Merge "Revert "Make /data/data a symlink to /data/user/0""
diff --git a/debuggerd/Android.bp b/debuggerd/Android.bp
index 79d5c08..eb5578f 100644
--- a/debuggerd/Android.bp
+++ b/debuggerd/Android.bp
@@ -1,6 +1,5 @@
 cc_defaults {
     name: "debuggerd_defaults",
-    defaults: ["linux_bionic_supported"],
     cflags: [
         "-Wall",
         "-Wextra",
diff --git a/debuggerd/debuggerd_test.cpp b/debuggerd/debuggerd_test.cpp
index 568879e..0b4bbfb 100644
--- a/debuggerd/debuggerd_test.cpp
+++ b/debuggerd/debuggerd_test.cpp
@@ -29,6 +29,7 @@
 
 #include <android-base/file.h>
 #include <android-base/logging.h>
+#include <android-base/macros.h>
 #include <android-base/parseint.h>
 #include <android-base/properties.h>
 #include <android-base/strings.h>
@@ -149,7 +150,7 @@
   // Returns -1 if we fail to read a response from tombstoned, otherwise the received return code.
   void FinishIntercept(int* result);
 
-  void StartProcess(std::function<void()> function);
+  void StartProcess(std::function<void()> function, std::function<pid_t()> forker = fork);
   void StartCrasher(const std::string& crash_type);
   void FinishCrasher();
   void AssertDeath(int signo);
@@ -195,14 +196,14 @@
   }
 }
 
-void CrasherTest::StartProcess(std::function<void()> function) {
+void CrasherTest::StartProcess(std::function<void()> function, std::function<pid_t()> forker) {
   unique_fd read_pipe;
   unique_fd crasher_read_pipe;
   if (!Pipe(&crasher_read_pipe, &crasher_pipe)) {
     FAIL() << "failed to create pipe: " << strerror(errno);
   }
 
-  crasher_pid = fork();
+  crasher_pid = forker();
   if (crasher_pid == -1) {
     FAIL() << "fork failed: " << strerror(errno);
   } else if (crasher_pid == 0) {
@@ -527,6 +528,37 @@
   ASSERT_MATCH(result, R"(#00 pc [0-9a-f]+\s+ /system/lib)" ARCH_SUFFIX R"(/libc.so \(tgkill)");
 }
 
+TEST_F(CrasherTest, fake_pid) {
+  int intercept_result;
+  unique_fd output_fd;
+
+  // Prime the getpid/gettid caches.
+  UNUSED(getpid());
+  UNUSED(gettid());
+
+  std::function<pid_t()> clone_fn = []() {
+    return syscall(__NR_clone, SIGCHLD, nullptr, nullptr, nullptr, nullptr);
+  };
+  StartProcess(
+      []() {
+        ASSERT_NE(getpid(), syscall(__NR_getpid));
+        ASSERT_NE(gettid(), syscall(__NR_gettid));
+        raise(SIGSEGV);
+      },
+      clone_fn);
+
+  StartIntercept(&output_fd);
+  FinishCrasher();
+  AssertDeath(SIGSEGV);
+  FinishIntercept(&intercept_result);
+
+  ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";
+
+  std::string result;
+  ConsumeFd(std::move(output_fd), &result);
+  ASSERT_MATCH(result, R"(#00 pc [0-9a-f]+\s+ /system/lib)" ARCH_SUFFIX R"(/libc.so \(tgkill)");
+}
+
 TEST(crash_dump, zombie) {
   pid_t forkpid = fork();
 
diff --git a/debuggerd/handler/debuggerd_handler.cpp b/debuggerd/handler/debuggerd_handler.cpp
index 6e3e6ac..8fd6e11 100644
--- a/debuggerd/handler/debuggerd_handler.cpp
+++ b/debuggerd/handler/debuggerd_handler.cpp
@@ -61,6 +61,16 @@
 
 #define CRASH_DUMP_PATH "/system/bin/" CRASH_DUMP_NAME
 
+// Wrappers that directly invoke the respective syscalls, in case the cached values are invalid.
+#pragma GCC poison getpid gettid
+static pid_t __getpid() {
+  return syscall(__NR_getpid);
+}
+
+static pid_t __gettid() {
+  return syscall(__NR_gettid);
+}
+
 static inline void futex_wait(volatile void* ftx, int value) {
   syscall(__NR_futex, ftx, FUTEX_WAIT, value, nullptr, nullptr, 0);
 }
@@ -124,7 +134,7 @@
   }
 
   if (signum == DEBUGGER_SIGNAL) {
-    async_safe_format_log(ANDROID_LOG_INFO, "libc", "Requested dump for tid %d (%s)", gettid(),
+    async_safe_format_log(ANDROID_LOG_INFO, "libc", "Requested dump for tid %d (%s)", __gettid(),
                           thread_name);
     return;
   }
@@ -177,7 +187,7 @@
   }
 
   async_safe_format_log(ANDROID_LOG_FATAL, "libc", "Fatal signal %d (%s)%s%s in tid %d (%s)",
-                        signum, signal_name, code_desc, addr_desc, gettid(), thread_name);
+                        signum, signal_name, code_desc, addr_desc, __gettid(), thread_name);
 }
 
