657e9005a
Denys Vlasenko
2017-07-31
Subject
hush: massage redirect code to be slightly more like ash
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shell/hush.c+72 -37
| @@ -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; | |