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hush: bit better comments in redirect code. No logic changes

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2016-08-20 15:16:00 +02:00
parent e9abe75fda
commit 869994cf4f
1 changed files with 38 additions and 11 deletions
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49
shell/hush.c
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@ -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<<HERE case */
if (squirrel && redir->rd_fd < 3
/* "rd_fd<<HERE" case */
if (redir->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) */