hush: reinstate cmd handling for NOMMU (with fat big warning).
hush: fix a case where none of pipe members could be started because of fork failure hush: rename functions: xxx_real -> xxx hush: try to add a bit more of vfork-friendliness hush: add rudimentary design docs hush: add TODO (newly discovered bug with globbing)
This commit is contained in:
Denis Vlasenko
parent
68e8e96d7f
commit
05743d7949
@ -664,6 +664,9 @@ enum {
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void re_exec(char **argv) ATTRIBUTE_NORETURN;
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void forkexit_or_rexec(char **argv);
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extern bool re_execed;
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int BUG_fork_is_unavailable_on_nommu(void);
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int BUG_daemon_is_unavailable_on_nommu(void);
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void BUG_bb_daemonize_is_unavailable_on_nommu(void);
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# define fork() BUG_fork_is_unavailable_on_nommu()
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# define daemon(a,b) BUG_daemon_is_unavailable_on_nommu()
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# define bb_daemonize(a) BUG_bb_daemonize_is_unavailable_on_nommu()
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182
shell/hush.c
182
shell/hush.c
@ -84,12 +84,24 @@
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#include "busybox.h" /* for APPLET_IS_NOFORK/NOEXEC */
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#if !BB_MMU
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/* A bit drastic. Can allow some simpler commands
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* by analysing command in generate_stream_from_list()
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*/
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#undef ENABLE_HUSH_TICK
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#define ENABLE_HUSH_TICK 0
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#if !BB_MMU && ENABLE_HUSH_TICK
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//#undef ENABLE_HUSH_TICK
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//#define ENABLE_HUSH_TICK 0
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#warning On NOMMU, hush command substitution is dangerous.
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#warning Dont use it for commands which produce lots of output.
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#warning For more info see shell/hush.c, generate_stream_from_list().
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#endif
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#if !BB_MMU && ENABLE_HUSH_JOB
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#undef ENABLE_HUSH_JOB
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#define ENABLE_HUSH_JOB 0
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#endif
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#if !ENABLE_HUSH_INTERACTIVE
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#undef ENABLE_FEATURE_EDITING
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#define ENABLE_FEATURE_EDITING 0
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#undef ENABLE_FEATURE_EDITING_FANCY_PROMPT
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#define ENABLE_FEATURE_EDITING_FANCY_PROMPT 0
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#endif
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@ -176,13 +188,6 @@ void xxfree(void *ptr)
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#endif
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#if !ENABLE_HUSH_INTERACTIVE
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#undef ENABLE_FEATURE_EDITING
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#define ENABLE_FEATURE_EDITING 0
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#undef ENABLE_FEATURE_EDITING_FANCY_PROMPT
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#define ENABLE_FEATURE_EDITING_FANCY_PROMPT 0
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#endif
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#define SPECIAL_VAR_SYMBOL 3
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#define PARSEFLAG_EXIT_FROM_LOOP 1
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@ -508,10 +513,10 @@ static int free_pipe_list(struct pipe *head, int indent);
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static int free_pipe(struct pipe *pi, int indent);
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/* really run the final data structures: */
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static int setup_redirects(struct child_prog *prog, int squirrel[]);
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static int run_list_real(struct pipe *pi);
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static int run_list(struct pipe *pi);
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static void pseudo_exec_argv(char **argv) ATTRIBUTE_NORETURN;
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static void pseudo_exec(struct child_prog *child) ATTRIBUTE_NORETURN;
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static int run_pipe_real(struct pipe *pi);
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static int run_pipe(struct pipe *pi);
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/* extended glob support: */
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static char **globhack(const char *src, char **strings);
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static int glob_needed(const char *s);
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@ -1416,7 +1421,7 @@ static void restore_redirects(int squirrel[])
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}
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}
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/* Called after [v]fork() in run_pipe_real(), or from builtin_exec().
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/* Called after [v]fork() in run_pipe(), or from builtin_exec().
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* Never returns.
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* XXX no exit() here. If you don't exec, use _exit instead.
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* The at_exit handlers apparently confuse the calling process,
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@ -1438,9 +1443,8 @@ static void pseudo_exec_argv(char **argv)
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/* If a variable is assigned in a forest, and nobody listens,
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* was it ever really set?
