Re: [PATCH 4/6] ch: events: Read and parse cloud-hypervisor events

Implement `chReadProcessEvents` and `chProcessEvents` to read events from event monitor FIFO file and parse them accordingly. Signed-off-by: Purna Pavan Chandra Aekkaladevi <paekkaladevi(a)linux.microsoft.com&gt; Co-authored-by: Vineeth Pillai <viremana(a)linux.microsoft.com&gt; --- src/ch/ch_events.c | 142 +++++++++++++++++++++++++++++++++++++++++++- src/ch/ch_events.h | 2 + src/ch/ch_monitor.h | 6 ++ 3 files changed, 149 insertions(+), 1 deletion(-) diff --git a/src/ch/ch_events.c b/src/ch/ch_events.c index 851fbc9f26..a028f9813e 100644 --- a/src/ch/ch_events.c +++ b/src/ch/ch_events.c @@ -28,6 +28,142 @@ VIR_LOG_INIT("ch.ch_events");

+static int virCHProcessEvents(virCHMonitor *mon) +{ + char *buf = mon->event_buffer.buffer; + ssize_t sz = mon->event_buffer.buf_fill_sz; + virJSONValue *obj = NULL;

+ int blocks = 0; + size_t i = 0; + char *json_start; + ssize_t start_index = -1; + ssize_t end_index = -1; + char tmp; + int ret = 0; + + while (i < sz) { + if (buf[i] == '{') { + blocks++; + if (blocks == 1) + start_index = i; + } else if (buf[i] == '}' && blocks > 0) { + blocks--; + if (blocks == 0) { + // valid json document + end_index = i; + + /* + * We may hit a corner case where a valid JSON + * doc happens to end right at the end of the buffer. + * virJSONValueFromString needs '\0' end the JSON doc. + * So we need to adjust the buffer accordingly. + */ + if (end_index == CH_EVENT_BUFFER_SZ - 1) { + if (start_index == 0) { + /* + * We have a valid JSON doc same as the buffer + * size. As per protocol, max JSON doc should be + * less than the buffer size. So this is an error. + * Ignore this JSON doc. + */ + VIR_WARN("Invalid JSON doc size. Expected <= %d", + CH_EVENT_BUFFER_SZ); + start_index = -1; + ret = -1; + break; + } + + /* + * Move the valid JSON doc to the start of the buffer so + * that we can safely fit a '\0' at the end. + */ + memmove(buf, buf+start_index, end_index-start_index+1); + end_index -= start_index; + start_index = 0; + } + + // temporarily null terminate the JSON doc + tmp = buf[end_index + 1]; + buf[end_index + 1] = '\0'; + json_start = buf + start_index; + + if ((obj = virJSONValueFromString(json_start))) { + /* Process the event string (obj) here */ + virJSONValueFree(obj); + } else { + VIR_WARN("Invalid JSON event doc: %s", json_start); + ret = -1; + } + + // replace the original character + buf[end_index + 1] = tmp; + start_index = -1; + } + } + + i++; + } + + if (start_index == -1) { + // We have processed all the JSON docs in the buffer. + mon->event_buffer.buf_fill_sz = 0; + } else if (start_index > 0) { + // We have an incomplete JSON doc at the end of the buffer. + // Move it to the start of the buffer. + mon->event_buffer.buf_fill_sz = sz - start_index; + memmove(buf, buf+start_index, mon->event_buffer.buf_fill_sz); + } + + return ret; +} + +static void virCHReadProcessEvents(virCHMonitor *mon, + int event_monitor_fd) +{ + size_t max_sz = CH_EVENT_BUFFER_SZ;

+ char *buf = mon->event_buffer.buffer; + virDomainObj *vm = mon->vm; + bool incomplete = false; + size_t sz = 0; + + memset(buf, 0, max_sz); + do { + ssize_t ret; + + ret = read(event_monitor_fd, buf + sz, max_sz - sz); + if (ret == 0 || (ret < 0 && errno == EINTR)) { + g_usleep(G_USEC_PER_SEC); + continue; + } else if (ret < 0) { + /* + * We should never reach here. read(2) says possible errors + * are EINTR, EAGAIN, EBADF, EFAULT, EINVAL, EIO, EISDIR + * We handle EINTR gracefully. There is some serious issue + * if we encounter any of the other errors(either in our code + * or in the system). Better to bail out. + */ + VIR_ERROR(_("Failed to read ch events!: %1$s"), g_strerror(errno)); + VIR_FORCE_CLOSE(event_monitor_fd); + abort(); + } + + sz += ret; + mon->event_buffer.buf_fill_sz = sz; + + if (virCHProcessEvents(mon) < 0) + VIR_WARN("Failed to parse and process events"); + + if (mon->event_buffer.buf_fill_sz != 0) + incomplete = true; + else + incomplete = false; + sz = mon->event_buffer.buf_fill_sz; + + } while (virDomainObjIsActive(vm) && (sz < max_sz) && incomplete); + + return; +} + static void virCHEventHandlerLoop(void *data) { virCHMonitor *mon = data; @@ -51,6 +187,9 @@ static void virCHEventHandlerLoop(void *data) } VIR_DEBUG("Opened the event monitor FIFO(%s)", mon->eventmonitorpath); + mon->event_buffer.buffer = g_malloc_n(sizeof(char), CH_EVENT_BUFFER_SZ); + mon->event_buffer.buf_fill_sz = 0; + /* * We would need to wait until VM is initialized. */ @@ -59,9 +198,10 @@ static void virCHEventHandlerLoop(void *data) while (g_atomic_int_get(&mon->event_handler_stop) == 0) { VIR_DEBUG("Reading events from event monitor file..."); - /* Read and process events here */ + virCHReadProcessEvents(mon, event_monitor_fd); } + g_free(mon->event_buffer.buffer); VIR_FORCE_CLOSE(event_monitor_fd); virObjectUnref(vm); diff --git a/src/ch/ch_events.h b/src/ch/ch_events.h index 4c8a48231d..2e9cdf03bb 100644 --- a/src/ch/ch_events.h +++ b/src/ch/ch_events.h @@ -22,5 +22,7 @@ #include "ch_monitor.h" +#define CH_EVENT_BUFFER_SZ PIPE_BUF + int virCHStartEventHandler(virCHMonitor *mon); void virCHStopEventHandler(virCHMonitor *mon); diff --git a/src/ch/ch_monitor.h b/src/ch/ch_monitor.h index 878a185f29..6b4045d300 100644 --- a/src/ch/ch_monitor.h +++ b/src/ch/ch_monitor.h @@ -99,6 +99,12 @@ struct _virCHMonitor { virThread event_handler_thread; int event_handler_stop; + struct { + // Buffer to hold the data read from pipe

+ char *buffer; + // Size of the data read from pipe in buffer

+ size_t buf_fill_sz; + } event_buffer; pid_t pid;