Fix infinite loop issue with correctly formed, but useless iMelody files (bug 2068782).
It is possible to construct a legitimate iMelody file that consists of only control
commands such as ledon, ledoff, etc. in an infinite loop. If there are no notes or
rests in the file, the iMelody parser will spin in an infinite loop sucking as many
CPU cycles as it can get. This fix ignores loops that contain no notes or rests since
they make no sense. The controls will be processed, but the loop will only execute
once.
diff --git a/arm-wt-22k/lib_src/eas_imelody.c b/arm-wt-22k/lib_src/eas_imelody.c
index bf4375f..05380e5 100644
--- a/arm-wt-22k/lib_src/eas_imelody.c
+++ b/arm-wt-22k/lib_src/eas_imelody.c
@@ -396,6 +396,9 @@
{
pData->repeatOffset = pData->startLine + (EAS_I32) pData->index;
+ /* save current time and check it later to make sure the loop isn't zero length */
+ pData->repeatTime = pData->time;
+
#ifdef _DEBUG_IMELODY
{ /* dpp: EAS_ReportEx(_EAS_SEVERITY_DETAIL, "Repeat offset = %d\n", pData->repeatOffset); */ }
#endif
@@ -410,9 +413,11 @@
#ifdef _DEBUG_IMELODY
{ /* dpp: EAS_ReportEx(_EAS_SEVERITY_DETAIL, "End repeat section, repeat offset = %d\n", pData->repeatOffset); */ }
#endif
- /* ignore invalid repeats */
- if (pData->repeatCount >= 0)
- {
+ /* ignore zero-length loops */
+ if (pData->repeatTime == pData->time) {
+ pData->repeatCount = -1;
+ pData->repeatOffset = -1;
+ } else if (pData->repeatCount >= 0) {
/* decrement repeat count (repeatCount == 0 means infinite loop) */
if (pData->repeatCount > 0)
diff --git a/arm-wt-22k/lib_src/eas_imelodydata.h b/arm-wt-22k/lib_src/eas_imelodydata.h
index 57c1ed0..17d03dc 100644
--- a/arm-wt-22k/lib_src/eas_imelodydata.h
+++ b/arm-wt-22k/lib_src/eas_imelodydata.h
@@ -56,6 +56,7 @@
EAS_I32 restTicks; /* ticks to rest after current note */
EAS_I32 startLine; /* file offset at start of line (for repeats) */
EAS_I32 repeatOffset; /* file offset to start of repeat section */
+ EAS_I32 repeatTime; /* time at start of repeat section */
S_METADATA_CB metadata; /* metadata callback */
EAS_I16 repeatCount; /* repeat counter */
EAS_U8 state; /* current state EAS_STATE_XXXX */
