Documentation
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Overview ¶
Package testbin places a built program into a test's directory.
On macOS every fresh copy of an executable is a never-seen binary that the system policy scanner assesses on its first exec. One is quick; a package run that copies the same built helper into dozens of fixtures queues them behind the scanner for longer than a test waits. A hard link shares the inode the scanner has already assessed, so the rule is to link first and copy only where a link is impossible: a temp directory on another filesystem, and Windows.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
func Place ¶
Place puts the program at src at dst. It removes dst first, then hard-links src to dst where the platform and filesystem allow it and returns nil; the fallback is a byte copy with the executable bit set (mode 0o755). Windows always takes the copy, because a link there needs a privilege the CI path does not have.
func PlaceCopy ¶
PlaceCopy puts a real byte copy of src at dst, never a link, and is the one entry point a test should use when the SUBJECT of the test is that the file is not the same binary. A hard link shares src's inode, so a guard that asks "is my parent this executable?" answers yes through a link and the test silently stops testing anything. cmd/nova-sandbox's probe-step guard is that test. Everywhere else, Place: a copy there only costs macOS's policy scanner time (see the package comment).
func WriteExecutable ¶
WriteExecutable is os.WriteFile for a file a test is about to exec: a fake tool, a stand-in script, a stub on PATH. It holds syscall.ForkLock for reading while the file is open for writing, so no other goroutine can fork in that window. Without it, a parallel test's fork inherits the write descriptor for the instant before its exec, and this test's exec of the file fails on Linux with ETXTBSY, "text file busy" (golang/go#22315): the flake internal/secrets' seat test hit the first time its package ran in parallel.
Types ¶
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Source Files