 /*
@@ -337,7 +347,7 @@
   // rt_tgsigqueueinfo(2) to preserve SA_SIGINFO) will cause it to be delivered
   // when our signal handler returns.
   if (crash_dump_started || info->si_signo != DEBUGGER_SIGNAL) {
-    int rc = syscall(SYS_rt_tgsigqueueinfo, getpid(), gettid(), info->si_signo, info);
+    int rc = syscall(SYS_rt_tgsigqueueinfo, __getpid(), __gettid(), info->si_signo, info);
     if (rc != 0) {
       fatal_errno("failed to resend signal during crash");
     }
@@ -362,7 +372,7 @@
     memset(&si, 0, sizeof(si));
     si.si_signo = signal_number;
     si.si_code = SI_USER;
-    si.si_pid = getpid();
+    si.si_pid = __getpid();
     si.si_uid = getuid();
     info = &si;
   } else if (info->si_code >= 0 || info->si_code == SI_TKILL) {
@@ -404,7 +414,7 @@
   debugger_thread_info thread_info = {
     .crash_dump_started = false,
     .pseudothread_tid = -1,
-    .crashing_tid = gettid(),
+    .crashing_tid = __gettid(),
     .signal_number = signal_number,
     .info = info
   };
diff --git a/init/builtins.cpp b/init/builtins.cpp
index 3dadfd7..27b72f9 100644
--- a/init/builtins.cpp
+++ b/init/builtins.cpp
@@ -150,7 +150,12 @@
 }
 
 static int do_domainname(const std::vector<std::string>& args) {
-    return write_file("/proc/sys/kernel/domainname", args[1]) ? 0 : 1;
+    std::string err;
+    if (!WriteFile("/proc/sys/kernel/domainname", args[1], &err)) {
+        LOG(ERROR) << err;
+        return -1;
+    }
+    return 0;
 }
 
 static int do_enable(const std::vector<std::string>& args) {
@@ -174,7 +179,12 @@
 }
 
 static int do_hostname(const std::vector<std::string>& args) {
-    return write_file("/proc/sys/kernel/hostname", args[1]) ? 0 : 1;
+    std::string err;
+    if (!WriteFile("/proc/sys/kernel/hostname", args[1], &err)) {
+        LOG(ERROR) << err;
+        return -1;
+    }
+    return 0;
 }
 
 static int do_ifup(const std::vector<std::string>& args) {
@@ -215,11 +225,19 @@
     }
 
     if (args.size() >= 4) {
-        uid_t uid = decode_uid(args[3].c_str());
+        uid_t uid;
+        std::string decode_uid_err;
+        if (!DecodeUid(args[3], &uid, &decode_uid_err)) {
+            LOG(ERROR) << "Unable to find UID for '" << args[3] << "': " << decode_uid_err;
+            return -1;
+        }
         gid_t gid = -1;
 
         if (args.size() == 5) {
-            gid = decode_uid(args[4].c_str());
+            if (!DecodeUid(args[4], &gid, &decode_uid_err)) {
+                LOG(ERROR) << "Unable to find GID for '" << args[3] << "': " << decode_uid_err;
+                return -1;
+            }
         }
 
         if (lchown(args[1].c_str(), uid, gid) == -1) {
@@ -643,29 +661,49 @@
 }
 
 static int do_write(const std::vector<std::string>& args) {
-    return write_file(args[1], args[2]) ? 0 : 1;
+    std::string err;
+    if (!WriteFile(args[1], args[2], &err)) {
+        LOG(ERROR) << err;
+        return -1;
+    }
+    return 0;
 }
 
 static int do_copy(const std::vector<std::string>& args) {
     std::string data;
-    if (read_file(args[1], &data)) {
-        return write_file(args[2], data) ? 0 : 1;
+    std::string err;
+    if (!ReadFile(args[1], &data, &err)) {
+        LOG(ERROR) << err;
+        return -1;
     }
-    return 1;
+    if (!WriteFile(args[2], data, &err)) {
+        LOG(ERROR) << err;
+        return -1;
+    }
+    return 0;
 }
 
