qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH v2 1/3] qemu-io: Add sigraise command


From: Max Reitz
Subject: Re: [Qemu-devel] [PATCH v2 1/3] qemu-io: Add sigraise command
Date: Fri, 05 Dec 2014 11:07:18 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0

On 2014-12-05 at 10:52, Markus Armbruster wrote:
Max Reitz <address@hidden> writes:

abort() has the sometimes undesirable side-effect of generating a core
dump. If that is not needed, SIGKILL has the same effect of abruptly
crash qemu; without a core dump.

Thus, -c abort is not always useful to simulate a qemu-io crash;
therefore, this patch adds a new sigraise command which allows to raise
any Unix signal.
Nitpick: signals are ISO C, not just UNIX.

Yes, but "Unix signal" is what the Wikipedia article is named, so... ;-)

Signed-off-by: Max Reitz <address@hidden>
---
  qemu-io-cmds.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
  1 file changed, 46 insertions(+)

diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index d94fb1e..942b694 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -2048,6 +2048,51 @@ static const cmdinfo_t abort_cmd = {
         .oneline        = "simulate a program crash using abort(3)",
  };
+static void sigraise_help(void)
+{
+    printf(
+"\n"
+" raises the given Unix signal\n"
+"\n"
+" Example:\n"
+" 'sigraise 9' - raises SIGKILL\n"
Assumes SIGKILL is encoded as 9, which is traditionally the case, but
not actually mandated by POSIX.

Yes, I know. The best would be to parse the signal like kill(1) does, but that would have been extra difficult and probably not worth the effort.

Furthermore, I know there is a song called "kill dash nine", so I guessed it would be enough (at least it'll have to be enough for test 039, thanks to "_supported_os Linux").

You could avoid hardcoding 9 with

     " 'sigraise %d' - raises SIGKILL\n"

with a SIGKILL as argument for %d.

Clever. Will do.

But then you'd have to face the fact that SIGKILL is POSIX, not ISO C.
The ISO C signals are SIGABRT, SIGFPE, SIGILL, SIGINT, SIGSEGV, SIGTERM.
Of these, SIGINT and SIGTERM don't dump core, in case you care.

Good to know. I guess I'll just go with SIGKILL anyway, it's ubiquitous enough.

+"\n"
+" Invokes raise(signal), where \"signal\" is the mandatory integer argument\n"
+" given to sigraise.\n"
+"\n");
+}
+
+static int sigraise_f(BlockDriverState *bs, int argc, char **argv);
+
+static const cmdinfo_t sigraise_cmd = {
+    .name       = "sigraise",
+    .cfunc      = sigraise_f,
+    .argmin     = 1,
+    .argmax     = 1,
+    .flags      = CMD_NOFILE_OK,
+    .args       = "signal",
+    .oneline    = "raises a Unix signal",
+    .help       = sigraise_help,
+};
+
+static int sigraise_f(BlockDriverState *bs, int argc, char **argv)
+{
+    int sig = cvtnum(argv[1]);
+    if (sig < 0) {
+        printf("non-numeric signal number argument -- %s\n", argv[1]);
+        return 0;
+    }
+
+    /* Using raise() to kill this process does not necessarily flush all open
+     * streams. At least stdout and stderr (although the latter should be
+     * non-buffered anyway) should be flushed, though. */
+    fflush(stdout);
+    fflush(stderr);
+
+    raise(sig);
+    return 0;
+}
+
  static void sleep_cb(void *opaque)
  {
      bool *expired = opaque;
@@ -2202,4 +2247,5 @@ static void __attribute((constructor)) 
init_qemuio_commands(void)
      qemuio_add_command(&wait_break_cmd);
      qemuio_add_command(&abort_cmd);
      qemuio_add_command(&sleep_cmd);
+    qemuio_add_command(&sigraise_cmd);
  }
Looks good otherwise.

Thanks :-)

Max



reply via email to

[Prev in Thread] Current Thread [Next in Thread]