intercept: Decouple hardcoding from the Steam logic

This allows us to match process names to work modes, so that we'll take one
path for Steam, and allow another path completely for "vendor offenders".

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

src/intercept/main.c

@@ -19,11 +19,24 @@
 #include "nica/nica.h"
 
 /**
- * Is this a process we're actually interested in?
+ * What's the known process name?
  */
-static bool process_supported = false;
 static const char *matched_process = NULL;
 
+/**
+ * We support a number of modes, but we mostly exist to make Steam behave
+ */
+typedef enum {
+        INTERCEPT_MODE_NONE = 0,
+        INTERCEPT_MODE_STEAM,
+        INTERCEPT_MODE_VENDOR_OFFENDER,
+} InterceptMode;
+
+/**
+ * by default, we're not "on"
+ */
+static InterceptMode work_mode = INTERCEPT_MODE_NONE;
+
 /* Patterns we'll permit Steam to privately load */
 static const char *steam_allowed[] = {
         /* general */
@@ -92,21 +105,16 @@ static inline char *get_process_name(void)
 }
 
 /**
- * Find out if we're being executed by a process we actually need to override,
- * otherwise we'd not be loaded by rtld-audit
+ * Determine if we're in a given process set, i.e. the process name matches
+ * the given table
  */
-static bool is_intercept_candidate(void)
+static bool is_in_process_set(char *process_name, const char **processes, size_t n_processes)
 {
-        autofree(char) *nom = NULL;
-
-        nom = get_process_name();
-        if (!nom) {
-                return false;
-        }
-
-        for (size_t i = 0; i < ARRAY_SIZE(wanted_steam_processes); i++) {
-                if (streq(wanted_steam_processes[i], nom)) {
-                        matched_process = wanted_steam_processes[i];
+        /* Are we some portion of the process set? */
+        for (size_t i = 0; i < n_processes; i++) {
+                if (streq(processes[i], process_name)) {
+                        work_mode = INTERCEPT_MODE_STEAM;
+                        matched_process = processes[i];
                         if (!getenv("LSI_DEBUG")) {
                                 return true;
                         }
@@ -119,6 +127,26 @@ static bool is_intercept_candidate(void)
         return false;
 }
 
+/**
+ * Find out if we're being executed by a process we actually need to override,
+ * otherwise we'd not be loaded by rtld-audit
+ */
+static void check_is_intercept_candidate(void)
+{
+        autofree(char) *nom = NULL;
+
+        nom = get_process_name();
+        if (!nom) {
+                return;
+        }
+
+        if (is_in_process_set(nom, wanted_steam_processes, ARRAY_SIZE(wanted_steam_processes))) {
+                work_mode = INTERCEPT_MODE_STEAM;
+        } else {
+                work_mode = INTERCEPT_MODE_NONE;
+        }
+}
+
 /**
  * la_version is our main entry point and will only continue if our
  * process is explicitly Steam
@@ -126,7 +154,7 @@ static bool is_intercept_candidate(void)
 _nica_public_ unsigned int la_version(unsigned int supported_version)
 {
         /* Unfortunately glibc will die if we tell it to skip us .. */
-        process_supported = is_intercept_candidate();
+        check_is_intercept_candidate();
         return supported_version;
 }
 
@@ -144,18 +172,10 @@ static void emit_overriden_lib(const char *lib_name)
 }
 
 /**
- * la_objsearch will allow us to blacklist certain LD_LIBRARY_PATH duplicate
- * libraries being loaded by the Steam client, such as the broken libSDL shipped
- * as a private vendored lib
+ * lsi_search_steam handles whitelisting for the main Steam processes
  */
-_nica_public_ char *la_objsearch(const char *name, __lsi_unused__ uintptr_t *cookie,
-                                 __lsi_unused__ unsigned int flag)
+char *lsi_search_steam(const char *name)
 {
-        /* We don't know about this process, so have glibc do its thing as normal */
-        if (!process_supported) {
-                return (char *)name;
-        }
-
         /* Find out if it exists */
         bool file_exists = nc_file_exists(name);
 
@@ -177,6 +197,28 @@ _nica_public_ char *la_objsearch(const char *name, __lsi_unused__ uintptr_t *coo
         return (char *)name;
 }
 
+/**
+ * la_objsearch will allow us to blacklist certain LD_LIBRARY_PATH duplicate
+ * libraries being loaded by the Steam client, such as the broken libSDL shipped
+ * as a private vendored lib
+ */
+_nica_public_ char *la_objsearch(const char *name, __lsi_unused__ uintptr_t *cookie,
+                                 __lsi_unused__ unsigned int flag)
+{
+        /* We don't know about this process, so have glibc do its thing as normal */
+        if (work_mode == INTERCEPT_MODE_NONE) {
+                return (char *)name;
+        }
+
+        switch (work_mode) {
+        case INTERCEPT_MODE_STEAM:
+                return lsi_search_steam(name);
+        case INTERCEPT_MODE_NONE:
+        default:
+                return (char *)name;
+        }
+}
+
 /*
  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
  *