/*
 * execute command tree
 */
int
execute(struct op * volatile t,
    /* if XEXEC don't fork */
    volatile int flags,
    volatile int * volatile xerrok)
{
	int i;
	volatile int rv = 0, dummy = 0;
	int pv[2];
	const char ** volatile ap = NULL;
	char ** volatile up;
	const char *s, *ccp;
	struct ioword **iowp;
	struct tbl *tp = NULL;
	char *cp;

	if (t == NULL)
		return (0);

	/* Caller doesn't care if XERROK should propagate. */
	if (xerrok == NULL)
		xerrok = &dummy;

	if ((flags&XFORK) && !(flags&XEXEC) && t->type != TPIPE)
		/* run in sub-process */
		return (exchild(t, flags & ~XTIME, xerrok, -1));

	newenv(E_EXEC);
	if (trap)
		runtraps(0);

	/* we want to run an executable, do some variance checks */
	if (t->type == TCOM) {
		/* check if this is 'var=<<EOF' */
		if (
		    /* we have zero arguments, i.e. no programme to run */
		    t->args[0] == NULL &&
		    /* we have exactly one variable assignment */
		    t->vars[0] != NULL && t->vars[1] == NULL &&
		    /* we have exactly one I/O redirection */
		    t->ioact != NULL && t->ioact[0] != NULL &&
		    t->ioact[1] == NULL &&
		    /* of type "here document" (or "here string") */
		    (t->ioact[0]->flag & IOTYPE) == IOHERE &&
		    /* the variable assignment begins with a valid varname */
		    (ccp = skip_wdvarname(t->vars[0], true)) != t->vars[0] &&
		    /* and has no right-hand side (i.e. "varname=") */
		    ccp[0] == CHAR && ccp[1] == '=' && ccp[2] == EOS &&
		    /* plus we can have a here document content */
		    herein(t->ioact[0], &cp) == 0 && cp && *cp) {
			char *sp = cp, *dp;
			size_t n = ccp - t->vars[0] + 2, z;

			/* drop redirection (will be garbage collected) */
			t->ioact = NULL;

			/* set variable to its expanded value */
			z = strlen(cp) + 1;
			if (notoktomul(z, 2) || notoktoadd(z * 2, n))
				internal_errorf(Toomem, (unsigned long)-1);
			dp = alloc(z * 2 + n, ATEMP);
			memcpy(dp, t->vars[0], n);
			t->vars[0] = dp;
			dp += n;
			while (*sp) {
				*dp++ = QCHAR;
				*dp++ = *sp++;
			}
			*dp = EOS;
			/* free the expanded value */
			afree(cp, APERM);
		}

		/*
		 * Clear subst_exstat before argument expansion. Used by
		 * null commands (see comexec() and c_eval()) and by c_set().
		 */
		subst_exstat = 0;

		/* for $LINENO */
		current_lineno = t->lineno;

		/*
		 * POSIX says expand command words first, then redirections,
		 * and assignments last..
		 */
		up = eval(t->args, t->u.evalflags | DOBLANK | DOGLOB | DOTILDE);
		if (flags & XTIME)
			/* Allow option parsing (bizarre, but POSIX) */
			timex_hook(t, &up);
		ap = (const char **)up;
		if (Flag(FXTRACE) && ap[0]) {
			shf_puts(substitute(str_val(global("PS4")), 0),
			    shl_out);
			for (i = 0; ap[i]; i++)
				shf_fprintf(shl_out, "%s%c", ap[i],
				    ap[i + 1] ? ' ' : '\n');
			shf_flush(shl_out);
		}
		if (ap[0])
			tp = findcom(ap[0], FC_BI|FC_FUNC);
	}
	flags &= ~XTIME;

	if (t->ioact != NULL || t->type == TPIPE || t->type == TCOPROC) {
		e->savefd = alloc2(NUFILE, sizeof(short), ATEMP);
		/* initialise to not redirected */
		memset(e->savefd, 0, NUFILE * sizeof(short));
	}

