1 files changed, 198 insertions, 0 deletions

diff --git a/src/lib/response_from_fd.c b/src/lib/response_from_fd.c
new file mode 100644
index 00000000..ea486600
--- /dev/null
+++ b/src/lib/response_from_fd.c
@@ -0,0 +1,198 @@
+/*
+  This file is part of libmicrohttpd
+  Copyright (C) 2007-2018 Daniel Pittman and Christian Grothoff
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+/**
+ * @file lib/response_from_fd.c
+ * @brief implementation of MHD_response_from_fd()
+ * @author Daniel Pittman
+ * @author Christian Grothoff
+ * @author Karlson2k (Evgeny Grin)
+ */
+#include "internal.h"
+
+
+/**
+ * Given a file descriptor, read data from the file
+ * to generate the response.
+ *
+ * @param cls pointer to the response
+ * @param pos offset in the file to access
+ * @param buf where to write the data
+ * @param max number of bytes to write at most
+ * @return number of bytes written
+ */
+static ssize_t
+file_reader (void *cls,
+             uint64_t pos,
+             char *buf,
+             size_t max)
+{
+  struct MHD_Response *response = cls;
+#if !defined(_WIN32) || defined(__CYGWIN__)
+  ssize_t n;
+#else  /* _WIN32 && !__CYGWIN__ */
+  const HANDLE fh = (HANDLE) _get_osfhandle (response->fd);
+#endif /* _WIN32 && !__CYGWIN__ */
+  const int64_t offset64 = (int64_t)(pos + response->fd_off);
+
+  if (offset64 < 0)
+    return MHD_CONTENT_READER_END_WITH_ERROR; /* seek to required position is not possible */
+
+#if !defined(_WIN32) || defined(__CYGWIN__)
+  if (max > SSIZE_MAX)
+    max = SSIZE_MAX; /* Clamp to maximum return value. */
+
+#if defined(HAVE_PREAD64)
+  n = pread64 (response->fd,
+               buf,
+               max,
+               offset64);
+#elif defined(HAVE_PREAD)
+  if ( (sizeof(off_t) < sizeof (uint64_t)) &&
+       (offset64 > (uint64_t)INT32_MAX) )
+    return MHD_CONTENT_READER_END_WITH_ERROR; /* Read at required position is not possible. */
+
+  n = pread (response->fd,
+             buf,
+             max,
+             (off_t) offset64);
+#else  /* ! HAVE_PREAD */
+#if defined(HAVE_LSEEK64)
+  if (lseek64 (response->fd,
+               offset64,
+               SEEK_SET) != offset64)
+    return MHD_CONTENT_READER_END_WITH_ERROR; /* can't seek to required position */
+#else  /* ! HAVE_LSEEK64 */
+  if ( (sizeof(off_t) < sizeof (uint64_t)) &&
+       (offset64 > (uint64_t)INT32_MAX) )
+    return MHD_CONTENT_READER_END_WITH_ERROR; /* seek to required position is not possible */
+
+  if (lseek (response->fd,
+             (off_t) offset64,
+             SEEK_SET) != (off_t) offset64)
+    return MHD_CONTENT_READER_END_WITH_ERROR; /* can't seek to required position */
+#endif /* ! HAVE_LSEEK64 */
+  n = read (response->fd,
+            buf,
+            max);
+
+#endif /* ! HAVE_PREAD */
+  if (0 == n)
+    return MHD_CONTENT_READER_END_OF_STREAM;
+  if (n < 0)
+    return MHD_CONTENT_READER_END_WITH_ERROR;
+  return n;
+#else /* _WIN32 && !__CYGWIN__ */
+  if (INVALID_HANDLE_VALUE == fh)
+    return MHD_CONTENT_READER_END_WITH_ERROR; /* Value of 'response->fd' is not valid. */
+  else
+    {
+      OVERLAPPED f_ol = {0, 0, {{0, 0}}, 0}; /* Initialize to zero. */
+      ULARGE_INTEGER pos_uli;
+      DWORD toRead = (max > INT32_MAX) ? INT32_MAX : (DWORD) max;
+      DWORD resRead;
+
+      pos_uli.QuadPart = (uint64_t) offset64; /* Simple transformation 64bit -> 2x32bit. */
+      f_ol.Offset = pos_uli.LowPart;
+      f_ol.OffsetHigh = pos_uli.HighPart;
+      if (! ReadFile (fh,
+                      (void*)buf,
+                      toRead,
+                      &resRead,
+                      &f_ol))
+        return MHD_CONTENT_READER_END_WITH_ERROR; /* Read error. */
+      if (0 == resRead)
+        return MHD_CONTENT_READER_END_OF_STREAM;
+      return (ssize_t) resRead;
+    }
+#endif /* _WIN32 && !__CYGWIN__ */
+}
+
+
+/**
+ * Destroy file reader context.  Closes the file
+ * descriptor.
+ *
+ * @param cls pointer to file descriptor
+ */
+static void
+free_callback (void *cls)
+{
+  struct MHD_Response *response = cls;
+
+  (void) close (response->fd);
+  response->fd = -1;
+}
+
+
+/**
+ * Create a response object based on an @a fd from which
+ * data is read.  The response object can be extended with
+ * header information and then be used any number of times.
+ *
+ * @param sc status code to return
+ * @param fd file descriptor referring to a file on disk with the
+ *        data; will be closed when response is destroyed;
+ *        fd should be in 'blocking' mode
+ * @param offset offset to start reading from in the file;
+ *        reading file beyond 2 GiB may be not supported by OS or
+ *        MHD build; see ::MHD_FEATURE_LARGE_FILE
+ * @param size size of the data portion of the response;
+ *        sizes larger than 2 GiB may be not supported by OS or
+ *        MHD build; see ::MHD_FEATURE_LARGE_FILE
+ * @return NULL on error (i.e. invalid arguments, out of memory)
+ * @ingroup response
+ */
+struct MHD_Response *
+MHD_response_from_fd (enum MHD_HTTP_StatusCode sc,
+                      int fd,
+                      uint64_t offset,
+                      uint64_t size)
+{
+  struct MHD_Response *response;
+
+  mhd_assert (-1 != fd);
+#if !defined(HAVE___LSEEKI64) && !defined(HAVE_LSEEK64)
+  if ( (sizeof (uint64_t) > sizeof (off_t)) &&
+       ( (size > (uint64_t)INT32_MAX) ||
+         (offset > (uint64_t)INT32_MAX) ||
+         ((size + offset) >= (uint64_t)INT32_MAX) ) )
+    return NULL;
+#endif
+  if ( ((int64_t) size < 0) ||
+       ((int64_t) offset < 0) ||
+       ((int64_t) (size + offset) < 0) )
+    return NULL;
+
+  response = MHD_response_from_callback (size,
+                                         4 * 1024,
+                                         &file_reader,
+                                         NULL,
+                                         &free_callback);
+  if (NULL == response)
+    return NULL;
+  response->fd = fd;
+  response->status_code = sc;
+  response->fd_off = offset;
+  response->crc_cls = response;
+  return response;
+}
+
+/* end of response_from_fd.c */
+