[NaCl SDK] nacl_io: big refactor to return error value (errno).

native_client_sdk/src/libraries/nacl_io/mount_node_http.cc

+/* Copyright (c) 2013 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "nacl_io/mount_node_http.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <ppapi/c/pp_errors.h>
+
+#include "nacl_io/mount_http.h"
+#include "nacl_io/osinttypes.h"
+
+#if defined(WIN32)
+#define snprintf _snprintf
+#endif
+
+namespace {
+
+// If we're attempting to read a partial request, but the server returns a full
+// request, we need to read all of the data up to the start of our partial
+// request into a dummy buffer. This is the maximum size of that buffer.
+const size_t MAX_READ_BUFFER_SIZE = 64 * 1024;
+const int32_t STATUSCODE_OK = 200;
+const int32_t STATUSCODE_PARTIAL_CONTENT = 206;
+
+StringMap_t ParseHeaders(const char* headers, int32_t headers_length) {
+  enum State {
+    FINDING_KEY,
+    SKIPPING_WHITESPACE,
+    FINDING_VALUE,
+  };
+
+  StringMap_t result;
+  std::string key;
+  std::string value;
+
+  State state = FINDING_KEY;
+  const char* start = headers;
+  for (int i = 0; i < headers_length; ++i) {
+    switch (state) {
+      case FINDING_KEY:
+        if (headers[i] == ':') {
+          // Found key.
+          key.assign(start, &headers[i] - start);
+          key = NormalizeHeaderKey(key);
+          state = SKIPPING_WHITESPACE;
+        }
+        break;
+
+      case SKIPPING_WHITESPACE:
+        if (headers[i] == ' ') {
+          // Found whitespace, keep going...
+          break;
+        }
+
+        // Found a non-whitespace, mark this as the start of the value.
+        start = &headers[i];
+        state = FINDING_VALUE;
+      // Fallthrough to start processing value without incrementing i.
+
+      case FINDING_VALUE:
+        if (headers[i] == '\n') {
+          // Found value.
+          value.assign(start, &headers[i] - start);
+          result[key] = value;
+          start = &headers[i + 1];
+          state = FINDING_KEY;
+        }
+        break;
+    }
+  }
+
+  return result;
+}
+
+bool ParseContentLength(const StringMap_t& headers, size_t* content_length) {
+  StringMap_t::const_iterator iter = headers.find("Content-Length");
+  if (iter == headers.end())
+    return false;
+
+  *content_length = strtoul(iter->second.c_str(), NULL, 10);
+  return true;
+}
+
+bool ParseContentRange(const StringMap_t& headers,
+                       size_t* read_start,
+                       size_t* read_end,
+                       size_t* entity_length) {
+  StringMap_t::const_iterator iter = headers.find("Content-Range");
+  if (iter == headers.end())
+    return false;
+
+  // The key should look like "bytes ##-##/##" or "bytes ##-##/*". The last
+  // value is the entity length, which can potentially be * (i.e. unknown).
+  int read_start_int;
+  int read_end_int;
+  int entity_length_int;
+  int result = sscanf(iter->second.c_str(),
+                      "bytes %" SCNuS "-%" SCNuS "/%" SCNuS,
+                      &read_start_int,
+                      &read_end_int,
+                      &entity_length_int);
+
+  // The Content-Range header specifies an inclusive range: e.g. the first ten
+  // bytes is "bytes 0-9/*". Convert it to a half-open range by incrementing
+  // read_end.
+  if (result == 2) {
+    *read_start = read_start_int;
+    *read_end = read_end_int + 1;
+    *entity_length = 0;
+    return true;
+  } else if (result == 3) {
+    *read_start = read_start_int;
+    *read_end = read_end_int + 1;
+    *entity_length = entity_length_int;
+    return true;
+  }
+
+  return false;
+}
+
+}  // namespace
+
+void MountNodeHttp::SetCachedSize(off_t size) {
+  has_cached_size_ = true;
+  stat_.st_size = size;
+}
+
+Error MountNodeHttp::FSync() { return ENOSYS; }
+
+Error MountNodeHttp::GetDents(size_t offs,
+                              struct dirent* pdir,
+                              size_t count,
+                              int* out_bytes) {
+  *out_bytes = 0;
+  return ENOSYS;
+}
+
+Error MountNodeHttp::GetStat(struct stat* stat) {
+  AutoLock lock(&lock_);
+
+  // Assume we need to 'HEAD' if we do not know the size, otherwise, assume
+  // that the information is constant.  We can add a timeout if needed.