 static int do_chown(const std::vector<std::string>& args) {
-    /* GID is optional. */
-    if (args.size() == 3) {
-        if (lchown(args[2].c_str(), decode_uid(args[1].c_str()), -1) == -1)
-            return -errno;
-    } else if (args.size() == 4) {
-        if (lchown(args[3].c_str(), decode_uid(args[1].c_str()),
-                   decode_uid(args[2].c_str())) == -1)
-            return -errno;
-    } else {
+    uid_t uid;
+    std::string decode_uid_err;
+    if (!DecodeUid(args[1], &uid, &decode_uid_err)) {
+        LOG(ERROR) << "Unable to find UID for '" << args[1] << "': " << decode_uid_err;
         return -1;
     }
+
+    // GID is optional and pushes the index of path out by one if specified.
+    const std::string& path = (args.size() == 4) ? args[3] : args[2];
+    gid_t gid = -1;
+
+    if (args.size() == 4) {
+        if (!DecodeUid(args[2], &gid, &decode_uid_err)) {
+            LOG(ERROR) << "Unable to find GID for '" << args[2] << "': " << decode_uid_err;
+            return -1;
+        }
+    }
+
+    if (lchown(path.c_str(), uid, gid) == -1) return -errno;
+
     return 0;
 }
 
diff --git a/init/init.cpp b/init/init.cpp
index 52f6b0c..b5f97e5 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -853,7 +853,9 @@
             }
         }
 
-        if (!write_file("/sys/fs/selinux/checkreqprot", "0")) {
+        std::string err;
+        if (!WriteFile("/sys/fs/selinux/checkreqprot", "0", &err)) {
+            LOG(ERROR) << err;
             security_failure();
         }
 
diff --git a/init/init_parser.cpp b/init/init_parser.cpp
index 620367a..1b31cf2 100644
--- a/init/init_parser.cpp
+++ b/init/init_parser.cpp
@@ -110,7 +110,9 @@
     LOG(INFO) << "Parsing file " << path << "...";
     Timer t;
     std::string data;
-    if (!read_file(path, &data)) {
+    std::string err;
+    if (!ReadFile(path, &data, &err)) {
+        LOG(ERROR) << err;
         return false;
     }
 
diff --git a/init/init_parser_test.cpp b/init/init_parser_test.cpp
index d8fd2ba..86d60d0 100644
--- a/init/init_parser_test.cpp
+++ b/init/init_parser_test.cpp
@@ -86,19 +86,29 @@
         ASSERT_EQ("", svc->seclabel());
     }
     if (uid) {
-        ASSERT_EQ(decode_uid("log"), svc->uid());
+        uid_t decoded_uid;
+        std::string err;
+        ASSERT_TRUE(DecodeUid("log", &decoded_uid, &err));
+        ASSERT_EQ(decoded_uid, svc->uid());
     } else {
         ASSERT_EQ(0U, svc->uid());
     }
     if (gid) {
-        ASSERT_EQ(decode_uid("shell"), svc->gid());
+        uid_t decoded_uid;
+        std::string err;
+        ASSERT_TRUE(DecodeUid("shell", &decoded_uid, &err));
+        ASSERT_EQ(decoded_uid, svc->gid());
     } else {
         ASSERT_EQ(0U, svc->gid());
     }
     if (supplementary_gids) {
         ASSERT_EQ(2U, svc->supp_gids().size());
-        ASSERT_EQ(decode_uid("system"), svc->supp_gids()[0]);
-        ASSERT_EQ(decode_uid("adb"), svc->supp_gids()[1]);
+        uid_t decoded_uid;
+        std::string err;
+        ASSERT_TRUE(DecodeUid("system", &decoded_uid, &err));
+        ASSERT_EQ(decoded_uid, svc->supp_gids()[0]);
+        ASSERT_TRUE(DecodeUid("adb", &decoded_uid, &err));
+        ASSERT_EQ(decoded_uid, svc->supp_gids()[1]);
     } else {
         ASSERT_EQ(0U, svc->supp_gids().size());
     }
diff --git a/init/init_test.cpp b/init/init_test.cpp
index 3da14b5..7093ba9 100644
--- a/init/init_test.cpp
+++ b/init/init_test.cpp
@@ -152,10 +152,11 @@
                                "on boot\n"
                                "execute 3";
     // clang-format on
-    // write_file() ensures the right mode is set
-    ASSERT_TRUE(write_file(std::string(dir.path) + "/a.rc", dir_a_script));
+    // WriteFile() ensures the right mode is set
+    std::string err;
+    ASSERT_TRUE(WriteFile(std::string(dir.path) + "/a.rc", dir_a_script, &err));
 
-    ASSERT_TRUE(write_file(std::string(dir.path) + "/b.rc", "on boot\nexecute 5"));
+    ASSERT_TRUE(WriteFile(std::string(dir.path) + "/b.rc", "on boot\nexecute 5", &err));
 
