From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:50614) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RBXPO-00062u-Hv for qemu-devel@nongnu.org; Wed, 05 Oct 2011 15:45:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RBXPN-0007AH-62 for qemu-devel@nongnu.org; Wed, 05 Oct 2011 15:45:38 -0400 Received: from mail-iy0-f173.google.com ([209.85.210.173]:48213) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RBXPN-0007AB-2w for qemu-devel@nongnu.org; Wed, 05 Oct 2011 15:45:37 -0400 Received: by iakc1 with SMTP id c1so1170068iak.4 for ; Wed, 05 Oct 2011 12:45:36 -0700 (PDT) Message-ID: <4E8CB3DB.7020204@codemonkey.ws> Date: Wed, 05 Oct 2011 14:45:31 -0500 From: Anthony Liguori MIME-Version: 1.0 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 3/4] savevm: improve subsections detection on load List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Juan Quintela Cc: pbonzini@redhat.com, qemu-devel@nongnu.org On 10/04/2011 09:38 AM, Juan Quintela wrote: > We add qemu_peek_buffer, that is identical to qemu_get_buffer, just > that it don't update f->buf_index. > > We add a paramenter to qemu_peek_byte() to be able to peek more than > one byte. > > Once this is done, to see if we have a subsection we look: > - 1st byte is QEMU_VM_SUBSECTION > - 2nd byte is a length, and is bigger than section name > - 3rd element is a string that starts with section_name > > So, we shouldn't have false positives (yes, content could still get us > wrong but probabilities are really low). > > Signed-off-by: Juan Quintela > --- > savevm.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++--------- > 1 files changed, 60 insertions(+), 11 deletions(-) > > diff --git a/savevm.c b/savevm.c > index 5fee4e2..db6ea12 100644 > --- a/savevm.c > +++ b/savevm.c > @@ -532,6 +532,37 @@ void qemu_put_byte(QEMUFile *f, int v) > qemu_fflush(f); > } > > +static int qemu_peek_buffer(QEMUFile *f, uint8_t *buf, int size1, int offset) > +{ > + int size, l; > + int index = f->buf_index + offset; > + > + if (f->is_write) { > + abort(); > + } > + > + size = size1; > + while (size> 0) { > + l = f->buf_size - index; > + if (l == 0) { > + qemu_fill_buffer(f); > + index = f->buf_index + offset; > + l = f->buf_size - index; > + if (l == 0) { > + break; > + } > + } > + if (l> size) { > + l = size; > + } > + memcpy(buf, f->buf + index, l); > + index += l; > + buf += l; > + size -= l; > + } > + return size1 - size; > +} > + > int qemu_get_buffer(QEMUFile *f, uint8_t *buf, int size1) > { > int size, l; Can we implement get_buffer in terms of peek_buffer and just increment f->buf_index in get_buffer? > @@ -561,19 +592,22 @@ int qemu_get_buffer(QEMUFile *f, uint8_t *buf, int size1) > return size1 - size; > } > > -static int qemu_peek_byte(QEMUFile *f) > +static int qemu_peek_byte(QEMUFile *f, int offset) > { > + int index = f->buf_index + offset; > + > if (f->is_write) { > abort(); > } > > - if (f->buf_index>= f->buf_size) { > + if (index>= f->buf_size) { > qemu_fill_buffer(f); > - if (f->buf_index>= f->buf_size) { > + index = f->buf_index + offset; > + if (index>= f->buf_size) { > return 0; > } > } > - return f->buf[f->buf_index]; > + return f->buf[index]; > } > > int qemu_get_byte(QEMUFile *f) > @@ -1687,22 +1721,37 @@ static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd, > return 0; > } > > - while (qemu_peek_byte(f) == QEMU_VM_SUBSECTION) { > + while (qemu_peek_byte(f, 0) == QEMU_VM_SUBSECTION) { > char idstr[256]; > int ret; > - uint8_t version_id, len; > + uint8_t version_id, len, size; > const VMStateDescription *sub_vmsd; > > - qemu_get_byte(f); /* subsection */ > - len = qemu_get_byte(f); > - qemu_get_buffer(f, (uint8_t *)idstr, len); > - idstr[len] = 0; > - version_id = qemu_get_be32(f); > + len = qemu_peek_byte(f, 1); > + if (len< strlen(vmsd->name) + 1) { > + /* subsection name has be be "section_name/a" */ > + return 0; > + } > + size = qemu_peek_buffer(f, (uint8_t *)idstr, len, 2); > + if (size != len) { > + return 0; > + } > + idstr[size] = 0; Regards, Anthony Liguori