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// Copyright (c) 2009 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 "webkit/glue/plugins/plugin_lib.h"
#include <dlfcn.h>
#if defined(OS_OPENBSD)
#include <sys/exec_elf.h>
#else
#include <elf.h>
#endif
#include "base/string_util.h"
#include "base/sys_string_conversions.h"
#include "base/utf_string_conversions.h"
#include "webkit/glue/plugins/plugin_list.h"
// These headers must be included in this order to make the declaration gods
// happy.
#include "base/third_party/nspr/prcpucfg_linux.h"
namespace {
// Copied from nsplugindefs.h instead of including the file since it has a bunch
// of dependencies.
enum nsPluginVariable {
nsPluginVariable_NameString = 1,
nsPluginVariable_DescriptionString = 2
};
// Read the ELF header and return true if it is usable on
// the current architecture (e.g. 32-bit ELF on 32-bit build).
// Returns false on other errors as well.
bool ELFMatchesCurrentArchitecture(const FilePath& filename) {
FILE* file = fopen(filename.value().c_str(), "rb");
if (!file)
return false;
char buffer[5];
if (fread(buffer, 5, 1, file) != 1) {
fclose(file);
return false;
}
fclose(file);
if (buffer[0] != ELFMAG0 ||
buffer[1] != ELFMAG1 ||
buffer[2] != ELFMAG2 ||
buffer[3] != ELFMAG3) {
// Not an ELF file, perhaps?
return false;
}
int elf_class = buffer[EI_CLASS];
#if defined(ARCH_CPU_32_BITS)
if (elf_class == ELFCLASS32)
return true;
#elif defined(ARCH_CPU_64_BITS)
if (elf_class == ELFCLASS64)
return true;
#endif
return false;
}
// This structure matches enough of nspluginwrapper's NPW_PluginInfo
// for us to extract the real plugin path.
struct __attribute__((packed)) NSPluginWrapperInfo {
char ident[32]; // NSPluginWrapper magic identifier (includes version).
char path[PATH_MAX]; // Path to wrapped plugin.
};
// Test a plugin for whether it's been wrapped by NSPluginWrapper, and
// if so attempt to unwrap it. Pass in an opened plugin handle; on
// success, |dl| and |unwrapped_path| will be filled in with the newly
// opened plugin. On failure, params are left unmodified.
void UnwrapNSPluginWrapper(void **dl, FilePath* unwrapped_path) {
NSPluginWrapperInfo* info =
reinterpret_cast<NSPluginWrapperInfo*>(dlsym(*dl, "NPW_Plugin"));
if (!info)
return; // Not a NSPW plugin.
// Here we could check the NSPW ident field for the versioning
// information, but the path field is available in all versions
// anyway.
// Grab the path to the wrapped plugin. Just in case the structure
// format changes, protect against the path not being null-terminated.
char* path_end = static_cast<char*>(memchr(info->path, '\0',
sizeof(info->path)));
if (!path_end)
path_end = info->path + sizeof(info->path);
FilePath path = FilePath(std::string(info->path, path_end - info->path));
if (!ELFMatchesCurrentArchitecture(path)) {
LOG(WARNING) << path.value() << " is nspluginwrapper wrapping a "
<< "plugin for a different architecture; it will "
<< "work better if you instead use a native plugin.";
return;
}
void* newdl = base::LoadNativeLibrary(path);
if (!newdl) {
// We couldn't load the unwrapped plugin for some reason, despite
// being able to load the wrapped one. Just use the wrapped one.
return;
}
// Unload the wrapped plugin, and use the wrapped plugin instead.
base::UnloadNativeLibrary(*dl);
*dl = newdl;
*unwrapped_path = path;
}
} // anonymous namespace
namespace NPAPI {
bool PluginLib::ReadWebPluginInfo(const FilePath& filename,
WebPluginInfo* info) {
// The file to reference is:
// http://mxr.mozilla.org/firefox/source/modules/plugin/base/src/nsPluginsDirUnix.cpp
// Skip files that aren't appropriate for our architecture.
if (!ELFMatchesCurrentArchitecture(filename))
return false;
void* dl = base::LoadNativeLibrary(filename);
if (!dl)
return false;
info->path = filename;
// Attempt to swap in the wrapped plugin if this is nspluginwrapper.
UnwrapNSPluginWrapper(&dl, &info->path);
// See comments in plugin_lib_mac regarding this symbol.
typedef const char* (*NP_GetMimeDescriptionType)();
NP_GetMimeDescriptionType NP_GetMIMEDescription =
reinterpret_cast<NP_GetMimeDescriptionType>(
dlsym(dl, "NP_GetMIMEDescription"));
const char* mime_description = NULL;
if (NP_GetMIMEDescription)
mime_description = NP_GetMIMEDescription();
if (mime_description)
ParseMIMEDescription(mime_description, &info->mime_types);
// The plugin name and description live behind NP_GetValue calls.
typedef NPError (*NP_GetValueType)(void* unused,
nsPluginVariable variable,
void* value_out);
NP_GetValueType NP_GetValue =
reinterpret_cast<NP_GetValueType>(dlsym(dl, "NP_GetValue"));
if (NP_GetValue) {
const char* name = NULL;
NP_GetValue(NULL, nsPluginVariable_NameString, &name);
if (name)
info->name = UTF8ToWide(name);
const char* description = NULL;
NP_GetValue(NULL, nsPluginVariable_DescriptionString, &description);
if (description)
info->desc = UTF8ToWide(description);
}
// Intentionally not unloading the plugin here, it can lead to crashes.
return true;
}
// static
void PluginLib::ParseMIMEDescription(
const std::string& description,
std::vector<WebPluginMimeType>* mime_types) {
// We parse the description here into WebPluginMimeType structures.
// Naively from the NPAPI docs you'd think you could use
// string-splitting, but the Firefox parser turns out to do something
// different: find the first colon, then the second, then a semi.
//
// See ParsePluginMimeDescription near
// http://mxr.mozilla.org/firefox/source/modules/plugin/base/src/nsPluginsDirUtils.h#53
std::string::size_type ofs = 0;
for (;;) {
WebPluginMimeType mime_type;
std::string::size_type end = description.find(':', ofs);
if (end == std::string::npos)
break;
mime_type.mime_type = description.substr(ofs, end - ofs);
ofs = end + 1;
end = description.find(':', ofs);
if (end == std::string::npos)
break;
const std::string extensions = description.substr(ofs, end - ofs);
SplitString(extensions, ',', &mime_type.file_extensions);
ofs = end + 1;
end = description.find(';', ofs);
// It's ok for end to run off the string here. If there's no
// trailing semicolon we consume the remainder of the string.
if (end != std::string::npos) {
mime_type.description = UTF8ToWide(description.substr(ofs, end - ofs));
} else {
mime_type.description = UTF8ToWide(description.substr(ofs));
}
mime_types->push_back(mime_type);
if (end == std::string::npos)
break;
ofs = end + 1;
}
}
} // namespace NPAPI
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