Build on API 21 headers

build.py

@@ -330,6 +330,12 @@ def build_binary(args):
     if 'test' in args.target:
         flag += ' B_TEST=1'
 
+    if flag:
+        run_ndk_build(flag + ' B_SHARED=1')
+
+    if 'magisk' in args.target:
+        clean_elf()
+
     if 'magiskinit' in args.target:
         dump_bin_header()
         flag += ' B_INIT=1'
@@ -346,9 +352,6 @@ def build_binary(args):
     if flag:
         run_ndk_build(flag)
 
-    if 'magisk' in args.target:
-        clean_elf()
-
     if 'busybox' in args.target:
         run_ndk_build('B_BB=1')
 
@@ -445,16 +448,15 @@ def setup_ndk(args):
     mv(op.join(ndk_root, f'android-ndk-r{ndk_ver}'), ndk_path)
 
     header('* Patching static libs')
-    for api in ['16', '21']:
     for target in ['aarch64-linux-android', 'arm-linux-androideabi',
                    'i686-linux-android', 'x86_64-linux-android']:
         arch = target.split('-')[0]
         lib_dir = op.join(
             ndk_path, 'toolchains', 'llvm', 'prebuilt', f'{os_name}-x86_64',
-                'sysroot', 'usr', 'lib', f'{target}', api)
+            'sysroot', 'usr', 'lib', f'{target}', '21')
         if not op.exists(lib_dir):
             continue
-            src_dir = op.join('tools', 'ndk-bins', api, arch)
+        src_dir = op.join('tools', 'ndk-bins', '21', arch)
         rm(op.join(src_dir, '.DS_Store'))
         for path in copy_tree(src_dir, lib_dir):
             vprint(f'Replaced {path}')

native/jni/Android.mk

@@ -8,7 +8,7 @@ ifdef B_MAGISK
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := magisk
-LOCAL_STATIC_LIBRARIES := libnanopb libsystemproperties libutils libphmap libxhook
+LOCAL_STATIC_LIBRARIES := libnanopb libsystemproperties libutils-shared libphmap libxhook
 
 LOCAL_SRC_FILES := \
     core/applets.cpp \
@@ -134,7 +134,7 @@ ifneq (,$(wildcard jni/test.cpp))
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := test
-LOCAL_STATIC_LIBRARIES := libutils libphmap
+LOCAL_STATIC_LIBRARIES := libutils-shared libphmap
 LOCAL_SRC_FILES := test.cpp
 include $(BUILD_EXECUTABLE)
 

native/jni/Application.mk

@@ -3,10 +3,19 @@ APP_CFLAGS       := -Wall -Oz -fomit-frame-pointer -flto
 APP_LDFLAGS      := -flto
 APP_CPPFLAGS     := -std=c++17
 APP_STL          := none
-APP_PLATFORM     := android-16
+APP_PLATFORM     := android-21
 APP_THIN_ARCHIVE := true
 APP_STRIP_MODE   := --strip-all
 
+ifneq ($(TARGET_ARCH),arm64)
+ifneq ($(TARGET_ARCH),x86_64)
+ifndef B_SHARED
+# Disable fortify on static 32-bit targets
+APP_CFLAGS       += -D_FORTIFY_SOURCE=0 -Wno-macro-redefined
+endif
+endif
+endif
+
 # Busybox should use stock libc.a
 ifdef B_BB
 APP_PLATFORM     := android-22

native/jni/external/systemproperties/include/private/hacks.h

@@ -11,10 +11,6 @@
 #define PR_SET_VMA_ANON_NAME 0
 #endif
 
-// Missing functions
-#define getline compat_getline
-ssize_t compat_getline(char **, size_t *, FILE *);
-
 // Rename symbols
 #pragma redefine_extname __system_property_set _system_property_set2
 #pragma redefine_extname __system_property_find _system_property_find2

native/jni/init/twostage.cpp

@@ -1,3 +1,11 @@
+// Force using legacy_signal_inlines.h
+#define __ANDROID_API_BACKUP__  __ANDROID_API__
+#undef  __ANDROID_API__
+#define __ANDROID_API__ 20
+#include <android/legacy_signal_inlines.h>
+#undef  __ANDROID_API__
+#define __ANDROID_API__ __ANDROID_API_BACKUP__
+
 #include <sys/mount.h>
 #include <map>
 

native/jni/utils/Android.mk

@@ -2,14 +2,7 @@ LOCAL_PATH := $(call my-dir)
 