     // clang-format off
     std::string start_script = "import " + std::string(first_import.path) + "\n"
diff --git a/init/property_service.cpp b/init/property_service.cpp
index 6f40d1c..e01cd0b 100644
--- a/init/property_service.cpp
+++ b/init/property_service.cpp
@@ -510,8 +510,9 @@
 static void load_properties_from_file(const char* filename, const char* filter) {
     Timer t;
     std::string data;
-    if (!read_file(filename, &data)) {
-        PLOG(WARNING) << "Couldn't load properties from " << filename;
+    std::string err;
+    if (!ReadFile(filename, &data, &err)) {
+        PLOG(WARNING) << "Couldn't load property file: " << err;
         return;
     }
     data.push_back('\n');
diff --git a/init/service.cpp b/init/service.cpp
index 3a9f622..4d9edc4 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -380,9 +380,18 @@
 }
 
 bool Service::ParseGroup(const std::vector<std::string>& args, std::string* err) {
-    gid_ = decode_uid(args[1].c_str());
+    std::string decode_uid_err;
+    if (!DecodeUid(args[1], &gid_, &decode_uid_err)) {
+        *err = "Unable to find GID for '" + args[1] + "': " + decode_uid_err;
+        return false;
+    }
     for (std::size_t n = 2; n < args.size(); n++) {
-        supp_gids_.emplace_back(decode_uid(args[n].c_str()));
+        gid_t gid;
+        if (!DecodeUid(args[n], &gid, &decode_uid_err)) {
+            *err = "Unable to find GID for '" + args[n] + "': " + decode_uid_err;
+            return false;
+        }
+        supp_gids_.emplace_back(gid);
     }
     return true;
 }
@@ -480,10 +489,25 @@
 template <typename T>
 bool Service::AddDescriptor(const std::vector<std::string>& args, std::string* err) {
     int perm = args.size() > 3 ? std::strtoul(args[3].c_str(), 0, 8) : -1;
-    uid_t uid = args.size() > 4 ? decode_uid(args[4].c_str()) : 0;
-    gid_t gid = args.size() > 5 ? decode_uid(args[5].c_str()) : 0;
+    uid_t uid = 0;
+    gid_t gid = 0;
     std::string context = args.size() > 6 ? args[6] : "";
 
+    std::string decode_uid_err;
+    if (args.size() > 4) {
+        if (!DecodeUid(args[4], &uid, &decode_uid_err)) {
+            *err = "Unable to find UID for '" + args[4] + "': " + decode_uid_err;
+            return false;
+        }
+    }
+
+    if (args.size() > 5) {
+        if (!DecodeUid(args[5], &gid, &decode_uid_err)) {
+            *err = "Unable to find GID for '" + args[5] + "': " + decode_uid_err;
+            return false;
+        }
+    }
+
     auto descriptor = std::make_unique<T>(args[1], args[2], uid, gid, perm, context);
 
     auto old =
@@ -522,7 +546,11 @@
 }
 
 bool Service::ParseUser(const std::vector<std::string>& args, std::string* err) {
-    uid_ = decode_uid(args[1].c_str());
+    std::string decode_uid_err;
+    if (!DecodeUid(args[1], &uid_, &decode_uid_err)) {
+        *err = "Unable to find UID for '" + args[1] + "': " + decode_uid_err;
+        return false;
+    }
     return true;
 }
 
@@ -936,15 +964,28 @@
     }
     uid_t uid = 0;
     if (command_arg > 3) {
-        uid = decode_uid(args[2].c_str());
+        std::string decode_uid_err;
+        if (!DecodeUid(args[2], &uid, &decode_uid_err)) {
+            LOG(ERROR) << "Unable to find UID for '" << args[2] << "': " << decode_uid_err;
+            return nullptr;
+        }
     }
     gid_t gid = 0;
     std::vector<gid_t> supp_gids;
     if (command_arg > 4) {
-        gid = decode_uid(args[3].c_str());
+        std::string decode_uid_err;
+        if (!DecodeUid(args[3], &gid, &decode_uid_err)) {
+            LOG(ERROR) << "Unable to find GID for '" << args[3] << "': " << decode_uid_err;
+            return nullptr;
+        }
         std::size_t nr_supp_gids = command_arg - 1 /* -- */ - 4 /* exec SECLABEL UID GID */;
         for (size_t i = 0; i < nr_supp_gids; ++i) {
-            supp_gids.push_back(decode_uid(args[4 + i].c_str()));
+            gid_t supp_gid;
+            if (!DecodeUid(args[4 + i], &supp_gid, &decode_uid_err)) {
+                LOG(ERROR) << "Unable to find UID for '" << args[4 + i] << "': " << decode_uid_err;
+                return nullptr;
+            }
+            supp_gids.push_back(supp_gid);
         }
     }
 
diff --git a/init/util.cpp b/init/util.cpp
index 87b8d9d..e7f724b 100644
--- a/init/util.cpp
+++ b/init/util.cpp
@@ -48,39 +48,33 @@
 #endif
 
 using android::base::boot_clock;
+using namespace std::literals::string_literals;
 