	/* mark for replacement later (unless TPIPE) */
	vp_pipest->flag |= INT_L;

	/* do redirection, to be restored in quitenv() */
	if (t->ioact != NULL)
		for (iowp = t->ioact; *iowp != NULL; iowp++) {
			if (iosetup(*iowp, tp) < 0) {
				exstat = rv = 1;
				/*
				 * Redirection failures for special commands
				 * cause (non-interactive) shell to exit.
				 */
				if (tp && tp->type == CSHELL &&
				    (tp->flag & SPEC_BI))
					errorfz();
				/* Deal with FERREXIT, quitenv(), etc. */
				goto Break;
			}
		}

	switch (t->type) {
	case TCOM:
		rv = comexec(t, tp, (const char **)ap, flags, xerrok);
		break;

	case TPAREN:
		rv = execute(t->left, flags | XFORK, xerrok);
		break;

	case TPIPE:
		flags |= XFORK;
		flags &= ~XEXEC;
		e->savefd[0] = savefd(0);
		e->savefd[1] = savefd(1);
		while (t->type == TPIPE) {
			openpipe(pv);
			/* stdout of curr */
			ksh_dup2(pv[1], 1, false);
			/**
			 * Let exchild() close pv[0] in child
			 * (if this isn't done, commands like
			 *	(: ; cat /etc/termcap) | sleep 1
			 * will hang forever).
			 */
			exchild(t->left, flags | XPIPEO | XCCLOSE,
			    NULL, pv[0]);
			/* stdin of next */
			ksh_dup2(pv[0], 0, false);
			closepipe(pv);
			flags |= XPIPEI;
			t = t->right;
		}
		/* stdout of last */
		restfd(1, e->savefd[1]);
		/* no need to re-restore this */
		e->savefd[1] = 0;
		/* Let exchild() close 0 in parent, after fork, before wait */
		i = exchild(t, flags | XPCLOSE | XPIPEST, xerrok, 0);
		if (!(flags&XBGND) && !(flags&XXCOM))
			rv = i;
		break;

	case TLIST:
		while (t->type == TLIST) {
			execute(t->left, flags & XERROK, NULL);
			t = t->right;
		}
		rv = execute(t, flags & XERROK, xerrok);
		break;

	case TCOPROC: {
#ifndef MKSH_NOPROSPECTOFWORK
		sigset_t omask;

		/*
		 * Block sigchild as we are using things changed in the
		 * signal handler
		 */
		sigprocmask(SIG_BLOCK, &sm_sigchld, &omask);
		e->type = E_ERRH;
		if ((i = kshsetjmp(e->jbuf))) {
			sigprocmask(SIG_SETMASK, &omask, NULL);
			quitenv(NULL);
			unwind(i);
			/* NOTREACHED */
		}
#endif
		/* Already have a (live) co-process? */
		if (coproc.job && coproc.write >= 0)
			errorf("coprocess already exists");

		/* Can we re-use the existing co-process pipe? */
		coproc_cleanup(true);

		/* do this before opening pipes, in case these fail */
		e->savefd[0] = savefd(0);
		e->savefd[1] = savefd(1);

		openpipe(pv);
		if (pv[0] != 0) {
			ksh_dup2(pv[0], 0, false);
			close(pv[0]);
		}
		coproc.write = pv[1];
		coproc.job = NULL;

		if (coproc.readw >= 0)
			ksh_dup2(coproc.readw, 1, false);
		else {
			openpipe(pv);
			coproc.read = pv[0];
			ksh_dup2(pv[1], 1, false);
			/* closed before first read */
			coproc.readw = pv[1];
			coproc.njobs = 0;
			/* create new coprocess id */
			++coproc.id;
		}
#ifndef MKSH_NOPROSPECTOFWORK
		sigprocmask(SIG_SETMASK, &omask, NULL);
		/* no more need for error handler */
		e->type = E_EXEC;
#endif

