ash: explain redirect code a bit

function old new delta redirect 1059 1054 -5
author: Denis Vlasenko <vda.linux@googlemail.com> 2008-07-24 07:54:57 +0000
committer: Denis Vlasenko <vda.linux@googlemail.com> 2008-07-24 07:54:57 +0000
commit: 0b76964ae11b1d71e8634d1d7d672219dd43bde9 (patch)
tree: 12fa3c1e68c6b5613f8b0d279319f524d1c21a14
parent: 2dc240c0d6e0b3b0b66f08ac9cc5584df824f959 (diff)
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1 files changed, 39 insertions, 29 deletions
diff --git a/shell/ash.c b/shell/ash.c
index 4263644fc..de1f8006d 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -594,8 +594,8 @@ struct nfile {
 struct ndup {
        smallint type;
-        union node *next;
+        union node *next; /* must match nfile's layout */
-        int fd;
+        int fd; /* must match nfile's layout */
        int dupfd;
        union node *vname;
 };
@@ -1634,12 +1634,6 @@ nextopt(const char *optstring)
 * The parsefile structure pointed to by the global variable parsefile
 * contains information about the current file being read.
 */
-struct redirtab {
-        struct redirtab *next;
-        int renamed[10];
-        int nullredirs;
-};
 struct shparam {
        int nparam;             /* # of positional parameters (without $0) */
 #if ENABLE_ASH_GETOPTS
@@ -1765,6 +1759,7 @@ static const struct {
 #endif
 };
+struct redirtab;
 struct globals_var {
        struct shparam shellparam;      /* $@ current positional parameters */
@@ -1777,7 +1772,7 @@ struct globals_var {
 extern struct globals_var *const ash_ptr_to_globals_var;
 #define G_var (*ash_ptr_to_globals_var)
 #define shellparam    (G_var.shellparam   )
-#define redirlist     (G_var.redirlist    )
+//#define redirlist     (G_var.redirlist    )
 #define g_nullredirs  (G_var.g_nullredirs )
 #define preverrout_fd (G_var.preverrout_fd)
 #define vartab        (G_var.vartab       )
@@ -4767,6 +4762,7 @@ openhere(union node *redir)
                }
        }
        if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
+                /* child */
                close(pip[0]);
                signal(SIGINT, SIG_IGN);
                signal(SIGQUIT, SIG_IGN);
@@ -4777,7 +4773,7 @@ openhere(union node *redir)
                signal(SIGPIPE, SIG_DFL);
                if (redir->type == NHERE)
                        full_write(pip[1], redir->nhere.doc->narg.text, len);
-                else
+                else /* NXHERE */
                        expandhere(redir->nhere.doc, pip[1]);
                _exit(EXIT_SUCCESS);
        }
@@ -4832,10 +4828,10 @@ openredirect(union node *redir)
                abort();
 #endif
                /* Fall through to eliminate warning. */
-        case NTOFD:
+//      case NTOFD:
-        case NFROMFD:
+//      case NFROMFD:
-                f = -1;
+//              f = -1;
-                break;
+//              break;
        case NHERE:
        case NXHERE:
                f = openhere(redir);
@@ -4873,19 +4869,26 @@ dupredirect(union node *redir, int f)
 {
        int fd = redir->nfile.fd;
-        if (redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD) {
+        if (f < 0) { /* redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD */
                if (redir->ndup.dupfd >= 0) {   /* if not ">&-" */
                        copyfd(redir->ndup.dupfd, fd);
                }
                return;
        }
        if (f != fd) {
                copyfd(f, fd);
                close(f);
        }
 }
+/**/
+struct redirtab {
+        struct redirtab *next;
+        int renamed[10];
+        int nullredirs;
+};
+#define redirlist     (G_var.redirlist    )
 /*
 * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
 * old file descriptors are stashed away so that the redirection can be
@@ -4921,36 +4924,43 @@ redirect(union node *redir, int flags)
        }
        do {
                fd = redir->nfile.fd;
-                if ((redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD)
+                if (redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD) {
-                 && redir->ndup.dupfd == fd)
+                        if (redir->ndup.dupfd == fd)
-                        continue; /* redirect from/to same file descriptor */
+                                continue; /* redirect from/to same file descriptor */
+                        newfd = -1;
-                newfd = openredirect(redir);
+                } else {
-                if (fd == newfd) {
+                        newfd = openredirect(redir); /* always >= 0 */
-                        /* Descriptor wasn't open before redirect.
