shim: Split majority of the code into shim.c

This helps separate the main launch entry from the bulk of the bootstrap
code, and will also allow us to build a new lsi-exec tool that will just
execute whatever you tell it to, with the full shim setup routine.

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

src/shim/main.c

@@ -0,0 +1,71 @@
+/*
+ * This file is part of linux-steam-integration.
+ *
+ * Copyright © 2016-2017 Ikey Doherty <ikey@solus-project.com>
+ *
+ * linux-steam-integration is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1
+ * of the License, or (at your option) any later version.
+ */
+
+#define _GNU_SOURCE
+
+#include <linux/limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "../common/files.h"
+#include "lsi.h"
+#include "shim.h"
+
+/**
+ * Helper to get the Steam binary, respecting "$SNAP" if needed
+ */
+static const char *shim_get_steam_binary(const char *prefix)
+{
+        static char tgt[PATH_MAX] = { 0 };
+
+        if (snprintf(tgt, sizeof(tgt), "%s%s", prefix ? prefix : "", STEAM_BINARY) < 0) {
+                return STEAM_BINARY;
+        }
+
+        return tgt;
+}
+
+int main(int argc, char **argv)
+{
+        const char *operation_prefix = NULL;
+        const char *steam_binary = NULL;
+
+        if (!shim_bootstrap()) {
+                return EXIT_FAILURE;
+        }
+
+#ifdef HAVE_SNAPD_SUPPORT
+        operation_prefix = getenv("SNAP");
+#endif
+
+        steam_binary = shim_get_steam_binary(operation_prefix);
+
+        if (!lsi_file_exists(steam_binary)) {
+                lsi_report_failure("Steam isn't currently installed at %s", steam_binary);
+                return EXIT_FAILURE;
+        }
+
+        return shim_execute(steam_binary, --argc, ++argv);
+}
+
+/*
+ * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 8
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * vi: set shiftwidth=8 tabstop=8 expandtab:
+ * :indentSize=8:tabSize=8:noTabs=true:
+ */

src/shim/meson.build

@@ -7,6 +7,7 @@ endif
 if shim_behaviour != 'none'
     shim_sources = [
         'shim.c',
+        'main.c',
     ]
 
     shim = executable(

src/shim/shim.c

@@ -24,6 +24,7 @@
 #include "../nica/files.h"
 #include "config.h"
 #include "lsi.h"
+#include "shim.h"
 
 /**
  * Required to force Steam into 32-bit detection mode, which is useful for
@@ -96,20 +97,6 @@ static void shim_set_ld_preload(const char *prefix)
         shim_export_merge_vars("LD_PRELOAD", prefix, REDIRECT_PATH);
 }
 
-/**
- * Helper to get the Steam binary, respecting "$SNAP" if needed
- */
-static const char *shim_get_steam_binary(const char *prefix)
-{
-        static char tgt[PATH_MAX] = { 0 };
-
-        if (snprintf(tgt, sizeof(tgt), "%s%s", prefix ? prefix : "", STEAM_BINARY) < 0) {
-                return STEAM_BINARY;
-        }
-
-        return tgt;
-}
-
 #ifdef HAVE_SNAPD_SUPPORT
 /**
  * This function is only used during our initial bootstrap phase to ensure
@@ -281,53 +268,42 @@ static void shim_export_extra(__lsi_unused__ const char *prefix)
 }
 #endif
 
-int main(int argc, char **argv)
+static LsiConfig lsi_config = { 0 };
+
+/* Public API */
+
+bool shim_bootstrap()
 {
-        LsiConfig config = { 0 };
-        bool is_x86_64;
-        const char *n_argv[argc + 2];
-        const char *exec_command = NULL;
-        /* Use the appropriate Steam depending on configuration */
-        const char *lsi_exec_bin = NULL;
-        int i = 1;
-        int8_t off = 0;
-        int (*vfunc)(const char *, char *const argv[]) = NULL;
         const char *operation_prefix = NULL;
 
 #ifdef HAVE_SNAPD_SUPPORT
+        /* Snapd specific prefix */
         operation_prefix = getenv("SNAP");
 #endif
 
-        lsi_exec_bin = shim_get_steam_binary(operation_prefix);
-
-        /* Initialise config */
-        if (!lsi_config_load(&config)) {
-                lsi_config_load_defaults(&config);
+        /* Ensure we now have some kind of config */
+        if (!lsi_config_load(&lsi_config)) {
+                lsi_config_load_defaults(&lsi_config);
         }
 
