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authorDenys Vlasenko <vda.linux@googlemail.com>2017-07-30 23:34:04 +0200
committerDenys Vlasenko <vda.linux@googlemail.com>2017-07-31 04:08:09 +0200
commit657e9005a9e31e1da094b260abaa8f335e92301f (patch)
tree6ee40b817a62ef8989532de792bb3a6d13cd19da
parentd07a15bd1ba99caa9386234cda1e8c83897c7553 (diff)
downloadbusybox-657e9005a9e31e1da094b260abaa8f335e92301f.tar.gz
hush: massage redirect code to be slightly more like ash
function old new delta save_fd_on_redirect - 203 +203 xdup_CLOEXEC_and_close - 75 +75 setup_redirects 245 250 +5 xdup_and_close 72 - -72 save_fds_on_redirect 221 - -221 ------------------------------------------------------------------------------ (add/remove: 2/2 grow/shrink: 1/0 up/down: 283/-293) Total: -10 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--shell/hush.c109
1 files changed, 72 insertions, 37 deletions
diff --git a/shell/hush.c b/shell/hush.c
index 0fae809b3..d4101d66f 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -1454,11 +1454,11 @@ static int fcntl_F_DUPFD(int fd, int avoid_fd)
return newfd;
}
-static int xdup_and_close(int fd, int F_DUPFD_maybe_CLOEXEC, int avoid_fd)
+static int xdup_CLOEXEC_and_close(int fd, int avoid_fd)
{
int newfd;
repeat:
- newfd = fcntl(fd, F_DUPFD_maybe_CLOEXEC, avoid_fd + 1);
+ newfd = fcntl(fd, F_DUPFD_CLOEXEC, avoid_fd + 1);
if (newfd < 0) {
if (errno == EBUSY)
goto repeat;
@@ -1469,6 +1469,8 @@ static int xdup_and_close(int fd, int F_DUPFD_maybe_CLOEXEC, int avoid_fd)
return fd;
xfunc_die();
}
+ if (F_DUPFD_CLOEXEC == F_DUPFD) /* if old libc (w/o F_DUPFD_CLOEXEC) */
+ fcntl(newfd, F_SETFD, FD_CLOEXEC);
close(fd);
return newfd;
}
@@ -1507,7 +1509,7 @@ static int save_FILEs_on_redirect(int fd, int avoid_fd)
while (fl) {
if (fd == fl->fd) {
/* We use it only on script files, they are all CLOEXEC */
- fl->fd = xdup_and_close(fd, F_DUPFD_CLOEXEC, avoid_fd);
+ fl->fd = xdup_CLOEXEC_and_close(fd, avoid_fd);
debug_printf_redir("redirect_fd %d: matches a script fd, moving it to %d\n", fd, fl->fd);
return 1;
}
@@ -6711,18 +6713,42 @@ static struct squirrel *add_squirrel(struct squirrel *sq, int fd, int avoid_fd)
return append_squirrel(sq, i, fd, moved_to);
}
+static struct squirrel *add_squirrel_closed(struct squirrel *sq, int fd)
+{
+ int i;
+
+ i = 0;
+ if (sq) while (sq[i].orig_fd >= 0) {
+ /* If we collide with an already moved fd... */
+ if (fd == sq[i].orig_fd) {
+ /* Examples:
+ * "echo 3>FILE 3>&- 3>FILE"
+ * "echo 3>&- 3>FILE"
+ * No need for last redirect to insert
+ * another "need to close 3" indicator.
+ */
+ debug_printf_redir("redirect_fd %d: already moved or closed\n", fd);
+ return sq;
+ }
+ i++;
+ }
+
+ debug_printf_redir("redirect_fd %d: previous fd was closed\n", fd);
+ return append_squirrel(sq, i, fd, -1);
+}
+
/* fd: redirect wants this fd to be used (e.g. 3>file).
* Move all conflicting internally used fds,
* and remember them so that we can restore them later.
