azkaban-developers

diff --git a/azkaban-common/src/main/c/execute-as-user.c b/azkaban-common/src/main/c/execute-as-user.c
new file mode 100644
index 0000000..117fd88
--- /dev/null
+++ b/azkaban-common/src/main/c/execute-as-user.c
@@ -0,0 +1,125 @@
+/*
+ * Copyright 2015 LinkedIn Corp.
+ *
+ * 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 <dirent.h>
+#include <fcntl.h>
+#include <fts.h>
+#include <errno.h>
+#include <grp.h>
+#include <unistd.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <sys/mount.h>
+#include <sys/types.h>
+#include <pwd.h>
+
+FILE *LOGFILE = NULL;
+FILE *ERRORFILE = NULL;
+int SETUID_OPER_FAILED = 10;
+int USER_NOT_FOUND = 20;
+int INVALID_INPUT = 30;
+
+/*
+ *  Change the real and effective user and group from super user to the specified user
+ *  
+ *  Adopted from:
+ *  ./hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/native/container-executor/impl/container-executor.c
+ *  
+ */
+
+int change_user(uid_t user, gid_t group) {
+    if (user == getuid() && user == geteuid() &&
+            group == getgid() && group == getegid()) {
+        return 0;
+    }
+
+    if (seteuid(0) != 0) {
+        fprintf(LOGFILE, "unable to reacquire root - %s\n", strerror(errno));
+        fprintf(LOGFILE, "Real: %d:%d; Effective: %d:%d\n",
+                getuid(), getgid(), geteuid(), getegid());
+        return SETUID_OPER_FAILED;
+    }
+    if (setgid(group) != 0) {
+        fprintf(LOGFILE, "unable to set group to %d - %s\n", group,
+                strerror(errno));
+        fprintf(LOGFILE, "Real: %d:%d; Effective: %d:%d\n",
+                getuid(), getgid(), geteuid(), getegid());
+        return SETUID_OPER_FAILED;
+    }
+    if (setuid(user) != 0) {
+        fprintf(LOGFILE, "unable to set user to %d - %s\n", user, strerror(errno));
+        fprintf(LOGFILE, "Real: %d:%d; Effective: %d:%d\n",
+                getuid(), getgid(), geteuid(), getegid());
+        return SETUID_OPER_FAILED;
+    }
+
+    return 0;
+}
+
+int main(int argc, char **argv){
+
+// set up the logging stream
+    if (!LOGFILE){
+        LOGFILE=stdout;
+    }
+    if (!ERRORFILE){
+        ERRORFILE=stderr;
+    }
+
+    if (argc < 3) {
+        fprintf(ERRORFILE, "Requires at least 3 variables: ./execute-as-user uid command [args]");
+        return INVALID_INPUT;
+    }
+
+    char *uid = argv[1];
+
+    // gather information about user
+    struct passwd *user_info = getpwnam(uid);
+    if (user_info == NULL){
+        fprintf(LOGFILE, "user does not exist: %s", uid);
+        return USER_NOT_FOUND;
+    }
+
+    // try to change user
+    fprintf(LOGFILE, "Changing user: user: %s, uid: %d, gid: %d\n", uid, user_info->pw_uid, user_info->pw_gid);
+    int retval = change_user(user_info->pw_uid, user_info->pw_gid);
+    if (retval != 0){
+        fprintf(LOGFILE, "Error changing user to %s\n", uid);
+        return SETUID_OPER_FAILED;
+    }
+
+    // execute the command
+    char **user_argv = &argv[2];
+    fprintf(LOGFILE, "user command starting from: %s\n", user_argv[0]);
+    fflush(LOGFILE);
+    retval = execvp(*user_argv, user_argv);
+    fprintf(LOGFILE, "system call return value: %d\n", retval);
+
+    // sometimes system(cmd) returns 256, which is interpreted to 0, making a failed job a successful job
+    // hence this goofy piece of if statement.
+    if (retval != 0){
+        return 1;
+    }
+    else{
+        return 0;
+    }
+
+}

diff --git a/build.gradle b/build.gradle
index d8afcca..d19ad19 100644
--- a/build.gradle
+++ b/build.gradle
@@ -80,6 +80,22 @@ project(':azkaban-common') {
     }
   }
 
+  apply plugin: 'c'
+  model {
+    components {
+      main(NativeExecutableSpec) {
+        sources {
+          c {
+            source {
+              srcDir "src/main"
+              include "**/*.c"
+            }
+          }
+        }
+      }
+    }
+  }
+
   dependencies {
     compile('com.google.guava:guava:13.0.1')
     compile('com.h2database:h2:1.3.170')