Fix backport of readdir patch

Backport changes from Google's master to fix build errors when using
readdir_r.

Signed-off-by: Wolfgang Wiedmeyer <wolfgit@wiedmeyer.de>

1 files changed, 21 insertions, 4 deletions

diff --git a/libprocessgroup/processgroup.cpp b/libprocessgroup/processgroup.cpp
index 0fa835b..2ac73b1 100644
--- a/libprocessgroup/processgroup.cpp
+++ b/libprocessgroup/processgroup.cpp
@@ -30,6 +30,7 @@
 #include <sys/types.h>
 
 #include <log/log.h>
+#include <memory>
 #include <private/android_filesystem_config.h>
 
 #include <utils/SystemClock.h>
@@ -37,6 +38,8 @@
 #include <processgroup/processgroup.h>
 #include "processgroup_priv.h"
 
+#define ACCT_CGROUP_PATH "/acct"
+
 struct ctx {
     bool initialized;
     int fd;
@@ -45,6 +48,21 @@ struct ctx {
     size_t buf_len;
 };
 
+static const char* getCgroupRootPath() {
+#ifdef USE_MEMCG
+    static const char* cgroup_root_path = NULL;
+    std::call_once(init_path_flag, [&]() {
+            // Check if mem cgroup is mounted, only then check for write-access to avoid
+            // SELinux denials
+            cgroup_root_path = access(MEM_CGROUP_TASKS, F_OK) || access(MEM_CGROUP_PATH, W_OK) ?
+                    ACCT_CGROUP_PATH : MEM_CGROUP_PATH;
+            });
+    return cgroup_root_path;
+#else
+    return ACCT_CGROUP_PATH;
+#endif
+}
+
 static int convertUidToPath(char *path, size_t size, uid_t uid)
 {
     return snprintf(path, size, "%s/%s%d",
@@ -162,7 +180,7 @@ static int removeProcessGroup(uid_t uid, int pid)
 
 static void removeUidProcessGroups(const char *uid_path)
 {
-    DIR *uid = opendir(uid_path);
+    std::unique_ptr<DIR, decltype(&closedir)> uid(opendir(uid_path), closedir);
     if (uid != NULL) {
         dirent* dir;
         while ((dir = readdir(uid.get())) != nullptr) {
@@ -180,14 +198,14 @@ static void removeUidProcessGroups(const char *uid_path)
             SLOGV("removing %s\n", path);
             rmdir(path);
         }
-        closedir(uid);
     }
 }
 
 void removeAllProcessGroups()
 {
     SLOGV("removeAllProcessGroups()");
-    DIR *root = opendir(PROCESSGROUP_CGROUP_PATH);
+    const char* cgroup_root_path = getCgroupRootPath();
+    std::unique_ptr<DIR, decltype(&closedir)> root(opendir(cgroup_root_path), closedir);
     if (root == NULL) {
         SLOGE("failed to open %s: %s", PROCESSGROUP_CGROUP_PATH, strerror(errno));
     } else {
@@ -207,7 +225,6 @@ void removeAllProcessGroups()
             SLOGV("removing %s\n", path);
             rmdir(path);
         }
-        closedir(root);
     }
 }