+  MountHttp* mount = static_cast<MountHttp*>(mount_);
+  if (stat_.st_size == 0 || !mount->cache_stat_) {
+    StringMap_t headers;
+    PP_Resource loader;
+    PP_Resource request;
+    PP_Resource response;
+    int32_t statuscode;
+    StringMap_t response_headers;
+    Error error = OpenUrl("HEAD",
+                          &headers,
+                          &loader,
+                          &request,
+                          &response,
+                          &statuscode,
+                          &response_headers);
+    if (error)
+      return error;
+
+    ScopedResource scoped_loader(mount_->ppapi(), loader);
+    ScopedResource scoped_request(mount_->ppapi(), request);
+    ScopedResource scoped_response(mount_->ppapi(), response);
+
+    size_t entity_length;
+    if (ParseContentLength(response_headers, &entity_length)) {
+      SetCachedSize(static_cast<off_t>(entity_length));
+    } else if (cache_content_ && !has_cached_size_) {
+      error = DownloadToCache();
+      // TODO(binji): this error should not be dropped, but it requires a bit
+      // of a refactor of the tests. See crbug.com/245431
+      // if (error)
+      //   return error;
+    } else {
+      // Don't use SetCachedSize here -- it is actually unknown.
+      stat_.st_size = 0;
+    }
+
+    stat_.st_atime = 0;  // TODO(binji): Use "Last-Modified".
+    stat_.st_mtime = 0;
+    stat_.st_ctime = 0;
+  }
+
+  // Fill the stat structure if provided
+  if (stat)
+    memcpy(stat, &stat_, sizeof(stat_));
+
+  return 0;
+}
+
+Error MountNodeHttp::Read(size_t offs,
+                          void* buf,
+                          size_t count,
+                          int* out_bytes) {
+  *out_bytes = 0;
+
+  AutoLock lock(&lock_);
+  if (cache_content_) {
+    if (cached_data_.empty()) {
+      Error error = DownloadToCache();
+      if (error)
+        return error;
+    }
+
+    return ReadPartialFromCache(offs, buf, count, out_bytes);
+  }
+
+  return DownloadPartial(offs, buf, count, out_bytes);
+}
+
+Error MountNodeHttp::FTruncate(off_t size) { return ENOSYS; }
+
+Error MountNodeHttp::Write(size_t offs,
+                           const void* buf,
+                           size_t count,
+                           int* out_bytes) {
+  // TODO(binji): support POST?
+  *out_bytes = 0;
+  return ENOSYS;
+}
+
+Error MountNodeHttp::GetSize(size_t* out_size) {
+  *out_size = 0;
+
+  // TODO(binji): This value should be cached properly; i.e. obey the caching
+  // headers returned by the server.
+  AutoLock lock(&lock_);
+  if (!has_cached_size_) {
+    // Even if DownloadToCache fails, the best result we can return is what
+    // was written to stat_.st_size.
+    if (cache_content_) {
+      Error error = DownloadToCache();
+      if (error)
+        return error;
+    }
+  }
+
+  *out_size = stat_.st_size;
+  return 0;
+}
+
+MountNodeHttp::MountNodeHttp(Mount* mount,
+                             const std::string& url,
+                             bool cache_content)
+    : MountNode(mount),
+      url_(url),
+      cache_content_(cache_content),
+      has_cached_size_(false) {}
+
+Error MountNodeHttp::OpenUrl(const char* method,
+                             StringMap_t* request_headers,
+                             PP_Resource* out_loader,
+                             PP_Resource* out_request,
+                             PP_Resource* out_response,
+                             int32_t* out_statuscode,
+                             StringMap_t* out_response_headers) {
+  // Assume lock_ is already held.
