external/bsd/kyua-cli/dist/utils/env.cpp

   1 // Copyright 2010 Google Inc.
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  28
  29 #include "utils/env.hpp"
  30
  31 #if defined(HAVE_CONFIG_H)
  32 #  include "config.h"
  33 #endif
  34
  35 #include <cerrno>
  36 #include <cstdlib>
  37 #include <cstring>
  38 #include <stdexcept>
  39
  40 #include "utils/format/macros.hpp"
  41 #include "utils/logging/macros.hpp"
  42 #include "utils/optional.ipp"
  43
  44 using utils::none;
  45 using utils::optional;
  46
  47
  48 extern "C" {
  49     extern char** environ;
  50 }
  51
  52
  53 /// Gets all environment variables.
  54 ///
  55 /// \return A mapping of (name, value) pairs describing the environment
  56 /// variables.
  57 std::map< std::string, std::string >
  58 utils::getallenv(void)
  59 {
  60     std::map< std::string, std::string > allenv;
  61     for (char** envp = environ; *envp != NULL; envp++) {
  62         const std::string oneenv = *envp;
  63         const std::string::size_type pos = oneenv.find('=');
  64         const std::string name = oneenv.substr(0, pos);
  65         const std::string value = oneenv.substr(pos + 1);
  66
  67         PRE(allenv.find(name) == allenv.end());
  68         allenv[name] = value;
  69     }
  70     return allenv;
  71 }
  72
  73
  74 /// Gets the value of an environment variable.
  75 ///
  76 /// \param name The name of the environment variable to query.
  77 ///
  78 /// \return The value of the environment variable if it is defined, or none
  79 /// otherwise.
  80 optional< std::string >
  81 utils::getenv(const std::string& name)
  82 {
  83     const char* value = std::getenv(name.c_str());
  84     if (value == NULL) {
  85         LD(F("Environment variable '%s' is not defined") % name);
  86         return none;
  87     } else {
  88         LD(F("Environment variable '%s' is '%s'") % name % value);
  89         return utils::make_optional(std::string(value));
  90     }
  91 }
  92
  93
  94 /// Gets the value of an environment variable with a default fallback.
  95 ///
  96 /// \param name The name of the environment variable to query.
  97 /// \param default_value The value to return if the variable is not defined.
  98 ///
  99 /// \return The value of the environment variable.
 100 std::string
 101 utils::getenv_with_default(const std::string& name,
 102                            const std::string& default_value)
 103 {
 104     const char* value = std::getenv(name.c_str());
 105     if (value == NULL) {
 106         LD(F("Environment variable '%s' is not defined; using default '%s'") %
 107            name % default_value);
 108         return default_value;
 109     } else {
 110         LD(F("Environment variable '%s' is '%s'") % name % value);
 111         return value;
 112     }
 113 }
 114
 115
 116 /// Sets the value of an environment variable.
 117 ///
 118 /// \param name The name of the environment variable to set.
 119 /// \param val The value to set the environment variable to.  May be empty.
 120 ///
 121 /// \throw std::runtime_error If there is an error setting the environment
 122 ///     variable.
 123 void
 124 utils::setenv(const std::string& name, const std::string& val)
 125 {
 126     LD(F("Setting environment variable '%s' to '%s'") % name % val);
 127 #if defined(HAVE_SETENV)
 128     if (::setenv(name.c_str(), val.c_str(), 1) == -1) {
 129         const int original_errno = errno;
 130         throw std::runtime_error(F("Failed to set environment variable '%s' to "
 131                                    "'%s': %s") %
 132                                  name % val % std::strerror(original_errno));
 133     }
 134 #elif defined(HAVE_PUTENV)
 135     if (::putenv((F("%s=%s") % name % val).c_str()) == -1) {
 136         const int original_errno = errno;
 137         throw std::runtime_error(F("Failed to set environment variable '%s' to "
 138                                    "'%s': %s") %
 139                                  name % val % std::strerror(original_errno));
 140     }
 141 #else
 142 #   error "Don't know how to set an environment variable."
 143 #endif
 144 }
 145
 146
 147 /// Unsets an environment variable.
 148 ///
 149 /// \param name The name of the environment variable to unset.
 150 ///
 151 /// \throw std::runtime_error If there is an error unsetting the environment
 152 ///     variable.
 153 void
 154 utils::unsetenv(const std::string& name)
 155 {
 156     LD(F("Unsetting environment variable '%s'") % name);
 157 #if defined(HAVE_UNSETENV)
 158     if (::unsetenv(name.c_str()) == -1) {
 159         const int original_errno = errno;
 160         throw std::runtime_error(F("Failed to unset environment variable "
 161                                    "'%s'") %
 162                                  name % std::strerror(original_errno));
 163     }
 164 #elif defined(HAVE_PUTENV)
 165     if (::putenv((F("%s=") % name).c_str()) == -1) {
 166         const int original_errno = errno;
 167         throw std::runtime_error(F("Failed to unset environment variable "
 168                                    "'%s'") %
 169                                  name % std::strerror(original_errno));
 170     }
 171 #else
 172 #   error "Don't know how to unset an environment variable."
 173 #endif
 174 }