-static unsigned int do_decode_uid(const char *s)
-{
-    unsigned int v;
+// DecodeUid() - decodes and returns the given string, which can be either the
+// numeric or name representation, into the integer uid or gid. Returns
+// UINT_MAX on error.
+bool DecodeUid(const std::string& name, uid_t* uid, std::string* err) {
+    *uid = UINT_MAX;
+    *err = "";
 
-    if (!s || *s == '\0')
-        return UINT_MAX;
-
-    if (isalpha(s[0])) {
-        struct passwd* pwd = getpwnam(s);
-        if (!pwd)
-            return UINT_MAX;
-        return pwd->pw_uid;
+    if (isalpha(name[0])) {
+        passwd* pwd = getpwnam(name.c_str());
+        if (!pwd) {
+            *err = "getpwnam failed: "s + strerror(errno);
+            return false;
+        }
+        *uid = pwd->pw_uid;
+        return true;
     }
 
     errno = 0;
-    v = (unsigned int) strtoul(s, 0, 0);
-    if (errno)
-        return UINT_MAX;
-    return v;
-}
-
-/*
- * decode_uid - decodes and returns the given string, which can be either the
- * numeric or name representation, into the integer uid or gid. Returns
- * UINT_MAX on error.
- */
-unsigned int decode_uid(const char *s) {
-    unsigned int v = do_decode_uid(s);
-    if (v == UINT_MAX) {
-        LOG(ERROR) << "decode_uid: Unable to find UID for '" << s << "'; returning UINT_MAX";
+    uid_t result = static_cast<uid_t>(strtoul(name.c_str(), 0, 0));
+    if (errno) {
+        *err = "strtoul failed: "s + strerror(errno);
+        return false;
     }
-    return v;
+    *uid = result;
+    return true;
 }
 
 /*
@@ -157,12 +151,14 @@
     return -1;
 }
 
-bool read_file(const std::string& path, std::string* content) {
+bool ReadFile(const std::string& path, std::string* content, std::string* err) {
     content->clear();
+    *err = "";
 
     android::base::unique_fd fd(
         TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_NOFOLLOW | O_CLOEXEC)));
     if (fd == -1) {
+        *err = "Unable to open '" + path + "': " + strerror(errno);
         return false;
     }
 
@@ -170,29 +166,35 @@
     // or group-writable files.
     struct stat sb;
     if (fstat(fd, &sb) == -1) {
-        PLOG(ERROR) << "fstat failed for '" << path << "'";
+        *err = "fstat failed for '" + path + "': " + strerror(errno);
         return false;
     }
     if ((sb.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
-        LOG(ERROR) << "skipping insecure file '" << path << "'";
+        *err = "Skipping insecure file '" + path + "'";
         return false;
     }
 
-    return android::base::ReadFdToString(fd, content);
+    if (!android::base::ReadFdToString(fd, content)) {
+        *err = "Unable to read '" + path + "': " + strerror(errno);
+        return false;
+    }
+    return true;
 }
 
-bool write_file(const std::string& path, const std::string& content) {
+bool WriteFile(const std::string& path, const std::string& content, std::string* err) {
+    *err = "";
+
     android::base::unique_fd fd(TEMP_FAILURE_RETRY(
         open(path.c_str(), O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC | O_CLOEXEC, 0600)));
     if (fd == -1) {
-        PLOG(ERROR) << "write_file: Unable to open '" << path << "'";
+        *err = "Unable to open '" + path + "': " + strerror(errno);
         return false;
     }
-    bool success = android::base::WriteStringToFd(content, fd);
-    if (!success) {
-        PLOG(ERROR) << "write_file: Unable to write to '" << path << "'";
+    if (!android::base::WriteStringToFd(content, fd)) {
+        *err = "Unable to write to '" + path + "': " + strerror(errno);
+        return false;
     }
-    return success;
+    return true;
 }
 
 int mkdir_recursive(const std::string& path, mode_t mode, selabel_handle* sehandle) {
diff --git a/init/util.h b/init/util.h
index 55ebded..4c33909 100644
--- a/init/util.h
+++ b/init/util.h
@@ -38,8 +38,8 @@
 int create_socket(const char* name, int type, mode_t perm, uid_t uid, gid_t gid,
                   const char* socketcon, selabel_handle* sehandle);
 
-bool read_file(const std::string& path, std::string* content);
-bool write_file(const std::string& path, const std::string& content);
+bool ReadFile(const std::string& path, std::string* content, std::string* err);
+bool WriteFile(const std::string& path, const std::string& content, std::string* err);
 
 class Timer {
   public:
@@ -61,7 +61,7 @@
 
 std::ostream& operator<<(std::ostream& os, const Timer& t);
 