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*/
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if (argv[0] == NULL) {
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if (!argv[0])
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_exit(EXIT_SUCCESS);
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}
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argv = expand_strvec_to_strvec(argv);
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@ -1484,15 +1488,15 @@ static void pseudo_exec_argv(char **argv)
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_exit(1);
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}
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/* Called after [v]fork() in run_pipe_real()
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/* Called after [v]fork() in run_pipe()
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*/
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static void pseudo_exec(struct child_prog *child)
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{
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// FIXME: buggy wrt NOMMU! Must not modify any global data
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// until it does exec/_exit, but currently it does.
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if (child->argv) {
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// until it does exec/_exit, but currently it does
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// (puts malloc'ed stuff into environment)
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if (child->argv)
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pseudo_exec_argv(child->argv);
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}
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if (child->group) {
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#if !BB_MMU
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@ -1501,11 +1505,12 @@ static void pseudo_exec(struct child_prog *child)
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int rcode;
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#if ENABLE_HUSH_INTERACTIVE
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debug_printf_exec("pseudo_exec: setting interactive_fd=0\n");
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interactive_fd = 0; /* crucial!!!! */
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// run_list_level now takes care of it?
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// debug_printf_exec("pseudo_exec: setting interactive_fd=0\n");
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// interactive_fd = 0; /* crucial!!!! */
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#endif
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debug_printf_exec("pseudo_exec: run_list_real\n");
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rcode = run_list_real(child->group);
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debug_printf_exec("pseudo_exec: run_list\n");
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rcode = run_list(child->group);
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/* OK to leak memory by not calling free_pipe_list,
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* since this process is about to exit */
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_exit(rcode);
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@ -1753,13 +1758,13 @@ static int checkjobs_and_fg_shell(struct pipe* fg_pipe)
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}
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#endif
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/* run_pipe_real() starts all the jobs, but doesn't wait for anything
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/* run_pipe() starts all the jobs, but doesn't wait for anything
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* to finish. See checkjobs().
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*
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* return code is normally -1, when the caller has to wait for children
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* to finish to determine the exit status of the pipe. If the pipe
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* is a simple builtin command, however, the action is done by the
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* time run_pipe_real returns, and the exit code is provided as the
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* time run_pipe returns, and the exit code is provided as the
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* return value.
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*
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* The input of the pipe is always stdin, the output is always
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@ -1772,7 +1777,7 @@ static int checkjobs_and_fg_shell(struct pipe* fg_pipe)
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* Returns -1 only if started some children. IOW: we have to
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* mask out retvals of builtins etc with 0xff!
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*/
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static int run_pipe_real(struct pipe *pi)
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static int run_pipe(struct pipe *pi)
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{
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int i;
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int nextin;
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@ -1785,7 +1790,7 @@ static int run_pipe_real(struct pipe *pi)
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int rcode;
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const int single_fg = (pi->num_progs == 1 && pi->followup != PIPE_BG);
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debug_printf_exec("run_pipe_real start: single_fg=%d\n", single_fg);
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debug_printf_exec("run_pipe start: single_fg=%d\n", single_fg);
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#if ENABLE_HUSH_JOB
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pi->pgrp = -1;
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@ -1801,11 +1806,11 @@ static int run_pipe_real(struct pipe *pi)
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if (single_fg && child->group && child->subshell == 0) {
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debug_printf("non-subshell grouping\n");
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setup_redirects(child, squirrel);
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debug_printf_exec(": run_list_real\n");
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rcode = run_list_real(child->group);
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debug_printf_exec(": run_list\n");
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rcode = run_list(child->group) & 0xff;
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restore_redirects(squirrel);
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debug_printf_exec("run_pipe_real return %d\n", rcode);
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return rcode; // do we need to add '... & 0xff' ?