+  PepperInterface* ppapi = mount_->ppapi();
+
+  MountHttp* mount_http = static_cast<MountHttp*>(mount_);
+  ScopedResource request(
+      ppapi, mount_http->MakeUrlRequestInfo(url_, method, request_headers));
+  if (!request.pp_resource())
+    return EINVAL;
+
+  URLLoaderInterface* loader_interface = ppapi->GetURLLoaderInterface();
+  URLResponseInfoInterface* response_interface =
+      ppapi->GetURLResponseInfoInterface();
+  VarInterface* var_interface = ppapi->GetVarInterface();
+
+  ScopedResource loader(ppapi, loader_interface->Create(ppapi->GetInstance()));
+  if (!loader.pp_resource())
+    return EINVAL;
+
+  int32_t result = loader_interface->Open(
+      loader.pp_resource(), request.pp_resource(), PP_BlockUntilComplete());
+  if (result != PP_OK)
+    return PPErrorToErrno(result);
+
+  ScopedResource response(
+      ppapi, loader_interface->GetResponseInfo(loader.pp_resource()));
+  if (!response.pp_resource())
+    return EINVAL;
+
+  // Get response statuscode.
+  PP_Var statuscode = response_interface->GetProperty(
+      response.pp_resource(), PP_URLRESPONSEPROPERTY_STATUSCODE);
+
+  if (statuscode.type != PP_VARTYPE_INT32)
+    return EINVAL;
+
+  *out_statuscode = statuscode.value.as_int;
+
+  // Only accept OK or Partial Content.
+  if (*out_statuscode != STATUSCODE_OK &&
+      *out_statuscode != STATUSCODE_PARTIAL_CONTENT) {
+    return EINVAL;
+  }
+
+  // Get response headers.
+  PP_Var response_headers_var = response_interface->GetProperty(
+      response.pp_resource(), PP_URLRESPONSEPROPERTY_HEADERS);
+
+  uint32_t response_headers_length;
+  const char* response_headers_str =
+      var_interface->VarToUtf8(response_headers_var, &response_headers_length);
+
+  *out_loader = loader.Release();
+  *out_request = request.Release();
+  *out_response = response.Release();
+  *out_response_headers =
+      ParseHeaders(response_headers_str, response_headers_length);
+
+  return 0;
+}
+
+Error MountNodeHttp::DownloadToCache() {
+  StringMap_t headers;
+  PP_Resource loader;
+  PP_Resource request;
+  PP_Resource response;
+  int32_t statuscode;
+  StringMap_t response_headers;
+  Error error = OpenUrl("GET",
+                        &headers,
+                        &loader,
+                        &request,
+                        &response,
+                        &statuscode,
+                        &response_headers);
+  if (error)
+    return error;
+
+  PepperInterface* ppapi = mount_->ppapi();
+  ScopedResource scoped_loader(ppapi, loader);
+  ScopedResource scoped_request(ppapi, request);
+  ScopedResource scoped_response(ppapi, response);
+
+  size_t content_length = 0;
+  if (ParseContentLength(response_headers, &content_length)) {
+    cached_data_.resize(content_length);
+    int real_size;
+    error = DownloadToBuffer(
+        loader, cached_data_.data(), content_length, &real_size);
+    if (error)
+      return error;
+
+    SetCachedSize(real_size);
+    cached_data_.resize(real_size);
+    return 0;
+  }
+
+  // We don't know how big the file is. Read in chunks.
+  cached_data_.resize(MAX_READ_BUFFER_SIZE);
+  size_t total_bytes_read = 0;
+  size_t bytes_to_read = MAX_READ_BUFFER_SIZE;
+  while (true) {
+    char* buf = cached_data_.data() + total_bytes_read;
+    int bytes_read;
+    error = DownloadToBuffer(loader, buf, bytes_to_read, &bytes_read);
+    if (error)
+      return error;
+
+    total_bytes_read += bytes_read;
+
+    if (bytes_read < bytes_to_read) {
+      SetCachedSize(total_bytes_read);
+      cached_data_.resize(total_bytes_read);
+      return 0;
+    }
+
+    cached_data_.resize(total_bytes_read + bytes_to_read);
+  }
+}
+
+Error MountNodeHttp::ReadPartialFromCache(size_t offs,
+                                          void* buf,
+                                          size_t count,
+                                          int* out_bytes) {
+  *out_bytes = 0;
+
+  if (offs > cached_data_.size())
+    return EINVAL;
+
+  count = std::min(count, cached_data_.size() - offs);
+  memcpy(buf, &cached_data_.data()[offs], count);
+
+  *out_bytes = count;
+  return 0;
+}
+
+Error MountNodeHttp::DownloadPartial(size_t offs,
+                                     void* buf,
+                                     size_t count,
+                                     int* out_bytes) {
+  *out_bytes = 0;
+
+  StringMap_t headers;
+
+  char buffer[100];
+  // Range request is inclusive: 0-99 returns 100 bytes.