-unsigned int decode_uid(const char *s);
+bool DecodeUid(const std::string& name, uid_t* uid, std::string* err);
 
 int mkdir_recursive(const std::string& pathname, mode_t mode, selabel_handle* sehandle);
 int wait_for_file(const char *filename, std::chrono::nanoseconds timeout);
diff --git a/init/util_test.cpp b/init/util_test.cpp
index ac23a32..4bb8a83 100644
--- a/init/util_test.cpp
+++ b/init/util_test.cpp
@@ -24,53 +24,67 @@
 #include <android-base/test_utils.h>
 #include <gtest/gtest.h>
 
-TEST(util, read_file_ENOENT) {
-  std::string s("hello");
-  errno = 0;
-  EXPECT_FALSE(read_file("/proc/does-not-exist", &s));
-  EXPECT_EQ(ENOENT, errno);
-  EXPECT_EQ("", s); // s was cleared.
+using namespace std::literals::string_literals;
+
+TEST(util, ReadFile_ENOENT) {
+    std::string s("hello");
+    std::string err;
+    errno = 0;
+    EXPECT_FALSE(ReadFile("/proc/does-not-exist", &s, &err));
+    EXPECT_EQ("Unable to open '/proc/does-not-exist': No such file or directory", err);
+    EXPECT_EQ(ENOENT, errno);
+    EXPECT_EQ("", s);  // s was cleared.
 }
 
-TEST(util, read_file_group_writeable) {
+TEST(util, ReadFileGroupWriteable) {
     std::string s("hello");
     TemporaryFile tf;
+    std::string err;
     ASSERT_TRUE(tf.fd != -1);
-    EXPECT_TRUE(write_file(tf.path, s)) << strerror(errno);
+    EXPECT_TRUE(WriteFile(tf.path, s, &err)) << strerror(errno);
+    EXPECT_EQ("", err);
     EXPECT_NE(-1, fchmodat(AT_FDCWD, tf.path, 0620, AT_SYMLINK_NOFOLLOW)) << strerror(errno);
-    EXPECT_FALSE(read_file(tf.path, &s)) << strerror(errno);
+    EXPECT_FALSE(ReadFile(tf.path, &s, &err)) << strerror(errno);
+    EXPECT_EQ("Skipping insecure file '"s + tf.path + "'", err);
     EXPECT_EQ("", s);  // s was cleared.
 }
 
-TEST(util, read_file_world_writeable) {
+TEST(util, ReadFileWorldWiteable) {
     std::string s("hello");
     TemporaryFile tf;
+    std::string err;
     ASSERT_TRUE(tf.fd != -1);
-    EXPECT_TRUE(write_file(tf.path, s.c_str())) << strerror(errno);
+    EXPECT_TRUE(WriteFile(tf.path, s, &err)) << strerror(errno);
+    EXPECT_EQ("", err);
     EXPECT_NE(-1, fchmodat(AT_FDCWD, tf.path, 0602, AT_SYMLINK_NOFOLLOW)) << strerror(errno);
-    EXPECT_FALSE(read_file(tf.path, &s)) << strerror(errno);
+    EXPECT_FALSE(ReadFile(tf.path, &s, &err)) << strerror(errno);
+    EXPECT_EQ("Skipping insecure file '"s + tf.path + "'", err);
     EXPECT_EQ("", s);  // s was cleared.
 }
 
-TEST(util, read_file_symbolic_link) {
+TEST(util, ReadFileSymbolicLink) {
     std::string s("hello");
     errno = 0;
     // lrwxrwxrwx 1 root root 13 1970-01-01 00:00 charger -> /sbin/healthd
-    EXPECT_FALSE(read_file("/charger", &s));
+    std::string err;
+    EXPECT_FALSE(ReadFile("/charger", &s, &err));
+    EXPECT_EQ("Unable to open '/charger': Too many symbolic links encountered", err);
     EXPECT_EQ(ELOOP, errno);
     EXPECT_EQ("", s);  // s was cleared.
 }
 
-TEST(util, read_file_success) {
-  std::string s("hello");
-  EXPECT_TRUE(read_file("/proc/version", &s));
-  EXPECT_GT(s.length(), 6U);
-  EXPECT_EQ('\n', s[s.length() - 1]);
-  s[5] = 0;
-  EXPECT_STREQ("Linux", s.c_str());
+TEST(util, ReadFileSuccess) {
+    std::string s("hello");
+    std::string err;
+    EXPECT_TRUE(ReadFile("/proc/version", &s, &err));
+    EXPECT_EQ("", err);
+    EXPECT_GT(s.length(), 6U);
+    EXPECT_EQ('\n', s[s.length() - 1]);
+    s[5] = 0;
+    EXPECT_STREQ("Linux", s.c_str());
 }
 
-TEST(util, write_file_binary) {
+TEST(util, WriteFileBinary) {
     std::string contents("abcd");
     contents.push_back('\0');
     contents.push_back('\0');
@@ -78,22 +92,28 @@
     ASSERT_EQ(10u, contents.size());
 
