wuggy/Dactyloidae
wuggy/Dactyloidae
1
0
Fork 0
mirror of https://repo.dactyloidae.xyz/Dactyloidae/UXP.git synced 2026-09-05 23:38:38 +09:00
Code Issues Projects Releases Packages Wiki Activity

Avoid potentially unsafe snprintf usage in FPSCounter.

Browse source 
snprintf returns the number of bytes it would have written when it runs out of space.
This patch makes sure we properly handle this unlikely event in FPSCounter.
This patch also makes sure we don't print out the contents of an uninitialized buffer.
This commit is contained in:
wolfbeast 2017-10-04 14:14:24 +02:00 • committed by Roy Tam
commit c585066b4c
1 changed files with 21 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

27
gfx/layers/composite/FPSCounter.cpp
View file

@ -210,7 +210,10 @@ FPSCounter::WriteFrameTimeStamps(PRFileDesc* fd)
const int bufferSize = 256;
char buffer[bufferSize];
int writtenCount = SprintfLiteral(buffer, "FPS Data for: %s\n", mFPSName);
MOZ_ASSERT(writtenCount >= 0);
MOZ_ASSERT(writtenCount < bufferSize);
if (writtenCount >= bufferSize) {
return;
}
PR_Write(fd, buffer, writtenCount);
ResetReverseIterator();
@ -225,8 +228,10 @@ FPSCounter::WriteFrameTimeStamps(PRFileDesc* fd)
while (HasNext(startTimeStamp)) {
TimeDuration duration = previousSample - nextTimeStamp;
writtenCount = SprintfLiteral(buffer, "%f,\n", duration.ToMilliseconds());
MOZ_ASSERT(writtenCount >= 0);
MOZ_ASSERT(writtenCount < bufferSize);
if (writtenCount >= bufferSize) {
continue;
}
PR_Write(fd, buffer, writtenCount);
previousSample = nextTimeStamp;
@ -299,8 +304,13 @@ FPSCounter::PrintFPS()
void
FPSCounter::PrintHistogram(std::map<int, int>& aHistogram)
{
if (aHistogram.size() == 0) {
return;
}
int length = 0;
const int kBufferLength = 512;
int availableSpace = kBufferLength;
char buffer[kBufferLength];
for (std::map<int, int>::iterator iter = aHistogram.begin();
@ -309,9 +319,14 @@ FPSCounter::PrintHistogram(std::map<int, int>& aHistogram)
int fps = iter->first;
int count = iter->second;
length += snprintf(buffer + length, kBufferLength - length,
"FPS: %d = %d. ", fps, count);
NS_ASSERTION(length >= kBufferLength, "Buffer overrun while printing FPS histogram.");
int lengthRequired = snprintf(buffer + length, availableSpace,
"FPS: %d = %d. ", fps, count);
// Ran out of buffer space. Oh well - just print what we have.
if (lengthRequired > availableSpace) {
break;
}
length += lengthRequired;
availableSpace -= lengthRequired;
}
printf_stderr("%s\n", buffer);