From aa1bc013ff54eb118855365945aae4218d099003 Mon Sep 17 00:00:00 2001
From: Wilfried Goesgens <dothebart@citadel.org>
Date: Sat, 8 Oct 2011 23:59:09 +0200
Subject: [PATCH] Add support for sending / reading to files; so far we just
 implement the linux sendfile facility

---
 libcitadel/configure.in     |   2 +
 libcitadel/lib/libcitadel.h |  17 ++++++
 libcitadel/lib/stringbuf.c  | 118 ++++++++++++++++++++++++++++++++++++
 3 files changed, 137 insertions(+)

diff --git a/libcitadel/configure.in b/libcitadel/configure.in
index eb3f4c0ed..d61a071c3 100755
--- a/libcitadel/configure.in
+++ b/libcitadel/configure.in
@@ -74,6 +74,8 @@ fi
 
 AC_CHECK_HEADER(CUnit/CUnit.h, [AC_DEFINE(ENABLE_TESTS, [], [whether we should compile the test-suite])])
 
+AC_CHECK_HEADER(sys/sendfile.h, [AC_DEFINE(LINUX_SENDFILE, [], [whether we have the linux sendfile api])])
+dnl TODO: we might need to check for the actual syntax....  
 
 
 AC_CHECK_HEADERS(iconv.h)
diff --git a/libcitadel/lib/libcitadel.h b/libcitadel/lib/libcitadel.h
index ac102b1b2..0ee29b20c 100644
--- a/libcitadel/lib/libcitadel.h
+++ b/libcitadel/lib/libcitadel.h
@@ -236,6 +236,23 @@ typedef struct _file_buffer {
 	int nBlobBytesWanted;
 } IOBuffer;
 
+
+typedef struct __fd_iobuffer {
+	IOBuffer *IOB;
+	int OtherFD;
+	long TotalSendSize;
+	long TotalSentAlready;
+	long ChunkSize;
+	long ChunkSendRemain;
+	StrBuf *ChunkBuffer; /* just used if we don't have sendfile */
+} FDIOBuffer;
+
+
+void FDIOBufferInit(FDIOBuffer *FDB, IOBuffer *IO, int FD, long TotalSendSize);
+int FileSendChunked(FDIOBuffer *FDB, const char **Err);
+int FileRecvChunked(FDIOBuffer *FDB, const char **Err);
+eReadState WriteIOBAlreadyRead(FDIOBuffer *FDB, const char **Error);
+
 long StrBuf_read_one_chunk_callback (int fd, short event, IOBuffer *FB);
 int StrBuf_write_one_chunk_callback(int fd, short event, IOBuffer *FB);
 
diff --git a/libcitadel/lib/stringbuf.c b/libcitadel/lib/stringbuf.c
index c8f8a6434..08e904b31 100644
--- a/libcitadel/lib/stringbuf.c
+++ b/libcitadel/lib/stringbuf.c
@@ -28,6 +28,9 @@
 #include <sys/types.h>
 #define SHOW_ME_VAPPEND_PRINTF
 #include <stdarg.h>
+#ifndef LINUX_SENDFILE
+#include <sys/sendfile.h>
+#endif
 #include "libcitadel.h"
 
 #ifdef HAVE_ICONV
@@ -38,6 +41,10 @@
 #include <execinfo.h>
 #endif
 
+#ifdef LINUX_SENDFILE
+#include <sys/sendfile.h>
+#endif
+
 #ifdef HAVE_ZLIB
 #include <zlib.h>
 int ZEXPORT compress_gzip(Bytef * dest, size_t * destLen,
@@ -3782,6 +3789,117 @@ long IOBufferStrLength(IOBuffer *FB)
 	return StrLength(FB->Buf) - (FB->ReadWritePointer - FB->Buf->buf);
 }
 
