The `grub_util_exec_redirect_all` helper function can be used to
spawn an executable and redirect its output to some files. After calling
`fork()`, the parent will wait for the child to terminate with
`waitpid()` while the child prepares its file descriptors, environment
and finally calls `execvp()`. If something in the children's setup
fails, it will stop by calling `exit(127)`.
Calling `exit()` will cause any function registered via `atexit()` to be
executed, which is usually the wrong thing to do in a child. And
actually, one can easily observe faulty behaviour on musl-based systems
without modprobe(8) installed: executing `grub-install --help` will call
`grub_util_exec_redirect_all` with "modprobe", which obviously fails if
modprobe(8) is not installed. Due to the child now exiting and invoking
the `atexit()` handlers, it will clean up some data structures of the
parent and cause it to be deadlocked in the `waitpid()` syscall.
The issue can easily be fixed by calling `_exit(127)` instead, which is
especially designed to be called when the atexit-handlers should not be
executed.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Depending on the OS/libc, device macros are defined in different
headers. This change ensures we include the right one.
sys/types.h - BSD
sys/mkdev.h - Sun
sys/sysmacros.h - glibc (Linux)
glibc currently pulls sys/sysmacros.h into sys/types.h, but this may
change in a future release.
https://sourceware.org/ml/libc-alpha/2015-11/msg00253.html
This makes it impossible to read from stdin without controlling tty:
10:/mnt # echo -e passwd\\npasswd | setsid ./grub-mkpasswd-pbkdf2
Enter password:
Reenter password: ./grub-mkpasswd-pbkdf2: error: failure to read password.
10:/mnt
canonicalize_file_name clashed with gnulib function. Additionally
it was declared in 2 places: emu/misc.h and util/misc.h. Added
grub_ prefix and removed second declaration.
* grub-core/osdep/unix/getroot.c (strip_extra_slashes): Move inside
!defined (__GNU__).
(xgetcwd): Likewise.
* include/grub/emu/hostdisk.h (grub_util_hurd_get_disk_info)
[__GNU__]: Add prototype.
* util/getroot.c (grub_util_biosdisk_get_grub_dev) [__GNU__]: Format
long int using %ld rather than %d.
We need to hide "modprobe efivars" error output to avoid confusion. So
consolidate grub_util_exec_* into single function that can optionally redirect
all three standard descriptors and make all other functions compatibility
wrappers.
Also remove include/grub/osdep/exec_unix.h which does not appear to be used
anywhere.
references to mdadm from otherwise generic code.
(grub_util_exec_pipe): Likewise.
(grub_util_exec_pipe_stderr): Likewise.
* grub-core/osdep/unix/getroot.c (grub_util_pull_lvm_by_command):
This function calls vgs, not mdadm; adjust variable names
accordingly.
Add grub_util_disable_fd_syncs call to turn grub_util_fd_sync calls into
no-ops, and use it in programs that copy files but do not need to take
special care to sync writes (grub-mknetdir, grub-rescue,
grub-mkstandalone).
On my laptop, this reduces partmap_test's runtime from 1236 seconds to
204 seconds.
the function of these files exceeds what can be sanely handled in shell
in posix-comaptible way. Also writing it in C extends the functionality
to non-UNIX-like OS and minimal environments.
