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Re: [Qemu-devel] [PATCH 2/2] Monitor: Make output buffer dynamic
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] Monitor: Make output buffer dynamic |
Date: |
Mon, 25 Mar 2013 22:07:36 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 |
Il 25/03/2013 20:40, Luiz Capitulino ha scritto:
> Commit f628926bb423fa8a7e0b114511400ea9df38b76a changed monitor_flush()
> to retry on qemu_chr_fe_write() errors. However, the Monitor's output
> buffer can keep growing while the retry is not issued and this can
> cause the buffer to overflow.
>
> To reproduce this issue, just start qemu and type on the Monitor:
>
> (qemu) ?
>
> This will cause the assertion to trig.
>
> To fix this problem this commit makes the Monitor buffer dynamic,
> which means that it can grow as much as needed.
What about using a GString instead?
Paolo
> Signed-off-by: Luiz Capitulino <address@hidden>
> ---
> monitor.c | 42 +++++++++++++++++++++++++-----------------
> 1 file changed, 25 insertions(+), 17 deletions(-)
>
> diff --git a/monitor.c b/monitor.c
> index 2d9e887..c93dfe7 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -188,8 +188,7 @@ struct Monitor {
> int reset_seen;
> int flags;
> int suspend_cnt;
> - uint8_t outbuf[1024];
> - int outbuf_index;
> + QString *outbuf;
> ReadLineState *rs;
> MonitorControl *mc;
> CPUArchState *mon_cpu;
> @@ -271,45 +270,52 @@ static gboolean monitor_unblocked(GIOChannel *chan,
> GIOCondition cond,
> void monitor_flush(Monitor *mon)
> {
> int rc;
> + size_t len;
> + const char *buf;
> +
> + buf = qstring_get_str(mon->outbuf);
> + len = qstring_get_length(mon->outbuf);
>
> - if (mon && mon->outbuf_index != 0 && !mon->mux_out) {
> - rc = qemu_chr_fe_write(mon->chr, mon->outbuf, mon->outbuf_index);
> - if (rc == mon->outbuf_index) {
> + if (mon && len && !mon->mux_out) {
> + rc = qemu_chr_fe_write(mon->chr, (const uint8_t *) buf, len);
> + if (rc == len) {
> /* all flushed */
> - mon->outbuf_index = 0;
> + QDECREF(mon->outbuf);
> + mon->outbuf = qstring_new();
> return;
> }
> if (rc > 0) {
> /* partinal write */
> - memmove(mon->outbuf, mon->outbuf + rc, mon->outbuf_index - rc);
> - mon->outbuf_index -= rc;
> + QString *tmp = qstring_from_str(buf + rc);
> + QDECREF(mon->outbuf);
> + mon->outbuf = tmp;
> }
> qemu_chr_fe_add_watch(mon->chr, G_IO_OUT, monitor_unblocked, mon);
> }
> }
>
> -/* flush at every end of line or if the buffer is full */
> +/* flush at every end of line */
> static void monitor_puts(Monitor *mon, const char *str)
> {
> char c;
>
> for(;;) {
> - assert(mon->outbuf_index < sizeof(mon->outbuf) - 1);
> c = *str++;
> if (c == '\0')
> break;
> - if (c == '\n')
> - mon->outbuf[mon->outbuf_index++] = '\r';
> - mon->outbuf[mon->outbuf_index++] = c;
> - if (mon->outbuf_index >= (sizeof(mon->outbuf) - 1)
> - || c == '\n')
> + if (c == '\n') {
> + qstring_append_chr(mon->outbuf, '\r');
> + }
> + qstring_append_chr(mon->outbuf, c);
> + if (c == '\n') {
> monitor_flush(mon);
> + }
> }
> }
>
> void monitor_vprintf(Monitor *mon, const char *fmt, va_list ap)
> {
> - char buf[4096];
> + char *buf;
>
> if (!mon)
> return;
> @@ -318,8 +324,9 @@ void monitor_vprintf(Monitor *mon, const char *fmt,
> va_list ap)
> return;
> }
>
> - vsnprintf(buf, sizeof(buf), fmt, ap);
> + buf = g_strdup_vprintf(fmt, ap);
> monitor_puts(mon, buf);
> + g_free(buf);
> }
>
> void monitor_printf(Monitor *mon, const char *fmt, ...)
> @@ -4732,6 +4739,7 @@ void monitor_init(CharDriverState *chr, int flags)
> }
>
> mon = g_malloc0(sizeof(*mon));
> + mon->outbuf = qstring_new();
>
> mon->chr = chr;
> mon->flags = flags;
>