88 lines
2.5 KiB
Kotlin
88 lines
2.5 KiB
Kotlin
@file:Suppress("TooManyFunctions")
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package co.electriccoin.zcash.spackle.io
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import kotlinx.coroutines.Dispatchers
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import kotlinx.coroutines.withContext
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import java.io.File
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import java.io.IOException
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import java.util.UUID
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suspend fun File.existsSuspend() = withContext(Dispatchers.IO) {
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exists()
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}
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suspend fun File.mkdirsSuspend() = withContext(Dispatchers.IO) {
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mkdirs()
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}
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suspend fun File.isDirectorySuspend() = withContext(Dispatchers.IO) {
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isDirectory
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}
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suspend fun File.isFileSuspend() = withContext(Dispatchers.IO) {
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isFile
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}
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suspend fun File.canWriteSuspend() = withContext(Dispatchers.IO) {
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canWrite()
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}
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suspend fun File.deleteSuspend() = withContext(Dispatchers.IO) {
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delete()
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}
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suspend fun File.renameToSuspend(destination: File) = withContext(Dispatchers.IO) {
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renameTo(destination)
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}
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suspend fun File.listFilesSuspend() = withContext(Dispatchers.IO) {
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listFiles()
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}
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/**
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* Given an ultimate output file destination, this generates a temporary file that [action] can write to. After action
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* is complete, the temp file is renamed to the expected output destination. Depending on the underlying filesystem,
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* this should effectively ensure that the file is perceived as being written atomically.
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*
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* @receiver Ultimate file that we desire to write to. Must be a file and not a directory.
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* @param action Action to perform on the file, specifically this should be writing data. This action should not
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* delete, rename, or do other operations in the filesystem.
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*/
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suspend fun File.writeAtomically(action: (suspend (File) -> Unit)) {
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val tempFile = withContext(Dispatchers.IO) {
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File(parentFile, name.newTempFileName()).also {
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it.deleteOnExit()
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}
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}
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var isWriteSuccessful = false
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try {
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action(tempFile)
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isWriteSuccessful = true
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} catch (@Suppress("TooGenericExceptionCaught") e: Exception) {
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tempFile.deleteSuspend()
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throw e
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} finally {
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if (isWriteSuccessful) {
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tempFile.moveTo(destination = this)
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}
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}
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}
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private suspend fun File.moveTo(destination: File) {
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val isRenameSuccessful = renameToSuspend(destination)
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if (!isRenameSuccessful) {
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if (existsSuspend()) {
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throw IOException("Couldn't move file $path to ${destination.path}")
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}
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// Otherwise no data was written, so there's no file to rename.
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}
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}
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// Note that adding uuid and .tmp could theoretically go past file name length limits on some filesystems
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private fun String.newTempFileName() = "$this-${UUID.randomUUID()}.tmp"
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