From c560dc7ee2156891dc0dd2c271e4e7218e914434 Mon Sep 17 00:00:00 2001
From: Tau <tau@nowhere>
Date: Thu, 8 Nov 2018 16:02:34 -0500
Subject: [PATCH] util/spike.c: Add configurable log "spike" injector

---
 util/meson.build |   2 +
 util/spike.c     | 191 +++++++++++++++++++++++++++++++++++++++++++++++
 util/spike.h     |   3 +
 3 files changed, 196 insertions(+)
 create mode 100644 util/spike.c
 create mode 100644 util/spike.h

diff --git a/util/meson.build b/util/meson.build
index 1d69d09..455c6a3 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -19,5 +19,7 @@ util_lib = static_library(
         'gfx.h',
         'setupapi.c',
         'setupapi.h',
+        'spike.c',
+        'spike.h',
     ],
 )
diff --git a/util/spike.c b/util/spike.c
new file mode 100644
index 0000000..f399d49
--- /dev/null
+++ b/util/spike.c
@@ -0,0 +1,191 @@
+#include <windows.h>
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "hook/pe.h"
+
+#include "util/dprintf.h"
+#include "util/spike.h"
+
+/* Spike functions. Their "style" is named after the libc function they bear
+   the closest resemblance to. */
+
+static void spike_fn_puts(const char *msg)
+{
+    char line[512];
+
+    sprintf_s(line, _countof(line), "%s\n", msg);
+    OutputDebugStringA(line);
+}
+
+static void spike_fn_fputs(const char *msg)
+{
+    OutputDebugStringA(msg);
+}
+
+static void spike_fn_vprintf(
+        const char *proc,
+        int line_no,
+        const char *fmt,
+        va_list ap)
+{
+    char msg[512];
+    char line[512];
+
+    vsprintf_s(msg, _countof(msg), fmt, ap);
+    sprintf_s(line, _countof(line), "%s:%i: %s", proc, line_no, msg);
+    OutputDebugStringA(line);
+}
+
+static void spike_fn_vwprintf(
+        const wchar_t *proc,
+        int line_no,
+        const wchar_t *fmt,
+        va_list ap)
+{
+    wchar_t msg[512];
+    wchar_t line[512];
+
+    vswprintf_s(msg, _countof(msg), fmt, ap);
+    swprintf_s(line, _countof(line), L"%s:%i: %s", proc, line_no, msg);
+    OutputDebugStringW(line);
+}
+
+static void spike_fn_perror(
+        int a1,
+        int a2,
+        int error,
+        const char *file,
+        int line_no,
+        const char *msg)
+{
+    char line[512];
+
+    sprintf_s(
+            line,
+            _countof(line),
+            "%s:%i:%08x: %s\n",
+            file,
+            line_no,
+            error,
+            msg);
+
+    OutputDebugStringA(line);
+}
+
+/* Spike inserters */
+
+static void spike_insert_jmp(ptrdiff_t rva, void *proc)
+{
+    uint8_t *base;
+    uint8_t *target;
+    uint8_t *func_ptr;
+    uint32_t delta;
+
+    base = (uint8_t *) GetModuleHandleW(NULL);
+
+    target = base + rva;
+    func_ptr = proc;
+    delta = func_ptr - target - 4; /* -4: EIP delta, after end of target insn */
+
+    pe_patch(target, &delta, sizeof(delta));
+}
+
+static void spike_insert_ptr(ptrdiff_t rva, void *ptr)
+{
+    uint8_t *base;
+    uint8_t *target;
+
+    base = (uint8_t *) GetModuleHandleW(NULL);
+    target = base + rva;
+
+    pe_patch(target, &ptr, sizeof(ptr));
+}
+
+static void spike_insert_log_levels(ptrdiff_t rva, size_t count)
+{
+    uint8_t *base;
+    uint32_t *levels;
+    size_t i;
+
+    base = (uint8_t *) GetModuleHandleW(NULL);
+    levels = (uint32_t *) (base + rva);
+
+    for (i = 0 ; i < count ; i++) {
+        levels[i] = 255;
+    }
+}
+
+/* Config reader */
+
+void spike_hook_init(void)
+{
+    int match;
+    int count;
+    int rva;
+    char line[80];
+    char *ret;
+    FILE *f;
+
+    f = fopen("spike.txt", "r");
+
+    if (f == NULL) {
+        return;
+    }
+
+    dprintf("Found spike config, inserting spikes\n");
+
+    for (;;) {
+        ret = fgets(line, sizeof(line), f);
+
+        if (ret == NULL) {
+            break;
+        }
+
+        if (line[0] == '#' || line[0] == '\r' || line[0] == '\n') {
+            continue;
+        }
+
+        match = sscanf(line, "levels %i %i", &rva, &count);
+
+        if (match == 2) {
+            spike_insert_log_levels((ptrdiff_t) rva, count);
+        }
+
+        match = sscanf(line, "j_vprintf %i", &rva);
+
+        if (match == 1) {
+            spike_insert_jmp((ptrdiff_t) rva, spike_fn_vprintf);
+        }
+
+        match = sscanf(line, "j_vwprintf %i", &rva);
+
+        if (match == 1) {
+            spike_insert_jmp((ptrdiff_t) rva, spike_fn_vwprintf);
+        }
+
+        match = sscanf(line, "j_puts %i", &rva);
+
+        if (match == 1) {
+            spike_insert_jmp((ptrdiff_t) rva, spike_fn_puts);
+        }
+
+        match = sscanf(line, "j_perror %i", &rva);
+
+        if (match == 1) {
+            spike_insert_jmp((ptrdiff_t) rva, spike_fn_perror);
+        }
+
+        match = sscanf(line, "c_fputs %i", &rva); /* c == "callback" */
+
+        if (match == 1) {
+            spike_insert_ptr((ptrdiff_t) rva, spike_fn_fputs);
+        }
+    }
+
+    dprintf("Spike insertion complete\n");
+    fclose(f);
+}
diff --git a/util/spike.h b/util/spike.h
new file mode 100644
index 0000000..a62b4c7
--- /dev/null
+++ b/util/spike.h
@@ -0,0 +1,3 @@
+#pragma once
+
+void spike_hook_init(void);