From 869994cf4f9647fdfb519a1945f8582e71d3df3d Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Sat, 20 Aug 2016 15:16:00 +0200 Subject: [PATCH] hush: bit better comments in redirect code. No logic changes Signed-off-by: Denys Vlasenko --- shell/hush.c | 49 ++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 38 insertions(+), 11 deletions(-) diff --git a/shell/hush.c b/shell/hush.c index b41d9d04b..9b45b312f 100644 --- a/shell/hush.c +++ b/shell/hush.c @@ -6099,10 +6099,12 @@ static int setup_redirects(struct command *prog, int squirrel[]) for (redir = prog->redirects; redir; redir = redir->next) { if (redir->rd_type == REDIRECT_HEREDOC2) { - /* rd_fd<rd_fd < 3 + /* "rd_fd<rd_fd <= 2 + && squirrel && squirrel[redir->rd_fd] < 0 ) { + /* Save old fds 0..2 if redirect uses them */ squirrel[redir->rd_fd] = dup(redir->rd_fd); } /* for REDIRECT_HEREDOC2, rd_filename holds _contents_ @@ -6114,7 +6116,7 @@ static int setup_redirects(struct command *prog, int squirrel[]) } if (redir->rd_dup == REDIRFD_TO_FILE) { - /* rd_fd<*>file case (<*> is <,>,>>,<>) */ + /* "rd_fd<*>file" case (<*> is <,>,>>,<>) */ char *p; if (redir->rd_filename == NULL) { /* Something went wrong in the parse. @@ -6127,20 +6129,33 @@ static int setup_redirects(struct command *prog, int squirrel[]) openfd = open_or_warn(p, mode); free(p); if (openfd < 0) { - /* this could get lost if stderr has been redirected, but - * bash and ash both lose it as well (though zsh doesn't!) */ -//what the above comment tries to say? + /* Error message from open_or_warn can be lost + * if stderr has been redirected, but bash + * and ash both lose it as well + * (though zsh doesn't!) + */ return 1; } } else { - /* rd_fd<*>rd_dup or rd_fd<*>- cases */ + /* "rd_fd<*>rd_dup" or "rd_fd<*>-" cases */ openfd = redir->rd_dup; } if (openfd != redir->rd_fd) { - if (squirrel && redir->rd_fd < 3 + if (redir->rd_fd <= 2 + && squirrel && squirrel[redir->rd_fd] < 0 ) { + /* Save old fds 0..2 if redirect uses them */ +//FIXME: script fd's also need this! "sh SCRIPT" and SCRIPT has "echo FOO 3>&-": +// open("SCRIPT", O_RDONLY) = 3 +// fcntl(3, F_SETFD, FD_CLOEXEC) = 0 +// read(3, "echo FOO 3>&-\n....", 4096) = N +// close(3) = 0 +// write(1, "FOO\n", 4) = 4 +// ... +// read(3, 0x205f8e0, 4096) = -1 EBADF <== BUG +// squirrel[redir->rd_fd] = dup(redir->rd_fd); } if (openfd == REDIRFD_CLOSE) { @@ -6159,7 +6174,7 @@ static int setup_redirects(struct command *prog, int squirrel[]) static void restore_redirects(int squirrel[]) { int i, fd; - for (i = 0; i < 3; i++) { + for (i = 0; i <= 2; i++) { fd = squirrel[i]; if (fd != -1) { /* We simply die on error */ @@ -7144,6 +7159,7 @@ static NOINLINE int run_pipe(struct pipe *pi) if (x->b_function == builtin_exec && argv_expanded[1] == NULL) { debug_printf("exec with redirects only\n"); rcode = setup_redirects(command, NULL); + /* rcode=1 can be if redir file can't be opened */ goto clean_up_and_ret1; } } @@ -7270,9 +7286,20 @@ static NOINLINE int run_pipe(struct pipe *pi) if (pipefds.rd > 1) close(pipefds.rd); /* Like bash, explicit redirects override pipes, - * and the pipe fd is available for dup'ing. */ - if (setup_redirects(command, NULL)) + * and the pipe fd (fd#1) is available for dup'ing: + * "cmd1 2>&1 | cmd2": fd#1 is duped to fd#2, thus stderr + * of cmd1 goes into pipe. + */ + if (setup_redirects(command, NULL)) { + /* Happens when redir file can't be opened: + * $ hush -c 'echo FOO >&2 | echo BAR 3>/qwe/rty; echo BAZ' + * FOO + * hush: can't open '/qwe/rty': No such file or directory + * BAZ + * (echo BAR is not executed, it hits _exit(1) below) + */ _exit(1); + } /* Stores to nommu_save list of env vars putenv'ed * (NOMMU, on MMU we don't need that) */