We have traditionally used custom printf formatters %Q and %R, where
%Q replaces the argument with a shell-quoted string, and %R replaces
the argument with a sysroot-prefixed shell-quoted string. They are
actually pretty useful, but unfortunately only supported by glibc.
We only used them in about a dozen places in the daemon (much code
having been replaced by OCaml which does not need them).
In every remaining case we were constructing a command using code like
this:
asprintf_nowarn (&cmd,
"cd %Q && find -print0 | %s -0 -o -H %s --quiet", ...);
We can replace this with:
char *cmd;
size_t cmd_size;
fp = open_memstream (&cmd, &cmd_size);
fprintf (fp, "cd ");
shell_quote (dir, fp);
fprintf (fp, " && find -print0 | %s -0 -o -H %s --quiet", ...);
fclose (fp);
(cherry picked from commit 0b3c6cc0c0)
GUESTFSD_EXT_CMD was used by OpenSUSE to track which external commands
are run by the daemon and package those commands into the appliance.
It is no longer used by recent SUSE builds, so remove it.
Thanks: Pino Toscano, Olaf Hering.
Declare most of the stringsbuf as CLEANUP_FREE_STRINGSBUF, so they are
freed completely on stack unwind: use take_stringsbuf() in return
places to take away from the stringsbuf its content, and remove all the
manual calls to free_stringslen (no more needed now).
This requires to not use free_stringslen anymore on failure in the
helper functions of stringsbuf, which now leave the content as-is (might
be still useful even on error).
This allows us to simplify the memory management of stringsbuf's, which
are not properly fully freed, fixing memory leaks in some error paths
(which were not calling free_stringslen).
If either zcat or cpio fails when spawned in initrd-list, pclose will
return the actual return value of it, but reply_with_perror still uses
errno regardless; thus, the reported error is:
libguestfs: error: initrd_list: pclose: Success
which is not much helpful.
Instead, when pclose returns > 0, extract the actual return value of the
subprocess, and print that. Thus now we get for example:
libguestfs: error: initrd_list: pclose: command failed with return code 1
Code like:
CLEANUP_FREE char *buf;
/* some code which might return early */
buf = malloc (10);
is a potential bug because the free (*buf) might be called when buf is
an uninitialized pointer. Initialize buf = NULL to avoid this.
Several of these are bugs, most are not bugs (because there is no
early return statement before the variable gets initialized).
However the compiler can elide the initialization, and even if it does
not the performance "penalty" is miniscule, and correctness is better.
Replace selected calls to 'perror (filename)' with:
fprintf (stderr, "syscall: %s: %m\n", filename);
so that more information is available about precisely which syscall
failed.
Note this is *not* reply_with_perror. These messages are only printed
in verbose output, for the benefit of debugging.
guestfsd calls many different tools. Keeping track of all of them is
error prone. This patch introduces a new helper macro to put the command
string into its own ELF section:
GUESTFSD_EXT_CMD(C_variable, command_name);
This syntax makes it still possible to grep for used command names.
The actual usage of the collected list could be like this:
objcopy -j .guestfsd_ext_cmds -O binary daemon/guestfsd /dev/stdout |
tr '\0' '\n' | sort -u
The resulting output will be used to tell mkinitrd which programs to
copy into the initrd.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
RWMJ:
- Move str_vgchange at request of author.
- Fix snprintf call in daemon/debug.c
The presumption is that all file descriptors should be created with
the close-on-exec flag set. The only exception are file descriptors
that we want passed through to exec'd subprocesses (mainly pipes and
stdin/stdout/stderr).
For open calls, we pass O_CLOEXEC as an extra flag, eg:
fd = open ("foo", O_RDONLY|O_CLOEXEC);
This is a Linux-ism, but using a macro we can easily make it portable.
For sockets, similarly:
sock = socket (..., SOCK_STREAM|SOCK_CLOEXEC, ...);
For accepted sockets, we use the Linux accept4 system call which
allows flags to be supplied, but we use the Gnulib 'accept4' module to
make this portable.
For dup, dup2, we use the Linux dup3 system call, and the Gnulib
modules 'dup3' and 'cloexec'.
Previously a lot of daemon code used three variables (a string list,
'int size' and 'int alloc') to track growable strings buffers. This
commit implements a simple struct containing the same variables, but
using size_t instead of int:
struct stringsbuf {
char **argv;
size_t size;
size_t alloc;
};
Use it like this:
DECLARE_STRINGSBUF (ret);
//...
if (add_string (&ret, str) == -1)
return NULL;
//...
if (end_stringsbuf (&ret) == -1)
return NULL;
return ret.argv;
Pengzhen Cao noticed that read-file would fail for files
larger than the protocol size; this is *not* the bug. However
it would also lose protocol synchronization after this.
The reason was that functions which return RBufferOut in the
generator must not 'touch' the *size_r parameter along error
return paths.
I fixed read-file and initrd-cat, and I checked that pread was
doing the right thing.
This also adds regression tests for read-file with various categories
of large file.
The RPC stubs already prefix the command name to error messages.
The daemon doesn't have to do this. As a (small) benefit this also
makes the daemon slightly smaller.
Code in the daemon such as:
if (argv[0] == NULL) {
reply_with_error ("passed an empty list");
return NULL;
}
now results in error messages like this:
><fs> command ""
libguestfs: error: command: passed an empty list
(whereas previously you would have seen ..command: command:..)
Nearly every file-related function in daemons/*.c is affected:
Remove this pair of statements from each affected do_* function:
- NEED_ROOT (return -1);
- ABS_PATH (dir, return -1);
and change the type of the corresponding parameter to "const char *".
* src/generator.ml: Emit NEED_ROOT just once, even when there are two or
more Pathname args.
Currently /sysroot is hard-coded throughout the daemon code.
This patch turns the path into a variable so that we can change
it in future, for example to allow standalone mode to be implemented.
This patch was tested by running all the C API tests successfully.
We are generally interested that the subcommand ran without
error, ie. had exit status of 0. 'pclose' returns the exit
status, so we now check that pclose (fp) != 0.
Add 'initrd-list' command to list the files inside (new-style)
initrd images. Update virt-inspector to use this instead of
the less efficient download/unpack locally method.
