From be2204824164a6ff04da025a18e397cf8ba4c6f8 Mon Sep 17 00:00:00 2001
From: Wilfried Goesgens <dothebart@citadel.org>
Date: Tue, 3 Jul 2012 00:57:25 +0200
Subject: [PATCH] FDIO: make splice runtime optional

  - splice tends to break. let the choice to the admin to enable it. Default to stable copying shit to userspace back and forth.
---
 libcitadel/lib/libcitadel.c |   6 +-
 libcitadel/lib/stringbuf.c  | 334 +++++++++++++++++++-----------------
 2 files changed, 180 insertions(+), 160 deletions(-)

diff --git a/libcitadel/lib/libcitadel.c b/libcitadel/lib/libcitadel.c
index 347184c4f..acb082bef 100644
--- a/libcitadel/lib/libcitadel.c
+++ b/libcitadel/lib/libcitadel.c
@@ -46,7 +46,7 @@ ConstStr RoomNetCfgStrs[maxRoomNetCfg] = {
 
 
 
-
+extern int EnableSplice;
 extern int BaseStrBufSize;
 char *libcitadel_version_string(void) {
 	return "libcitadel(unnumbered)";
@@ -58,7 +58,11 @@ int libcitadel_version_number(void) {
 
 void StartLibCitadel(size_t basesize)
 {
+	const char *Splice;
 	BaseStrBufSize = basesize;
+	Splice = getenv("LIBCITADEL_ENABLE_SPLICE");
+	if (Splice != NULL)
+		EnableSplice = atol(Splice);
 }
 
 void ShutDownLibCitadel(void)
diff --git a/libcitadel/lib/stringbuf.c b/libcitadel/lib/stringbuf.c
index 3e81aac65..963c55f6a 100644
--- a/libcitadel/lib/stringbuf.c
+++ b/libcitadel/lib/stringbuf.c
@@ -50,6 +50,7 @@ int ZEXPORT compress_gzip(Bytef * dest, size_t * destLen,
                           const Bytef * source, uLong sourceLen, int level);
 #endif
 int BaseStrBufSize = 64;
+int EnableSplice = 0;
 
 const char *StrBufNOTNULL = ((char*) NULL) - 1;
 
@@ -3886,23 +3887,28 @@ void FDIOBufferInit(FDIOBuffer *FDB, IOBuffer *IO, int FD, long TotalSendSize)
 	FDB->ChunkSize = 
 		FDB->TotalSendSize = TotalSendSize;
 	FDB->IOB = IO;
-#ifndef LINUX_SPLICE
-	FDB->ChunkBuffer = NewStrBufPlain(NULL, TotalSendSize + 1);
-#else
-	pipe(FDB->SplicePipe);
+#ifdef LINUX_SPLICE
+	if (EnableSplice)
+		pipe(FDB->SplicePipe);
+	else
 #endif
+		FDB->ChunkBuffer = NewStrBufPlain(NULL, TotalSendSize + 1);
+
 	FDB->OtherFD = FD;
 }
 
 void FDIOBufferDelete(FDIOBuffer *FDB)
 {
-#ifndef LINUX_SPLICE
-	FreeStrBuf(&FDB->ChunkBuffer);
-#else
-	close(FDB->SplicePipe[0]);
-	close(FDB->SplicePipe[1]);
-	
+#ifdef LINUX_SPLICE
+	if (EnableSplice)
+	{
+		close(FDB->SplicePipe[0]);
+		close(FDB->SplicePipe[1]);
+	}
+	else
 #endif
+		FreeStrBuf(&FDB->ChunkBuffer);
+	
 	close(FDB->OtherFD);
 	memset(FDB, 0, sizeof(FDIOBuffer));	
 }
@@ -3911,65 +3917,69 @@ int FileSendChunked(FDIOBuffer *FDB, const char **Err)
 {
 	ssize_t sent, pipesize;
 #ifdef LINUX_SPLICE
-	if (FDB->PipeSize == 0)
+	if (EnableSplice)
 	{
-		pipesize = splice(FDB->OtherFD,
-				  &FDB->TotalSentAlready, 
-				  FDB->SplicePipe[1],
-				  NULL, 
-				  FDB->ChunkSendRemain, 
-				  SPLICE_F_MOVE);
+		if (FDB->PipeSize == 0)
+		{
+			pipesize = splice(FDB->OtherFD,
+					  &FDB->TotalSentAlready, 
+					  FDB->SplicePipe[1],
+					  NULL, 
+					  FDB->ChunkSendRemain, 
+					  SPLICE_F_MOVE);
 	