+  snprintf(&buffer[0],
+           sizeof(buffer),
+           "bytes=%" PRIuS "-%" PRIuS,
+           offs,
+           offs + count - 1);
+  headers["Range"] = buffer;
+
+  PP_Resource loader;
+  PP_Resource request;
+  PP_Resource response;
+  int32_t statuscode;
+  StringMap_t response_headers;
+  Error error = OpenUrl("GET",
+                        &headers,
+                        &loader,
+                        &request,
+                        &response,
+                        &statuscode,
+                        &response_headers);
+  if (error)
+    return error;
+
+  PepperInterface* ppapi = mount_->ppapi();
+  ScopedResource scoped_loader(ppapi, loader);
+  ScopedResource scoped_request(ppapi, request);
+  ScopedResource scoped_response(ppapi, response);
+
+  size_t read_start = 0;
+  if (statuscode == STATUSCODE_OK) {
+    // No partial result, read everything starting from the part we care about.
+    size_t content_length;
+    if (ParseContentLength(response_headers, &content_length)) {
+      if (offs >= content_length)
+        return EINVAL;
+
+      // Clamp count, if trying to read past the end of the file.
+      if (offs + count > content_length) {
+        count = content_length - offs;
+      }
+    }
+  } else if (statuscode == STATUSCODE_PARTIAL_CONTENT) {
+    // Determine from the headers where we are reading.
+    size_t read_end;
+    size_t entity_length;
+    if (ParseContentRange(
+            response_headers, &read_start, &read_end, &entity_length)) {
+      if (read_start > offs || read_start > read_end) {
+        // If this error occurs, the server is returning bogus values.
+        return EINVAL;
+      }
+
+      // Clamp count, if trying to read past the end of the file.
+      count = std::min(read_end - read_start, count);
+    } else {
+      // Partial Content without Content-Range. Assume that the server gave us
+      // exactly what we asked for. This can happen even when the server
+      // returns 200 -- the cache may return 206 in this case, but not modify
+      // the headers.
+      read_start = offs;
+    }
+  }
+
+  if (read_start < offs) {
+    // We aren't yet at the location where we want to start reading. Read into
+    // our dummy buffer until then.
+    size_t bytes_to_read = offs - read_start;
+    if (buffer_.size() < bytes_to_read)
+      buffer_.resize(std::min(bytes_to_read, MAX_READ_BUFFER_SIZE));
+
+    while (bytes_to_read > 0) {
+      int32_t bytes_read;
+      Error error =
+          DownloadToBuffer(loader, buffer_.data(), buffer_.size(), &bytes_read);
+      if (error)
+        return error;
+
+      bytes_to_read -= bytes_read;
+    }
+  }
+
+  return DownloadToBuffer(loader, buf, count, out_bytes);
+}
+
+Error MountNodeHttp::DownloadToBuffer(PP_Resource loader,
+                                      void* buf,
+                                      size_t count,
+                                      int* out_bytes) {
+  *out_bytes = 0;
+
+  PepperInterface* ppapi = mount_->ppapi();
+  URLLoaderInterface* loader_interface = ppapi->GetURLLoaderInterface();
+
+  char* out_buffer = static_cast<char*>(buf);
+  size_t bytes_to_read = count;
+  while (bytes_to_read > 0) {
+    int32_t bytes_read = loader_interface->ReadResponseBody(
+        loader, out_buffer, bytes_to_read, PP_BlockUntilComplete());
+
+    if (bytes_read == 0) {
+      // This is not an error -- it may just be that we were trying to read
+      // more data than exists.
+      *out_bytes = count - bytes_to_read;
+      return 0;
+    }
+
+    if (bytes_read < 0)
+      return PPErrorToErrno(bytes_read);
+
+    assert(bytes_read <= bytes_to_read);
+    bytes_to_read -= bytes_read;
+    out_buffer += bytes_read;
+  }
+
+  *out_bytes = count;
+  return 0;
+}