Build magiskboot with crt0

native/src/Android.mk

@@ -109,6 +109,12 @@ LOCAL_SRC_FILES := \
 
 LOCAL_LDFLAGS := -static -T src/lto_fix.lds
 
+ifdef B_CRT0
+LOCAL_STATIC_LIBRARIES += crt0
+LOCAL_CFLAGS += -DUSE_MUSL_PRINTF
+LOCAL_LDFLAGS := -lm -Wl,--wrap=qsort
+endif
+
 include $(BUILD_EXECUTABLE)
 
 endif

native/src/base/files.cpp

@@ -75,12 +75,8 @@ void file_readline(bool trim, FILE *fp, const function<bool(string_view)> &fn) {
 }
 
 void file_readline(bool trim, const char *file, const function<bool(string_view)> &fn) {
-    int fd = xopen(file, O_RDONLY | O_CLOEXEC);
-    if (fd >= 0) {
-        auto fp = fdopen(fd, "re");
-        file_readline(trim, fp, fn);
-        fclose(fp);
-    }
+    if (auto fp = open_file(file, "re"))
+        file_readline(trim, fp.get(), fn);
 }
 
 void file_readline(const char *file, const function<bool(string_view)> &fn) {
@@ -101,12 +97,8 @@ void parse_prop_file(FILE *fp, const function<bool(string_view, string_view)> &f
 }
 
 void parse_prop_file(const char *file, const function<bool(string_view, string_view)> &fn) {
-    int fd = xopen(file, O_RDONLY | O_CLOEXEC);
-    if (fd >= 0) {
-        auto fp = fdopen(fd, "re");
-        parse_prop_file(fp, fn);
-        fclose(fp);
-    }
+    if (auto fp = open_file(file, "re"))
+        parse_prop_file(fp.get(), fn);
 }
 
 std::vector<mount_info> parse_mount_info(const char *pid) {

native/src/base/misc.cpp

@@ -290,3 +290,37 @@ const char *rust::Utf8CStr::data() const {
 size_t rust::Utf8CStr::length() const {
     return cxx$utf8str$len(this);
 }
+
+#define elm(i) (p + (i * size))
+
+// An alternative qsort implementation. Only used when linking with crt0
+extern "C"
+void __wrap_qsort(void *ptr, size_t count, size_t size, int (*comp)(const void*, const void*)) {
+    // Create the index array
+    uint8_t *p = (uint8_t *) ptr;
+    vector<int> v(count);
+    std::iota(v.begin(), v.end(), 0);
+
+    // Sort the index array
+    std::sort(v.begin(), v.end(), [=](int a, int b) {
+        return comp(elm(a), elm(b)) < 0;
+    });
+
+    // Reorganize the array with index array
+    void *t = malloc(size);
+    for (int i = 0; i < count; ++i) {
+        if (v[i] != i) {
+            memcpy(t, elm(i), size);
+            int j = i;
+            int k;
+            while (i != (k = v[j])) {
+                memcpy(elm(j), elm(k), size);
+                v[j] = j;
+                j = k;
+            }
+            memcpy(elm(j), t, size);
+            v[j] = j;
+        }
+    }
+    free(t);
+}

native/src/boot/main.cpp

@@ -6,6 +6,11 @@
 
 using namespace std;
 
+#ifdef USE_MUSL_PRINTF
+// Switch to use the musl vfprintf
+__asm__(".global vfprintf \n vfprintf = musl_vfprintf");
+#endif
+
 static void print_formats() {
     for (int fmt = GZIP; fmt < LZOP; ++fmt) {
         fprintf(stderr, "%s ", fmt2name[(format_t) fmt]);

native/src/sepolicy/policydb.cpp

@@ -103,8 +103,7 @@ sepolicy *sepolicy::from_file(const char *file) {
 
     policy_file_t pf;
     policy_file_init(&pf);
-    int fd = xopen(file, O_RDONLY | O_CLOEXEC);
-    auto fp = make_file(fdopen(fd, "re"));
+    auto fp = xopen_file(file, "re");
     pf.fp = fp.get();
     pf.type = PF_USE_STDIO;
 
@@ -124,7 +123,6 @@ sepolicy *sepolicy::compile_split() {
     cil_db_t *db = nullptr;
     sepol_policydb_t *pdb = nullptr;
     FILE *f;
-    int fd;
     int policy_ver;
     const char *cil_file;
 #if MAGISK_DEBUG
@@ -150,15 +148,13 @@ sepolicy *sepolicy::compile_split() {
     cil_set_target_platform(db, SEPOL_TARGET_SELINUX);
     cil_set_attrs_expand_generated(db, 1);
 
-    fd = xopen(SELINUX_VERSION, O_RDONLY | O_CLOEXEC);
-    f = fdopen(fd, "re");
+    f = xfopen(SELINUX_VERSION, "re");
     fscanf(f, "%d", &policy_ver);
     fclose(f);
     cil_set_policy_version(db, policy_ver);
 
     // Get mapping version
-    fd = xopen(VEND_POLICY_DIR "plat_sepolicy_vers.txt", O_RDONLY | O_CLOEXEC);
-    f = fdopen(fd, "re");
+    f = xfopen(VEND_POLICY_DIR "plat_sepolicy_vers.txt", "re");
     fscanf(f, "%s", plat_ver);
     fclose(f);