mirror of
https://github.com/sheumann/hush.git
synced 2025-01-01 02:32:25 +00:00
hush: NOMMU-safe support of big heredocs
function old new delta setup_heredoc 116 215 +99
This commit is contained in:
Denis Vlasenko
parent
d4a24f2aae
commit
50f3aa4547
304
shell/hush.c
304
shell/hush.c
@ -22,7 +22,7 @@
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*
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* Other credits:
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* o_addchr derived from similar w_addchar function in glibc-2.2.
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* setup_redirect, redirect_opt_num, and big chunks of main
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* parse_redirect, redirect_opt_num, and big chunks of main
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* and many builtins derived from contributions by Erik Andersen.
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* Miscellaneous bugfixes from Matt Kraai.
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*
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@ -75,6 +75,9 @@
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#endif
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#include "math.h"
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#include "match.h"
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#ifndef PIPE_BUF
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# define PIPE_BUF 4096 /* amount of buffering in a pipe */
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#endif
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#ifdef WANT_TO_TEST_NOMMU
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# undef BB_MMU
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@ -2052,26 +2055,186 @@ static char **expand_assignments(char **argv, int count)
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}
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//TODO: fix big string case!
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#if BB_MMU
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void re_execute_shell(const char *s, int is_heredoc); /* never called */
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#define clean_up_after_re_execute() ((void)0)
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static void reset_traps_to_defaults(void)
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{
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unsigned sig;
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int dirty;
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if (!G.traps)
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return;
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dirty = 0;
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for (sig = 0; sig < NSIG; sig++) {
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if (!G.traps[sig])
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continue;
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free(G.traps[sig]);
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G.traps[sig] = NULL;
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/* There is no signal for 0 (EXIT) */
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if (sig == 0)
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continue;
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/* there was a trap handler, we are removing it
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* (if sig has non-DFL handling,
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* we don't need to do anything) */
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if (sig < 32 && (G.non_DFL_mask & (1 << sig)))
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continue;
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sigdelset(&G.blocked_set, sig);
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dirty = 1;
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}
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if (dirty)
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sigprocmask(SIG_SETMASK, &G.blocked_set, NULL);
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}
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#else /* !BB_MMU */
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static void re_execute_shell(const char *s, int is_heredoc) NORETURN;
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static void re_execute_shell(const char *s, int is_heredoc)
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{
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char param_buf[sizeof("-$%x:%x:%x:%x") + sizeof(unsigned) * 4];
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struct variable *cur;
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char **argv, **pp, **pp2;
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unsigned cnt;
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sprintf(param_buf, "-$%x:%x:%x" USE_HUSH_LOOPS(":%x")
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, (unsigned) G.root_pid
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, (unsigned) G.last_bg_pid
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, (unsigned) G.last_exitcode
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USE_HUSH_LOOPS(, G.depth_of_loop)
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);
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/* 1:hush 2:-$<pid>:<pid>:<exitcode>:<depth> <vars...>
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* 3:-c 4:<cmd> <argN...> 5:NULL
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*/
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cnt = 5 + G.global_argc;
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for (cur = G.top_var; cur; cur = cur->next) {
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if (!cur->flg_export || cur->flg_read_only)
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cnt += 2;
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}
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G.argv_from_re_execing = pp = xzalloc(sizeof(argv[0]) * cnt);
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*pp++ = (char *) G.argv0_for_re_execing;
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*pp++ = param_buf;
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for (cur = G.top_var; cur; cur = cur->next) {
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if (cur->varstr == hush_version_str)
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continue;
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if (cur->flg_read_only) {
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*pp++ = (char *) "-R";
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*pp++ = cur->varstr;
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} else if (!cur->flg_export) {
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*pp++ = (char *) "-V";
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*pp++ = cur->varstr;
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}
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}
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//TODO: pass functions
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/* We can pass activated traps here. Say, -Tnn:trap_string
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*
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* However, POSIX says that subshells reset signals with traps
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* to SIG_DFL.
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* I tested bash-3.2 and it not only does that with true subshells
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* of the form ( list ), but with any forked children shells.
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* I set trap "echo W" WINCH; and then tried:
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*
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* { echo 1; sleep 20; echo 2; } &
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* while true; do echo 1; sleep 20; echo 2; break; done &
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* true | { echo 1; sleep 20; echo 2; } | cat
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*
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* In all these cases sending SIGWINCH to the child shell
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* did not run the trap. If I add trap "echo V" WINCH;
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* _inside_ group (just before echo 1), it works.
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*
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* I conclude it means we don't need to pass active traps here.
