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Re: [Qemu-devel] [PATCH 1/1] Support abstract socket namespace in AF_UNI
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] [PATCH 1/1] Support abstract socket namespace in AF_UNIX socket family. |
Date: |
Mon, 07 Jan 2013 08:07:47 -0600 |
User-agent: |
Notmuch/0.13.2+93~ged93d79 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) |
Alexander Barabash <address@hidden> writes:
> The abstract socket namespace is a nonportable Linux extension.
> The sockets' names in this namespace have no connection
> with file system pathnames. To specify a named AF_UNIX socket
> in the abstract socket namespace, start the socket's path option
> with a backslash followed by zero: \0.
>
> Signed-off-by: Alexander Barabash <address@hidden>
Magic interpretation of path names is a bad thing in general.
I think it would be better to add a flag 'abstract=on' which
indicates to use the abstract namespace. As an example:
qemu -chardev foo,path=bar,abstract=on
vs:
qemu -chardev foo,path="\\\\0bar"
I think the former is quite a bit more user friendly.
Regards,
Anthony Liguori
> ---
> qemu-sockets.c | 58
> +++++++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 55 insertions(+), 3 deletions(-)
>
> diff --git a/qemu-sockets.c b/qemu-sockets.c
> index 3537bf3..70c8ad5 100644
> --- a/qemu-sockets.c
> +++ b/qemu-sockets.c
> @@ -663,11 +663,50 @@ int inet_nonblocking_connect(const char *str,
>
> #ifndef _WIN32
>
> +/*
> + * The abstract socket namespace is a nonportable Linux extension.
> + * The sockets' names in this namespace have no connection
> + * with file system pathnames. To specify a named AF_UNIX socket
> + * in the abstract socket namespace, start the socket's path option
> + * with a backslash followed by zero: \0.
> + */
> +static
> +char *get_abstract_namespace_path(const char *path, int
> *abstract_path_length)
> +{
> + char *abstract_path;
> + char *inp;
> + char *outp;
> + char c;
> +
> + *abstract_path_length = 0;
> + if ((path == NULL) || (path[0] != '\\') || (path[1] != '0')) {
> + return NULL;
> + }
> + abstract_path = g_strdup(path + 2);
> + for (inp = abstract_path, outp = abstract_path; (c = *inp); ++inp,
> ++outp) {
> + if (c == '\\') {
> + c = *++inp;
> + if (c == '\\') {
> + *outp = c;
> + } else if (c == '0') {
> + *outp = '\0';
> + }
> + } else {
> + *outp = c;
> + }
> + }
> + *abstract_path_length = outp - abstract_path;
> + return abstract_path;
> +}
> +
> int unix_listen_opts(QemuOpts *opts, Error **errp)
> {
> struct sockaddr_un un;
> const char *path = qemu_opt_get(opts, "path");
> + int abstract_path_length;
> + char *abstract_path;
> int sock, fd;
> + socklen_t addrlen = sizeof(un);
>
> sock = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
> if (sock < 0) {
> @@ -675,9 +714,18 @@ int unix_listen_opts(QemuOpts *opts, Error **errp)
> return -1;
> }
>
> + abstract_path = get_abstract_namespace_path(path, &abstract_path_length);
> +
> memset(&un, 0, sizeof(un));
> un.sun_family = AF_UNIX;
> - if (path && strlen(path)) {
> + if (abstract_path != NULL) {
> + if (abstract_path_length > sizeof(un.sun_path) - 1) {
> + abstract_path_length = sizeof(un.sun_path) - 1;
> + }
> + memcpy(un.sun_path + 1, abstract_path, abstract_path_length);
> + addrlen =
> + offsetof(struct sockaddr_un, sun_path) + 1 +
> abstract_path_length;
> + } else if (path && strlen(path)) {
> snprintf(un.sun_path, sizeof(un.sun_path), "%s", path);
> } else {
> char *tmpdir = getenv("TMPDIR");
> @@ -694,8 +742,10 @@ int unix_listen_opts(QemuOpts *opts, Error **errp)
> qemu_opt_set(opts, "path", un.sun_path);
> }
>
> - unlink(un.sun_path);
> - if (bind(sock, (struct sockaddr*) &un, sizeof(un)) < 0) {
> + if (abstract_path == NULL) {
> + unlink(un.sun_path);
> + }
> + if (bind(sock, (struct sockaddr *) &un, addrlen) < 0) {
> error_set_errno(errp, errno, QERR_SOCKET_BIND_FAILED);
> goto err;
> }
> @@ -704,10 +754,12 @@ int unix_listen_opts(QemuOpts *opts, Error **errp)
> goto err;
> }
>
> + g_free(abstract_path);
> return sock;
>
> err:
> closesocket(sock);
> + g_free(abstract_path);
> return -1;
> }
>
> --
> 1.7.9.5