* [PATCH v2 1/2] hw/nvram/fw_cfg: Simplify fw_cfg_add_from_generator() error propagation
2020-07-21 13:19 [PATCH v2 0/2] hw/nvram/fw_cfg: Let fw_cfg_add_from_generator() return boolean value Philippe Mathieu-Daudé
@ 2020-07-21 13:19 ` Philippe Mathieu-Daudé
2020-07-21 14:35 ` Markus Armbruster
2020-07-21 13:19 ` [PATCH v2 2/2] hw/nvram/fw_cfg: Let fw_cfg_add_from_generator() return boolean value Philippe Mathieu-Daudé
2020-07-21 14:52 ` [PATCH v2 0/2] " Philippe Mathieu-Daudé
2 siblings, 1 reply; 5+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-07-21 13:19 UTC (permalink / raw)
To: qemu-devel
Cc: Laszlo Ersek, Paolo Bonzini, Philippe Mathieu-Daudé,
Gerd Hoffmann, Markus Armbruster
Document FWCfgDataGeneratorClass::get_data() return NULL
on error, and non-NULL on success. This allow us to simplify
fw_cfg_add_from_generator(). Since we don't need a local
variable to propagate the error, we can remove the ERRP_GUARD()
macro.
Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
include/hw/nvram/fw_cfg.h | 4 +++-
hw/nvram/fw_cfg.c | 3 +--
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
index 11feae3177..bbcf405649 100644
--- a/include/hw/nvram/fw_cfg.h
+++ b/include/hw/nvram/fw_cfg.h
@@ -32,7 +32,9 @@ typedef struct FWCfgDataGeneratorClass {
* @obj: the object implementing this interface
* @errp: pointer to a NULL-initialized error object
*
- * Returns: reference to a byte array containing the data.
+ * Returns: reference to a byte array containing the data on success,
+ * or NULL on error.
+ *
* The caller should release the reference when no longer
* required.
*/
diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index 3b1811d3bf..dfa1f2012a 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -1035,7 +1035,6 @@ void *fw_cfg_modify_file(FWCfgState *s, const char *filename,
void fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
const char *gen_id, Error **errp)
{
- ERRP_GUARD();
FWCfgDataGeneratorClass *klass;
GByteArray *array;
Object *obj;
@@ -1053,7 +1052,7 @@ void fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
}
klass = FW_CFG_DATA_GENERATOR_GET_CLASS(obj);
array = klass->get_data(obj, errp);
- if (*errp) {
+ if (!array) {
return;
}
size = array->len;
--
2.21.3
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v2 2/2] hw/nvram/fw_cfg: Let fw_cfg_add_from_generator() return boolean value
2020-07-21 13:19 [PATCH v2 0/2] hw/nvram/fw_cfg: Let fw_cfg_add_from_generator() return boolean value Philippe Mathieu-Daudé
2020-07-21 13:19 ` [PATCH v2 1/2] hw/nvram/fw_cfg: Simplify fw_cfg_add_from_generator() error propagation Philippe Mathieu-Daudé
@ 2020-07-21 13:19 ` Philippe Mathieu-Daudé
2020-07-21 14:52 ` [PATCH v2 0/2] " Philippe Mathieu-Daudé
2 siblings, 0 replies; 5+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-07-21 13:19 UTC (permalink / raw)
To: qemu-devel
Cc: Peter Maydell, Philippe Mathieu-Daudé, Markus Armbruster,
Gerd Hoffmann, Paolo Bonzini, Laszlo Ersek
Commits b6d7e9b66f..a43770df5d simplified the error propagation.
Similarly to commit 6fd5bef10b "qom: Make functions taking Error**
return bool, not void", let fw_cfg_add_from_generator() return a
boolean value, not void.
This allow to simplify parse_fw_cfg() and fixes the error handling
issue reported by Coverity (CID 1430396):
In parse_fw_cfg():
Variable assigned once to a constant guards dead code.
Local variable local_err is assigned only once, to a constant
value, making it effectively constant throughout its scope.
If this is not the intent, examine the logic to see if there
is a missing assignment that would make local_err not remain
constant.
It's the call of fw_cfg_add_from_generator():
Error *local_err = NULL;
fw_cfg_add_from_generator(fw_cfg, name, gen_id, errp);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
return 0;
If it fails, parse_fw_cfg() sets an error and returns 0, which is
wrong. Harmless, because the only caller passes &error_fatal.
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Fixes: Coverity CID 1430396: 'Constant' variable guards dead code (DEADCODE)
Fixes: 6552d87c48 ("softmmu/vl: Let -fw_cfg option take a 'gen_id' argument")
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
v2: Added impact assessment (Markus)
---
include/hw/nvram/fw_cfg.h | 4 +++-
hw/nvram/fw_cfg.c | 10 ++++++----
softmmu/vl.c | 6 +-----
3 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
index bbcf405649..f190c428e8 100644
--- a/include/hw/nvram/fw_cfg.h
+++ b/include/hw/nvram/fw_cfg.h
@@ -304,8 +304,10 @@ void *fw_cfg_modify_file(FWCfgState *s, const char *filename, void *data,
* will be used; also, a new entry will be added to the file directory
* structure residing at key value FW_CFG_FILE_DIR, containing the item name,
* data size, and assigned selector key value.
+ *
+ * Returns: %true on success, %false on error.
*/
-void fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
+bool fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
const char *gen_id, Error **errp);
FWCfgState *fw_cfg_init_io_dma(uint32_t iobase, uint32_t dma_iobase,
diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index dfa1f2012a..f3a4728288 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -1032,7 +1032,7 @@ void *fw_cfg_modify_file(FWCfgState *s, const char *filename,
return NULL;
}
-void fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
+bool fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
const char *gen_id, Error **errp)
{
FWCfgDataGeneratorClass *klass;
@@ -1043,20 +1043,22 @@ void fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
obj = object_resolve_path_component(object_get_objects_root(), gen_id);
if (!obj) {
error_setg(errp, "Cannot find object ID '%s'", gen_id);
- return;
+ return false;
}
if (!object_dynamic_cast(obj, TYPE_FW_CFG_DATA_GENERATOR_INTERFACE)) {
error_setg(errp, "Object ID '%s' is not a '%s' subclass",
gen_id, TYPE_FW_CFG_DATA_GENERATOR_INTERFACE);
- return;
+ return false;
}
klass = FW_CFG_DATA_GENERATOR_GET_CLASS(obj);
array = klass->get_data(obj, errp);
if (!array) {
- return;
+ return false;
}
size = array->len;
fw_cfg_add_file(s, filename, g_byte_array_free(array, TRUE), size);
+
+ return true;
}
static void fw_cfg_machine_reset(void *opaque)
diff --git a/softmmu/vl.c b/softmmu/vl.c
index f476ef89ed..3416241557 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -2070,11 +2070,7 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp)
size = strlen(str); /* NUL terminator NOT included in fw_cfg blob */
buf = g_memdup(str, size);
} else if (nonempty_str(gen_id)) {
- Error *local_err = NULL;
-
- fw_cfg_add_from_generator(fw_cfg, name, gen_id, errp);
- if (local_err) {
- error_propagate(errp, local_err);
+ if (!fw_cfg_add_from_generator(fw_cfg, name, gen_id, errp)) {
return -1;
}
return 0;
--
2.21.3
^ permalink raw reply related [flat|nested] 5+ messages in thread