     TemporaryFile tf;
+    std::string err;
     ASSERT_TRUE(tf.fd != -1);
-    EXPECT_TRUE(write_file(tf.path, contents)) << strerror(errno);
+    EXPECT_TRUE(WriteFile(tf.path, contents, &err)) << strerror(errno);
+    EXPECT_EQ("", err);
 
     std::string read_back_contents;
-    EXPECT_TRUE(read_file(tf.path, &read_back_contents)) << strerror(errno);
+    EXPECT_TRUE(ReadFile(tf.path, &read_back_contents, &err)) << strerror(errno);
+    EXPECT_EQ("", err);
     EXPECT_EQ(contents, read_back_contents);
     EXPECT_EQ(10u, read_back_contents.size());
 }
 
-TEST(util, write_file_not_exist) {
+TEST(util, WriteFileNotExist) {
     std::string s("hello");
     std::string s2("hello");
     TemporaryDir test_dir;
     std::string path = android::base::StringPrintf("%s/does-not-exist", test_dir.path);
-    EXPECT_TRUE(write_file(path, s));
-    EXPECT_TRUE(read_file(path, &s2));
+    std::string err;
+    EXPECT_TRUE(WriteFile(path, s, &err));
+    EXPECT_EQ("", err);
+    EXPECT_TRUE(ReadFile(path, &s2, &err));
+    EXPECT_EQ("", err);
     EXPECT_EQ(s, s2);
     struct stat sb;
     int fd = open(path.c_str(), O_RDONLY | O_NOFOLLOW | O_CLOEXEC);
@@ -103,22 +123,38 @@
     EXPECT_EQ(0, unlink(path.c_str()));
 }
 
-TEST(util, write_file_exist) {
+TEST(util, WriteFileExist) {
     std::string s2("");
     TemporaryFile tf;
     ASSERT_TRUE(tf.fd != -1);
-    EXPECT_TRUE(write_file(tf.path, "1hello1")) << strerror(errno);
-    EXPECT_TRUE(read_file(tf.path, &s2));
+    std::string err;
+    EXPECT_TRUE(WriteFile(tf.path, "1hello1", &err)) << strerror(errno);
+    EXPECT_EQ("", err);
+    EXPECT_TRUE(ReadFile(tf.path, &s2, &err));
+    EXPECT_EQ("", err);
     EXPECT_STREQ("1hello1", s2.c_str());
-    EXPECT_TRUE(write_file(tf.path, "2ll2"));
-    EXPECT_TRUE(read_file(tf.path, &s2));
+    EXPECT_TRUE(WriteFile(tf.path, "2ll2", &err));
+    EXPECT_EQ("", err);
+    EXPECT_TRUE(ReadFile(tf.path, &s2, &err));
+    EXPECT_EQ("", err);
     EXPECT_STREQ("2ll2", s2.c_str());
 }
 
-TEST(util, decode_uid) {
-  EXPECT_EQ(0U, decode_uid("root"));
-  EXPECT_EQ(UINT_MAX, decode_uid("toot"));
-  EXPECT_EQ(123U, decode_uid("123"));
+TEST(util, DecodeUid) {
+    uid_t decoded_uid;
+    std::string err;
+
+    EXPECT_TRUE(DecodeUid("root", &decoded_uid, &err));
+    EXPECT_EQ("", err);
+    EXPECT_EQ(0U, decoded_uid);
+
+    EXPECT_FALSE(DecodeUid("toot", &decoded_uid, &err));
+    EXPECT_EQ("getpwnam failed: No such file or directory", err);
+    EXPECT_EQ(UINT_MAX, decoded_uid);
+
+    EXPECT_TRUE(DecodeUid("123", &decoded_uid, &err));
+    EXPECT_EQ("", err);
+    EXPECT_EQ(123U, decoded_uid);
 }
 
 TEST(util, is_dir) {
diff --git a/liblog/fake_log_device.c b/liblog/fake_log_device.c
index ae7a334..1483c24 100644
--- a/liblog/fake_log_device.c
+++ b/liblog/fake_log_device.c
@@ -15,9 +15,7 @@
  */
 /*
  * Intercepts log messages intended for the Android log device.
- * When running in the context of the simulator, the messages are
- * passed on to the underlying (fake) log device.  When not in the
- * simulator, messages are printed to stderr.
+ * Messages are printed to stderr.
  */
 #include <ctype.h>
 #include <errno.h>
@@ -561,7 +559,8 @@
  *  tag (N bytes -- null-terminated ASCII string)
  *  message (N bytes -- null-terminated ASCII string)
  */
-static ssize_t logWritev(int fd, const struct iovec* vector, int count) {
+LIBLOG_HIDDEN ssize_t fakeLogWritev(int fd, const struct iovec* vector,
+                                    int count) {
   LogState* state;
 
   /* Make sure that no-one frees the LogState while we're using it.
@@ -626,8 +625,18 @@
 