+                        if (fd == newfd) {
-                         * Mark it for close in the future */
+                                /* Descriptor wasn't open before redirect.
-                        if (sv && sv->renamed[fd] == EMPTY)
+                                 * Mark it for close in the future */
-                                sv->renamed[fd] = CLOSED;
+                                if (sv && sv->renamed[fd] == EMPTY)
-                        continue;
+                                        sv->renamed[fd] = CLOSED;
+                                continue;
+                        }
                }
                if (sv && sv->renamed[fd] == EMPTY) {
+                        /* Copy old descriptor */
                        i = fcntl(fd, F_DUPFD, 10);
                        if (i == -1) {
                                i = errno;
-                                if (i != EBADF) {
+                                if (i != EBADF) { /* strange error */
                                        close(newfd);
                                        errno = i;
                                        ash_msg_and_raise_error("%d: %m", fd);
                                        /* NOTREACHED */
                                }
+                                /* it is not open - ok */
                        } else {
+                                /* it is open, save its copy */
                                sv->renamed[fd] = i;
                                close(fd);
                        }
                } else {
                        close(fd);
                }
+                /* Here fd is closed */
+                /* NTOFD/NFROMFD: copy redir->ndup.dupfd to fd */
+                /* else: move newfd to fd */
                dupredirect(redir, newfd);
        } while ((redir = redir->nfile.next) != NULL);
        INT_ON;
author	Denis Vlasenko <vda.linux@googlemail.com>	2008-07-24 07:54:57 +0000
committer	Denis Vlasenko <vda.linux@googlemail.com>	2008-07-24 07:54:57 +0000
commit	0b76964ae11b1d71e8634d1d7d672219dd43bde9 (patch)
tree	12fa3c1e68c6b5613f8b0d279319f524d1c21a14
parent	2dc240c0d6e0b3b0b66f08ac9cc5584df824f959 (diff)
download	busybox-w32-0b76964ae11b1d71e8634d1d7d672219dd43bde9.tar.gz busybox-w32-0b76964ae11b1d71e8634d1d7d672219dd43bde9.tar.bz2 busybox-w32-0b76964ae11b1d71e8634d1d7d672219dd43bde9.zip

diff --git a/shell/ash.c b/shell/ash.c index 4263644fc..de1f8006d 100644 --- a/shell/ash.c +++ b/shell/ash.c
@@ -594,8 +594,8 @@ struct nfile {
594		594
595	struct ndup {	595	struct ndup {
596	smallint type;	596	smallint type;
597	union node *next;	597	union node next; / must match nfile's layout */
598	int fd;	598	int fd; /* must match nfile's layout */
599	int dupfd;	599	int dupfd;
600	union node *vname;	600	union node *vname;
601	};	601	};
@@ -1634,12 +1634,6 @@ nextopt(const char *optstring)
1634	* The parsefile structure pointed to by the global variable parsefile	1634	* The parsefile structure pointed to by the global variable parsefile
1635	* contains information about the current file being read.	1635	* contains information about the current file being read.
