summaryrefslogtreecommitdiffstats
path: root/netwerk/base/nsReadLine.h
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--netwerk/base/nsReadLine.h131
1 files changed, 131 insertions, 0 deletions
diff --git a/netwerk/base/nsReadLine.h b/netwerk/base/nsReadLine.h
new file mode 100644
index 0000000000..f1e4693f92
--- /dev/null
+++ b/netwerk/base/nsReadLine.h
@@ -0,0 +1,131 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsReadLine_h__
+#define nsReadLine_h__
+
+#include "nsIInputStream.h"
+#include "mozilla/Likely.h"
+
+/**
+ * @file
+ * Functions to read complete lines from an input stream.
+ *
+ * To properly use the helper function in here (NS_ReadLine) the caller should
+ * create a nsLineBuffer<T> with new, and pass it to NS_ReadLine every time it
+ * wants a line out.
+ *
+ * When done, the object should be deleted.
+ */
+
+/**
+ * @internal
+ * Buffer size. This many bytes will be buffered. If a line is longer than this,
+ * the partial line will be appended to the out parameter of NS_ReadLine and the
+ * buffer will be emptied.
+ * Note: if you change this constant, please update the regression test in
+ * netwerk/test/unit/test_readline.js accordingly (bug 397850).
+ */
+#define kLineBufferSize 4096
+
+/**
+ * @internal
+ * Line buffer structure, buffers data from an input stream.
+ * The buffer is empty when |start| == |end|.
+ * Invariant: |start| <= |end|
+ */
+template <typename CharT>
+class nsLineBuffer {
+ public:
+ nsLineBuffer() : start(buf), end(buf) {}
+
+ CharT buf[kLineBufferSize + 1];
+ CharT* start;
+ CharT* end;
+};
+
+/**
+ * Read a line from an input stream. Lines are separated by '\r' (0x0D) or '\n'
+ * (0x0A), or "\r\n" or "\n\r".
+ *
+ * @param aStream
+ * The stream to read from
+ * @param aBuffer
+ * The line buffer to use. A single line buffer must not be used with
+ * different input streams.
+ * @param aLine [out]
+ * The string where the line will be stored.
+ * @param more [out]
+ * Whether more data is available in the buffer. If true, NS_ReadLine may
+ * be called again to read further lines. Otherwise, further calls to
+ * NS_ReadLine will return an error.
+ *
+ * @retval NS_OK
+ * Read successful
+ * @retval error
+ * Input stream returned an error upon read. See
+ * nsIInputStream::read.
+ */
+template <typename CharT, class StreamType, class StringType>
+nsresult NS_ReadLine(StreamType* aStream, nsLineBuffer<CharT>* aBuffer,
+ StringType& aLine, bool* more) {
+ CharT eolchar = 0; // the first eol char or 1 after \r\n or \n\r is found
+
+ aLine.Truncate();
+
+ while (true) { // will be returning out of this loop on eol or eof
+ if (aBuffer->start == aBuffer->end) { // buffer is empty. Read into it.
+ uint32_t bytesRead;
+ nsresult rv = aStream->Read(aBuffer->buf, kLineBufferSize, &bytesRead);
+ if (NS_FAILED(rv) || MOZ_UNLIKELY(bytesRead == 0)) {
+ *more = false;
+ return rv;
+ }
+ aBuffer->start = aBuffer->buf;
+ aBuffer->end = aBuffer->buf + bytesRead;
+ *(aBuffer->end) = '\0';
+ }
+
+ /*
+ * Walk the buffer looking for an end-of-line.
+ * There are 3 cases to consider:
+ * 1. the eol char is the last char in the buffer
+ * 2. the eol char + one more char at the end of the buffer
+ * 3. the eol char + two or more chars at the end of the buffer
+ * we need at least one char after the first eol char to determine if
+ * it's a \r\n or \n\r sequence (and skip over it), and we need one
+ * more char after the end-of-line to set |more| correctly.
+ */
+ CharT* current = aBuffer->start;
+ if (MOZ_LIKELY(eolchar == 0)) {
+ for (; current < aBuffer->end; ++current) {
+ if (*current == '\n' || *current == '\r') {
+ eolchar = *current;
+ *current++ = '\0';
+ aLine.Append(aBuffer->start);
+ break;
+ }
+ }
+ }
+ if (MOZ_LIKELY(eolchar != 0)) {
+ for (; current < aBuffer->end; ++current) {
+ if ((eolchar == '\r' && *current == '\n') ||
+ (eolchar == '\n' && *current == '\r')) {
+ eolchar = 1;
+ continue;
+ }
+ aBuffer->start = current;
+ *more = true;
+ return NS_OK;
+ }
+ }
+
+ if (eolchar == 0) aLine.Append(aBuffer->start);
+ aBuffer->start = aBuffer->end; // mark the buffer empty
+ }
+}
+
+#endif // nsReadLine_h__