Re: [Qemu-devel] [PATCH/RFC 4/7] Allow saving screendump to a UNIX socket

["Daniel P. Berrange" <berrange@redhat.com>]

On Mon, Mar 12, 2012 at 02:11:30PM +0100, Marc-André Lureau wrote:
> By using the 'unix:' prefix notation, similar to the migration uri, we
> can now dump to a UNIX socket. IO is still sync
> ---
>  hw/vga.c    |   64 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  qemu-file.h |    1 +
>  2 files changed, 63 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/vga.c b/hw/vga.c
> index 24af4a1..bb5df70 100644
> --- a/hw/vga.c
> +++ b/hw/vga.c
> @@ -30,6 +30,7 @@
>  #include "pixel_ops.h"
>  #include "qemu-timer.h"
>  #include "xen.h"
> +#include "qemu_socket.h"
>  
>  //#define DEBUG_VGA
>  //#define DEBUG_VGA_MEM
> @@ -37,6 +38,14 @@
>  
>  //#define DEBUG_BOCHS_VBE
>  
> +#ifdef DEBUG_VGA
> +#define DPRINTF(fmt, ...) \
> +    do { printf("vga: " fmt, ## __VA_ARGS__); } while (0)
> +#else
> +#define DPRINTF(fmt, ...) \
> +    do { } while (0)
> +#endif
> +
>  /*
>   * Video Graphics Array (VGA)
>   *
> @@ -2362,7 +2371,58 @@ void vga_init_vbe(VGACommonState *s, MemoryRegion *system_memory)
>  /********************************************************/
>  /* vga screen dump */
>  
> -int ppm_save(const char *filename, struct DisplaySurface *ds)
> +#if !defined(WIN32)
> +static QEMUFile *qemu_fopen_unix(const char *path, const char *mode)
> +{
> +    struct sockaddr_un addr;
> +    int ret, fd;
> +
> +    addr.sun_family = AF_UNIX;
> +    snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);
> +
> +    fd = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
> +    if (fd == -1) {
> +        DPRINTF("Unable to open socket: %s\n", strerror(errno));
> +        return NULL;
> +    }
> +
> +    do {
> +        ret = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
> +        if (ret == -1) {
> +            ret = -errno;
> +        }
> +    } while (ret == -EINTR);
> +
> +    if (ret < 0) {
> +        DPRINTF("connect failed: %s\n": strerror(errno));
> +        return NULL;
> +    }
> +
> +    return qemu_fopen_socket(fd, mode);
> +}
> +#endif
> +
> +QEMUFile *qemu_fopen_uri(const char *uri, const char *mode)
> +{
> +    QEMUFile *f = NULL;
> +    const char *p;
> +
> +    g_return_val_if_fail(uri != NULL, NULL);
> +    g_return_val_if_fail(mode != NULL, NULL);
> +
> +#if !defined(WIN32)
> +    if (strstart(uri, "unix:", &p)) {
> +        f = qemu_fopen_unix(p, mode);
> +    }
> +#endif
> +    if (f == NULL) {
> +        f = qemu_fopen(uri, mode);
> +    }
> +
> +    return f;
> +}
> +
> +int ppm_save(const char *uri, struct DisplaySurface *ds)
>  {
>      QEMUFile *f;
>      uint8_t *d, *d1;
> @@ -2372,7 +2432,7 @@ int ppm_save(const char *filename, struct DisplaySurface *ds)
>      char *linebuf, *pbuf;
>      gchar *header;
>  
> -    f = qemu_fopen(filename, "wb");
> +    f = qemu_fopen_uri(uri, "wb");
>      g_return_val_if_fail(f != NULL, -1);
>  
>      header = g_strdup_printf("P6\n%d %d\n%d\n", ds->width, ds->height, 255);
> diff --git a/qemu-file.h b/qemu-file.h
> index efd6b1c..0914d83 100644
> --- a/qemu-file.h
> +++ b/qemu-file.h
> @@ -68,6 +68,7 @@ QEMUFile *qemu_fopen_ops(void *opaque, QEMUFilePutBufferFunc *put_buffer,
>  QEMUFile *qemu_fopen(const char *filename, const char *mode);
>  QEMUFile *qemu_fdopen(int fd, const char *mode);
>  QEMUFile *qemu_fopen_socket(int fd, const char *mode);
> +QEMUFile *qemu_fopen_uri(const char *uri, const char *mode);
>  QEMUFile *qemu_popen(FILE *popen_file, const char *mode);
>  QEMUFile *qemu_popen_cmd(const char *command, const char *mode);
>  int qemu_stdio_fd(QEMUFile *f);

It would be even more broadly useful if the screendump command was
extended to allow a file descriptor to be just passed across to
QEMU, avoiding the need to interact with the filesystem namespace
at all.

Regards,
Daniel
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