+
+
+void FDIOBufferInit(FDIOBuffer *FDB, IOBuffer *IO, int FD, long TotalSendSize)
+{
+	memset(FDB, 0, sizeof(FDIOBuffer));
+	FDB->ChunkSize = 
+		FDB->TotalSendSize = TotalSendSize;
+	FDB->IOB = IO;
+#ifndef LINUX_SENDFILE
+	FDB->ChunkBuffer = NewStrBuf();
+#endif
+	FDB->OtherFD = FD;
+}
+
+int FileSendChunked(FDIOBuffer *FDB, const char **Err)
+{
+
+#ifdef LINUX_SENDFILE
+	ssize_t sent;
+	sent = sendfile(FDB->IOB->fd, FDB->OtherFD, &FDB->TotalSentAlready, FDB->ChunkSendRemain);
+	if (sent == -1)
+	{
+		*Err = strerror(errno);
+		return sent;
+	}
+	FDB->ChunkSendRemain -= sent;
+	return FDB->ChunkSendRemain;
+#else
+#endif
+	return 0;
+}
+
+int FileRecvChunked(FDIOBuffer *FDB, const char **Err)
+{
+
+#ifdef LINUX_SENDFILE
+	ssize_t sent;
+	sent = sendfile(FDB->OtherFD, FDB->IOB->fd, &FDB->TotalSentAlready, FDB->ChunkSendRemain);
+	if (sent == -1)
+	{
+		*Err = strerror(errno);
+		return sent;
+	}
+	FDB->ChunkSendRemain -= sent;
+	return FDB->ChunkSendRemain;
+#else
+#endif
+	return 0;
+}
+
+eReadState WriteIOBAlreadyRead(FDIOBuffer *FDB, const char **Error)
+{
+	int IsNonBlock;
+	int fdflags;
+	long rlen;
+	long should_write;
+	int nSuccessLess = 0;
+	struct timeval tv;
+	fd_set rfds;
+
+	fdflags = fcntl(FDB->OtherFD, F_GETFL);
+	IsNonBlock = (fdflags & O_NONBLOCK) == O_NONBLOCK;
+
+	while ((FDB->IOB->ReadWritePointer - FDB->IOB->Buf->buf < FDB->IOB->Buf->BufUsed) &&
+	       (FDB->ChunkSendRemain > 0))
+	{
+		if (IsNonBlock){
+			tv.tv_sec = 1; /* selectresolution; */
+			tv.tv_usec = 0;
+			
+			FD_ZERO(&rfds);
+			FD_SET(FDB->OtherFD, &rfds);
+			if (select(FDB->OtherFD + 1, NULL, &rfds, NULL, &tv) == -1) {
+				*Error = strerror(errno);
+				return eReadFail;
+			}
+		}
+		if (IsNonBlock && !  FD_ISSET(FDB->OtherFD, &rfds)) {
+			nSuccessLess ++;
+			continue;
+		}
+
+		should_write = FDB->IOB->Buf->BufUsed - 
+			(FDB->IOB->ReadWritePointer - FDB->IOB->Buf->buf);
+		if (should_write > FDB->ChunkSendRemain)
+			should_write = FDB->ChunkSendRemain;
+
+		rlen = write(FDB->OtherFD, 
+			     FDB->IOB->ReadWritePointer, 
+			     should_write);
+		if (rlen < 1) {
+			*Error = strerror(errno);
+						
+			return eReadFail;
+		}
+		FDB->TotalSentAlready += rlen;
+		FDB->IOB->ReadWritePointer += rlen;
+		FDB->ChunkSendRemain -= rlen;
+	}
+	if (FDB->IOB->ReadWritePointer >= FDB->IOB->Buf->buf + FDB->IOB->Buf->BufUsed)
+	{
+		FlushStrBuf(FDB->IOB->Buf);
+		FDB->IOB->ReadWritePointer = NULL;
+	}
+
+	if (FDB->ChunkSendRemain == 0)
+		return eReadSuccess;
+	else 
+		return eMustReadMore;
+}
+
 /*******************************************************************************
  *           File I/O; Prefer buffered read since its faster!                  *
  *******************************************************************************/
-- 
2.30.2