redirect: Cheeky initial hack to see if we can replace paths

This is a very ugly hack right now but we'll prettify it and make
it all more generic, but right now it'll hotswap the depthblur
in Ark for the one coming from "TheCenter" mod.

Signed-off-by: Ikey Doherty <ikey@solus-project.com>

src/redirect/main.c

@@ -13,11 +13,13 @@
 
 #include <dlfcn.h>
 #include <errno.h>
+#include <libgen.h>
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/stat.h>
 
 #include "nica/util.h"
 
@@ -54,6 +56,12 @@ typedef struct LsiRedirectTable {
  */
 static LsiRedirectTable lsi_table = { 0 };
 
+static inline bool lsi_file_exists(const char *path)
+{
+        struct stat st = { .st_ino = 0 };
+        return (lstat(path, &st) == 0);
+}
+
 /**
  * Determine the basename'd process
  */
@@ -167,10 +175,46 @@ __attribute__((constructor)) static void lsi_redirect_init(void)
         fprintf(stderr, "Enabled lsi_redirect for: %s\n", process_name);
 }
 
+static char *lsi_redirect_replace_path(const char *path)
+{
+        char *dir = NULL;
+        autofree(char) *tmp = NULL;
+        char *transformed_path = NULL;
+
+        /* This is where we'd need to look at what game we are, and what we'd need
+         * to replace. For now, we're going to cheat, and give it a fixed path.
+         */
+        if (!strstr(path,
+                    "/ARK/ShooterGame/Content/PrimalEarth/Environment/Water/"
+                    "Water_DepthBlur_MIC.uasset")) {
+                return strdup(path);
+        }
+
+        tmp = strdup(path);
+        dir = dirname(tmp);
+
+        /* We want this guy: */
+        const char *new_path = "../../../Mods/TheCenter/Assets/Mic/Water_DepthBlur_MIC.uasset";
+        if (asprintf(&transformed_path, "%s/%s", dir, new_path) < 0) {
+                fputs("OUT OF MEMORY\n", stderr);
+                abort();
+        }
+
+        if (!lsi_file_exists(transformed_path)) {
+                fprintf(stderr, "Target path does not exist: %s\n", new_path);
+                free(transformed_path);
+                return strdup(path);
+        }
+
+        fprintf(stderr, "Replaced '%s' with '%s'\n", path, transformed_path);
+        return transformed_path;
+}
+
 _nica_public_ int open(const char *p, int flags, ...)
 {
         va_list va;
         mode_t mode;
+        autofree(char) *replaced_path = NULL;
 
         /* Must ensure we're **really** initialised, as we might see open happen
          * before the constructor..
@@ -187,9 +231,8 @@ _nica_public_ int open(const char *p, int flags, ...)
                 return lsi_table.open(p, flags, mode);
         }
 
-        /* TODO: Add redirection code here for paths */
-        fprintf(stderr, "begin open: %s\n", p);
-        return lsi_table.open(p, flags, mode);
+        replaced_path = lsi_redirect_replace_path(p);
+        return lsi_table.open(replaced_path, flags, mode);
 }
 
 /*