1636	*/	1636	*/
1637	struct redirtab {
1638	struct redirtab *next;
1639	int renamed[10];
1640	int nullredirs;
1641	};
1642
1643	struct shparam {	1637	struct shparam {
1644	int nparam; /* # of positional parameters (without $0) */	1638	int nparam; /* # of positional parameters (without $0) */
1645	#if ENABLE_ASH_GETOPTS	1639	#if ENABLE_ASH_GETOPTS
@@ -1765,6 +1759,7 @@ static const struct {
1765	#endif	1759	#endif
1766	};	1760	};
1767		1761
		1762	struct redirtab;
1768		1763
1769	struct globals_var {	1764	struct globals_var {
1770	struct shparam shellparam; /* $@ current positional parameters */	1765	struct shparam shellparam; /* $@ current positional parameters */
@@ -1777,7 +1772,7 @@ struct globals_var {
1777	extern struct globals_var *const ash_ptr_to_globals_var;	1772	extern struct globals_var *const ash_ptr_to_globals_var;
1778	#define G_var (*ash_ptr_to_globals_var)	1773	#define G_var (*ash_ptr_to_globals_var)
1779	#define shellparam (G_var.shellparam )	1774	#define shellparam (G_var.shellparam )
1780	#define redirlist (G_var.redirlist )	1775	//#define redirlist (G_var.redirlist )
1781	#define g_nullredirs (G_var.g_nullredirs )	1776	#define g_nullredirs (G_var.g_nullredirs )
1782	#define preverrout_fd (G_var.preverrout_fd)	1777	#define preverrout_fd (G_var.preverrout_fd)
1783	#define vartab (G_var.vartab )	1778	#define vartab (G_var.vartab )
@@ -4767,6 +4762,7 @@ openhere(union node *redir)
4767	}	4762	}
4768	}	4763	}
4769	if (forkshell((struct job )NULL, (union node )NULL, FORK_NOJOB) == 0) {	4764	if (forkshell((struct job )NULL, (union node )NULL, FORK_NOJOB) == 0) {
		4765	/* child */
4770	close(pip[0]);	4766	close(pip[0]);
4771	signal(SIGINT, SIG_IGN);	4767	signal(SIGINT, SIG_IGN);
4772	signal(SIGQUIT, SIG_IGN);	4768	signal(SIGQUIT, SIG_IGN);
@@ -4777,7 +4773,7 @@ openhere(union node *redir)
4777	signal(SIGPIPE, SIG_DFL);	4773	signal(SIGPIPE, SIG_DFL);
4778	if (redir->type == NHERE)	4774	if (redir->type == NHERE)
4779	full_write(pip[1], redir->nhere.doc->narg.text, len);	4775	full_write(pip[1], redir->nhere.doc->narg.text, len);
4780	else	4776	else /* NXHERE */
4781	expandhere(redir->nhere.doc, pip[1]);	4777	expandhere(redir->nhere.doc, pip[1]);
4782	_exit(EXIT_SUCCESS);	4778	_exit(EXIT_SUCCESS);
4783	}	4779	}
@@ -4832,10 +4828,10 @@ openredirect(union node *redir)
4832	abort();	4828	abort();
4833	#endif	4829	#endif
4834	/* Fall through to eliminate warning. */	4830	/* Fall through to eliminate warning. */
4835	case NTOFD:	4831	// case NTOFD:
4836	case NFROMFD:	4832	// case NFROMFD:
4837	f = -1;	4833	// f = -1;
4838	break;	4834	// break;
4839	case NHERE:	4835	case NHERE:
4840	case NXHERE:	4836	case NXHERE:
4841	f = openhere(redir);	4837	f = openhere(redir);
@@ -4873,19 +4869,26 @@ dupredirect(union node *redir, int f)
4873	{	4869	{
4874	int fd = redir->nfile.fd;	4870	int fd = redir->nfile.fd;
4875		4871
4876	if (redir->nfile.type == NTOFD \|\| redir->nfile.type == NFROMFD) {	4872	if (f < 0) { /* redir->nfile.type == NTOFD \|\| redir->nfile.type == NFROMFD */
