WTYPE(1), // type of thread wait
+        PR_STATE(1), // numeric scheduling state
+        PR_SNAME(1), // printable character representing pr_state
+        PR_NICE(1), // nice for cpu usage
+        PR_PRI(4), // priority, high value = high priority
+        PR_POLICY(4), // scheduling policy
+        PR_CLNAME(8), // printable character representing pr_policy
+        PR_ONPRO(Native.POINTER_SIZE), // processor on which thread last ran
+        PR_BINDPRO(Native.POINTER_SIZE), // processor to which thread is bound
+        SIZE(0);
+
+        private int size;
+
+        LwpsInfoT(int bytes) {
+            size = bytes;
+        }
+
+        public int size() {
+            return size;
+        }
+    }
+
+    private static Map<LwpsInfoT, Integer> lwpsInfoOffsets = initLwpsOffsets();
+
+    enum PsInfoT {
+        PR_FLAG(4), // process flags from proc struct p_flag
+        PR_FLAG2(4), // process flags from proc struct p_flag2 *
+        PR_NLWP(4), // number of threads in process
+        PR_PAD1(4), // reserved for future use
+        PR_UID(8), // real user id
+        PR_EUID(8), // effective user id
+        PR_GID(8), // real group id
+        PR_EGID(8), // effective group id
+        PR_PID(8), // unique process id
+        PR_PPID(8), // process id of parent
+        PR_PGID(8), // pid of process group leader
+        PR_SID(8), // session id
+        PR_TTYDEV(8), // controlling tty device
+        PR_ADDR(8), // internal address of proc struct
+        PR_SIZE(8), // process image size in kb (1024) units
+        PR_RSSIZE(8), // resident set size in kb (1024) units
+        PR_START(16), // process start time, time since epoch
+        PR_TIME(16), // usr+sys cpu time for this process
+        PR_CID(2), // corral id
+        PR_PAD2(2), // reserved for future use
+        PR_ARGC(4), // initial argument count
+        PR_ARGV(8), // address of initial argument vector in user process
+        PR_ENVP(8), // address of initial environment vector in user process
+        PR_FNAME(16), // last component of exec()ed pathname
+        PR_PSARGS(80), // initial characters of arg list
+        PR_PAD(64), // reserved for future use
+        PR_LWP(lwpsInfoOffsets.get(LwpsInfoT.SIZE)), // "representative" thread info
+        SIZE(0);
+
+        private int size;
+
+        PsInfoT(int bytes) {
+            size = bytes;
+        }
+
+        public int size() {
+            return size;
+        }
+    }
+
+    private static Map<PsInfoT, Integer> psInfoOffsets = initPsOffsets();
+
+    private PsInfo() {
+    }
+
+    private static Map<LwpsInfoT, Integer> initLwpsOffsets() {
+        Map<LwpsInfoT, Integer> infoMap = new EnumMap<>(LwpsInfoT.class);
+        int offset = 0;
+        for (LwpsInfoT field : LwpsInfoT.values()) {
+            infoMap.put(field, offset);
+            offset += field.size;
+        }
+        return infoMap;
+    }
+
+    private static Map<PsInfoT, Integer> initPsOffsets() {
+        Map<PsInfoT, Integer> infoMap = new EnumMap<>(PsInfoT.class);
+        int offset = 0;
+        for (PsInfoT field : PsInfoT.values()) {
+            infoMap.put(field, offset);
+            offset += field.size;
+        }
+        return infoMap;
+    }
+
+    /**
+     * Reads the pr_argc, pr_argv, and pr_envp fields from /proc/pid/psinfo
+     *
+     * @param pid
+     *            The process ID
+     * @return A triplet containing the argc, argv, and envp values, or null if
+     *         unable to read
+     */
+    public static Triplet<Integer, Long, Long> queryArgsEnvAddrs(int pid) {
+        File procpsinfo = new File("/proc/" + pid + "/psinfo");
+        try (RandomAccessFile psinfo = new RandomAccessFile(procpsinfo, "r");
+                FileChannel chan = psinfo.getChannel();
+                ByteArrayOutputStream out = new ByteArrayOutputStream()) {
+            int bufferSize = psInfoOffsets.get(PsInfoT.SIZE);
+            if (bufferSize > chan.size()) {
+                bufferSize = (int) chan.size();
+            }
+
+            ByteBuffer buf = ByteBuffer.allocate(bufferSize);
+            if (chan.read(buf) >= psInfoOffsets.get(PsInfoT.PR_FNAME)) {
+                // We've read bytes up to at least the argc,argv,envp
+                // Now grab the elements we want
+                int argc = buf.getInt(psInfoOffsets.get(PsInfoT.PR_ARGC));
+                long argv = buf.getLong(psInfoOffsets.get(PsInfoT.PR_ARGV));
+                long envp = buf.getLong(psInfoOffsets.get(PsInfoT.PR_ENVP));
+                return new Triplet<>(argc, argv, envp);
+            }
+        } catch (IOException e) {
+            LOG.debug("Failed to read file: {} ", procpsinfo);
+        }
+        return null;
+    }
+
+    /**
+     * Read the argument and environment strings from process address space
+     *
+     * @param pid
+     *            the process id
+     * @return A pair containing a list of the arguments and a map of environment
+     *         variables
+     */
+    public static Pair<List<String>, Map<String, String>> queryArgsEnv(int pid) {
+        List<String> args = new ArrayList<>();
+        Map<String, String> env = new LinkedHashMap<>();
+
+        // Get the arg count and list of env vars
+        Triplet<Integer, Long, Long> addrs = queryArgsEnvAddrs(pid);