		/*
		 * exchild() closes coproc.* in child after fork,
		 * will also increment coproc.njobs when the
		 * job is actually created.
		 */
		flags &= ~XEXEC;
		exchild(t->left, flags | XBGND | XFORK | XCOPROC | XCCLOSE,
		    NULL, coproc.readw);
		break;
	}

	case TASYNC:
		/*
		 * XXX non-optimal, I think - "(foo &)", forks for (),
		 * forks again for async... parent should optimise
		 * this to "foo &"...
		 */
		rv = execute(t->left, (flags&~XEXEC)|XBGND|XFORK, xerrok);
		break;

	case TOR:
	case TAND:
		rv = execute(t->left, XERROK, xerrok);
		if ((rv == 0) == (t->type == TAND))
			rv = execute(t->right, XERROK, xerrok);
		flags |= XERROK;
		if (xerrok)
			*xerrok = 1;
		break;

	case TBANG:
		rv = !execute(t->right, XERROK, xerrok);
		flags |= XERROK;
		if (xerrok)
			*xerrok = 1;
		break;

	case TDBRACKET: {
		Test_env te;

		te.flags = TEF_DBRACKET;
		te.pos.wp = t->args;
		te.isa = dbteste_isa;
		te.getopnd = dbteste_getopnd;
		te.eval = test_eval;
		te.error = dbteste_error;

		rv = test_parse(&te);
		break;
	}

	case TFOR:
	case TSELECT: {
		volatile bool is_first = true;
		ap = (t->vars == NULL) ? e->loc->argv + 1 :
		    (const char **)eval((const char **)t->vars,
		    DOBLANK | DOGLOB | DOTILDE);
		e->type = E_LOOP;
		while ((i = kshsetjmp(e->jbuf))) {
			if ((e->flags&EF_BRKCONT_PASS) ||
			    (i != LBREAK && i != LCONTIN)) {
				quitenv(NULL);
				unwind(i);
			} else if (i == LBREAK) {
				rv = 0;
				goto Break;
			}
		}
		/* in case of a continue */
		rv = 0;
		if (t->type == TFOR) {
			while (*ap != NULL) {
				setstr(global(t->str), *ap++, KSH_UNWIND_ERROR);
				rv = execute(t->left, flags & XERROK, xerrok);
			}
		} else {
			/* TSELECT */
			for (;;) {
				if (!(ccp = do_selectargs(ap, is_first))) {
					rv = 1;
					break;
				}
				is_first = false;
				setstr(global(t->str), ccp, KSH_UNWIND_ERROR);
				execute(t->left, flags & XERROK, xerrok);
			}
		}
		break;
	}

	case TWHILE:
	case TUNTIL:
		e->type = E_LOOP;
		while ((i = kshsetjmp(e->jbuf))) {
			if ((e->flags&EF_BRKCONT_PASS) ||
			    (i != LBREAK && i != LCONTIN)) {
				quitenv(NULL);
				unwind(i);
			} else if (i == LBREAK) {
				rv = 0;
				goto Break;
			}
		}
		/* in case of a continue */
		rv = 0;
		while ((execute(t->left, XERROK, NULL) == 0) ==
		    (t->type == TWHILE))
			rv = execute(t->right, flags & XERROK, xerrok);
		break;

	case TIF:
	case TELIF:
		if (t->right == NULL)
			/* should be error */
			break;
		rv = execute(t->left, XERROK, NULL) == 0 ?
		    execute(t->right->left, flags & XERROK, xerrok) :
		    execute(t->right->right, flags & XERROK, xerrok);
		break;

