New upstream version 2.0

[sven/jattach.git] / src / posix / jattach.c

diff --git a/src/posix/jattach.c b/src/posix/jattach.c
new file mode 100644 (file)
index 0000000..804d13d
--- /dev/null
+++ b/src/posix/jattach.c
@@ -0,0 +1,88 @@
+/*
+ * Copyright 2021 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <unistd.h>
+#include "psutil.h"
+
+
+extern int is_openj9_process(int pid);
+extern int jattach_openj9(int pid, int nspid, int argc, char** argv);
+extern int jattach_hotspot(int pid, int nspid, int argc, char** argv);
+
+
+__attribute__((visibility("default")))
+int jattach(int pid, int argc, char** argv) {
+    uid_t my_uid = geteuid();
+    gid_t my_gid = getegid();
+    uid_t target_uid = my_uid;
+    gid_t target_gid = my_gid;
+    int nspid;
+    if (get_process_info(pid, &target_uid, &target_gid, &nspid) < 0) {
+        fprintf(stderr, "Process %d not found\n", pid);
+        return 1;
+    }
+
+    // Container support: switch to the target namespaces.
+    // Network and IPC namespaces are essential for OpenJ9 connection.
+    enter_ns(pid, "net");
+    enter_ns(pid, "ipc");
+    int mnt_changed = enter_ns(pid, "mnt");
+
+    // In HotSpot, dynamic attach is allowed only for the clients with the same euid/egid.
+    // If we are running under root, switch to the required euid/egid automatically.
+    if ((my_gid != target_gid && setegid(target_gid) != 0) ||
+        (my_uid != target_uid && seteuid(target_uid) != 0)) {
+        perror("Failed to change credentials to match the target process");
+        return 1;
+    }
+
+    get_tmp_path(mnt_changed > 0 ? nspid : pid);
+
+    // Make write() return EPIPE instead of abnormal process termination
+    signal(SIGPIPE, SIG_IGN);
+
+    if (is_openj9_process(nspid)) {
+        return jattach_openj9(pid, nspid, argc, argv);
+    } else {
+        return jattach_hotspot(pid, nspid, argc, argv);
+    }
+}
+
+int main(int argc, char** argv) {
+    if (argc < 3) {
+        printf("jattach " JATTACH_VERSION " built on " __DATE__ "\n"
+               "Copyright 2021 Andrei Pangin\n"
+               "\n"
+               "Usage: jattach <pid> <cmd> [args ...]\n"
+               "\n"
+               "Commands:\n"
+               "    load  threaddump   dumpheap  setflag    properties\n"
+               "    jcmd  inspectheap  datadump  printflag  agentProperties\n"
+               );
+        return 1;
+    }
+
+    int pid = atoi(argv[1]);
+    if (pid <= 0) {
+        fprintf(stderr, "%s is not a valid process ID\n", argv[1]);
+        return 1;
+    }
+
+    return jattach(pid, argc - 2, argv + 2);
+}