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* exec syscall below resets them to SIG_DFL for us.
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*/
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*pp++ = (char *) (is_heredoc ? "-<" : "-c");
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*pp++ = (char *) s;
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pp2 = G.global_argv;
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while (*pp2)
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*pp++ = *pp2++;
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/* *pp = NULL; - is already there */
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debug_printf_exec("re_execute_shell pid:%d cmd:'%s'\n", getpid(), s);
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sigprocmask(SIG_SETMASK, &G.inherited_set, NULL);
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execv(bb_busybox_exec_path, G.argv_from_re_execing);
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/* Fallback. Useful for init=/bin/hush usage etc */
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if (G.argv0_for_re_execing[0] == '/')
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execv(G.argv0_for_re_execing, G.argv_from_re_execing);
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xfunc_error_retval = 127;
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bb_error_msg_and_die("can't re-execute the shell");
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}
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static void clean_up_after_re_execute(void)
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{
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char **pp = G.argv_from_re_execing;
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if (pp) {
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/* Must match re_execute_shell's allocations (if any) */
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free(pp);
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G.argv_from_re_execing = NULL;
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}
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}
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#endif /* !BB_MMU */
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static void setup_heredoc(int fd, const char *heredoc)
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{
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struct fd_pair pair;
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pid_t pid;
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int len, written;
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xpiped_pair(pair);
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xmove_fd(pair.rd, fd);
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len = strlen(heredoc);
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/* Try writing without forking. Newer kernels have
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* dynamically growing pipes. Must use non-blocking write! */
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ndelay_on(pair.wr);
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while (1) {
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written = write(pair.wr, heredoc, len);
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if (written <= 0)
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break;
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len -= written;
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if (len == 0) {
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close(pair.wr);
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return;
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}
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heredoc += written;
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}
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ndelay_off(pair.wr);
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/* Okay, pipe buffer was not big enough */
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/* Note: we must not create a stray child (bastard? :)
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* for the unsuspecting parent process. We create a grandchild
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* and exit before we exec the process which consumes heredoc
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* (that exec happens after we return from this function) */
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pid = vfork();
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if (pid < 0)
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bb_perror_msg_and_die("vfork");
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if (pid == 0) { /* child */
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die_sleep = 0;
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close(pair.rd);
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xwrite_str(pair.wr, heredoc);
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if (pid == 0) {
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/* child */
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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)
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_exit(0);
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/* grandchild */
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close(fd); /* read side of the pipe */
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#if BB_MMU
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full_write(pair.wr, heredoc, len);
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_exit(0);
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#else
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/* Delegate blocking writes to another process */
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# if ENABLE_HUSH_JOB
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die_sleep = 0; /* do not restore tty pgrp on xfunc death */
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# endif
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xmove_fd(pair.wr, STDOUT_FILENO);
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re_execute_shell(heredoc, 1);
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#endif
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}
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/* parent */
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die_sleep = -1;
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#if ENABLE_HUSH_JOB
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die_sleep = -1; /* restore tty pgrp on xfunc death */
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#endif
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clean_up_after_re_execute();
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close(pair.wr);
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xmove_fd(pair.rd, fd);
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wait(NULL); /* wiat till child has died */
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}
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/* squirrel != NULL means we squirrel away copies of stdin, stdout,
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@ -2329,122 +2492,6 @@ static void pseudo_exec_argv(nommu_save_t *nommu_save,
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_exit(EXIT_FAILURE);
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}
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#if BB_MMU
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static void reset_traps_to_defaults(void)
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{
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unsigned sig;
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int dirty;
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if (!G.traps)
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return;
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dirty = 0;
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for (sig = 0; sig < NSIG; sig++) {
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if (!G.traps[sig])
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continue;
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free(G.traps[sig]);
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G.traps[sig] = NULL;
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/* There is no signal for 0 (EXIT) */
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if (sig == 0)
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continue;
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/* there was a trap handler, we are removing it
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* (if sig has non-DFL handling,
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* we don't need to do anything) */
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if (sig < 32 && (G.non_DFL_mask & (1 << sig)))
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continue;
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sigdelset(&G.blocked_set, sig);
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dirty = 1;
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}
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if (dirty)
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sigprocmask(SIG_SETMASK, &G.blocked_set, NULL);
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}
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#define clean_up_after_re_execute() ((void)0)
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#else /* !BB_MMU */