	case TCASE:
		i = 0;
		ccp = evalstr(t->str, DOTILDE);
		for (t = t->left; t != NULL && t->type == TPAT; t = t->right) {
			for (ap = (const char **)t->vars; *ap; ap++) {
				if (i || ((s = evalstr(*ap, DOTILDE|DOPAT)) &&
				    gmatchx(ccp, s, false))) {
					rv = execute(t->left, flags & XERROK,
					    xerrok);
					i = 0;
					switch (t->u.charflag) {
					case '&':
						i = 1;
						/* FALLTHROUGH */
					case '|':
						goto TCASE_next;
					}
					goto TCASE_out;
				}
			}
			i = 0;
 TCASE_next:
			/* empty */;
		}
 TCASE_out:
		break;

	case TBRACE:
		rv = execute(t->left, flags & XERROK, xerrok);
		break;

	case TFUNCT:
		rv = define(t->str, t);
		break;

	case TTIME:
		/*
		 * Clear XEXEC so nested execute() call doesn't exit
		 * (allows "ls -l | time grep foo").
		 */
		rv = timex(t, flags & ~XEXEC, xerrok);
		break;

	case TEXEC:
		/* an eval'd TCOM */
		s = t->args[0];
		up = makenv();
		restoresigs();
		cleanup_proc_env();
		{
			union mksh_ccphack cargs;

			cargs.ro = t->args;
			execve(t->str, cargs.rw, up);
			rv = errno;
		}
		if (rv == ENOEXEC)
			scriptexec(t, (const char **)up);
		else
			errorf("%s: %s", s, cstrerror(rv));
	}
 Break:
	exstat = rv & 0xFF;
	if (vp_pipest->flag & INT_L) {
		unset(vp_pipest, 1);
		vp_pipest->flag = DEFINED | ISSET | INTEGER | RDONLY |
		    ARRAY | INT_U;
		vp_pipest->val.i = rv;
	}

	/* restores IO */
	quitenv(NULL);
	if ((flags&XEXEC))
		/* exit child */
		unwind(LEXIT);
	if (rv != 0 && !(flags & XERROK) &&
	    (xerrok == NULL || !*xerrok)) {
		if (Flag(FERREXIT) & 0x80) {
			/* inside eval */
			Flag(FERREXIT) = 0;
		} else {
			trapsig(ksh_SIGERR);
			if (Flag(FERREXIT))
				unwind(LERROR);
		}
	}
	return (rv);
}
示例#2
0
文件: misc.c 项目: rovaughn/distro
char *
do_realpath(const char *upath)
{
	char *xp, *ip, *tp, *ipath, *ldest = NULL;
	XString xs;
	size_t pos, len;
	int llen;
	struct stat sb;
#ifdef MKSH__NO_PATH_MAX
	size_t ldestlen = 0;
#define pathlen sb.st_size
#define pathcnd (ldestlen < (pathlen + 1))
#else
#define pathlen PATH_MAX
#define pathcnd (!ldest)
#endif
	/* max. recursion depth */
	int symlinks = 32;

	if (mksh_abspath(upath)) {
		/* upath is an absolute pathname */
		strdupx(ipath, upath, ATEMP);
	} else {
		/* upath is a relative pathname, prepend cwd */
		if ((tp = ksh_get_wd()) == NULL || !mksh_abspath(tp))
			return (NULL);
		ipath = shf_smprintf("%s%s%s", tp, "/", upath);
		afree(tp, ATEMP);
	}

	/* ipath and upath are in memory at the same time -> unchecked */
	Xinit(xs, xp, strlen(ip = ipath) + 1, ATEMP);

	/* now jump into the deep of the loop */
	goto beginning_of_a_pathname;

	while (*ip) {
		/* skip slashes in input */
		while (*ip == '/')
			++ip;
		if (!*ip)
			break;

		/* get next pathname component from input */
		tp = ip;
		while (*ip && *ip != '/')
			++ip;
		len = ip - tp;

		/* check input for "." and ".." */
		if (tp[0] == '.') {
			if (len == 1)
				/* just continue with the next one */
				continue;
			else if (len == 2 && tp[1] == '.') {
				/* strip off last pathname component */
				while (xp > Xstring(xs, xp))
					if (*--xp == '/')
						break;
				/* then continue with the next one */
				continue;
			}
		}

