Add a fake-self option to control the self symlink

* main.c (argp_parse, main): Add the --fake-self option.
* main.h: Publish it.
* rootdir.c (rootdir_gc_fakeself, rootdir_entries,
  rootdir_create_node): Use it.

3 files changed, 35 insertions, 13 deletions

diff --git a/main.c b/main.c
index 09cffc7..26f5248 100644
--- a/main.c
+++ b/main.c
@@ -13,6 +13,7 @@
 /* Command-line options */
 int opt_clk_tck;
 mode_t opt_stat_mode;
+pid_t opt_fake_self;
 
 static error_t
 argp_parser (int key, char *arg, struct argp_state *state)
@@ -32,6 +33,17 @@ argp_parser (int key, char *arg, struct argp_state *state)
       if (*endp || ! *arg || opt_stat_mode & ~07777)
 	error (1, 0, "--stat-mode: MODE should be an octal mode");
       break;
+
+    case 'S':
+      if (arg)
+        {
+	  opt_fake_self = strtol (arg, &endp, 0);
+	  if (*endp || ! *arg)
+	    error (1, 0, "--fake-self: PID must be an integer");
+	}
+      else
+	opt_fake_self = 1;
+      break;
   }
 
   return 0;
@@ -48,6 +60,10 @@ struct argp argp = {
 	"You can use this option to override its mode to be more permissive "
 	"for compatibility purposes.  "
 	"(default: 0400)" },
+    { "fake-self", 'S', "PID", OPTION_ARG_OPTIONAL,
+	"Provide a fake \"self\" symlink to the given PID, for compatibility "
+	"purposes.  If PID is omitted, \"self\" will point to init.  "
+	"(default: no self link)" },
     {}
   },
   .parser = argp_parser,
@@ -95,6 +111,7 @@ int main (int argc, char **argv)
 
   opt_clk_tck = sysconf(_SC_CLK_TCK);
   opt_stat_mode = 0400;
+  opt_fake_self = -1;
   argp_parse (&argp, argc, argv, 0, 0, 0);
 
   task_get_bootstrap_port (mach_task_self (), &bootstrap);
diff --git a/main.h b/main.h
index 6669d32..361380b 100644
--- a/main.h
+++ b/main.h
@@ -1,3 +1,4 @@
 /* Startup options */
 extern int opt_clk_tck;
 extern mode_t opt_stat_mode;
+extern pid_t opt_fake_self;
diff --git a/rootdir.c b/rootdir.c
index 1d9c083..833fc15 100644
--- a/rootdir.c
+++ b/rootdir.c
@@ -156,9 +156,8 @@ rootdir_gc_empty (void *hook, void **contents, size_t *contents_len)
 static error_t
 rootdir_gc_fakeself (void *hook, void **contents, size_t *contents_len)
 {
-  *contents = "1";
-  *contents_len = strlen (*contents);
-  return 0;
+  *contents_len = asprintf ((char **) contents, "%d", opt_fake_self);
+  return *contents_len >= 0 ? 0 : ENOMEM;
 }
 
 
@@ -177,7 +176,15 @@ rootdir_symlink_make_node (void *dir_hook, void *entry_hook)
   return np;
 }
 
-static struct procfs_dir_entry rootdir_entries[] = {
+static const struct procfs_dir_entry rootdir_entries[] = {
+  {
+    .name = "self",
+    .make_node = rootdir_symlink_make_node,
+    .hook = & (struct procfs_node_ops) {
+      .get_contents = rootdir_gc_fakeself,
+      .cleanup_contents = procfs_cleanup_contents_with_free,
+    },
+  },
   {
     .name = "version",
     .make_node = rootdir_file_make_node,
@@ -217,13 +224,6 @@ static struct procfs_dir_entry rootdir_entries[] = {
       .get_contents = rootdir_gc_empty,
     },
   },
-  {
-    .name = "self",
-    .make_node = rootdir_symlink_make_node,
-    .hook = & (struct procfs_node_ops) {
-      .get_contents = rootdir_gc_fakeself,
-    },
-  },
   {}
 };
 
@@ -231,14 +231,18 @@ error_t
 rootdir_create_node (struct node **np)
 {
   struct ps_context *pc;
+  const struct procfs_dir_entry *entries;
   error_t err;
 
   err = ps_context_create (getproc (), &pc);
   if (err)
     return err;
 
-  *np = procfs_dir_make_node (rootdir_entries, pc,
-			      (void (*)(void *)) ps_context_free);
+  entries = rootdir_entries;
+  if (opt_fake_self < 0)
+    entries++;
+
+  *np = procfs_dir_make_node (entries, pc, (void (*)(void *)) ps_context_free);
   return 0;
 }