-		if (pipesize == -1)
+			if (pipesize == -1)
+			{
+				*Err = strerror(errno);
+				return pipesize;
+			}
+			FDB->PipeSize = pipesize;
+		}
+		sent =  splice(FDB->SplicePipe[0],
+			       NULL, 
+			       FDB->IOB->fd,
+			       NULL, 
+			       FDB->PipeSize,
+			       SPLICE_F_MORE | SPLICE_F_MOVE | SPLICE_F_NONBLOCK);
+		if (sent == -1)
 		{
 			*Err = strerror(errno);
-			return pipesize;
+			return sent;
 		}
-		FDB->PipeSize = pipesize;
-	}
-	sent =  splice(FDB->SplicePipe[0],
-		       NULL, 
-		       FDB->IOB->fd,
-		       NULL, 
-		       FDB->PipeSize,
-		       SPLICE_F_MORE | SPLICE_F_MOVE | SPLICE_F_NONBLOCK);
-	if (sent == -1)
-	{
-		*Err = strerror(errno);
+		FDB->PipeSize -= sent;
+		FDB->ChunkSendRemain -= sent;
 		return sent;
 	}
-	FDB->PipeSize -= sent;
-	FDB->ChunkSendRemain -= sent;
-	return sent;
-#else
-
-	char *pRead;
-	long nRead = 0;
-
-	pRead = FDB->ChunkBuffer->buf;
-	while ((FDB->ChunkBuffer->BufUsed < FDB->TotalSendSize) && (nRead >= 0))
+	else
+#endif
 	{
-		nRead = read(FDB->OtherFD, pRead, FDB->TotalSendSize - FDB->ChunkBuffer->BufUsed);
-		if (nRead > 0) {
-			FDB->ChunkBuffer->BufUsed += nRead;
-			FDB->ChunkBuffer->buf[FDB->ChunkBuffer->BufUsed] = '\0';
-		}
-		else if (nRead == 0) {}
-		else return nRead;
+		char *pRead;
+		long nRead = 0;
+
+		pRead = FDB->ChunkBuffer->buf;
+		while ((FDB->ChunkBuffer->BufUsed < FDB->TotalSendSize) && (nRead >= 0))
+		{
+			nRead = read(FDB->OtherFD, pRead, FDB->TotalSendSize - FDB->ChunkBuffer->BufUsed);
+			if (nRead > 0) {
+				FDB->ChunkBuffer->BufUsed += nRead;
+				FDB->ChunkBuffer->buf[FDB->ChunkBuffer->BufUsed] = '\0';
+			}
+			else if (nRead == 0) {}
+			else return nRead;
 		
-	}
+		}
 
-	nRead = write(FDB->IOB->fd, FDB->ChunkBuffer->buf + FDB->TotalSentAlready, FDB->ChunkSendRemain);
+		nRead = write(FDB->IOB->fd, FDB->ChunkBuffer->buf + FDB->TotalSentAlready, FDB->ChunkSendRemain);
 
-	if (nRead >= 0) {
-		FDB->TotalSentAlready += nRead;
-		FDB->ChunkSendRemain -= nRead;
-		return FDB->ChunkSendRemain;
-	}
-	else {
-		return nRead;
+		if (nRead >= 0) {
+			FDB->TotalSentAlready += nRead;
+			FDB->ChunkSendRemain -= nRead;
+			return FDB->ChunkSendRemain;
+		}
+		else {
+			return nRead;
+		}
 	}
-#endif
 }
 
 int FileRecvChunked(FDIOBuffer *FDB, const char **Err)
@@ -3977,68 +3987,71 @@ int FileRecvChunked(FDIOBuffer *FDB, const char **Err)
 	ssize_t sent, pipesize;
 
