getgrnam, getgrgid, getpwnam, getpwuid for host

The functions now read /etc/group and /etc/passwd on host machines.
Android-specific IDs are not recognized in the host.

getpwent and getgrent are still not working though. They require a
bigger refactoring to sequentially advance in the database files.

Bug: 171718702
Test: run assemble_cvd in aosp_cf_arm64_phone
Change-Id: Ie8da382a467bbd0bffac7b4b8592cd871db80181

libc/bionic/empty_android_ids.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#if defined(__ANDROID__)
+#error "This file is for host only"
+#endif
+
+struct android_id_info {
+  const char name[17];
+  unsigned aid;
+};
+
+static const struct android_id_info android_ids[] = {};
+
+#define android_id_count 0

libc/bionic/grp_pwd.cpp

@@ -46,24 +46,30 @@
 #include "private/android_filesystem_config.h"
 #include "platform/bionic/macros.h"
 
+#if defined(__ANDROID__)
 // Generated android_ids array
 #include "generated_android_ids.h"
+#else
+// Empty array for host; everything is from the database files
+#include "empty_android_ids.h"
+#endif
+
 #include "grp_pwd_file.h"
 
 static PasswdFile passwd_files[] = {
-  { "/system/etc/passwd", "system_" },
-  { "/vendor/etc/passwd", "vendor_" },
-  { "/odm/etc/passwd", "odm_" },
-  { "/product/etc/passwd", "product_" },
-  { "/system_ext/etc/passwd", "system_ext_" },
+    {"/etc/passwd", "system_"},  // symlinks to /system/etc/passwd in Android
+    {"/vendor/etc/passwd", "vendor_"},
+    {"/odm/etc/passwd", "odm_"},
+    {"/product/etc/passwd", "product_"},
+    {"/system_ext/etc/passwd", "system_ext_"},
 };
 
 static GroupFile group_files[] = {
-  { "/system/etc/group", "system_" },
-  { "/vendor/etc/group", "vendor_" },
-  { "/odm/etc/group", "odm_" },
-  { "/product/etc/group", "product_" },
-  { "/system_ext/etc/group", "system_ext_" },
+    {"/etc/group", "system_"},  // symlinks to /system/etc/group in Android
+    {"/vendor/etc/group", "vendor_"},
+    {"/odm/etc/group", "odm_"},
+    {"/product/etc/group", "product_"},
+    {"/system_ext/etc/group", "system_ext_"},
 };
 
 // POSIX seems to envisage an implementation where the <pwd.h> functions are
@@ -194,6 +200,7 @@ static bool platform_id_secondary_user_allowed(id_t id) {
   return false;
 }
 
+#if defined(__ANDROID__)
 static bool is_valid_app_id(id_t id, bool is_group) {
   id_t appid = id % AID_USER_OFFSET;
 
@@ -226,6 +233,12 @@ static bool is_valid_app_id(id_t id, bool is_group) {
 
   return false;
 }
+#else
+static bool is_valid_app_id(id_t, bool) {
+  // Host doesn't have the concept of app_id
+  return false;
+}
+#endif  // if defined(__ANDROID__)
 
 // This provides an iterater for app_ids within the first user's app id's.
 static id_t get_next_app_id(id_t current_id, bool is_group) {
@@ -386,6 +399,7 @@ static void print_app_name_from_gid(const gid_t gid, char* buffer, const int buf
   }
 }
 
+#if defined(__ANDROID__)
 static bool device_launched_before_api_29() {
   // Check if ro.product.first_api_level is set to a value > 0 and < 29, if so, this device was
   // launched before API 29 (Q). Any other value is considered to be either in development or
@@ -420,6 +434,12 @@ static bool is_oem_id(id_t id) {
   return (id >= AID_OEM_RESERVED_START && id <= AID_OEM_RESERVED_END) ||
          (id >= AID_OEM_RESERVED_2_START && id <= AID_OEM_RESERVED_2_END);
 }
+#else
+static bool is_oem_id(id_t) {
+  // no OEM ids in host
+  return false;
+}
+#endif  // if defined(__ANDROID__)
 
 // Translate an OEM name to the corresponding user/group id.
 static id_t oem_id_from_name(const char* name) {
@@ -522,7 +542,7 @@ passwd* getpwuid_internal(uid_t uid, passwd_state_t* state) {
     return android_iinfo_to_passwd(state, android_id_info);
   }
 
-  // Handle OEM range.
+  // Find an entry from the database file
   passwd* pw = oem_id_to_passwd(uid, state);
   if (pw != nullptr) {
     return pw;
@@ -540,6 +560,7 @@ passwd* getpwnam_internal(const char* login, passwd_state_t* state) {
     return android_iinfo_to_passwd(state, android_id_info);
   }
 
+  // Find an entry from the database file
   for (auto& passwd_file : passwd_files) {
     if (passwd_file.FindByName(login, state)) {
       return &state->passwd_;
@@ -681,7 +702,7 @@ static group* getgrgid_internal(gid_t gid, group_state_t* state) {
     return android_iinfo_to_group(state, android_id_info);
   }
 
-  // Handle OEM range.
+  // Find an entry from the database file
   group* grp = oem_id_to_group(gid, state);
   if (grp != nullptr) {
     return grp;
@@ -699,6 +720,7 @@ static group* getgrnam_internal(const char* name, group_state_t* state) {
     return android_iinfo_to_group(state, android_id_info);
   }
 
+  // Find an entry from the database file
   for (auto& group_file : group_files) {
     if (group_file.FindByName(name, state)) {
       return &state->group_;

libc/bionic/grp_pwd_file.cpp

@@ -268,6 +268,7 @@ bool MmapFile::Find(Line* line, Predicate predicate) {
 
   while (line_beginning < end) {
     line_beginning = ParseLine(line_beginning, end, line->fields, line->kNumFields);
+#if defined(__ANDROID__)
     // To comply with Treble, users/groups from each partition need to be prefixed with
     // the partition name.
     if (required_prefix_ != nullptr) {
@@ -280,6 +281,7 @@ bool MmapFile::Find(Line* line, Predicate predicate) {
         continue;
       }
     }
+#endif
     if (predicate(line)) return true;
   }
 

libc/bionic/grp_pwd_file.h

@@ -65,7 +65,10 @@ class MmapFile {
   const char* filename_ = nullptr;
   const char* start_ = nullptr;
   const char* end_ = nullptr;
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-private-field"
   const char* required_prefix_;
+#pragma clang diagnostic pop
 };
 
 class PasswdFile {