+        if (addrs != null) {
+            // Open a file descriptor to the address space
+            String procas = "/proc/" + pid + "/as";
+            int fd = LIBC.open(procas, 0);
+            if (fd < 0) {
+                LOG.trace("No permission to read file: {} ", procas);
+                return new Pair<>(args, env);
+            }
+            try {
+
+                // Non-null addrs means argc > 0
+                int argc = addrs.getA();
+                long argv = addrs.getB();
+                long envp = addrs.getC();
+                // Most of this method is a direct copy of the Solaris equivalent, except the
+                // Data model is in another structure /proc/pid/status but we can back into the
+                // increment using the known offsets
+                long increment = (envp - argv) / (argc + 1);
+
+                // Reusable buffer
+                long bufStart = 0;
+                Memory buffer = new Memory(PAGE_SIZE * 2);
+                size_t bufSize = new size_t(buffer.size());
+
+                // Read the pointers to the arg strings
+                // We know argc so we can count them
+                long[] argp = new long[argc];
+                long offset = argv;
+                for (int i = 0; i < argc; i++) {
+                    bufStart = conditionallyReadBufferFromStartOfPage(fd, buffer, bufSize, bufStart, offset);
+                    argp[i] = bufStart == 0 ? 0 : getOffsetFromBuffer(buffer, offset - bufStart, increment);
+                    offset += increment;
+                }
+
+                // Also read the pointers to the env strings
+                // We don't know how many, so stop when we get to null pointer
+                List<Long> envPtrList = new ArrayList<>();
+                offset = envp;
+                long addr = 0;
+                int limit = 500; // sane max env strings to stop at
+                do {
+                    bufStart = conditionallyReadBufferFromStartOfPage(fd, buffer, bufSize, bufStart, offset);
+                    addr = bufStart == 0 ? 0 : getOffsetFromBuffer(buffer, offset - bufStart, increment);
+                    if (addr != 0) {
+                        envPtrList.add(addr);
+                    }
+                    offset += increment;
+                } while (addr != 0 && --limit > 0);
+
+                // Now read the arg strings from the buffer
+                for (int i = 0; i < argp.length && argp[i] != 0; i++) {
+                    bufStart = conditionallyReadBufferFromStartOfPage(fd, buffer, bufSize, bufStart, argp[i]);
+                    if (bufStart != 0) {
+                        String argStr = buffer.getString(argp[i] - bufStart);
+                        if (!argStr.isEmpty()) {
+                            args.add(argStr);
+                        }
+                    }
+                }
+
+                // And now read the env strings from the buffer
+                for (Long envPtr : envPtrList) {
+                    bufStart = conditionallyReadBufferFromStartOfPage(fd, buffer, bufSize, bufStart, envPtr);
+                    if (bufStart != 0) {
+                        String envStr = buffer.getString(envPtr - bufStart);
+                        int idx = envStr.indexOf('=');
+                        if (idx > 0) {
+                            env.put(envStr.substring(0, idx), envStr.substring(idx + 1));
+                        }
+                    }
+                }
+            } finally {
+                LIBC.close(fd);
+            }
+        }
+        return new Pair<>(args, env);
+    }
+
+    /**
+     * Reads the page containing addr into buffer, unless the buffer already
+     * contains that page (as indicated by the bufStart address), in which case
+     * nothing is changed.
+     *
+     * @param fd
+     *            The file descriptor for the address space
+     * @param buffer
+     *            An allocated buffer, possibly with data reread from bufStart
+     * @param bufSize
+     *            The size of the buffer
+     * @param bufStart
+     *            The start of data currently in bufStart, or 0 if uninitialized
+     * @param addr
+     *            THe address whose page to read into the buffer
+     * @return The new starting pointer for the buffer
+     */
+    private static long conditionallyReadBufferFromStartOfPage(int fd, Memory buffer, size_t bufSize, long bufStart,
+            long addr) {
+        // If we don't have the right buffer, update it
+        if (addr < bufStart || addr - bufStart > PAGE_SIZE) {
+            long newStart = Math.floorDiv(addr, PAGE_SIZE) * PAGE_SIZE;
+            ssize_t result = LIBC.pread(fd, buffer, bufSize, new NativeLong(newStart));
+            // May return less than asked but should be at least a full page
+            if (result.longValue() < PAGE_SIZE) {
+                LOG.debug("Failed to read page from address space: {} bytes read", result.longValue());
+                return 0;
+            }
+            return newStart;
+        }
+        return bufStart;
+    }
+
+    private static long getOffsetFromBuffer(Memory buffer, long offset, long increment) {
+        return increment == 8 ? buffer.getLong(offset) : buffer.getInt(offset);
+    }
+}