-        is_x86_64 = lsi_system_is_64bit();
-
-        if (!lsi_file_exists(lsi_exec_bin)) {
-                lsi_report_failure("Steam isn't currently installed at %s", lsi_exec_bin);
-                return EXIT_FAILURE;
-        }
+        errno = 0;
 
         /* We might have additional variables we need to export */
         shim_export_extra(operation_prefix);
 
         /* Force STEAM_RUNTIME into the environment */
-        if (config.use_native_runtime) {
+        if (lsi_config.use_native_runtime) {
                 /* Explicitly disable the runtime */
                 setenv("STEAM_RUNTIME", "0", 1);
 #ifdef HAVE_LIBINTERCEPT
                 /* Only use libintercept in combination with native runtime! */
-                if (config.use_libintercept) {
+                if (lsi_config.use_libintercept) {
                         shim_set_audit_path(operation_prefix);
                 }
 #endif
 #ifdef HAVE_LIBREDIRECT
                 /* Only use libredirect in combination with native runtime! */
-                if (config.use_libredirect) {
+                if (lsi_config.use_libredirect) {
                         shim_set_ld_preload(operation_prefix);
                 }
 #endif
@@ -353,37 +329,56 @@ int main(int argc, char **argv)
         unsetenv("XMODIFIERS");
         unsetenv("GTK_MODULES");
 
-        memset(&n_argv, 0, sizeof(char *) * (argc + 2));
+        if (errno != 0) {
+                lsi_report_failure("Failed to bootstrap LSI: %s", strerror(errno));
+                return false;
+        }
+
+        /* All done now. */
+        return true;
+}
+
+int shim_execute(const char *command, int argc, char **argv)
+{
+        bool is_x86_64;
+        const char *n_argv[argc + 3];
+        const char *exec_command = NULL;
+        int i = 1;
+        int8_t off = 1;
+        int (*vfunc)(const char *, char *const argv[]) = NULL;
+
+        is_x86_64 = lsi_system_is_64bit();
+        memset(&n_argv, 0, sizeof(char *) * (argc + 3));
 
         /* If we're 64-bit and 32-bit is forced, proxy via linux32 */
-        if (config.force_32 && is_x86_64) {
+        if (lsi_config.force_32 && is_x86_64) {
                 exec_command = EMUL32BIN;
                 n_argv[0] = EMUL32BIN;
-                n_argv[1] = lsi_exec_bin;
-                off = 1;
+                n_argv[1] = command;
+                off = 2;
                 /* Use linux32 in the path */
                 vfunc = execvp;
         } else {
                 /* Directly call lsi_exec_bin */
-                exec_command = lsi_exec_bin;
-                n_argv[0] = lsi_exec_bin;
+                exec_command = command;
+                n_argv[0] = command;
                 /* Full path here due to shadow nature */
                 vfunc = execv;
         }
 
         /* Point arguments to arguments passed to us */
-        for (i = 1; i < argc; i++) {
+        for (i = 0; i < argc; i++) {
                 n_argv[i + off] = argv[i];
         }
         n_argv[i + 1 + off] = NULL;
 
         /* Go execute steam. */
         if (vfunc(exec_command, (char **)n_argv) < 0) {
-                lsi_report_failure("Failed to launch Steam: %s [%s]",
-                                   strerror(errno),
-                                   lsi_exec_bin);
+                lsi_report_failure("Failed to launch command: %s [%s]", strerror(errno), command);
                 return EXIT_FAILURE;
         }
+        /* Can't happen */
+        return EXIT_FAILURE;
 }
 
 /*

src/shim/shim.h

@@ -0,0 +1,40 @@
+/*
+ * This file is part of linux-steam-integration.
+ *
+ * Copyright © 2016-2017 Ikey Doherty <ikey@solus-project.com>
+ *
+ * linux-steam-integration is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1
+ * of the License, or (at your option) any later version.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdbool.h>
+
+/**
+ * Attempt to bootstrap the shim environment prior to execution of
+ * a command.
+ */
+bool shim_bootstrap(void);
+
+/**
+ * Execute the given command
+ *
+ * @note If this succeeds, we will not return
+ */
+int shim_execute(const char *command, int argc, char **argv);
+
+/*
+ * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 8
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * vi: set shiftwidth=8 tabstop=8 expandtab:
+ * :indentSize=8:tabSize=8:noTabs=true:
+ */