Add example code for an external file system for httpd

addons/httpd/fs_example/fs_example.c

@@ -0,0 +1,160 @@
+/**
+ * @file
+ * HTTPD custom file system example
+ *
+ * This file demonstrates how to add support for an external file system to httpd.
+ * It provides access to the specified root directory and uses stdio.h file functions
+ * to read files.
+ *
+ * ATTENTION: This implementation is *not* secure: no checks are added to ensure
+ * files are only read below the specified root directory!
+ */
+ 
+ /*
+ * Copyright (c) 2017 Simon Goldschmidt
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without modification, 
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission. 
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
+ * OF SUCH DAMAGE.
+ *
+ * This file is part of the lwIP TCP/IP stack.
+ * 
+ * Author: Simon Goldschmidt <goldsimon@gmx.de>
+ *
+ */
+
+#include "lwip/opt.h"
+#include "fs_example.h"
+
+#include "lwip/apps/fs.h"
+
+#include <stdio.h>
+#include <string.h>
+
+/** define LWIP_HTTPD_EXAMPLE_CUSTOMFILES to 1 to enable this file system*/
+#ifndef LWIP_HTTPD_EXAMPLE_CUSTOMFILES
+#define LWIP_HTTPD_EXAMPLE_CUSTOMFILES 0
+#endif
+
+#if LWIP_HTTPD_EXAMPLE_CUSTOMFILES
+
+const char* fs_ex_root_dir;
+
+void
+fs_ex_init(const char *httpd_root_dir)
+{
+  fs_ex_root_dir = strdup(httpd_root_dir);
+}
+
+#if LWIP_HTTPD_CUSTOM_FILES
+int
+fs_open_custom(struct fs_file *file, const char *name)
+{
+  char full_filename[256];
+  FILE *f;
+
+  snprintf(full_filename, 255, "%s%s", fs_ex_root_dir, name);
+  full_filename[255] = 0;
+
+  f = fopen(full_filename, "rb");
+  if (f != NULL) {
+    if (!fseek(f, 0, SEEK_END)) {
+      int len = (int)ftell(f);
+      if(!fseek(f, 0, SEEK_SET)) {
+        memset(file, 0, sizeof(struct fs_file));
+        file->len = len;
+        file->pextension = f;
+        return 1;
+      }
+    }
+    fclose(f);
+  }
+  return 0;
+}
+
+void
+fs_close_custom(struct fs_file *file)
+{
+  if (file && file->pextension) {
+    fclose((FILE*)file->pextension);
+    file->pextension = NULL;
+  }
+}
+
+#if LWIP_HTTPD_FS_ASYNC_READ
+u8_t
+fs_canread_custom(struct fs_file *file)
+{
+  /* This function is only necessary for asynchronous I/O:
+     If reading would block, return 0 and implement fs_wait_read_custom() to call the
+     supplied callback if reading works. */
+  LWIP_UNUSED_ARG(file);
+  return 1;
+}
+
+u8_t
+fs_wait_read_custom(struct fs_file *file, fs_wait_cb callback_fn, void *callback_arg)
+{
+  /* not implemented in this example */
+  LWIP_UNUSED_ARG(file);
+  LWIP_UNUSED_ARG(callback_fn);
+  LWIP_UNUSED_ARG(callback_arg);
+  /* Return
+     - 1 if ready to read (at least one byte)
+     - 0 if reading should be delayed (call 'tcpip_callback(callback_fn, callback_arg)' when ready) */
+  return 0;
+}
+
+int
+fs_read_async_custom(struct fs_file *file, char *buffer, int count, fs_wait_cb callback_fn, void *callback_arg)
+{
+  FILE *f = (FILE*)file->pextension;
+  int len = (int)fread(buffer, 1, count, f);
+
+  LWIP_UNUSED_ARG(callback_fn);
+  LWIP_UNUSED_ARG(callback_arg);
+
+  file->index += len;
+
+  /* Return
+     - FS_READ_EOF if all bytes have been read
+     - FS_READ_DELAYED if reading is delayed (call 'tcpip_callback(callback_fn, callback_arg)' when done) */
+  return len;
+}
+
+#else /* LWIP_HTTPD_FS_ASYNC_READ */
+int
+fs_read_custom(struct fs_file *file, char *buffer, int count)
+{
+  FILE *f = (FILE*)file->pextension;
+  int len = (int)fread(buffer, 1, count, f);
+
+  file->index += len;
+
+  /* Return FS_READ_EOF if all bytes have been read */
+  return len;
+}
+
+#endif /* LWIP_HTTPD_FS_ASYNC_READ */
+#endif /* LWIP_HTTPD_CUSTOM_FILES */
+
+#endif /* LWIP_HTTPD_EXAMPLE_CUSTOMFILES */

addons/httpd/fs_example/fs_example.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2017 Simon Goldschmidt
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without modification, 
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission. 
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
+ * OF SUCH DAMAGE.
+ *
+ * This file is part of the lwIP TCP/IP stack.
+ * 
+ * Author: Simon Goldschmidt <goldsimon@gmx.de>
+ *
+ */
+
+#ifndef LWIP_HDR_HTTP_EXAMPLES_FS_EXAMPLE
+#define LWIP_HDR_HTTP_EXAMPLES_FS_EXAMPLE
+
+void fs_ex_init(const char *httpd_root_dir);
+
+#endif /* LWIP_HDR_HTTP_EXAMPLES_FS_EXAMPLE */