bonic: libc: cpuacct support for setuid functions

Any of the setuid functions now updates /acct/uid/ with its own tid
before changing users. This is so we can properly account for cpu time
per uid.

Change-Id: I34186cf4d5228cac8439e582a9e26c01ef3011e4
Signed-off-by: Mike Chan <mike@android.com>

2 files changed, 68 insertions, 0 deletions

diff --git a/libc/bionic/cpuacct.c b/libc/bionic/cpuacct.c
new file mode 100644
index 0000000..abdbc51
--- /dev/null
+++ b/libc/bionic/cpuacct.c
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+#include <sys/stat.h>
+//#include <sys/types.h>
+
+int cpuacct_add(uid_t uid)
+{
+    int count;
+    FILE *fp;
+    char buf[80];
+
+    count = snprintf(buf, sizeof(buf), "/acct/uid/%d/tasks", uid);
+    fp = fopen(buf, "w+");
+    if (!fp) {
+        /* Note: sizeof("tasks") returns 6, which includes the NULL char */
+        buf[count - sizeof("tasks")] = 0;
+        if (mkdir(buf, 0775) < 0)
+            return -errno;
+
+        /* Note: sizeof("tasks") returns 6, which includes the NULL char */
+        buf[count - sizeof("tasks")] = '/';
+        fp = fopen(buf, "w+");
+    }
+    if (!fp)
+        return -errno;
+
+    fprintf(fp, "0");
+    if (fclose(fp))
+        return -errno;
+
+    return 0;
+}
diff --git a/libc/bionic/fork.c b/libc/bionic/fork.c
index 1c6a4ba..e20f548 100644
--- a/libc/bionic/fork.c
+++ b/libc/bionic/fork.c
@@ -43,6 +43,14 @@ int  fork(void)
     ret = __fork();
     if (ret != 0) {  /* not a child process */
         __timer_table_start_stop(0);
+    } else {
+        /*
+         * Newly created process must update cpu accounting.
+         * Call cpuacct_add passing in our uid, which will take
+         * the current task id and add it to the uid group passed
+         * as a parameter.
+         */
+        cpuacct_add(getuid());
     }
     return ret;
 }