 #ifdef LINUX_SPLICE
-	if (FDB->PipeSize == 0)
+	if (EnableSplice)
 	{
-		pipesize = splice(FDB->IOB->fd,
-				  NULL, 
-				  FDB->SplicePipe[1],
-				  NULL, 
-				  FDB->ChunkSendRemain, 
-				  SPLICE_F_MORE | SPLICE_F_MOVE|SPLICE_F_NONBLOCK);
-
-		if (pipesize == -1)
+		if (FDB->PipeSize == 0)
 		{
-			*Err = strerror(errno);
-			return pipesize;
+			pipesize = splice(FDB->IOB->fd,
+					  NULL, 
+					  FDB->SplicePipe[1],
+					  NULL, 
+					  FDB->ChunkSendRemain, 
+					  SPLICE_F_MORE | SPLICE_F_MOVE|SPLICE_F_NONBLOCK);
+
+			if (pipesize == -1)
+			{
+				*Err = strerror(errno);
+				return pipesize;
+			}
+			FDB->PipeSize = pipesize;
 		}
-		FDB->PipeSize = pipesize;
-	}
 	
-	sent = splice(FDB->SplicePipe[0],
-		      NULL, 
-		      FDB->OtherFD,
-		      &FDB->TotalSentAlready, 
-		      FDB->PipeSize,
-		      SPLICE_F_MORE | SPLICE_F_MOVE);
-
-	if (sent == -1)
-	{
-		*Err = strerror(errno);
+		sent = splice(FDB->SplicePipe[0],
+			      NULL, 
+			      FDB->OtherFD,
+			      &FDB->TotalSentAlready, 
+			      FDB->PipeSize,
+			      SPLICE_F_MORE | SPLICE_F_MOVE);
+
+		if (sent == -1)
+		{
+			*Err = strerror(errno);
+			return sent;
+		}
+		FDB->PipeSize -= sent;
+		FDB->ChunkSendRemain -= sent;
 		return sent;
 	}
-	FDB->PipeSize -= sent;
-	FDB->ChunkSendRemain -= sent;
-	return sent;
-#else
-	
-	sent = read(FDB->IOB->fd, FDB->ChunkBuffer->buf, FDB->ChunkSendRemain);
-	if (sent > 0) {
-		int nWritten = 0;
-		int rc; 
+	else
+#endif
+	{
+		sent = read(FDB->IOB->fd, FDB->ChunkBuffer->buf, FDB->ChunkSendRemain);
+		if (sent > 0) {
+			int nWritten = 0;
+			int rc; 
 		
-		FDB->ChunkBuffer->BufUsed = sent;
+			FDB->ChunkBuffer->BufUsed = sent;
 
-		while (nWritten < FDB->ChunkBuffer->BufUsed) {
-			rc =  write(FDB->OtherFD, FDB->ChunkBuffer->buf + nWritten, FDB->ChunkBuffer->BufUsed - nWritten);
-			if (rc < 0) {
-				*Err = strerror(errno);
-				return rc;
-			}
-			nWritten += rc;
+			while (nWritten < FDB->ChunkBuffer->BufUsed) {
+				rc =  write(FDB->OtherFD, FDB->ChunkBuffer->buf + nWritten, FDB->ChunkBuffer->BufUsed - nWritten);
+				if (rc < 0) {
+					*Err = strerror(errno);
+					return rc;
+				}
+				nWritten += rc;
 
+			}
+			FDB->ChunkBuffer->BufUsed = 0;
+			FDB->TotalSentAlready += sent;
+			FDB->ChunkSendRemain -= sent;
+			return FDB->ChunkSendRemain;
 		}
-		FDB->ChunkBuffer->BufUsed = 0;
-		FDB->TotalSentAlready += sent;
-		FDB->ChunkSendRemain -= sent;
-		return FDB->ChunkSendRemain;
-	}
-	else if (sent < 0) {
-		*Err = strerror(errno);
-		return sent;
+		else if (sent < 0) {
+			*Err = strerror(errno);
+			return sent;
+		}
+		return 0;
 	}
-
-#endif
-	return 0;
 }
 
 int FileMoveChunked(FDIOBuffer *FDB, const char **Err)
@@ -4046,68 +4059,71 @@ int FileMoveChunked(FDIOBuffer *FDB, const char **Err)
 	ssize_t sent, pipesize;
 
