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Reset default signal handlers on child processes before spawning them. #732

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Sep 27, 2024
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Reset default signal handlers on child processes before spawning them. #732

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45 changes: 34 additions & 11 deletions Sources/Testing/ExitTests/SpawnProcess.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -54,25 +54,44 @@ func spawnExecutable(

#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD)
return try withUnsafeTemporaryAllocation(of: P<posix_spawn_file_actions_t>.self, capacity: 1) { fileActions in
guard 0 == posix_spawn_file_actions_init(fileActions.baseAddress!) else {
let fileActions = fileActions.baseAddress!
guard 0 == posix_spawn_file_actions_init(fileActions) else {
throw CError(rawValue: swt_errno())
}
defer {
_ = posix_spawn_file_actions_destroy(fileActions.baseAddress!)
_ = posix_spawn_file_actions_destroy(fileActions)
}

return try withUnsafeTemporaryAllocation(of: P<posix_spawnattr_t>.self, capacity: 1) { attrs in
guard 0 == posix_spawnattr_init(attrs.baseAddress!) else {
let attrs = attrs.baseAddress!
guard 0 == posix_spawnattr_init(attrs) else {
throw CError(rawValue: swt_errno())
}
defer {
_ = posix_spawnattr_destroy(attrs.baseAddress!)
_ = posix_spawnattr_destroy(attrs)
}

// Flags to set on the attributes value before spawning the process.
var flags = CShort(0)

// Reset signal handlers to their defaults.
withUnsafeTemporaryAllocation(of: sigset_t.self, capacity: 1) { noSignals in
let noSignals = noSignals.baseAddress!
sigemptyset(noSignals)
posix_spawnattr_setsigmask(attrs, noSignals)
flags |= CShort(POSIX_SPAWN_SETSIGMASK)
}
withUnsafeTemporaryAllocation(of: sigset_t.self, capacity: 1) { allSignals in
let allSignals = allSignals.baseAddress!
sigfillset(allSignals)
posix_spawnattr_setsigdefault(attrs, allSignals);
flags |= CShort(POSIX_SPAWN_SETSIGDEF)
}

// Do not forward standard I/O.
_ = posix_spawn_file_actions_addopen(fileActions.baseAddress!, STDIN_FILENO, "/dev/null", O_RDONLY, 0)
_ = posix_spawn_file_actions_addopen(fileActions.baseAddress!, STDOUT_FILENO, "/dev/null", O_WRONLY, 0)
_ = posix_spawn_file_actions_addopen(fileActions.baseAddress!, STDERR_FILENO, "/dev/null", O_WRONLY, 0)
_ = posix_spawn_file_actions_addopen(fileActions, STDIN_FILENO, "/dev/null", O_RDONLY, 0)
_ = posix_spawn_file_actions_addopen(fileActions, STDOUT_FILENO, "/dev/null", O_WRONLY, 0)
_ = posix_spawn_file_actions_addopen(fileActions, STDERR_FILENO, "/dev/null", O_WRONLY, 0)

#if os(Linux) || os(FreeBSD)
var highestFD = CInt(0)
Expand All @@ -83,7 +102,7 @@ func spawnExecutable(
throw SystemError(description: "A child process inherit a file handle without an associated file descriptor. Please file a bug report at https://github.com/swiftlang/swift-testing/issues/new")
}
#if SWT_TARGET_OS_APPLE
_ = posix_spawn_file_actions_addinherit_np(fileActions.baseAddress!, fd)
_ = posix_spawn_file_actions_addinherit_np(fileActions, fd)
#elseif os(Linux) || os(FreeBSD)
highestFD = max(highestFD, fd)
#endif
Expand All @@ -92,17 +111,21 @@ func spawnExecutable(

#if SWT_TARGET_OS_APPLE
// Close all other file descriptors open in the parent.
_ = posix_spawnattr_setflags(attrs.baseAddress!, CShort(POSIX_SPAWN_CLOEXEC_DEFAULT))
flags |= CShort(POSIX_SPAWN_CLOEXEC_DEFAULT)
#elseif os(Linux) || os(FreeBSD)
// This platform doesn't have POSIX_SPAWN_CLOEXEC_DEFAULT, but we can at
// least close all file descriptors higher than the highest inherited one.
// We are assuming here that the caller didn't set FD_CLOEXEC on any of
// these file descriptors.
_ = swt_posix_spawn_file_actions_addclosefrom_np(fileActions.baseAddress!, highestFD + 1)
_ = swt_posix_spawn_file_actions_addclosefrom_np(fileActions, highestFD + 1)
#else
#warning("Platform-specific implementation missing: cannot close unused file descriptors")
#endif

// Set flags; make sure to keep this call below any code that might modify
// the flags mask!
_ = posix_spawnattr_setflags(attrs, flags)

var argv: [UnsafeMutablePointer<CChar>?] = [strdup(executablePath)]
argv += arguments.lazy.map { strdup($0) }
argv.append(nil)
Expand All @@ -121,7 +144,7 @@ func spawnExecutable(
}

var pid = pid_t()
guard 0 == posix_spawn(&pid, executablePath, fileActions.baseAddress!, attrs.baseAddress, argv, environ) else {
guard 0 == posix_spawn(&pid, executablePath, fileActions, attrs, argv, environ) else {
throw CError(rawValue: swt_errno())
}
return pid
Expand Down