LibCore: Report error condition when reading process statistics failed

Author: https://github.com/tomuta
Commit: https://github.com/SerenityOS/serenity/commit/cf89180c350
Pull-request: https://github.com/SerenityOS/serenity/pull/4736

Applications/SystemMonitor/ProcessModel.cpp

@@ -358,57 +358,59 @@ void ProcessModel::update()
 
     HashTable<PidAndTid> live_pids;
     u64 sum_ticks_scheduled = 0;
-    for (auto& it : all_processes) {
-        for (auto& thread : it.value.threads) {
-            ThreadState state;
-            state.pid = it.value.pid;
-            state.user = it.value.username;
-            state.pledge = it.value.pledge;
-            state.veil = it.value.veil;
-            state.syscall_count = thread.syscall_count;
-            state.inode_faults = thread.inode_faults;
-            state.zero_faults = thread.zero_faults;
-            state.cow_faults = thread.cow_faults;
-            state.unix_socket_read_bytes = thread.unix_socket_read_bytes;
-            state.unix_socket_write_bytes = thread.unix_socket_write_bytes;
-            state.ipv4_socket_read_bytes = thread.ipv4_socket_read_bytes;
-            state.ipv4_socket_write_bytes = thread.ipv4_socket_write_bytes;
-            state.file_read_bytes = thread.file_read_bytes;
-            state.file_write_bytes = thread.file_write_bytes;
-            state.amount_virtual = it.value.amount_virtual;
-            state.amount_resident = it.value.amount_resident;
-            state.amount_dirty_private = it.value.amount_dirty_private;
-            state.amount_clean_inode = it.value.amount_clean_inode;
-            state.amount_purgeable_volatile = it.value.amount_purgeable_volatile;
-            state.amount_purgeable_nonvolatile = it.value.amount_purgeable_nonvolatile;
+    if (all_processes.has_value()) {
+        for (auto& it : all_processes.value()) {
+            for (auto& thread : it.value.threads) {
+                ThreadState state;
+                state.pid = it.value.pid;
+                state.user = it.value.username;
+                state.pledge = it.value.pledge;
+                state.veil = it.value.veil;
+                state.syscall_count = thread.syscall_count;
+                state.inode_faults = thread.inode_faults;
+                state.zero_faults = thread.zero_faults;
+                state.cow_faults = thread.cow_faults;
+                state.unix_socket_read_bytes = thread.unix_socket_read_bytes;
+                state.unix_socket_write_bytes = thread.unix_socket_write_bytes;
+                state.ipv4_socket_read_bytes = thread.ipv4_socket_read_bytes;
+                state.ipv4_socket_write_bytes = thread.ipv4_socket_write_bytes;
+                state.file_read_bytes = thread.file_read_bytes;
+                state.file_write_bytes = thread.file_write_bytes;
+                state.amount_virtual = it.value.amount_virtual;
+                state.amount_resident = it.value.amount_resident;
+                state.amount_dirty_private = it.value.amount_dirty_private;
+                state.amount_clean_inode = it.value.amount_clean_inode;
+                state.amount_purgeable_volatile = it.value.amount_purgeable_volatile;
+                state.amount_purgeable_nonvolatile = it.value.amount_purgeable_nonvolatile;
 
-            state.name = thread.name;
-            state.executable = it.value.executable;
+                state.name = thread.name;
+                state.executable = it.value.executable;
 