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debug_printf_exec("run_pipe return %d\n", rcode);
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return rcode;
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}
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if (single_fg && child->argv != NULL) {
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@ -1847,7 +1852,7 @@ static int run_pipe_real(struct pipe *pi)
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rcode = x->function(argv_expanded) & 0xff;
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free(argv_expanded);
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restore_redirects(squirrel);
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debug_printf_exec("run_pipe_real return %d\n", rcode);
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debug_printf_exec("run_pipe return %d\n", rcode);
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return rcode;
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}
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}
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@ -1864,7 +1869,7 @@ static int run_pipe_real(struct pipe *pi)
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rcode = run_nofork_applet_prime(&nofork_save, a, argv_expanded) & 0xff;
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free(argv_expanded);
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restore_redirects(squirrel);
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debug_printf_exec("run_pipe_real return %d\n", rcode);
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debug_printf_exec("run_pipe return %d\n", rcode);
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return rcode;
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}
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}
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@ -1892,24 +1897,22 @@ static int run_pipe_real(struct pipe *pi)
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if ((i + 1) < pi->num_progs)
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xpipe(pipefds);
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#if BB_MMU
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child->pid = fork();
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#else
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child->pid = vfork();
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#endif
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child->pid = BB_MMU ? fork() : vfork();
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if (!child->pid) { /* child */
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#if ENABLE_HUSH_JOB
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/* Every child adds itself to new process group
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* with pgid == pid of first child in pipe */
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* with pgid == pid_of_first_child_in_pipe */
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if (run_list_level == 1 && interactive_fd) {
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pid_t pgrp;
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/* Don't do pgrp restore anymore on fatal signals */
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set_fatal_sighandler(SIG_DFL);
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if (pi->pgrp < 0) /* true for 1st process only */
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pi->pgrp = getpid();
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if (setpgid(0, pi->pgrp) == 0 && pi->followup != PIPE_BG) {
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pgrp = pi->pgrp;
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if (pgrp < 0) /* true for 1st process only */
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pgrp = getpid();
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if (setpgid(0, pgrp) == 0 && pi->followup != PIPE_BG) {
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/* We do it in *every* child, not just first,
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* to avoid races */
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tcsetpgrp(interactive_fd, pi->pgrp);
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tcsetpgrp(interactive_fd, pgrp);
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}
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}
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#endif
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@ -1930,7 +1933,7 @@ static int run_pipe_real(struct pipe *pi)
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if (child->pid < 0) { /* [v]fork failed */
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/* Clearly indicate, was it fork or vfork */
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bb_perror_msg(BB_MMU ? "cannot fork" : "cannot vfork");
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bb_perror_msg(BB_MMU ? "fork" : "vfork");
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} else {
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pi->running_progs++;
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#if ENABLE_HUSH_JOB
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@ -1948,7 +1951,12 @@ static int run_pipe_real(struct pipe *pi)
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nextin = pipefds[0];
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}
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debug_printf_exec("run_pipe_real return -1\n");
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if (!pi->running_progs) {
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debug_printf_exec("run_pipe return 1 (all forks failed, no children)\n");
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return 1;
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}
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debug_printf_exec("run_pipe return -1 (%u children started)\n", pi->running_progs);
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return -1;
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}
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@ -2017,7 +2025,7 @@ static void debug_print_tree(struct pipe *pi, int lvl)
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/* NB: called by pseudo_exec, and therefore must not modify any
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* global data until exec/_exit (we can be a child after vfork!) */
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static int run_list_real(struct pipe *pi)
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static int run_list(struct pipe *pi)
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{
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struct pipe *rpipe;
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#if ENABLE_HUSH_LOOPS
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@ -2026,7 +2034,6 @@ static int run_list_real(struct pipe *pi)
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char **for_list = NULL;
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int flag_rep = 0;
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#endif
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int save_num_progs;
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int flag_skip = 1;
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int rcode = 0; /* probably for gcc only */
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int flag_restore = 0;
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@ -2038,7 +2045,7 @@ static int run_list_real(struct pipe *pi)
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reserved_style rword;
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reserved_style skip_more_for_this_rword = RES_XXXX;
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debug_printf_exec("run_list_real start lvl %d\n", run_list_level + 1);
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debug_printf_exec("run_list start lvl %d\n", run_list_level + 1);
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#if ENABLE_HUSH_LOOPS
