feat: add spoofer

- spoofer redirects reads to /proc to ./proc

src/spoof/spoofer.c

@@ -0,0 +1,39 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <dlfcn.h>
+
+static FILE *(*real_fopen)(const char *path, const char *mode) = NULL;
+
+static void init_real_fopen(void) {
+    if (!real_fopen) {
+        real_fopen = dlsym(RTLD_NEXT, "fopen");
+        if (!real_fopen) {
+            fprintf(stderr, "proc_redirect: dlsym(fopen) failed: %s\n", dlerror());
+            abort();
+        }
+    }
+}
+
+FILE *fopen(const char *path, const char *mode) {
+    init_real_fopen();
+
+    if (path && strncmp(path, "/proc/", 6) == 0) {
+        const char *rel_suffix = path + 1;
+        size_t len = strlen(rel_suffix) + 3;
+        char *new_path = malloc(len);
+        if (!new_path) {
+            fprintf(stderr, "proc_redirect: malloc failed\n");
+            abort();
+        }
+        new_path[0] = '.';
+        new_path[1] = '/';
+        strcpy(new_path + 2, rel_suffix);
+
+        FILE *f = real_fopen(new_path, mode);
+        free(new_path);
+        return f;
+    }
+
+    return real_fopen(path, mode);
+}