commit bc1ad9671ac1ac2c1dc263844c1b0f763f72257f
author Rick Yiu <rickyiu@google.com> Mon Oct 26 20:32:52 2020 +0800
committer Rick Yiu <rickyiu@google.com> Tue Nov 03 20:56:48 2020 +0800
tree 27f93a026992d3a286f45f6092d50a26050f6511
parent 346e6792b45cafc8d3b8dcf993584b98743a4688

libprocessgroup: Support write to file feature

There may be some use cases that it needs to write string to a
file. This patch support write "Value" to "FilePath", where
both parameters could use special string "<uid>" and "<pid>" to
represent actual uid and pid.

Bug: 170507963
Test: function works
Change-Id: I543846f523518a9bcb3dd1b3437163a1b3157d95

libprocessgroup/task_profiles.cpp

diff --git a/libprocessgroup/task_profiles.cpp b/libprocessgroup/task_profiles.cpp
index a638fca..4e767db 100644
--- a/libprocessgroup/task_profiles.cpp
+++ b/libprocessgroup/task_profiles.cpp
@@ -24,6 +24,7 @@
 #include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/stringprintf.h>
+#include <android-base/strings.h>
 #include <android-base/threads.h>
 
 #include <cutils/android_filesystem_config.h>
@@ -38,6 +39,7 @@
 
 using android::base::GetThreadId;
 using android::base::StringPrintf;
+using android::base::StringReplace;
 using android::base::unique_fd;
 using android::base::WriteStringToFile;
 
@@ -257,6 +259,39 @@
     return true;
 }
 
+bool WriteFileAction::ExecuteForProcess(uid_t uid, pid_t pid) const {
+    std::string filepath(filepath_), value(value_);
+
+    filepath = StringReplace(filepath, "<uid>", std::to_string(uid), true);
+    filepath = StringReplace(filepath, "<pid>", std::to_string(pid), true);
+    value = StringReplace(value, "<uid>", std::to_string(uid), true);
+    value = StringReplace(value, "<pid>", std::to_string(pid), true);
+
+    if (!WriteStringToFile(value, filepath)) {
+        PLOG(ERROR) << "Failed to write '" << value << "' to " << filepath;
+        return false;
+    }
+
+    return true;
+}
+
+bool WriteFileAction::ExecuteForTask(int tid) const {
+    std::string filepath(filepath_), value(value_);
+    int uid = getuid();
+
+    filepath = StringReplace(filepath, "<uid>", std::to_string(uid), true);
+    filepath = StringReplace(filepath, "<pid>", std::to_string(tid), true);
+    value = StringReplace(value, "<uid>", std::to_string(uid), true);
+    value = StringReplace(value, "<pid>", std::to_string(tid), true);
+
+    if (!WriteStringToFile(value, filepath)) {
+        PLOG(ERROR) << "Failed to write '" << value << "' to " << filepath;
+        return false;
+    }
+
+    return true;
+}
+
 bool ApplyProfileAction::ExecuteForProcess(uid_t uid, pid_t pid) const {
     for (const auto& profile : profiles_) {
         if (!profile->ExecuteForProcess(uid, pid)) {
@@ -459,6 +494,18 @@
                 } else {
                     LOG(WARNING) << "SetClamps: invalid parameter: " << boost_value;
                 }
+            } else if (action_name == "WriteFile") {
+                std::string attr_filepath = params_val["FilePath"].asString();
+                std::string attr_value = params_val["Value"].asString();
+                if (!attr_filepath.empty() && !attr_value.empty()) {
+                    profile->Add(std::make_unique<WriteFileAction>(attr_filepath, attr_value));
+                } else if (attr_filepath.empty()) {
+                    LOG(WARNING) << "WriteFile: invalid parameter: "
+                                 << "empty filepath";
+                } else if (attr_value.empty()) {
+                    LOG(WARNING) << "WriteFile: invalid parameter: "
+                                 << "empty value";
+                }
             } else {
                 LOG(WARNING) << "Unknown profile action: " << action_name;
             }