[Qemu-devel] [PATCH v2 2/2] doc: Introduce coding style for errors

["Lluís Vilanova" <vilanova@ac.upc.edu>]

Gives some general guidelines for reporting errors in QEMU.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
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 HACKING |   31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/HACKING b/HACKING
index 12fbc8a..e59bc34 100644
--- a/HACKING
+++ b/HACKING
@@ -157,3 +157,34 @@ painful. These are:
  * you may assume that integers are 2s complement representation
  * you may assume that right shift of a signed integer duplicates
    the sign bit (ie it is an arithmetic shift, not a logical shift)
+
+7. Error reporting
+
+QEMU provides two different mechanisms for reporting errors. You should use one
+of these mechanisms instead of manually reporting them (i.e., do not use
+'printf', 'exit' or 'abort').
+
+7.1. Errors in user inputs
+
+QEMU provides the functions in "include/qemu/error-report.h" to report errors
+related to inputs provided by the user (e.g., command line arguments or
+configuration files).
+
+These functions generate error messages with a uniform format that can reference
+a location on the offending input.
+
+7.2. Other errors
+
+QEMU provides the functions in "include/qapi/error.h" to report other types of
+errors (i.e., not triggered by command line arguments or configuration files).
+
+Functions in this header are used to accumulate error messages in an 'Error'
+object, which can be propagated up the call chain where it is finally reported.
+
+In its simplest form, you can immediately report an error with:
+
+    error_setg(&error_warn, "Error with %s", "arguments");
+
+See the "include/qapi/error.h" header for additional convenience functions and
+special arguments. Specially, see 'error_fatal' and 'error_abort' to show errors
+and immediately terminate QEMU.