 /*
  * Free up our state and close the fake descriptor.
+ *
+ * The logger API has no means or need to 'stop' or 'close' using the logs,
+ * and as such, there is no way for that 'stop' or 'close' to translate into
+ * a close operation to the fake log handler. fakeLogClose is provided for
+ * completeness only.
+ *
+ * We have no intention of adding a log close operation as it would complicate
+ * every user of the logging API with no gain since the only valid place to
+ * call is in the exit handler. Logging can continue in the exit handler to
+ * help debug HOST tools ...
  */
-static int logClose(int fd) {
+LIBLOG_HIDDEN int fakeLogClose(int fd) {
   deleteFakeFd(fd);
   return 0;
 }
@@ -635,7 +644,7 @@
 /*
  * Open a log output device and return a fake fd.
  */
-static int logOpen(const char* pathName, int flags __unused) {
+LIBLOG_HIDDEN int fakeLogOpen(const char* pathName) {
   LogState* logState;
   int fd = -1;
 
@@ -654,66 +663,6 @@
   return fd;
 }
 
-/*
- * Runtime redirection.  If this binary is running in the simulator,
- * just pass log messages to the emulated device.  If it's running
- * outside of the simulator, write the log messages to stderr.
- */
-
-static int (*redirectOpen)(const char* pathName, int flags) = NULL;
-static int (*redirectClose)(int fd) = NULL;
-static ssize_t (*redirectWritev)(int fd, const struct iovec* vector,
-                                 int count) = NULL;
-
-static void setRedirects() {
-  const char* ws;
-
-  /* Wrapsim sets this environment variable on children that it's
-   * created using its LD_PRELOAD wrapper.
-   */
-  ws = getenv("ANDROID_WRAPSIM");
-  if (ws != NULL && strcmp(ws, "1") == 0) {
-    /* We're running inside wrapsim, so we can just write to the device. */
-    redirectOpen = (int (*)(const char* pathName, int flags))open;
-    redirectClose = close;
-    redirectWritev = writev;
-  } else {
-    /* There's no device to delegate to; handle the logging ourselves. */
-    redirectOpen = logOpen;
-    redirectClose = logClose;
-    redirectWritev = logWritev;
-  }
-}
-
-LIBLOG_HIDDEN int fakeLogOpen(const char* pathName, int flags) {
-  if (redirectOpen == NULL) {
-    setRedirects();
-  }
-  return redirectOpen(pathName, flags);
-}
-
-/*
- * The logger API has no means or need to 'stop' or 'close' using the logs,
- * and as such, there is no way for that 'stop' or 'close' to translate into
- * a close operation to the fake log handler. fakeLogClose is provided for
- * completeness only.
- *
- * We have no intention of adding a log close operation as it would complicate
- * every user of the logging API with no gain since the only valid place to
- * call is in the exit handler. Logging can continue in the exit handler to
- * help debug HOST tools ...
- */
-LIBLOG_HIDDEN int fakeLogClose(int fd) {
-  /* Assume that open() was called first. */
-  return redirectClose(fd);
-}
-
-LIBLOG_HIDDEN ssize_t fakeLogWritev(int fd, const struct iovec* vector,
-                                    int count) {
-  /* Assume that open() was called first. */
-  return redirectWritev(fd, vector, count);
-}
-
 LIBLOG_HIDDEN ssize_t __send_log_msg(char* buf __unused,
                                      size_t buf_size __unused) {
   return -ENODEV;
diff --git a/liblog/fake_log_device.h b/liblog/fake_log_device.h
index 462d026..7b0e745 100644
--- a/liblog/fake_log_device.h
+++ b/liblog/fake_log_device.h
@@ -23,7 +23,7 @@
 
 struct iovec;
 
-LIBLOG_HIDDEN int fakeLogOpen(const char* pathName, int flags);
+LIBLOG_HIDDEN int fakeLogOpen(const char* pathName);
 LIBLOG_HIDDEN int fakeLogClose(int fd);
 LIBLOG_HIDDEN ssize_t fakeLogWritev(int fd, const struct iovec* vector,
                                     int count);
diff --git a/liblog/fake_writer.c b/liblog/fake_writer.c
index 969661a..403dc72 100644
--- a/liblog/fake_writer.c
+++ b/liblog/fake_writer.c
@@ -55,9 +55,9 @@
       continue;
     }
     snprintf(buf, sizeof(buf), "/dev/log_%s", android_log_id_to_name(i));
-    logFds[i] = fakeLogOpen(buf, O_WRONLY);
+    logFds[i] = fakeLogOpen(buf);
     if (logFds[i] < 0) {
-      fprintf(stderr, "fakeLogOpen(%s, O_WRONLY) failed\n", buf);
+      fprintf(stderr, "fakeLogOpen(%s) failed\n", buf);
     }
   }
   return 0;