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static void re_execute_shell(const char *s) NORETURN;
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static void re_execute_shell(const char *s)
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{
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char param_buf[sizeof("-$%x:%x:%x:%x") + sizeof(unsigned) * 4];
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struct variable *cur;
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char **argv, **pp, **pp2;
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unsigned cnt;
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sprintf(param_buf, "-$%x:%x:%x" USE_HUSH_LOOPS(":%x")
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, (unsigned) G.root_pid
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, (unsigned) G.last_bg_pid
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, (unsigned) G.last_exitcode
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USE_HUSH_LOOPS(, G.depth_of_loop)
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);
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/* 1:hush 2:-$<pid>:<pid>:<exitcode>:<depth> <vars...>
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* 3:-c 4:<cmd> <argN...> 5:NULL
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*/
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cnt = 5 + G.global_argc;
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for (cur = G.top_var; cur; cur = cur->next) {
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if (!cur->flg_export || cur->flg_read_only)
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cnt += 2;
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}
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G.argv_from_re_execing = pp = xzalloc(sizeof(argv[0]) * cnt);
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*pp++ = (char *) G.argv0_for_re_execing;
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*pp++ = param_buf;
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for (cur = G.top_var; cur; cur = cur->next) {
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if (cur->varstr == hush_version_str)
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continue;
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if (cur->flg_read_only) {
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*pp++ = (char *) "-R";
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*pp++ = cur->varstr;
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} else if (!cur->flg_export) {
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*pp++ = (char *) "-V";
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*pp++ = cur->varstr;
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}
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}
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//TODO: pass functions
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/* We can pass activated traps here. Say, -Tnn:trap_string
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*
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* However, POSIX says that subshells reset signals with traps
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* to SIG_DFL.
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* I tested bash-3.2 and it not only does that with true subshells
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* of the form ( list ), but with any forked children shells.
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* I set trap "echo W" WINCH; and then tried:
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*
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* { echo 1; sleep 20; echo 2; } &
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* while true; do echo 1; sleep 20; echo 2; break; done &
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* true | { echo 1; sleep 20; echo 2; } | cat
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*
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* In all these cases sending SIGWINCH to the child shell
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* did not run the trap. If I add trap "echo V" WINCH;
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* _inside_ group (just before echo 1), it works.
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*
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* I conclude it means we don't need to pass active traps here.
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* exec syscall below resets them to SIG_DFL for us.
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*/
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*pp++ = (char *) "-c";
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*pp++ = (char *) s;
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pp2 = G.global_argv;
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while (*pp2)
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*pp++ = *pp2++;
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/* *pp = NULL; - is already there */
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debug_printf_exec("re_execute_shell pid:%d cmd:'%s'\n", getpid(), s);
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sigprocmask(SIG_SETMASK, &G.inherited_set, NULL);
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execv(bb_busybox_exec_path, G.argv_from_re_execing);
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/* Fallback. Useful for init=/bin/hush usage etc */
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if (G.argv0_for_re_execing[0] == '/')
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execv(G.argv0_for_re_execing, G.argv_from_re_execing);
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xfunc_error_retval = 127;
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bb_error_msg_and_die("can't re-execute the shell");
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}
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static void clean_up_after_re_execute(void)
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{
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char **pp = G.argv_from_re_execing;
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if (pp) {
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/* Must match re_execute_shell's allocations (if any) */
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free(pp);
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G.argv_from_re_execing = NULL;
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}
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}
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#endif
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static int run_list(struct pipe *pi);
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/* Called after [v]fork() in run_pipe
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@ -2477,7 +2524,7 @@ static void pseudo_exec(nommu_save_t *nommu_save,
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* since this process is about to exit */
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_exit(rcode);
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#else
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re_execute_shell(command->group_as_string);
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re_execute_shell(command->group_as_string, 0);
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#endif
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}
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@ -4105,7 +4152,7 @@ static FILE *generate_stream_from_string(const char *s)
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* huge=`cat BIG` # was blocking here forever
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* echo OK
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*/
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re_execute_shell(s);
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re_execute_shell(s, 0);
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#endif
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}
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@ -5317,7 +5364,7 @@ int hush_main(int argc, char **argv)
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while (1) {
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opt = getopt(argc, argv, "c:xins"
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#if !BB_MMU
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"$:!:?:D:R:V:"
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"<:$:!:?:D:R:V:"
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#endif
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);
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if (opt <= 0)
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@ -5346,6 +5393,9 @@ int hush_main(int argc, char **argv)
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* operate, so simply do nothing here. */
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break;
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#if !BB_MMU
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case '<': /* "big heredoc" support */
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full_write(STDOUT_FILENO, optarg, strlen(optarg));
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_exit(0);
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case '$':
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G.root_pid = bb_strtou(optarg, &optarg, 16);
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optarg++;
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