From 10fd0e0c7fc4459f65c1e6029d44cd522e18becb Mon Sep 17 00:00:00 2001
From: "Jay Freeman (saurik)" <saurik@saurik.com>
Date: Thu, 25 Jun 2015 10:19:08 +0000
Subject: On iOS 8.3, allow symbolic links as /Applications.

---
 extrainst_.mm | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)

(limited to 'extrainst_.mm')

diff --git a/extrainst_.mm b/extrainst_.mm
index a938b04..8d4d15b 100644
--- a/extrainst_.mm
+++ b/extrainst_.mm
@@ -44,6 +44,9 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <dlfcn.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <string.h>
 
 #include "csstore.hpp"
 
@@ -129,6 +132,99 @@ void FixCache(NSString *home, NSString *plist) {
         printf("you must reboot to finalize your cache.\n");
 }
 
+#define INSTALLD "/usr/libexec/installd"
+
+static void *(*$memmem)(const void *, size_t, const void *, size_t);
+
+static bool PatchInstall() {
+    int fd(open(INSTALLD, O_RDWR));
+    if (fd == -1)
+        return false;
+
+    struct stat stat;
+    if (fstat(fd, &stat) == -1) {
+        close(fd);
+        return false;
+    }
+
+    size_t size(stat.st_size);
+    void *data(mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0));
+    close(fd);
+    if (data == MAP_FAILED)
+        return false;
+
+    bool changed(false);
+    for (;;) {
+        void *name($memmem(data, size, "__restrict", 10));
+        if (name == NULL)
+            break;
+        else {
+            memcpy(name, "__uicache_", 10);
+            changed = true;
+        }
+    }
+
+    munmap(data, size);
+
+    if (changed) {
+        system("ldid -s "INSTALLD"");
+        system("cp -af "INSTALLD" "INSTALLD"_");
+        system("mv -f "INSTALLD"_ "INSTALLD"");
+    }
+
+    return true;
+}
+
+#define SubstrateLaunchDaemons_ "/Library/LaunchDaemons"
+#define SubstrateVariable_ "DYLD_INSERT_LIBRARIES"
+#define SubstrateLibrary_ "/usr/lib/libuicache.dylib"
+
+static bool HookInstall() {
+    NSString *file([NSString stringWithFormat:@"%@/%s.plist", @ SubstrateLaunchDaemons_, "com.apple.mobile.installd"]);
+    if (file == nil)
+        return false;
+
+    NSMutableDictionary *root([NSMutableDictionary dictionaryWithContentsOfFile:file]);
+    if (root == nil)
+        return false;
+
+    NSMutableDictionary *environment([root objectForKey:@"EnvironmentVariables"]);
+    if (environment == nil) {
+        environment = [NSMutableDictionary dictionaryWithCapacity:1];
+        if (environment == nil)
+            return false;
+
+        [root setObject:environment forKey:@"EnvironmentVariables"];
+    }
+
+    NSString *variable([environment objectForKey:@ SubstrateVariable_]);
+    if (variable == nil || [variable length] == 0)
+        [environment setObject:@ SubstrateLibrary_ forKey:@ SubstrateVariable_];
+    else {
+        NSArray *dylibs([variable componentsSeparatedByString:@":"]);
+        if (dylibs == nil)
+            return false;
+
+        NSUInteger index([dylibs indexOfObject:@ SubstrateLibrary_]);
+        if (index != NSNotFound)
+            return false;
+
+        [environment setObject:[NSString stringWithFormat:@"%@:%@", variable, @ SubstrateLibrary_] forKey:@ SubstrateVariable_];
+    }
+
+    NSString *error;
+    NSData *data([NSPropertyListSerialization dataFromPropertyList:root format:NSPropertyListBinaryFormat_v1_0 errorDescription:&error]);
+    if (data == nil)
+        return false;
+
+    if (![data writeToFile:file atomically:YES])
+        return false;
+
+    system("launchctl unload /Library/LaunchDaemons/com.apple.mobile.installd.plist");
+    system("launchctl load /Library/LaunchDaemons/com.apple.mobile.installd.plist");
+    return true;
+}
+
 int main(int argc, const char *argv[]) {
     if (argc < 2 || (
         strcmp(argv[1], "install") != 0 &&
@@ -137,6 +233,13 @@ int main(int argc, const char *argv[]) {
 
     NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
 
+    $memmem = reinterpret_cast<void *(*)(const void *, size_t, const void *, size_t)>(dlsym(RTLD_DEFAULT, "memmem"));
+
+    if (kCFCoreFoundationVersionNumber >= 1143) // XXX: iOS 8.3+
+        if (PatchInstall())
+            if (HookInstall())
+                FinishCydia("reboot");
+
     if (kCFCoreFoundationVersionNumber >= 700 && kCFCoreFoundationVersionNumber < 800) { // XXX: iOS 6.x
         NSString *home(@"/var/mobile");
         NSString *plist([NSString stringWithFormat:@"%@/Library/Caches/com.apple.mobile.installation.plist", home]);
-- 
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