4877	if (redir->ndup.dupfd >= 0) { /* if not ">&-" */	4873	if (redir->ndup.dupfd >= 0) { /* if not ">&-" */
4878	copyfd(redir->ndup.dupfd, fd);	4874	copyfd(redir->ndup.dupfd, fd);
4879	}	4875	}
4880	return;	4876	return;
4881	}	4877	}
4882
4883	if (f != fd) {	4878	if (f != fd) {
4884	copyfd(f, fd);	4879	copyfd(f, fd);
4885	close(f);	4880	close(f);
4886	}	4881	}
4887	}	4882	}
4888		4883
		4884	/**/
		4885	struct redirtab {
		4886	struct redirtab *next;
		4887	int renamed[10];
		4888	int nullredirs;
		4889	};
		4890	#define redirlist (G_var.redirlist )
		4891
4889	/*	4892	/*
4890	* Process a list of redirection commands. If the REDIR_PUSH flag is set,	4893	* Process a list of redirection commands. If the REDIR_PUSH flag is set,
4891	* old file descriptors are stashed away so that the redirection can be	4894	* old file descriptors are stashed away so that the redirection can be
@@ -4921,36 +4924,43 @@ redirect(union node *redir, int flags)
4921	}	4924	}
4922	do {	4925	do {
4923	fd = redir->nfile.fd;	4926	fd = redir->nfile.fd;
4924	if ((redir->nfile.type == NTOFD \|\| redir->nfile.type == NFROMFD)	4927	if (redir->nfile.type == NTOFD \|\| redir->nfile.type == NFROMFD) {
4925	&& redir->ndup.dupfd == fd)	4928	if (redir->ndup.dupfd == fd)
4926	continue; /* redirect from/to same file descriptor */	4929	continue; /* redirect from/to same file descriptor */
4927		4930	newfd = -1;
4928	newfd = openredirect(redir);	4931	} else {
4929	if (fd == newfd) {	4932	newfd = openredirect(redir); /* always >= 0 */
4930	/* Descriptor wasn't open before redirect.	4933	if (fd == newfd) {
4931	* Mark it for close in the future */	4934	/* Descriptor wasn't open before redirect.
4932	if (sv && sv->renamed[fd] == EMPTY)	4935	* Mark it for close in the future */
4933	sv->renamed[fd] = CLOSED;	4936	if (sv && sv->renamed[fd] == EMPTY)
4934	continue;	4937	sv->renamed[fd] = CLOSED;
		4938	continue;
		4939	}
4935	}	4940	}
4936	if (sv && sv->renamed[fd] == EMPTY) {	4941	if (sv && sv->renamed[fd] == EMPTY) {
		4942	/* Copy old descriptor */
4937	i = fcntl(fd, F_DUPFD, 10);	4943	i = fcntl(fd, F_DUPFD, 10);
4938
4939	if (i == -1) {	4944	if (i == -1) {
4940	i = errno;	4945	i = errno;
4941	if (i != EBADF) {	4946	if (i != EBADF) { /* strange error */
4942	close(newfd);	4947	close(newfd);
4943	errno = i;	4948	errno = i;
4944	ash_msg_and_raise_error("%d: %m", fd);	4949	ash_msg_and_raise_error("%d: %m", fd);
4945	/* NOTREACHED */	4950	/* NOTREACHED */
4946	}	4951	}
		4952	/* it is not open - ok */
4947	} else {	4953	} else {
		4954	/* it is open, save its copy */
4948	sv->renamed[fd] = i;	4955	sv->renamed[fd] = i;
4949	close(fd);	4956	close(fd);
4950	}	4957	}
4951	} else {	4958	} else {
4952	close(fd);	4959	close(fd);
4953	}	4960	}
		4961	/* Here fd is closed */
		4962	/* NTOFD/NFROMFD: copy redir->ndup.dupfd to fd */
		4963	/* else: move newfd to fd */
4954	dupredirect(redir, newfd);	4964	dupredirect(redir, newfd);
4955	} while ((redir = redir->nfile.next) != NULL);	4965	} while ((redir = redir->nfile.next) != NULL);
4956	INT_ON;	4966	INT_ON;