*/
-static int save_fds_on_redirect(int fd, int avoid_fd, struct squirrel **sqp)
+static int save_fd_on_redirect(int fd, int avoid_fd, struct squirrel **sqp)
{
if (avoid_fd < 9) /* the important case here is that it can be -1 */
avoid_fd = 9;
#if ENABLE_HUSH_INTERACTIVE
if (fd != 0 && fd == G.interactive_fd) {
- G.interactive_fd = xdup_and_close(G.interactive_fd, F_DUPFD_CLOEXEC, avoid_fd);
+ G.interactive_fd = xdup_CLOEXEC_and_close(G.interactive_fd, avoid_fd);
debug_printf_redir("redirect_fd %d: matches interactive_fd, moving it to %d\n", fd, G.interactive_fd);
return 1; /* "we closed fd" */
}
@@ -6748,7 +6774,6 @@ static int save_fds_on_redirect(int fd, int avoid_fd, struct squirrel **sqp)
static void restore_redirects(struct squirrel *sq)
{
-
if (sq) {
int i = 0;
while (sq[i].orig_fd >= 0) {
@@ -6775,13 +6800,15 @@ static void restore_redirects(struct squirrel *sq)
* and stderr if they are redirected. */
static int setup_redirects(struct command *prog, struct squirrel **sqp)
{
- int openfd, mode;
struct redir_struct *redir;
for (redir = prog->redirects; redir; redir = redir->next) {
+ int newfd;
+ int closed;
+
if (redir->rd_type == REDIRECT_HEREDOC2) {
/* "rd_fd<<HERE" case */
- save_fds_on_redirect(redir->rd_fd, /*avoid:*/ 0, sqp);
+ save_fd_on_redirect(redir->rd_fd, /*avoid:*/ 0, sqp);
/* for REDIRECT_HEREDOC2, rd_filename holds _contents_
* of the heredoc */
debug_printf_parse("set heredoc '%s'\n",
@@ -6793,6 +6820,8 @@ static int setup_redirects(struct command *prog, struct squirrel **sqp)
if (redir->rd_dup == REDIRFD_TO_FILE) {
/* "rd_fd<*>file" case (<*> is <,>,>>,<>) */
char *p;
+ int mode;
+
if (redir->rd_filename == NULL) {
/*
* Examples:
@@ -6804,9 +6833,9 @@ static int setup_redirects(struct command *prog, struct squirrel **sqp)
}
mode = redir_table[redir->rd_type].mode;
p = expand_string_to_string(redir->rd_filename, /*unbackslash:*/ 1);
- openfd = open_or_warn(p, mode);
+ newfd = open_or_warn(p, mode);
free(p);
- if (openfd < 0) {
+ if (newfd < 0) {
/* Error message from open_or_warn can be lost
* if stderr has been redirected, but bash
* and ash both lose it as well
@@ -6814,40 +6843,46 @@ static int setup_redirects(struct command *prog, struct squirrel **sqp)
*/
return 1;
}
- if (openfd == redir->rd_fd && sqp) {
+ if (newfd == redir->rd_fd && sqp) {
/* open() gave us precisely the fd we wanted.
* This means that this fd was not busy
* (not opened to anywhere).
* Remember to close it on restore:
*/
- struct squirrel *sq = *sqp;
- int i = 0;
- if (sq) while (sq[i].orig_fd >= 0)
- i++;
- *sqp = append_squirrel(sq, i, openfd, -1); /* -1 = "it was closed" */
- debug_printf_redir("redir to previously closed fd %d\n", openfd);
+ *sqp = add_squirrel_closed(*sqp, newfd);
+ debug_printf_redir("redir to previously closed fd %d\n", newfd);
}
} else {
- /* "rd_fd<*>rd_dup" or "rd_fd<*>-" cases */
- openfd = redir->rd_dup;
- }
-
- if (openfd != redir->rd_fd) {
- int closed = save_fds_on_redirect(redir->rd_fd, /*avoid:*/ openfd, sqp);
- if (openfd == REDIRFD_CLOSE) {
- /* "rd_fd >&-" means "close me" */
- if (!closed) {
- /* ^^^ optimization: saving may already
- * have closed it. If not... */
- close(redir->rd_fd);
- }
- } else {
- xdup2(openfd, redir->rd_fd);
- if (redir->rd_dup == REDIRFD_TO_FILE)
- /* "rd_fd > FILE" */
- close(openfd);
- /* else: "rd_fd > rd_dup" */
- }
+ /* "rd_fd>&rd_dup" or "rd_fd>&-" case */
+ newfd = redir->rd_dup;
+ }
+
+ if (newfd == redir->rd_fd)
+ continue;
+
+ /* if "N>FILE": move newfd to redir->rd_fd */
+ /* if "N>&M": dup newfd to redir->rd_fd */
+ /* if "N>&-": close redir->rd_fd (newfd is REDIRFD_CLOSE) */
+
+ closed = save_fd_on_redirect(redir->rd_fd, /*avoid:*/ newfd, sqp);
+ if (newfd == REDIRFD_CLOSE) {
+ /* "N>&-" means "close me" */
+ if (!closed) {
+ /* ^^^ optimization: saving may already
+ * have closed it. If not... */
+ close(redir->rd_fd);
+ }
+ /* Sometimes we do another close on restore, getting EBADF.
+ * Consider "echo 3>FILE 3>&-"
+ * first redirect remembers "need to close 3",
+ * and second redirect closes 3! Restore code then closes 3 again.
+ */
+ } else {
+ xdup2(newfd, redir->rd_fd);
+ if (redir->rd_dup == REDIRFD_TO_FILE)
+ /* "rd_fd > FILE" */
+ close(newfd);
+ /* else: "rd_fd > rd_dup" */
}
}
return 0;