 # All Magisk common code lives here
 
-include $(CLEAR_VARS)
-LOCAL_MODULE:= libutils
-LOCAL_C_INCLUDES := jni/include $(LOCAL_PATH)/include out/generated
-LOCAL_EXPORT_C_INCLUDES := $(LOCAL_C_INCLUDES)
-LOCAL_EXPORT_STATIC_LIBRARIES := libcxx
-LOCAL_STATIC_LIBRARIES := libcxx
-LOCAL_SRC_FILES := \
-    missing.cpp \
+UTILS_SRC_FILES := \
     new.cpp \
     files.cpp \
     misc.cpp \
@@ -18,4 +11,20 @@ LOCAL_SRC_FILES := \
     xwrap.cpp \
     stream.cpp
 
+include $(CLEAR_VARS)
+LOCAL_MODULE:= libutils
+LOCAL_C_INCLUDES := jni/include $(LOCAL_PATH)/include out/generated
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_C_INCLUDES)
+LOCAL_EXPORT_STATIC_LIBRARIES := libcxx
+LOCAL_STATIC_LIBRARIES := libcxx
+LOCAL_SRC_FILES := $(UTILS_SRC_FILES) missing.cpp
+include $(BUILD_STATIC_LIBRARY)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE:= libutils-shared
+LOCAL_C_INCLUDES := jni/include $(LOCAL_PATH)/include out/generated
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_C_INCLUDES)
+LOCAL_EXPORT_STATIC_LIBRARIES := libcxx
+LOCAL_STATIC_LIBRARIES := libcxx
+LOCAL_SRC_FILES := $(UTILS_SRC_FILES)
 include $(BUILD_STATIC_LIBRARY)

native/jni/utils/missing.cpp

@@ -1,19 +1,19 @@
-/*
- * Host all missing/incomplete implementation in bionic
- * Copied from various sources
- * */
+// This file implements all missing symbols that should exist in normal API 21
+// libc.a but missing in our extremely lean libc.a replacements.
 
-#include <stdlib.h>
-#include <string.h>
-#include <errno.h>
+#include <cstdlib>
+#include <cstring>
+#include <cerrno>
 #include <mntent.h>
+#include <unistd.h>
+#include <sys/syscall.h>
 
-#include "missing.hpp"
+extern "C" {
 
 /* Original source: https://github.com/freebsd/freebsd/blob/master/contrib/file/src/getline.c
  * License: BSD, full copyright notice please check original source */
 
-ssize_t compat_getdelim(char **buf, size_t *bufsiz, int delimiter, FILE *fp) {
+ssize_t getdelim(char **buf, size_t *bufsiz, int delimiter, FILE *fp) {
     char *ptr, *eptr;
 
     if (*buf == nullptr || *bufsiz == 0) {
@@ -49,14 +49,14 @@ ssize_t compat_getdelim(char **buf, size_t *bufsiz, int delimiter, FILE *fp) {
     }
 }
 
-ssize_t compat_getline(char **buf, size_t *bufsiz, FILE *fp) {
+ssize_t getline(char **buf, size_t *bufsiz, FILE *fp) {
     return getdelim(buf, bufsiz, '\n', fp);
 }
 
 /* Original source: https://android.googlesource.com/platform/bionic/+/master/libc/bionic/mntent.cpp
  * License: AOSP, full copyright notice please check original source */
 