		/* store output position away, then append slash to output */
		pos = Xsavepos(xs, xp);
		/* 1 for the '/' and len + 1 for tp and the NUL from below */
		XcheckN(xs, xp, 1 + len + 1);
		Xput(xs, xp, '/');

		/* append next pathname component to output */
		memcpy(xp, tp, len);
		xp += len;
		*xp = '\0';

		/* lstat the current output, see if it's a symlink */
		if (mksh_lstat(Xstring(xs, xp), &sb)) {
			/* lstat failed */
			if (errno == ENOENT) {
				/* because the pathname does not exist */
				while (*ip == '/')
					/* skip any trailing slashes */
					++ip;
				/* no more components left? */
				if (!*ip)
					/* we can still return successfully */
					break;
				/* more components left? fall through */
			}
			/* not ENOENT or not at the end of ipath */
			goto notfound;
		}

		/* check if we encountered a symlink? */
		if (S_ISLNK(sb.st_mode)) {
#ifndef MKSH__NO_SYMLINK
			/* reached maximum recursion depth? */
			if (!symlinks--) {
				/* yep, prevent infinite loops */
				errno = ELOOP;
				goto notfound;
			}

			/* get symlink(7) target */
			if (pathcnd) {
#ifdef MKSH__NO_PATH_MAX
				if (notoktoadd(pathlen, 1)) {
					errno = ENAMETOOLONG;
					goto notfound;
				}
#endif
				ldest = aresize(ldest, pathlen + 1, ATEMP);
			}
			llen = readlink(Xstring(xs, xp), ldest, pathlen);
			if (llen < 0)
				/* oops... */
				goto notfound;
			ldest[llen] = '\0';

			/*
			 * restart if symlink target is an absolute path,
			 * otherwise continue with currently resolved prefix
			 */
			/* append rest of current input path to link target */
			tp = shf_smprintf("%s%s%s", ldest, *ip ? "/" : "", ip);
			afree(ipath, ATEMP);
			ip = ipath = tp;
			if (!mksh_abspath(ldest)) {
				/* symlink target is a relative path */
				xp = Xrestpos(xs, xp, pos);
			} else
#endif
			  {
				/* symlink target is an absolute path */
				xp = Xstring(xs, xp);
 beginning_of_a_pathname:
				/* assert: (ip == ipath)[0] == '/' */
				/* assert: xp == xs.beg => start of path */

				/* exactly two leading slashes? (SUSv4 3.266) */
				if (ip[1] == '/' && ip[2] != '/') {
					/* keep them, e.g. for UNC pathnames */
					Xput(xs, xp, '/');
				}
			}
		}
		/* otherwise (no symlink) merely go on */
	}

	/*
	 * either found the target and successfully resolved it,
	 * or found its parent directory and may create it
	 */
	if (Xlength(xs, xp) == 0)
		/*
		 * if the resolved pathname is "", make it "/",
		 * otherwise do not add a trailing slash
		 */
		Xput(xs, xp, '/');
	Xput(xs, xp, '\0');

	/*
	 * if source path had a trailing slash, check if target path
	 * is not a non-directory existing file
	 */
	if (ip > ipath && ip[-1] == '/') {
		if (stat(Xstring(xs, xp), &sb)) {
			if (errno != ENOENT)
				goto notfound;
		} else if (!S_ISDIR(sb.st_mode)) {
			errno = ENOTDIR;
			goto notfound;
		}
		/* target now either does not exist or is a directory */
	}

	/* return target path */
	if (ldest != NULL)
		afree(ldest, ATEMP);
	afree(ipath, ATEMP);
	return (Xclose(xs, xp));

 notfound:
	/* save; freeing memory might trash it */
	llen = errno;
	if (ldest != NULL)
		afree(ldest, ATEMP);
	afree(ipath, ATEMP);
	Xfree(xs, xp);
	errno = llen;
	return (NULL);

#undef pathlen
#undef pathcnd
}