libprocinfo: add support for parsing process state.

Bug: http://b/63008395
Test: libprocinfo_test32
Change-Id: I20a337bb5075bcdb325d2b48e174b0b5ef896261

libprocinfo/include/procinfo/process.h

@@ -35,8 +35,18 @@ namespace procinfo {
 
 #if defined(__linux__)
 
+enum ProcessState {
+  kProcessStateUnknown,
+  kProcessStateRunning,
+  kProcessStateSleeping,
+  kProcessStateUninterruptibleWait,
+  kProcessStateStopped,
+  kProcessStateZombie,
+};
+
 struct ProcessInfo {
   std::string name;
+  ProcessState state;
   pid_t tid;
   pid_t pid;
   pid_t ppid;

libprocinfo/process.cpp

@@ -44,6 +44,24 @@ bool GetProcessInfo(pid_t tid, ProcessInfo* process_info) {
   return GetProcessInfoFromProcPidFd(dirfd.get(), process_info);
 }
 
+static ProcessState parse_state(const char* state) {
+  switch (*state) {
+    case 'R':
+      return kProcessStateRunning;
+    case 'S':
+      return kProcessStateSleeping;
+    case 'D':
+      return kProcessStateUninterruptibleWait;
+    case 'T':
+      return kProcessStateStopped;
+    case 'Z':
+      return kProcessStateZombie;
+    default:
+      LOG(ERROR) << "unknown process state: " << *state;
+      return kProcessStateUnknown;
+  }
+}
+
 bool GetProcessInfoFromProcPidFd(int fd, ProcessInfo* process_info) {
   int status_fd = openat(fd, "status", O_RDONLY | O_CLOEXEC);
 
@@ -60,7 +78,7 @@ bool GetProcessInfoFromProcPidFd(int fd, ProcessInfo* process_info) {
   }
 
   int field_bitmap = 0;
-  static constexpr int finished_bitmap = 127;
+  static constexpr int finished_bitmap = 255;
   char* line = nullptr;
   size_t len = 0;
 
@@ -98,6 +116,9 @@ bool GetProcessInfoFromProcPidFd(int fd, ProcessInfo* process_info) {
     } else if (header == "Gid:") {
       process_info->gid = atoi(tab + 1);
       field_bitmap |= 64;
+    } else if (header == "State:") {
+      process_info->state = parse_state(tab + 1);
+      field_bitmap |= 128;
     }
   }
 

libprocinfo/process_test.cpp

@@ -21,6 +21,7 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+#include <chrono>
 #include <set>
 #include <thread>
 #include <vector>
@@ -29,6 +30,8 @@
 
 #include <android-base/stringprintf.h>
 
+using namespace std::chrono_literals;
+
 #if !defined(__BIONIC__)
 #include <syscall.h>
 static pid_t gettid() {
@@ -82,3 +85,34 @@ TEST(process_info, process_tids_smoke) {
     }
   }).join();
 }
+
+TEST(process_info, process_state) {
+  int pipefd[2];
+  ASSERT_EQ(0, pipe2(pipefd, O_CLOEXEC));
+  pid_t forkpid = fork();
+
+  ASSERT_NE(-1, forkpid);
+  if (forkpid == 0) {
+    close(pipefd[1]);
+    char buf;
+    TEMP_FAILURE_RETRY(read(pipefd[0], &buf, 1));
+    _exit(0);
+  }
+
+  // Give the child some time to get to the read.
+  std::this_thread::sleep_for(100ms);
+
+  android::procinfo::ProcessInfo procinfo;
+  ASSERT_TRUE(android::procinfo::GetProcessInfo(forkpid, &procinfo));
+  ASSERT_EQ(android::procinfo::kProcessStateSleeping, procinfo.state);
+
+  ASSERT_EQ(0, kill(forkpid, SIGKILL));
+
+  // Give the kernel some time to kill the child.
+  std::this_thread::sleep_for(100ms);
+
+  ASSERT_TRUE(android::procinfo::GetProcessInfo(forkpid, &procinfo));
+  ASSERT_EQ(android::procinfo::kProcessStateZombie, procinfo.state);
+
+  ASSERT_EQ(forkpid, waitpid(forkpid, nullptr, 0));
+}