Move function for classifying a string as a mime type into MimeUtil

net/base/mime_util.cc

Index: net/base/mime_util.cc
diff --git a/net/base/mime_util.cc b/net/base/mime_util.cc
index 8ff58e6d579b674bddb20da134a4aaf7f7e0e8bf..d97983b5348809f4afd980b9a6bd58df22a34eb8 100644
--- a/net/base/mime_util.cc
+++ b/net/base/mime_util.cc
@@ -43,6 +43,8 @@ class MimeUtil : public PlatformMimeUtil {
   bool MatchesMimeType(const std::string &mime_type_pattern,
                        const std::string &mime_type) const;
 
+  bool IsStringMimeType(const std::string& type_string) const;
+
   bool AreSupportedMediaCodecs(const std::vector<std::string>& codecs) const;
 
   void ParseCodecString(const std::string& codecs,
@@ -486,6 +488,40 @@ bool MimeUtil::MatchesMimeType(const std::string& mime_type_pattern,
   return true;
 }
 
+bool MimeUtil::IsStringMimeType(const std::string& type_string) const {

[rvargas (doing something else), 2012/06/01 01:51:14]

Shouldn't this build upon IsSupportedMimeType instead?

[Greg Billock, 2012/06/01 04:58:22]

How so? I think this function would basically have to do the same checks anyway,
since IsSupportedMimeTypes is about a whitelist, whereas this is checking
syntactically whether a string is a valid mime type specifier.

[rvargas (doing something else), 2012/06/01 19:11:25]

You're right, the "supported" part makes all the difference :)

+  // MIME types are always ASCII and case-insensitive (at least, the top-level
+  // and secondary types we care about).
+  if (!IsStringASCII(type_string))
+    return false;
+  std::string raw_type = type_string;
+  StringToLowerASCII(&raw_type);

[rvargas (doing something else), 2012/06/01 19:11:25]

either this is not needed, or the comparisons should be case sensitive.

[Greg Billock, 2012/06/05 01:08:56]

Done.

+
+  // See http://www.iana.org/assignments/media-types/index.html
+  if (StartsWithASCII(raw_type, "application/", false) ||

[rvargas (doing something else), 2012/06/01 19:11:25]

Then let's follow the pattern of this class and make this into a static array.

[Greg Billock, 2012/06/05 01:08:56]

Done.

+      StartsWithASCII(raw_type, "audio/", false) ||
+      StartsWithASCII(raw_type, "example/", false) ||
+      StartsWithASCII(raw_type, "image/", false) ||
+      StartsWithASCII(raw_type, "message/", false) ||
+      StartsWithASCII(raw_type, "model/", false) ||
+      StartsWithASCII(raw_type, "multipart/", false) ||
+      StartsWithASCII(raw_type, "text/", false) ||
+      StartsWithASCII(raw_type, "video/", false) ||
+      raw_type == "*/*" || raw_type == "*") {
+    return true;
+  }
+
+  // If there's a "/" separator character, and the token before it is

[rvargas (doing something else), 2012/06/01 01:51:14]

If we have no code to cover this case maybe we can add something specifically
for it. Enumerating mime types again doesn't make much sense.

+  // "x-" + (ascii characters), it is also a MIME type.
+  size_t slash = raw_type.find('/');
+  if (slash < 3 || slash == std::string::npos || slash == raw_type.length() - 1)
+    return false;
+
+  if (StartsWithASCII(raw_type, "x-", false))
+    return true;
+
+  return false;
+}
+
 bool MimeUtil::AreSupportedMediaCodecs(
     const std::vector<std::string>& codecs) const {
   return AreSupportedCodecs(codecs_map_, codecs);
@@ -578,6 +614,10 @@ bool MatchesMimeType(const std::string& mime_type_pattern,
   return g_mime_util.Get().MatchesMimeType(mime_type_pattern, mime_type);
 }
 
+bool IsStringMimeType(const std::string& type_string) {
+  return g_mime_util.Get().IsStringMimeType(type_string);
+}
+
 bool AreSupportedMediaCodecs(const std::vector<std::string>& codecs) {
   return g_mime_util.Get().AreSupportedMediaCodecs(codecs);
 }