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getEnv(): Return std::optional

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This allows distinguishing between an empty value and no value.
This commit is contained in:
Eelco Dolstra 2019-11-22 16:06:44 +01:00
parent fd900c45b5
commit ba87b08f85
No known key found for this signature in database
GPG key ID: 8170B4726D7198DE
17 changed files with 60 additions and 63 deletions
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35
src/libutil/util.cc
View file

@ -58,10 +58,11 @@ std::string SysError::addErrno(const std::string & s)
}
string getEnv(const string & key, const string & def)
std::optional<std::string> getEnv(const std::string & key)
{
char * value = getenv(key.c_str());
return value ? string(value) : def;
if (!value) return {};
return std::string(value);
}
@ -438,7 +439,7 @@ void deletePath(const Path & path, unsigned long long & bytesFreed)
static Path tempName(Path tmpRoot, const Path & prefix, bool includePid,
int & counter)
{
tmpRoot = canonPath(tmpRoot.empty() ? getEnv("TMPDIR", "/tmp") : tmpRoot, true);
tmpRoot = canonPath(tmpRoot.empty() ? getEnv("TMPDIR").value_or("/tmp") : tmpRoot, true);
if (includePid)
return (format("%1%/%2%-%3%-%4%") % tmpRoot % prefix % getpid() % counter++).str();
else
@ -480,7 +481,7 @@ Path createTempDir(const Path & tmpRoot, const Path & prefix,
std::string getUserName()
{
auto pw = getpwuid(geteuid());
std::string name = pw ? pw->pw_name : getEnv("USER", "");
std::string name = pw ? pw->pw_name : getEnv("USER").value_or("");
if (name.empty())
throw Error("cannot figure out user name");
return name;
@ -488,8 +489,8 @@ std::string getUserName()
static Lazy<Path> getHome2([]() {
Path homeDir = getEnv("HOME");
if (homeDir.empty()) {
auto homeDir = getEnv("HOME");
if (!homeDir) {
std::vector<char> buf(16384);
struct passwd pwbuf;
struct passwd * pw;
@ -498,7 +499,7 @@ static Lazy<Path> getHome2([]() {
throw Error("cannot determine user's home directory");
homeDir = pw->pw_dir;
}
return homeDir;
return *homeDir;
});
Path getHome() { return getHome2(); }
@ -506,25 +507,21 @@ Path getHome() { return getHome2(); }
Path getCacheDir()
{
Path cacheDir = getEnv("XDG_CACHE_HOME");
if (cacheDir.empty())
cacheDir = getHome() + "/.cache";
return cacheDir;
auto cacheDir = getEnv("XDG_CACHE_HOME");
return cacheDir ? *cacheDir : getHome() + "/.cache";
}
Path getConfigDir()
{
Path configDir = getEnv("XDG_CONFIG_HOME");
if (configDir.empty())
configDir = getHome() + "/.config";
return configDir;
auto configDir = getEnv("XDG_CONFIG_HOME");
return configDir ? *configDir : getHome() + "/.config";
}
std::vector<Path> getConfigDirs()
{
Path configHome = getConfigDir();
string configDirs = getEnv("XDG_CONFIG_DIRS");
string configDirs = getEnv("XDG_CONFIG_DIRS").value_or("");
std::vector<Path> result = tokenizeString<std::vector<string>>(configDirs, ":");
result.insert(result.begin(), configHome);
return result;
@ -533,10 +530,8 @@ std::vector<Path> getConfigDirs()
Path getDataDir()
{
Path dataDir = getEnv("XDG_DATA_HOME");
if (dataDir.empty())
dataDir = getHome() + "/.local/share";
return dataDir;
auto dataDir = getEnv("XDG_DATA_HOME");
return dataDir ? *dataDir : getHome() + "/.local/share";
}

2
src/libutil/util.hh
View file

@ -35,7 +35,7 @@ extern const std::string nativeSystem;
/* Return an environment variable. */
string getEnv(const string & key, const string & def = "");
std::optional<std::string> getEnv(const std::string & key);
/* Get the entire environment. */
std::map<std::string, std::string> getEnv();