-            state.ppid = it.value.ppid;
-            state.tid = thread.tid;
-            state.pgid = it.value.pgid;
-            state.sid = it.value.sid;
-            state.times_scheduled = thread.times_scheduled;
-            state.ticks_user = thread.ticks_user;
-            state.ticks_kernel = thread.ticks_kernel;
-            state.cpu = thread.cpu;
-            state.cpu_percent = 0;
-            state.priority = thread.priority;
-            state.effective_priority = thread.effective_priority;
-            state.state = thread.state;
-            sum_ticks_scheduled += thread.ticks_user + thread.ticks_kernel;
-            {
+                state.ppid = it.value.ppid;
+                state.tid = thread.tid;
+                state.pgid = it.value.pgid;
+                state.sid = it.value.sid;
+                state.times_scheduled = thread.times_scheduled;
+                state.ticks_user = thread.ticks_user;
+                state.ticks_kernel = thread.ticks_kernel;
+                state.cpu = thread.cpu;
+                state.cpu_percent = 0;
+                state.priority = thread.priority;
+                state.effective_priority = thread.effective_priority;
+                state.state = thread.state;
+                sum_ticks_scheduled += thread.ticks_user + thread.ticks_kernel;
+                {
+                    auto pit = m_threads.find({ it.value.pid, thread.tid });
+                    if (pit == m_threads.end())
+                        m_threads.set({ it.value.pid, thread.tid }, make<Thread>());
+                }
                 auto pit = m_threads.find({ it.value.pid, thread.tid });
-                if (pit == m_threads.end())
-                    m_threads.set({ it.value.pid, thread.tid }, make<Thread>());
-            }
-            auto pit = m_threads.find({ it.value.pid, thread.tid });
-            ASSERT(pit != m_threads.end());
-            (*pit).value->previous_state = (*pit).value->current_state;
-            (*pit).value->current_state = state;
+                ASSERT(pit != m_threads.end());
+                (*pit).value->previous_state = (*pit).value->current_state;
+                (*pit).value->current_state = state;
 
-            live_pids.set({ it.value.pid, thread.tid });
+                live_pids.set({ it.value.pid, thread.tid });
+            }
         }
     }
 

DevTools/Profiler/main.cpp

@@ -197,10 +197,14 @@ bool generate_profile(pid_t pid)
     String process_name;
 
     auto all_processes = Core::ProcessStatisticsReader::get_all();
-    if (auto it = all_processes.find(pid); it != all_processes.end())
-        process_name = it->value.name;
-    else
+    if (all_processes.has_value()) {
+        if (auto it = all_processes.value().find(pid); it != all_processes.value().end())
+            process_name = it->value.name;
+        else
+            process_name = "(unknown)";
+    } else {
         process_name = "(unknown)";
+    }
 
     if (profiling_enable(pid) < 0) {
         int saved_errno = errno;

Libraries/LibCore/ProcessStatisticsReader.cpp

@@ -37,7 +37,7 @@ namespace Core {
 
 HashMap<uid_t, String> ProcessStatisticsReader::s_usernames;
 
-HashMap<pid_t, Core::ProcessStatistics> ProcessStatisticsReader::get_all()
+Optional<HashMap<pid_t, Core::ProcessStatistics>> ProcessStatisticsReader::get_all()
 {
     auto file = Core::File::construct("/proc/all");
     if (!file->open(Core::IODevice::ReadOnly)) {
@@ -49,7 +49,8 @@ HashMap<pid_t, Core::ProcessStatistics> ProcessStatisticsReader::get_all()
 
     auto file_contents = file->read_all();
     auto json = JsonValue::from_string(file_contents);
-    ASSERT(json.has_value());
+    if (!json.has_value())
+        return {};
     json.value().as_array().for_each([&](auto& value) {
         const JsonObject& process_object = value.as_object();
         Core::ProcessStatistics process;

Libraries/LibCore/ProcessStatisticsReader.h

@@ -86,7 +86,7 @@ struct ProcessStatistics {
 
 class ProcessStatisticsReader {
 public:
-    static HashMap<pid_t, Core::ProcessStatistics> get_all();
+    static Optional<HashMap<pid_t, Core::ProcessStatistics>> get_all();
 
 private:
     static String username_from_uid(uid_t);

Libraries/LibGUI/RunningProcessesModel.cpp

@@ -50,14 +50,15 @@ void RunningProcessesModel::update()
 
     Core::ProcessStatisticsReader reader;
     auto processes = reader.get_all();
-
-    for (auto& it : processes) {
-        Process process;
-        process.pid = it.value.pid;
-        process.uid = it.value.uid;
-        process.icon = FileIconProvider::icon_for_executable(it.value.executable).bitmap_for_size(16);
-        process.name = it.value.name;
-        m_processes.append(move(process));
+    if (processes.has_value()) {
+        for (auto& it : processes.value()) {
+            Process process;
+            process.pid = it.value.pid;
+            process.uid = it.value.uid;
+            process.icon = FileIconProvider::icon_for_executable(it.value.executable).bitmap_for_size(16);
+            process.name = it.value.name;
+            m_processes.append(move(process));
+        }
     }
 
     did_update();

