reaper/TreeWatch: do not null-terminate buffer in IsPopulated(), construct std::string_view

MaxKellermann · MaxKellermann · commit e240d592c0cc · 2026-02-12T17:17:46.000+01:00
diff --git a/src/reaper/UnifiedWatch.cxx b/src/reaper/UnifiedWatch.cxx
@@ -24,12 +24,12 @@ static bool
 IsPopulated(FileDescriptor fd) noexcept
 {
 	char buffer[4096];
-	ssize_t nbytes = pread(fd.Get(), buffer, sizeof(buffer) - 1, 0);
+	ssize_t nbytes = pread(fd.Get(), buffer, sizeof(buffer), 0);
 	if (nbytes <= 0)
 		return false;
 
-	buffer[nbytes] = 0;
-	return strstr(buffer, "populated 0") == nullptr;
+	const std::string_view contents{buffer, static_cast<std::size_t>(nbytes)};
+	return !contents.contains("populated 0"sv);
 }
 
 class UnifiedCgroupWatch::Group {

Original file line number	Diff line number	Diff line change
`@@ -24,12 +24,12 @@ static bool`
`24`	`24`	`IsPopulated(FileDescriptor fd) noexcept`
`25`	`25`	`{`
`26`	`26`	`char buffer[4096];`
`27`		`- ssize_t nbytes = pread(fd.Get(), buffer, sizeof(buffer) - 1, 0);`
	`27`	`+ ssize_t nbytes = pread(fd.Get(), buffer, sizeof(buffer), 0);`
`28`	`28`	`if (nbytes <= 0)`
`29`	`29`	`return false;`
`30`	`30`
`31`		`- buffer[nbytes] = 0;`
`32`		`- return strstr(buffer, "populated 0") == nullptr;`
	`31`	`+ const std::string_view contents{buffer, static_cast<std::size_t>(nbytes)};`
	`32`	`+ return !contents.contains("populated 0"sv);`
`33`	`33`	`}`
`34`	`34`
`35`	`35`	`class UnifiedCgroupWatch::Group {`