-struct mntent *compat_getmntent_r(FILE* fp, struct mntent* e, char* buf, int buf_len) {
+struct mntent *getmntent_r(FILE *fp, struct mntent *e, char *buf, int buf_len) {
     memset(e, 0, sizeof(*e));
     while (fgets(buf, buf_len, fp) != nullptr) {
         // Entries look like "proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0".
@@ -79,31 +79,58 @@ struct mntent *compat_getmntent_r(FILE* fp, struct mntent* e, char* buf, int buf
     return nullptr;
 }
 
-FILE *compat_setmntent(const char* path, const char* mode) {
+FILE *setmntent(const char *path, const char *mode) {
     return fopen(path, mode);
 }
 
-int compat_endmntent(FILE* fp) {
+int endmntent(FILE *fp) {
     if (fp != nullptr) {
         fclose(fp);
     }
     return 1;
 }
 
-char *compat_hasmntopt(const struct mntent* mnt, const char* opt) {
-    char* token = mnt->mnt_opts;
-    char* const end = mnt->mnt_opts + strlen(mnt->mnt_opts);
-    const size_t optLen = strlen(opt);
-    while (token) {
-        char* const tokenEnd = token + optLen;
-        if (tokenEnd > end) break;
-        if (memcmp(token, opt, optLen) == 0 &&
-            (*tokenEnd == '\0' || *tokenEnd == ',' || *tokenEnd == '=')) {
-            return token;
-        }
-        token = strchr(token, ',');
-        if (token) token++;
-    }
-    return nullptr;
+// Missing system call wrappers
+
+int setns(int fd, int nstype) {
+    return syscall(__NR_setns, fd, nstype);
 }
 
+int unshare(int flags) {
+    return syscall(__NR_unshare, flags);
+}
+
+int accept4(int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags) {
+    return syscall(__NR_accept4, sockfd, addr, addrlen, flags);
+}
+
+int dup3(int oldfd, int newfd, int flags) {
+    return syscall(__NR_dup3, oldfd, newfd, flags);
+}
+
+ssize_t readlinkat(int dirfd, const char *pathname, char *buf, size_t bufsiz) {
+    return syscall(__NR_readlinkat, dirfd, pathname, buf, bufsiz);
+}
+
+int symlinkat(const char *target, int newdirfd, const char *linkpath) {
+    return syscall(__NR_symlinkat, target, newdirfd, linkpath);
+}
+
+int linkat(int olddirfd, const char *oldpath,
+           int newdirfd, const char *newpath, int flags) {
+    return syscall(__NR_linkat, olddirfd, oldpath, newdirfd, newpath, flags);
+}
+
+int inotify_init1(int flags) {
+    return syscall(__NR_inotify_init1, flags);
+}
+
+int faccessat(int dirfd, const char *pathname, int mode, int flags) {
+    return syscall(__NR_faccessat, dirfd, pathname, mode, flags);
+}
+
+#if !defined(__LP64__)
+void android_set_abort_message(const char *msg) {}
+#endif
+
+} // extern "C"

