Re: [PATCH] osdep: Introduce qemu_get_fd() to wrap the common codes

[Markus Armbruster]

Christian Schoenebeck <qemu_oss@crudebyte.com> writes:

> On Donnerstag, 18. August 2022 14:06:04 CEST Guoyi Tu wrote:
>> Ping...
>> 
>> Any comments are welcome
>> 
>> On 8/12/22 19:01, Guoyi Tu wrote:
>> > socket_get_fd() have much the same codes as monitor_fd_param(),
>> > so qemu_get_fd() is introduced to implement the common logic.
>> > now socket_get_fd() and monitor_fd_param() directly call this
>> > function.
>
> s/have/has/, s/now/Now/, some proper rephrasing wouldn't hurt either.
>
>> > Signed-off-by: Guoyi Tu <tugy@chinatelecom.cn>
>> > ---
>> > 
>> >   include/qemu/osdep.h |  1 +
>> >   monitor/misc.c       | 21 +--------------------
>> >   util/osdep.c         | 25 +++++++++++++++++++++++++
>> >   util/qemu-sockets.c  | 17 +++++------------
>> >   4 files changed, 32 insertions(+), 32 deletions(-)
>> > 
>> > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
>> > index b1c161c035..b920f128a7 100644
>> > --- a/include/qemu/osdep.h
>> > +++ b/include/qemu/osdep.h
>> > @@ -491,6 +491,7 @@ int qemu_open_old(const char *name, int flags, ...);
>> > 
>> >   int qemu_open(const char *name, int flags, Error **errp);
>> >   int qemu_create(const char *name, int flags, mode_t mode, Error **errp);
>> >   int qemu_close(int fd);
>> > 
>> > +int qemu_get_fd(Monitor *mon, const char *fdname, Error **errp);
>> > 
>> >   int qemu_unlink(const char *name);
>> >   #ifndef _WIN32
>> >   int qemu_dup_flags(int fd, int flags);
>> > 
>> > diff --git a/monitor/misc.c b/monitor/misc.c
>> > index 3d2312ba8d..0d3372cf2b 100644
>> > --- a/monitor/misc.c
>> > +++ b/monitor/misc.c
>> > @@ -1395,26 +1395,7 @@ void monitor_fdset_dup_fd_remove(int dup_fd)
>> > 
>> >   int monitor_fd_param(Monitor *mon, const char *fdname, Error **errp)
>> >   {
>> > 
>> > -    int fd;
>> > -    Error *local_err = NULL;
>> > -
>> > -    if (!qemu_isdigit(fdname[0]) && mon) {
>> > -        fd = monitor_get_fd(mon, fdname, &local_err);
>> > -    } else {
>> > -        fd = qemu_parse_fd(fdname);
>> > -        if (fd == -1) {
>> > -            error_setg(&local_err, "Invalid file descriptor number '%s'",
>> > -                       fdname);
>> > -        }
>> > -    }
>> > -    if (local_err) {
>> > -        error_propagate(errp, local_err);
>> > -        assert(fd == -1);
>> > -    } else {
>> > -        assert(fd != -1);
>> > -    }
>> > -
>> > -    return fd;
>> > +    return qemu_get_fd(mon, fdname, errp);
>> > 
>> >   }

This becomes a trivial wrapper around qemu_get_fd().  Why do we need
both functions?

>> >  
>> >   /* Please update hmp-commands.hx when adding or changing commands */
>> > 
>> > diff --git a/util/osdep.c b/util/osdep.c
>> > index 60fcbbaebe..c57551ca78 100644
>> > --- a/util/osdep.c
>> > +++ b/util/osdep.c
>> > @@ -23,6 +23,7 @@
>> > 
>> >    */
>> >   #include "qemu/osdep.h"
>> >   #include "qapi/error.h"
>> > 
>> > +#include "qemu/ctype.h"
>> > 
>> >   #include "qemu/cutils.h"
>> >   #include "qemu/sockets.h"
>> >   #include "qemu/error-report.h"
>> > 
>> > @@ -413,6 +414,30 @@ int qemu_close(int fd)
>> > 
>> >       return close(fd);
>> >   }
>> > 
>> > +int qemu_get_fd(Monitor *mon, const char *fdname, Error **errp)
>> > +{
>> > +    int fd;
>> > +    Error *local_err = NULL;
>> > +
>> > +    if (!qemu_isdigit(fdname[0]) && mon) {
>> > +        fd = monitor_get_fd(mon, fdname, &local_err);
>> > +    } else {
>> > +        fd = qemu_parse_fd(fdname);
>> > +        if (fd == -1) {
>> > +            error_setg(&local_err, "Invalid file descriptor number '%s'",
>> > +                       fdname);
>> > +        }
>> > +    }
>> > +    if (local_err) {
>> > +        error_propagate(errp, local_err);
>> > +        assert(fd == -1);
>> > +    } else {
>> > +        assert(fd != -1);
>> > +    }
>> > +
>> > +    return fd;
>> > +}
>> > +
>
> Up to here you are basically just moving the code of monitor_fd_param() to a 
> project wide shared new function qemu_get_fd(), but why? I mean you could 
> simply call monitor_fd_param() in socket_get_fd() below, no?

Point.

>> >   /*
>> >    * Delete a file from the filesystem, unless the filename is
>> > 
>> > /dev/fdset/...
>> > 
>> >    *
>> > 
>> > diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
>> > index 13b5b197f9..92960ee6eb 100644
>> > --- a/util/qemu-sockets.c
>> > +++ b/util/qemu-sockets.c
>> > @@ -1142,19 +1142,12 @@ static int socket_get_fd(const char *fdstr,
>> > Error **errp)
>> > 
>> >   {
>> >       Monitor *cur_mon = monitor_cur();
>> >       int fd;
>> > 
>> > -    if (cur_mon) {
>> > -        fd = monitor_get_fd(cur_mon, fdstr, errp);
>> > -        if (fd < 0) {
>> > -            return -1;
>> > -        }
>> > -    } else {
>> > -        if (qemu_strtoi(fdstr, NULL, 10, &fd) < 0) {
>> > -            error_setg_errno(errp, errno,
>> > -                             "Unable to parse FD number %s",
>> > -                             fdstr);
>> > -            return -1;
>> > -        }
>> > +
>> > +    fd = qemu_get_fd(cur_mon, fdstr, errp);
>> > +    if (fd < 0) {
>> > +        return -1;
>> > 
>> >       }
>
> This part looks like behaviour change to me. Haven't looked into the details 
> though whether it would be OK. Just saying.

When factoring out code that isn't obviously the same, it often makes
sense to first make it more obviously the same in-place, and only then
factor it out.

In this case: have PATCH 1/2 change socket_get_fd() in-place to make the
code obviously common, then de-duplicate it in PATCH 2/2.

>
>> > 
>> > +
>
> Unintentional white line added?
>
>> > 
>> >       if (!fd_is_socket(fd)) {
>> >           error_setg(errp, "File descriptor '%s' is not a socket", fdstr);
>> >           close(fd);