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/* check syntax for "for" */
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@ -2047,7 +2054,7 @@ static int run_list_real(struct pipe *pi)
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&& (rpipe->next == NULL)
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) {
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syntax("malformed for"); /* no IN or no commands after IN */
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debug_printf_exec("run_list_real lvl %d return 1\n", run_list_level);
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debug_printf_exec("run_list lvl %d return 1\n", run_list_level);
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return 1;
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}
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if ((rpipe->res_word == RES_IN && rpipe->next->res_word == RES_IN && rpipe->next->progs[0].argv != NULL)
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@ -2055,7 +2062,7 @@ static int run_list_real(struct pipe *pi)
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) {
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/* TODO: what is tested in the first condition? */
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syntax("malformed for"); /* 2nd condition: not followed by IN */
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debug_printf_exec("run_list_real lvl %d return 1\n", run_list_level);
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debug_printf_exec("run_list lvl %d return 1\n", run_list_level);
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return 1;
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}
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}
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@ -2103,9 +2110,10 @@ static int run_list_real(struct pipe *pi)
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signal_SA_RESTART(SIGTSTP, handler_ctrl_z);
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signal(SIGINT, handler_ctrl_c);
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}
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#endif
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#endif /* JOB */
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for (; pi; pi = flag_restore ? rpipe : pi->next) {
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//why? int save_num_progs;
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rword = pi->res_word;
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#if ENABLE_HUSH_LOOPS
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if (rword == RES_WHILE || rword == RES_UNTIL || rword == RES_FOR) {
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@ -2178,12 +2186,12 @@ static int run_list_real(struct pipe *pi)
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#endif
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if (pi->num_progs == 0)
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continue;
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save_num_progs = pi->num_progs; /* save number of programs */
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debug_printf_exec(": run_pipe_real with %d members\n", pi->num_progs);
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rcode = run_pipe_real(pi);
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//why? save_num_progs = pi->num_progs;
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debug_printf_exec(": run_pipe with %d members\n", pi->num_progs);
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rcode = run_pipe(pi);
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if (rcode != -1) {
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/* We only ran a builtin: rcode was set by the return value
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* of run_pipe_real(), and we don't need to wait for anything. */
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* of run_pipe(), and we don't need to wait for anything. */
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} else if (pi->followup == PIPE_BG) {
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/* What does bash do with attempts to background builtins? */
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/* Even bash 3.2 doesn't do that well with nested bg:
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@ -2196,7 +2204,6 @@ static int run_list_real(struct pipe *pi)
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rcode = EXIT_SUCCESS;
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} else {
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#if ENABLE_HUSH_JOB
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/* Paranoia, just "interactive_fd" should be enough? */
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if (run_list_level == 1 && interactive_fd) {
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/* waits for completion, then fg's main shell */
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rcode = checkjobs_and_fg_shell(pi);
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@ -2210,7 +2217,7 @@ static int run_list_real(struct pipe *pi)
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}
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debug_printf_exec(": setting last_return_code=%d\n", rcode);
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last_return_code = rcode;
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pi->num_progs = save_num_progs; /* restore number of programs */
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//why? pi->num_progs = save_num_progs;
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#if ENABLE_HUSH_IF
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if (rword == RES_IF || rword == RES_ELIF)
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next_if_code = rcode; /* can be overwritten a number of times */
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@ -2241,7 +2248,7 @@ static int run_list_real(struct pipe *pi)
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signal(SIGINT, SIG_IGN);
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}
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#endif
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debug_printf_exec("run_list_real lvl %d return %d\n", run_list_level + 1, rcode);
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debug_printf_exec("run_list lvl %d return %d\n", run_list_level + 1, rcode);
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return rcode;
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}
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@ -2315,19 +2322,19 @@ static int free_pipe_list(struct pipe *head, int indent)
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}
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/* Select which version we will use */
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static int run_list(struct pipe *pi)
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static int run_and_free_list(struct pipe *pi)
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{
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int rcode = 0;
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debug_printf_exec("run_list entered\n");
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if (fake_mode == 0) {
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debug_printf_exec(": run_list_real with %d members\n", pi->num_progs);
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rcode = run_list_real(pi);
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debug_printf_exec("run_and_free_list entered\n");
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if (!fake_mode) {
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debug_printf_exec(": run_list with %d members\n", pi->num_progs);
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rcode = run_list(pi);
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}
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/* free_pipe_list has the side effect of clearing memory.