MenuApplets/ResourceGraph/main.cpp

@@ -147,10 +147,10 @@ private:
         idle = 0;
 
         auto all_processes = Core::ProcessStatisticsReader::get_all();
-        if (all_processes.is_empty())
+        if (!all_processes.has_value() || all_processes.value().is_empty())
             return false;
 
-        for (auto& it : all_processes) {
+        for (auto& it : all_processes.value()) {
             for (auto& jt : it.value.threads) {
                 if (it.value.pid == 0)
                     idle += jt.ticks_user + jt.ticks_kernel;

Userland/killall.cpp

@@ -41,8 +41,10 @@ static void print_usage_and_exit()
 static int kill_all(const String& process_name, const unsigned signum)
 {
     auto processes = Core::ProcessStatisticsReader().get_all();
+    if (!processes.has_value())
+        return 1;
 
-    for (auto& it : processes) {
+    for (auto& it : processes.value()) {
         if (it.value.name == process_name) {
             int ret = kill(it.value.pid, signum);
             if (ret < 0)

Userland/lsof.cpp

@@ -166,9 +166,11 @@ int main(int argc, char* argv[])
     }
 
     printf("%-28s %4s %4s %-10s %4s %s\n", "COMMAND", "PID", "PGID", "USER", "FD", "NAME");
+    auto processes = Core::ProcessStatisticsReader::get_all();
+    if (!processes.has_value())
+        return 1;
     if (arg_pid == -1) {
-        auto processes = Core::ProcessStatisticsReader::get_all();
-        for (auto process : processes) {
+        for (auto process : processes.value()) {
             if (process.key == 0)
                 continue;
             auto open_files = get_open_files_by_pid(process.key);
@@ -187,14 +189,13 @@ int main(int argc, char* argv[])
             }
         }
     } else {
-        auto processes = Core::ProcessStatisticsReader::get_all();
         auto open_files = get_open_files_by_pid(arg_pid);
 
         if (open_files.is_empty())
             return 0;
 
         for (auto file : open_files) {
-            display_entry(file, processes.get(arg_pid).value());
+            display_entry(file, processes.value().get(arg_pid).value());
         }
     }
 

Userland/pidof.cpp

@@ -40,8 +40,10 @@ static int pid_of(const String& process_name, bool single_shot, bool omit_pid, p
     bool displayed_at_least_one = false;
 
     auto processes = Core::ProcessStatisticsReader().get_all();
+    if (!processes.has_value())
+        return 1;
 
-    for (auto& it : processes) {
+    for (auto& it : processes.value()) {
         if (it.value.name == process_name) {
             if (!omit_pid || it.value.pid != pid) {
                 printf(" %d" + (displayed_at_least_one ? 0 : 1), it.value.pid);

Userland/ps.cpp

@@ -120,8 +120,10 @@ int main(int argc, char** argv)
     printf("\n");
 
     auto all_processes = Core::ProcessStatisticsReader::get_all();
+    if (!all_processes.has_value())
+        return 1;
 
-    for (const auto& it : all_processes) {
+    for (const auto& it : all_processes.value()) {
         const auto& proc = it.value;
         auto tty = proc.tty;
 

Userland/top.cpp

@@ -92,11 +92,12 @@ struct Snapshot {
 
 static Snapshot get_snapshot()
 {
-    Snapshot snapshot;
-
     auto all_processes = Core::ProcessStatisticsReader::get_all();
+    if (!all_processes.has_value())
+        return {};
 
-    for (auto& it : all_processes) {
+    Snapshot snapshot;
+    for (auto& it : all_processes.value()) {
         auto& stats = it.value;
         for (auto& thread : stats.threads) {
             snapshot.sum_times_scheduled += thread.times_scheduled;

Userland/w.cpp

@@ -77,6 +77,10 @@ int main()
     }
 
     auto process_statistics = Core::ProcessStatisticsReader::get_all();
+    if (!process_statistics.has_value()) {
+        warnln("Error: Could not get process statistics");
+        return 1;
+    }
 
     auto now = time(nullptr);
 
@@ -110,7 +114,7 @@ int main()
 
         String what = "n/a";
 
-        for (auto& it : process_statistics) {
+        for (auto& it : process_statistics.value()) {
             if (it.value.tty == tty && it.value.pid == it.value.pgid)
                 what = it.value.name;
         }