1 files changed, 197 insertions, 0 deletions
diff --git a/lib/fdbuf/fdibuf.cc b/lib/fdbuf/fdibuf.cc
new file mode 100644
index 0000000..205d63c
--- /dev/null
+++ b/lib/fdbuf/fdibuf.cc
@@ -0,0 +1,197 @@
+// Copyright (C) 2017 Bruce Guenter <bruce@untroubled.org>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+#include "fdbuf.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+
+///////////////////////////////////////////////////////////////////////////////
+// Class fdibuf
+///////////////////////////////////////////////////////////////////////////////
+fdibuf::fdibuf(int fdesc, bool dc, unsigned bufsz)
+  : fdbuf(fdesc, dc, bufsz)
+{
+}
+
+fdibuf::fdibuf(const char* filename, unsigned bufsz)
+  : fdbuf(open(filename, O_RDONLY), true, bufsz)
+{
+  if(fd == -1) {
+    flags = flag_error;
+    errnum = errno;
+  }
+}
+
+fdibuf::~fdibuf()
+{
+}
+
+bool fdibuf::eof() const
+{
+  return (flags & flag_eof) && (bufstart >= buflength);
+}
+
+bool fdibuf::operator!() const
+{
+  return eof() || error() || closed();
+}
+
+// refill is protected -- no locking
+bool fdibuf::refill()
+{
+  if(flags)
+    return false;
+  if(bufstart != 0) {
+    if(bufstart < buflength) {
+      buflength -= bufstart;
+      memcpy(buf, buf+bufstart, buflength);
+    } else
+      buflength = 0;
+    bufstart = 0;
+  }
+  unsigned oldbuflength = buflength;
+  if(buflength < bufsize) {
+    ssize_t red = _read(buf+buflength, bufsize-buflength);
+    if(red < 0) {
+      errnum = errno;
+      flags |= flag_error;
+    }
+    else if(red == 0)
+      flags |= flag_eof;
+    else {
+      buflength += red;
+      offset += red;
+    }
+  }
+  return buflength > oldbuflength;
+}
+
+bool fdibuf::get(char& ch)
+{
+  lock();
+  count = 0;
+  if(bufstart >= buflength)
+    refill();
+  bool r = true;
+  if(eof() || error())
+    r = false;
+  else {
+    ch = buf[bufstart++];
+    count = 1;
+  }
+  unlock();
+  return r;
+}
+
+bool fdibuf::read_large(char* data, unsigned datalen)
+{
+  lock();
+  count = 0;
+
+  // If there's any content in the buffer, memcpy it out first.
+  unsigned len = buflength - bufstart;
+  if(len > datalen)
+    len = datalen;
+  memcpy(data, buf+bufstart, len);
+  data += len;
+  datalen -= len;
+  bufstart += len;
+  count += len;
+
+  // After the buffer is empty and there's still data to read,
+  // read it straight from the fd instead of copying it through the buffer.
+  while(datalen > 0) {
+    ssize_t red = _read(data, datalen);
+    if(red < 0) {
+      errnum = errno;
+      flags |= flag_error;
+      break;
+    }
+    else if(red == 0) {
+      flags |= flag_eof;
+      break;
+    }
+    data += red;
+    datalen -= red;
+    offset += red;
+    count += red;
+  }
+  unlock();
+  return datalen == 0;
+}
+
+bool fdibuf::read(char* data, unsigned datalen)
+{
+  if(datalen >= bufsize)
+    return read_large(data, datalen);
+  lock();
+  count = 0;
+  char* ptr = data;
+  while(datalen && !eof()) {
+    if(bufstart >= buflength)
+      refill();
+    unsigned len = buflength-bufstart;
+    if(len > datalen)
+      len = datalen;
+    memcpy(ptr, buf+bufstart, len);
+    bufstart += len;
+    datalen -= len;
+    ptr += len;
+    count += len;
+  }
+  unlock();
+  return !datalen;
+}
+
+bool fdibuf::seek(unsigned o)
+{
+  lock();
+  unsigned buf_start = offset - buflength;
+  if(o >= buf_start && o < offset) {
+    bufstart = o - buf_start;
+  }
+  else {
+    if(lseek(fd, o, SEEK_SET) != (off_t)o) {
+      errnum = errno;
+      flags |= flag_error;
+      unlock();
+      return false;
+    }
+    offset = o;
+    buflength = bufstart = 0;
+  }
+  count = 0;
+  flags &= ~flag_eof;
+  unlock();
+  return true;
+}
+
+bool fdibuf::seekfwd(unsigned o)
+{
+  return seek(tell() + o);
+}
+
+ssize_t fdibuf::_read(char* buf, ssize_t len)
+{
+  return ::read(fd, buf, len);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Globals
+///////////////////////////////////////////////////////////////////////////////
+fdibuf fin(0);