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81d863fd41
The current code is not able to unset an environment variable, only to set it to an empty value. This patch refactors a bit the Message class and uses a new EnvChanger helper class that allows to change temporarily an environment variable and that is able to unset variables if needed.
The patch also adds new functions hasEnv and unsetEnv in environment.cpp.
Open issues:
* there may be systems where unsetenv is not available and putenv("name=") does not do the right thing;
* unsetenv may lead to leaks on some platforms.
* when using unsetenv, we may need to remove strings from the internal map that setEnv uses.
100 lines
2.8 KiB
C++
100 lines
2.8 KiB
C++
// -*- C++ -*-
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/**
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* \file environment.h
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* This file is part of LyX, the document processor.
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* Licence details can be found in the file COPYING.
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*
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* \author Angus Leeming
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*
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* Full author contact details are available in file CREDITS.
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*/
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#ifndef LYX_ENVIRONMENT_H
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#define LYX_ENVIRONMENT_H
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#include <string>
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#include <vector>
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namespace lyx {
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namespace support {
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/// @returns true if the environment variable @c name exists.
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bool hasEnv(std::string const & name);
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/// @returns the contents of the environment variable @c name encoded in utf8.
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std::string const getEnv(std::string const & name);
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/** @returns the contents of the environment variable @c name,
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* split into path elements using the OS-dependent separator token
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* and encoded in utf8.
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* Each element is then passed through os::internal_path() to
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* guarantee that it is in the form of a unix-style path.
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* If the environment variable is not set, then the function returns
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* an empty vector.
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*/
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std::vector<std::string> const getEnvPath(std::string const & name);
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/** Set the contents of the environment variable @c name to @c value.
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* \p value is encoded in utf8.
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* @returns true if the variable was set successfully.
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*/
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bool setEnv(std::string const & name, std::string const & value);
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/** Set the contents of the environment variable @c name
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* using the paths stored in the @c env vector (encoded in utf8).
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* Each element is passed through os::external_path().
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* Multiple elements are concatenated into a single string using
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* os::path_separator().
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*/
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void setEnvPath(std::string const & name, std::vector<std::string> const & env);
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/** Prepend a list of paths to that returned by the environment variable.
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* Identical paths occurring later in the list are removed.
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* @param name the name of the environment variable (encoded in utf8).
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* @prefix the list of paths in OS-native syntax (encoded in utf8).
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* Eg "/foo/bar:/usr/bin:/usr/local/bin" on *nix,
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* "C:\foo\bar;C:\windows" on Windows.
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*/
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void prependEnvPath(std::string const & name, std::string const & prefix);
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/** Remove the variable @c name from the environment.
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* @returns true if the variable was unset successfully.
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*/
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bool unsetEnv(std::string const & name);
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/** Utility class to change temporarily an environment variable. The
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* variable is reset to its original state when the dummy EnvChanger
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* variable is deleted.
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*/
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class EnvChanger {
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public:
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///
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EnvChanger(std::string const & name, std::string const & value)
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: name_(name), set_(hasEnv(name)), value_(getEnv(name))
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{
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setEnv(name, value);
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}
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///
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~EnvChanger()
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{
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if (set_)
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setEnv(name_, value_);
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else
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unsetEnv(name_);
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}
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private:
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/// the name of the variable
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std::string name_;
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/// was the variable set?
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bool set_;
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///
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std::string value_;
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};
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} // namespace support
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} // namespace lyx
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#endif // LYX_ENVIRONMENT_H
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