Add --argv0 option

bubblewrap.c

@@ -72,6 +72,7 @@ static const char *opt_exec_label = NULL;
 static const char *opt_file_label = NULL;
 static bool opt_as_pid_1;
 
+static const char *opt_argv0 = NULL;
 static const char *opt_chdir_path = NULL;
 static bool opt_assert_userns_disabled = FALSE;
 static bool opt_disable_userns = FALSE;
@@ -309,6 +310,7 @@ usage (int ecode, FILE *out)
            "    --help                       Print this help\n"
            "    --version                    Print version\n"
            "    --args FD                    Parse NUL-separated args from FD\n"
+           "    --argv0 VALUE                Set argv[0] to the value VALUE before running the program\n"
            "    --unshare-all                Unshare every namespace we support by default\n"
            "    --share-net                  Retain the network namespace (can only combine with --unshare-all)\n"
            "    --unshare-user               Create new user namespace (may be automatically implied if not setuid)\n"
@@ -1728,6 +1730,18 @@ parse_args_recurse (int          *argcp,
           argv += 1;
           argc -= 1;
         }
+      else if (strcmp (arg, "--argv0") == 0)
+        {
+          if (argc < 2)
+            die ("--argv0 takes one argument");
+
+          if (opt_argv0 != NULL)
+            die ("--argv0 used multiple times");
+
+          opt_argv0 = argv[1];
+          argv++;
+          argc--;
+        }
       else if (strcmp (arg, "--unshare-all") == 0)
         {
           /* Keep this in order with the older (legacy) --unshare arguments,
@@ -2641,6 +2655,7 @@ main (int    argc,
   int res UNUSED;
   cleanup_free char *args_data UNUSED = NULL;
   int intermediate_pids_sockets[2] = {-1, -1};
+  const char *exec_path = NULL;
 
   /* Handle --version early on before we try to acquire/drop
    * any capabilities so it works in a build environment;
@@ -3351,7 +3366,11 @@ main (int    argc,
          we don't want to error out here */
     }
 
-  if (execvp (argv[0], argv) == -1)
+  exec_path = argv[0];
+  if (opt_argv0 != NULL)
+    argv[0] = (char *) opt_argv0;
+
+  if (execvp (exec_path, argv) == -1)
     {
       if (setup_finished_pipe[1] != -1)
         {
@@ -3362,7 +3381,7 @@ main (int    argc,
           /* Ignore res, if e.g. the parent died and closed setup_finished_pipe[0]
              we don't want to error out here */
         }
-      die_with_error ("execvp %s", argv[0]);
+      die_with_error ("execvp %s", exec_path);
     }
 
   return 0;

bwrap.xml

@@ -92,6 +92,10 @@
         multiple sources.
       </para></listitem>
     </varlistentry>
+    <varlistentry>
+      <term><option>--argv0 <arg choice="plain">VALUE</arg></option></term>
+      <listitem><para>Set argv[0] to the value <arg choice="plain">VALUE</arg> before running the program</para></listitem>
+    </varlistentry>
   </variablelist>
   <para>Options related to kernel namespaces:</para>
   <variablelist>

completions/bash/bwrap

@@ -32,6 +32,7 @@ _bwrap() {
 		$boolean_optons
 		--add-seccomp-fd
 		--args
+		--argv0
 		--bind
 		--bind-data
 		--block-fd

completions/zsh/_bwrap

@@ -29,6 +29,7 @@ _bwrap_args=(
     '--add-seccomp-fd[Load and use seccomp rules from FD]: :_guard "[0-9]#" "file descriptor to read seccomp rules from"'
     '--assert-userns-disabled[Fail unless further use of user namespace inside sandbox is disabled]'
     '--args[Parse NUL-separated args from FD]: :_guard "[0-9]#" "file descriptor with NUL-separated arguments"'
+    '--argv0[Set argv0 to the value VALUE before running the program]:value:'
     '--as-pid-1[Do not install a reaper process with PID=1]'
     '--bind-try[Equal to --bind but ignores non-existent SRC]:source:_files:destination:_files'
     '--bind[Bind mount the host path SRC on DEST]:source:_files:destination:_files'

tests/test-run.sh

@@ -8,7 +8,7 @@ srcd=$(cd $(dirname "$0") && pwd)
 
 bn=$(basename "$0")
 
-echo "1..58"
+echo "1..59"
 
 # Test help
 ${BWRAP} --help > help.txt
@@ -532,4 +532,12 @@ echo "PWD=$(pwd -P)" > reference
 assert_files_equal stdout reference
 echo "ok - environment manipulation"
 
+$RUN sh -c 'echo $0' > stdout
+assert_file_has_content stdout sh
+$RUN --argv0 sh sh -c 'echo $0' > stdout
+assert_file_has_content stdout sh
+$RUN --argv0 right sh -c 'echo $0' > stdout
+assert_file_has_content stdout right
+echo "ok - argv0 manipulation"
+
 echo "ok - End of test"