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* In the long run that function can be merged with run_list_real,
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* In the long run that function can be merged with run_list,
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* but doing that now would hobble the debugging effort. */
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free_pipe_list(pi, 0);
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debug_printf_exec("run_list return %d\n", rcode);
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free_pipe_list(pi, /* indent: */ 0);
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debug_printf_exec("run_nad_free_list return %d\n", rcode);
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return rcode;
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}
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@ -3221,15 +3228,17 @@ static FILE *generate_stream_from_list(struct pipe *head)
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int pid, channel[2];
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xpipe(channel);
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pid = fork();
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if (pid < 0) {
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bb_perror_msg_and_die("fork");
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} else if (pid == 0) {
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/* *** NOMMU WARNING *** */
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/* By using vfork here, we suspend parent till child exits or execs.
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* If child will not do it before it fills the pipe, it can block forever
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* in write(STDOUT_FILENO), and parent (shell) will be also stuck.
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*/
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pid = BB_MMU ? fork() : vfork();
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if (pid < 0)
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bb_perror_msg_and_die(BB_MMU ? "fork" : "vfork");
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if (pid == 0) { /* child */
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close(channel[0]);
|
||||
if (channel[1] != 1) {
|
||||
dup2(channel[1], 1);
|
||||
close(channel[1]);
|
||||
}
|
||||
xmove_fd(channel[1], 1);
|
||||
/* Prevent it from trying to handle ctrl-z etc */
|
||||
#if ENABLE_HUSH_JOB
|
||||
run_list_level = 1;
|
||||
@ -3241,11 +3250,12 @@ static FILE *generate_stream_from_list(struct pipe *head)
|
||||
* everywhere outside actual command execution. */
|
||||
/*set_jobctrl_sighandler(SIG_IGN);*/
|
||||
set_misc_sighandler(SIG_DFL);
|
||||
_exit(run_list_real(head)); /* leaks memory */
|
||||
_exit(run_list(head)); /* leaks memory */
|
||||
}
|
||||
close(channel[1]);
|
||||
pf = fdopen(channel[0], "r");
|
||||
return pf;
|
||||
/* head is freed by the caller */
|
||||
}
|
||||
|
||||
/* Return code is exit status of the process that is run. */
|
||||
@ -3269,7 +3279,8 @@ static int process_command_subs(o_string *dest, struct p_context *ctx,
|
||||
b_free(&result);
|
||||
|
||||
p = generate_stream_from_list(inner.list_head);
|
||||
if (p == NULL) return 1;
|
||||
if (p == NULL)
|
||||
return 1;
|
||||
close_on_exec_on(fileno(p));
|
||||
setup_file_in_str(&pipe_str, p);
|
||||
|
||||
@ -3294,7 +3305,7 @@ static int process_command_subs(o_string *dest, struct p_context *ctx,
|
||||
* at the same time. That would be a lot of work, and contrary
|
||||
* to the KISS philosophy of this program. */
|
||||
retcode = fclose(p);
|
||||
free_pipe_list(inner.list_head, 0);
|
||||
free_pipe_list(inner.list_head, /* indent: */ 0);
|
||||
debug_printf("closed FILE from child, retcode=%d\n", retcode);
|
||||
return retcode;
|
||||
}
|
||||
@ -3674,8 +3685,8 @@ static int parse_and_run_stream(struct in_str *inp, int parse_flag)
