[Qemu-devel] [PATCH 1/3] qemu-error: add {error, warn}_report_once_cond

[Cornelia Huck]

Add two functions to print an error/warning report once depending
on a passed-in condition variable and flip it if printed. This is
useful if you want to print a message not once-globally, but e.g.
once-per-device.

Inspired by warn_once() in hw/vfio/ccw.c.

Signed-off-by: Cornelia Huck <address@hidden>
---
 include/qemu/error-report.h |  5 +++++
 util/qemu-error.c           | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/include/qemu/error-report.h b/include/qemu/error-report.h
index 72fab2b031..d2a6515e68 100644
--- a/include/qemu/error-report.h
+++ b/include/qemu/error-report.h
@@ -44,6 +44,11 @@ void error_report(const char *fmt, ...) GCC_FMT_ATTR(1, 2);
 void warn_report(const char *fmt, ...) GCC_FMT_ATTR(1, 2);
 void info_report(const char *fmt, ...) GCC_FMT_ATTR(1, 2);
 
+void error_report_once_cond(bool *printed, const char *fmt, ...)
+    GCC_FMT_ATTR(2, 3);
+void warn_report_once_cond(bool *printed, const char *fmt, ...)
+    GCC_FMT_ATTR(2, 3);
+
 /*
  * Similar to error_report(), except it prints the message just once.
  * Return true when it prints, false otherwise.
diff --git a/util/qemu-error.c b/util/qemu-error.c
index a25d3b94c6..0894ab6995 100644
--- a/util/qemu-error.c
+++ b/util/qemu-error.c
@@ -310,3 +310,47 @@ void info_report(const char *fmt, ...)
     vreport(REPORT_TYPE_INFO, fmt, ap);
     va_end(ap);
 }
+
+/*
+ * If *printed is false, print an error message to current monitor if we
+ * have one, else to stderr, and flip *printed to true.
+ * If printed is NULL, do not print anything.
+ * Format arguments like sprintf().  The resulting message should be
+ * a single phrase, with no newline or trailing punctuation.
+ * Prepend the current location and append a newline.
+ * It's wrong to call this in a QMP monitor.  Use error_setg() there.
+ */
+void error_report_once_cond(bool *printed, const char *fmt, ...)
+{
+    va_list ap;
+
+    if (!printed || *printed) {
+        return;
+    }
+    *printed = true;
+    va_start(ap, fmt);
+    vreport(REPORT_TYPE_ERROR, fmt, ap);
+    va_end(ap);
+}
+
+/*
+ * If *printed is false, print a warning message to current monitor if we
+ * have one, else to stderr, and flip *printed to true.
+ * If printed is NULL, do not print anything.
+ * Format arguments like sprintf().  The resulting message should be
+ * a single phrase, with no newline or trailing punctuation.
+ * Prepend the current location and append a newline.
+ * It's wrong to call this in a QMP monitor.  Use error_setg() there.
+ */
+void warn_report_once_cond(bool *printed, const char *fmt, ...)
+{
+    va_list ap;
+
+    if (!printed || *printed) {
+        return;
+    }
+    *printed = true;
+    va_start(ap, fmt);
+    vreport(REPORT_TYPE_WARNING, fmt, ap);
+    va_end(ap);
+}
-- 
2.14.4