 #ifdef LINUX_SPLICE
-	if (FDB->PipeSize == 0)
+	if (EnableSplice)
 	{
-		pipesize = splice(FDB->IOB->fd,
-				  &FDB->TotalReadAlready, 
-				  FDB->SplicePipe[1],
-				  NULL, 
-				  FDB->ChunkSendRemain, 
-				  SPLICE_F_MORE | SPLICE_F_MOVE|SPLICE_F_NONBLOCK);
-
-		if (pipesize == -1)
+		if (FDB->PipeSize == 0)
+		{
+			pipesize = splice(FDB->IOB->fd,
+					  &FDB->TotalReadAlready, 
+					  FDB->SplicePipe[1],
+					  NULL, 
+					  FDB->ChunkSendRemain, 
+					  SPLICE_F_MORE | SPLICE_F_MOVE|SPLICE_F_NONBLOCK);
+			
+			if (pipesize == -1)
+			{
+				*Err = strerror(errno);
+				return pipesize;
+			}
+			FDB->PipeSize = pipesize;
+		}
+		
+		sent = splice(FDB->SplicePipe[0],
+			      NULL, 
+			      FDB->OtherFD,
+			      &FDB->TotalSentAlready, 
+			      FDB->PipeSize,
+			      SPLICE_F_MORE | SPLICE_F_MOVE);
+		
+		if (sent == -1)
 		{
 			*Err = strerror(errno);
-			return pipesize;
+			return sent;
 		}
-		FDB->PipeSize = pipesize;
-	}
-	
-	sent = splice(FDB->SplicePipe[0],
-		      NULL, 
-		      FDB->OtherFD,
-		      &FDB->TotalSentAlready, 
-		      FDB->PipeSize,
-		      SPLICE_F_MORE | SPLICE_F_MOVE);
-
-	if (sent == -1)
-	{
-		*Err = strerror(errno);
+		FDB->PipeSize -= sent;
+		FDB->ChunkSendRemain -= sent;
 		return sent;
 	}
-	FDB->PipeSize -= sent;
-	FDB->ChunkSendRemain -= sent;
-	return sent;
-#else
-	
-	sent = read(FDB->IOB->fd, FDB->ChunkBuffer->buf, FDB->ChunkSendRemain);
-	if (sent > 0) {
-		int nWritten = 0;
-		int rc; 
+	else
+#endif	
+	{
+		sent = read(FDB->IOB->fd, FDB->ChunkBuffer->buf, FDB->ChunkSendRemain);
+		if (sent > 0) {
+			int nWritten = 0;
+			int rc; 
 		
-		FDB->ChunkBuffer->BufUsed = sent;
+			FDB->ChunkBuffer->BufUsed = sent;
 
-		while (nWritten < FDB->ChunkBuffer->BufUsed) {
-			rc =  write(FDB->OtherFD, FDB->ChunkBuffer->buf + nWritten, FDB->ChunkBuffer->BufUsed - nWritten);
-			if (rc < 0) {
-				*Err = strerror(errno);
-				return rc;
-			}
-			nWritten += rc;
+			while (nWritten < FDB->ChunkBuffer->BufUsed) {
+				rc =  write(FDB->OtherFD, FDB->ChunkBuffer->buf + nWritten, FDB->ChunkBuffer->BufUsed - nWritten);
+				if (rc < 0) {
+					*Err = strerror(errno);
+					return rc;
+				}
+				nWritten += rc;
 
+			}
+			FDB->ChunkBuffer->BufUsed = 0;
+			FDB->TotalSentAlready += sent;
+			FDB->ChunkSendRemain -= sent;
+			return FDB->ChunkSendRemain;
 		}
-		FDB->ChunkBuffer->BufUsed = 0;
-		FDB->TotalSentAlready += sent;
-		FDB->ChunkSendRemain -= sent;
-		return FDB->ChunkSendRemain;
-	}
-	else if (sent < 0) {
-		*Err = strerror(errno);
-		return sent;
+		else if (sent < 0) {
+			*Err = strerror(errno);
+			return sent;
+		}
+		return 0;
 	}
-
-#endif
-	return 0;
 }
 
 eReadState WriteIOBAlreadyRead(FDIOBuffer *FDB, const char **Error)
-- 
2.30.2