Pipe (Part 2); This Needs Work

dependencies/trampoline/src

@@ -1 +1 @@
-Subproject commit 4d09fd9396be364fd3c1582fb945b394b265371f
+Subproject commit b2cf446e9dd5593c388c1f244c527741070f7a26

launcher/src/main.cpp

@@ -2,6 +2,10 @@
 #include <libreborn/libreborn.h>
 #include <sys/stat.h>
 
+#ifdef MCPI_USE_NATIVE_TRAMPOLINE
+#include <trampoline/types.h>
+#endif
+
 #include "bootstrap.h"
 #include "options/parser.h"
 #include "crash-report.h"
@@ -24,6 +28,9 @@ static void setup_environment(const options_t &options) {
 #else
     bind_to_env("_MCPI_ONLY_GENERATE", options.only_generate);
 #endif
+#ifdef MCPI_USE_NATIVE_TRAMPOLINE
+    bind_to_env(TRAMPOLINE_USE_PTRACE_ENV, options.use_ptrace_trampoline);
+#endif
 
     // GTK Dark Mode
 #ifndef MCPI_HEADLESS_MODE

launcher/src/options/option-list.h

@@ -9,4 +9,7 @@ OPTION(print_available_feature_flags, "print-available-feature-flags", -6, "Prin
 OPTION(benchmark, "benchmark", -7, "Run Benchmark")
 #else
 OPTION(only_generate, "only-generate", -8, "Generate World And Exit")
+#endif
+#ifdef MCPI_USE_NATIVE_TRAMPOLINE
+OPTION(use_ptrace_trampoline, "use-ptrace-trampoline", -9, "Use PTrace For Calling Host Functions Instead Of Pipes")
 #endif

media-layer/trampoline/src/guest/guest.cpp

@@ -1,15 +1,78 @@
 #include <unistd.h>
 #include <libreborn/libreborn.h>
+#include <string>
 
 #include "guest.h"
 
-uint32_t _raw_trampoline(const uint32_t id, const uint32_t length, const unsigned char *args) {
+// Syscall Method
+static uint32_t trampoline_syscall(const uint32_t id, const uint32_t length, const unsigned char *args) {
     // Make Syscall
-    long ret = syscall(0x1337 /* See trampoline.patch */, id, length, args);
+    long ret = syscall(TRAMPOLINE_SYSCALL, id, length, args);
     if (ret == -1) {
         // Error
         ERR("Trampoline Error: %s", strerror(errno));
     }
     // Return
     return *(uint32_t *) args;
+}
+
+// Pipe Method
+#ifdef MCPI_USE_NATIVE_TRAMPOLINE
+static int get_pipe(const char *env) {
+    const char *value = getenv(env);
+    if (value == nullptr) {
+        IMPOSSIBLE();
+    }
+    std::string str = value;
+    return std::stoi(str);
+}
+static uint32_t trampoline_pipe(const uint32_t id, const uint32_t length, const unsigned char *args) {
+    // Get Pipes
+    static int arguments_pipe = -1;
+    static int return_value_pipe = -1;
+    if (arguments_pipe == -1) {
+        arguments_pipe = get_pipe(TRAMPOLINE_ARGUMENTS_PIPE_ENV);
+        return_value_pipe = get_pipe(TRAMPOLINE_RETURN_VALUE_PIPE_ENV);
+    }
+    // Write Arguments
+    trampoline_pipe_arguments data = {
+        .id = id,
+        .length = length,
+        .args_addr = uint32_t(args)
+    };
+    if (write(arguments_pipe, &data, sizeof(trampoline_pipe_arguments)) != sizeof(trampoline_pipe_arguments)) {
+        ERR("Unable To Write Trampoline Command");
+    }
+    // Return
+    uint32_t ret;
+    if (read(return_value_pipe, &ret, sizeof(uint32_t)) != sizeof(uint32_t)) {
+        ERR("Unable To Read Trampoline Return Value");
+    }
+    return ret;
+}
+#else
+static uint32_t trampoline_pipe(__attribute__((unused)) const uint32_t id, __attribute__((unused)) const uint32_t length, __attribute__((unused)) const unsigned char *args) {
+    IMPOSSIBLE();
+}
+#endif
+
+// Main Function
+uint32_t _raw_trampoline(const uint32_t id, const uint32_t length, const unsigned char *args) {
+    // Configure Method
+    static int use_syscall = -1;
+    if (use_syscall == -1) {
+        use_syscall =
+#ifdef MCPI_USE_NATIVE_TRAMPOLINE
+            getenv(TRAMPOLINE_USE_PTRACE_ENV) != nullptr
+#else
+            1
+#endif
+            ;
+    }
+    // Use Correct Method
+    if (use_syscall) {
+        return trampoline_syscall(id, length, args);
+    } else {
+        return trampoline_pipe(id, length, args);
+    }
 }