|
||||
done_word(&temp, &ctx);
|
||||
done_pipe(&ctx, PIPE_SEQ);
|
||||
debug_print_tree(ctx.list_head, 0);
|
||||
debug_printf_exec("parse_stream_outer: run_list\n");
|
||||
run_list(ctx.list_head);
|
||||
debug_printf_exec("parse_stream_outer: run_and_free_list\n");
|
||||
run_and_free_list(ctx.list_head);
|
||||
} else {
|
||||
if (ctx.old_flag != 0) {
|
||||
free(ctx.stack);
|
||||
@ -3684,7 +3695,7 @@ static int parse_and_run_stream(struct in_str *inp, int parse_flag)
|
||||
temp.nonnull = 0;
|
||||
temp.o_quote = 0;
|
||||
inp->p = NULL;
|
||||
free_pipe_list(ctx.list_head, 0);
|
||||
free_pipe_list(ctx.list_head, /* indent: */ 0);
|
||||
}
|
||||
b_free(&temp);
|
||||
} while (rcode != -1 && !(parse_flag & PARSEFLAG_EXIT_FROM_LOOP)); /* loop on syntax errors, return on EOF */
|
||||
@ -3898,14 +3909,13 @@ int hush_main(int argc, char **argv)
|
||||
|
||||
if (argv[optind] == NULL) {
|
||||
opt = parse_and_run_file(stdin);
|
||||
goto final_return;
|
||||
}
|
||||
|
||||
} else {
|
||||
debug_printf("\nrunning script '%s'\n", argv[optind]);
|
||||
global_argv = argv + optind;
|
||||
global_argc = argc - optind;
|
||||
input = xfopen(argv[optind], "r");
|
||||
opt = parse_and_run_file(input);
|
||||
}
|
||||
|
||||
final_return:
|
||||
|
||||
|
||||
39
shell/hush_doc.txt
Normal file
39
shell/hush_doc.txt
Normal file
@ -0,0 +1,39 @@
|
||||
This is how hush runs commands:
|
||||
|
||||
/* callsite: process_command_subs */
|
||||
generate_stream_from_list(struct pipe *head) - handles `cmds`
|
||||
create UNIX pipe
|
||||
[v]fork
|
||||
child:
|
||||
redirect pipe output to stdout
|
||||
_exit(run_list(head)); /* leaks memory */
|
||||
parent:
|
||||
return UNIX pipe's output fd
|
||||
/* head is freed by the caller */
|
||||
|
||||
/* callsite: parse_and_run_stream */
|
||||
run_and_free_list(struct pipe *)
|
||||
run_list(struct pipe *)
|
||||
free_pipe_list(struct pipe *)
|
||||
|
||||
/* callsites: generate_stream_from_list, run_and_free_list, pseudo_exec, run_pipe */
|
||||
run_list(struct pipe *) - handles "cmd; cmd2 && cmd3", while/for/do loops
|
||||
run_pipe - for every pipe in list
|
||||
|
||||
/* callsite: run_list */
|
||||
run_pipe - runs "cmd1 | cmd2 | cmd3 [&]"
|
||||
run_list - used if only one cmd and it is of the form "{ cmd4; cmd5 && cmd6; }"
|
||||
forks for every cmd if more than one cmd or if & is there
|
||||
pseudo_exec - runs each "cmdN" (handles builtins etc)
|
||||
|
||||
/* callsite: run_pipe_real */
|
||||
pseudo_exec - runs "cmd" (handles builtins etc)
|
||||
exec - execs external programs
|
||||
run_list - used if cmdN is "(cmds)" or "{cmds;}"
|
||||
/* problem: putenv's malloced strings into environ -
|
||||
** with vfork they will leak into parent process
|
||||
*/
|
||||
/* problem with ENABLE_FEATURE_SH_STANDALONE:
|
||||
** run_applet_no_and_exit(a, argv) uses exit - this can interfere
|
||||
** with vfork - switch to _exit there?
|
||||
*/
|
||||
@ -1,6 +1,9 @@
|
||||
#!/bin/sh
|
||||
|
||||
test -x hush || { echo "No ./hush?!"; exit; }
|
||||
test -x hush || {
|
||||
echo "No ./hush?! Perhaps you want to run 'ln -s ../../busybox hush'"
|
||||
exit
|
||||
}
|
||||
|
||||
PATH="$PWD:$PATH" # for hush and recho/zecho/printenv
|
||||
export PATH
|
||||
|
||||
19
shell/hush_test/zbad2
Normal file
19
shell/hush_test/zbad2
Normal file
@ -0,0 +1,19 @@
|
||||
## TODO: fix and add to testsuite
|
||||
|
||||
## # bash zbad2
|
||||
## ZVAR=z.map
|
||||
## *.map
|
||||
## # hush zbad2
|
||||
## ZVAR=z.map
|
||||
## z.map <====== !!!
|
||||
|
||||
## hush does globbing for "VAR=val" too!
|
||||
## it should do it only for non-assignments.
|
||||
## even if word looks like assignment, it can be non-assignemnt:
|
||||
## ZVAR=*.map /bin/echo ZVAR=*.map
|
||||
## ^dont_glob ^glob
|
||||
|
||||
>ZVAR=z.map
|
||||
ZVAR=*.map /bin/echo ZVAR=*.map
|
||||
ZVAR=*.map
|
||||
echo "$ZVAR"
|
||||
Loading…
Reference in New Issue
Block a user