native/jni/utils/missing.hpp

@@ -2,73 +2,8 @@
 
 #include <sys/syscall.h>
 #include <unistd.h>
-#include <mntent.h>
 
-// Missing libc functions
-#define getline       compat_getline
-#define getdelim      compat_getdelim
-#define getmntent_r   compat_getmntent_r
-#define setmntent     compat_setmntent
-#define endmntent     compat_endmntent
-#define hasmntopt     compat_hasmntopt
-
-// Missing syscall wrappers
-#define setns         compat_setns
-#define unshare       compat_unshare
-#define accept4       compat_accept4
-#define dup3          compat_dup3
-#define readlinkat    compat_readlinkat
-#define symlinkat     compat_symlinkat
-#define linkat        compat_linkat
-#define inotify_init1 compat_inotify_init1
-#define faccessat     compat_faccessat
-#define sigtimedwait  compat_sigtimedwait
-
-ssize_t compat_getline(char **lineptr, size_t *n, FILE *stream);
-ssize_t compat_getdelim(char **lineptr, size_t *n, int delim, FILE *stream);
-struct mntent *compat_getmntent_r(FILE* fp, struct mntent* e, char* buf, int buf_len);
-FILE *compat_setmntent(const char* path, const char* mode);
-int compat_endmntent(FILE* fp);
-char *compat_hasmntopt(const struct mntent* mnt, const char* opt);
-
-static inline int compat_setns(int fd, int nstype) {
-    return syscall(__NR_setns, fd, nstype);
-}
-
-static inline int compat_unshare(int flags) {
-    return syscall(__NR_unshare, flags);
-}
-
-static inline int compat_accept4(int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags) {
-    return syscall(__NR_accept4, sockfd, addr, addrlen, flags);
-}
-
-static inline int compat_dup3(int oldfd, int newfd, int flags) {
-    return syscall(__NR_dup3, oldfd, newfd, flags);
-}
-
-static inline ssize_t compat_readlinkat(int dirfd, const char *pathname, char *buf, size_t bufsiz) {
-    return syscall(__NR_readlinkat, dirfd, pathname, buf, bufsiz);
-}
-
-static inline int compat_symlinkat(const char *target, int newdirfd, const char *linkpath) {
-    return syscall(__NR_symlinkat, target, newdirfd, linkpath);
-}
-
-static inline int compat_linkat(int olddirfd, const char *oldpath,
-        int newdirfd, const char *newpath, int flags) {
-    return syscall(__NR_linkat, olddirfd, oldpath, newdirfd, newpath, flags);
-}
-
-static inline int compat_inotify_init1(int flags) {
-    return syscall(__NR_inotify_init1, flags);
-}
-
-static inline int compat_faccessat(int dirfd, const char *pathname, int mode, int flags) {
-    return syscall(__NR_faccessat, dirfd, pathname, mode, flags);
-}
-
-static inline int compat_sigtimedwait(const sigset_t* set, siginfo_t* info, const timespec* timeout) {
+static inline int sigtimedwait(const sigset_t* set, siginfo_t* info, const timespec* timeout) {
     union {
         sigset_t set;
         sigset_t set64;

native/jni/utils/selinux.cpp

@@ -1,3 +1,5 @@
+#include <unistd.h>
+#include <sys/syscall.h>
 #include <sys/xattr.h>
 
 #include <utils.hpp>

native/jni/utils/stream.cpp

@@ -1,3 +1,4 @@
+#include <unistd.h>
 #include <cstddef>
 
 #include <utils.hpp>

native/jni/utils/xwrap.cpp

@@ -8,6 +8,7 @@
 #include <sys/mman.h>
 #include <sys/sendfile.h>
 #include <sys/ptrace.h>
+#include <sys/inotify.h>
 
 #include <utils.hpp>
 
@@ -198,26 +199,9 @@ int xlisten(int sockfd, int backlog) {
     return ret;
 }
 
-static int accept4_compat(int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags) {
-    int fd = accept(sockfd, addr, addrlen);
-    if (fd < 0) {
-        PLOGE("accept");
-    } else {
-        if (flags & SOCK_CLOEXEC)
-            fcntl(fd, F_SETFD, FD_CLOEXEC);
-        if (flags & SOCK_NONBLOCK) {
-            int i = fcntl(fd, F_GETFL);
-            fcntl(fd, F_SETFL, i | O_NONBLOCK);
-        }
-    }
-    return fd;
-}
-
 int xaccept4(int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags) {
     int fd = accept4(sockfd, addr, addrlen, flags);
     if (fd < 0) {
-        if (errno == ENOSYS)
-            return accept4_compat(sockfd, addr, addrlen, flags);
         PLOGE("accept4");
     }
     return fd;