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#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <bits/ensure.h>
#include <mlibc/allocator.hpp>
#include <mlibc/debug.hpp>
#include <frg/string.hpp>
#include <frg/vector.hpp>
namespace {
char *empty_environment[] = { nullptr };
}
char **environ = empty_environment;
namespace {
size_t find_environ_index(frg::string_view name) {
for(size_t i = 0; environ[i]; i++) {
frg::string_view view{environ[i]};
size_t s = view.find_first('=');
if(s == size_t(-1)) {
mlibc::infoLogger() << "mlibc: environment string \""
<< frg::escape_fmt{view.data(), view.size()}
<< "\" does not contain an equals sign (=)" << frg::endlog;
continue;
}
if(view.sub_string(0, s) == name)
return i;
}
return -1;
}
// Environment vector that is mutated by putenv() and setenv().
// Cannot be global as it is accessed during library initialization.
frg::vector<char *, MemoryAllocator> &get_vector() {
static frg::vector<char *, MemoryAllocator> vector{getAllocator()};
return vector;
}
void update_vector() {
auto &vector = get_vector();
if(environ == vector.data())
return;
// If the environ variable was changed, we copy the environment.
// Note that we must only copy the pointers but not the strings themselves!
vector.clear();
for(size_t i = 0; environ[i]; i++)
vector.push(environ[i]);
vector.push(nullptr);
environ = vector.data();
}
void assign_variable(frg::string_view name, const char *string, bool overwrite) {
auto &vector = get_vector();
__ensure(environ == vector.data());
auto k = find_environ_index(name);
if(k != size_t(-1)) {
if(overwrite)
vector[k] = const_cast<char *>(string);
}else{
// Last pointer of environ must always be a null delimiter.
__ensure(!vector.back());
vector.back() = const_cast<char *>(string);
vector.push(nullptr);
}
// push() might have re-allocated the vector.
environ = vector.data();
}
void unassign_variable(frg::string_view name) {
auto &vector = get_vector();
__ensure(environ == vector.data());
auto k = find_environ_index(name);
if(k == size_t(-1))
return;
// Last pointer of environ must always be a null delimiter.
__ensure(vector.size() >= 2 && !vector.back());
std::swap(vector[k], vector[vector.size() - 2]);
vector.pop();
vector.back() = nullptr;
// pop() might have re-allocated the vector.
environ = vector.data();
}
} // anonymous namespace
char *getenv(const char *name) {
auto k = find_environ_index(name);
if(k == size_t(-1))
return nullptr;
frg::string_view view{environ[k]};
size_t s = view.find_first('=');
__ensure(s != size_t(-1));
return const_cast<char *>(view.data() + s + 1);
}
namespace mlibc {
int putenv(char *string) {
frg::string_view view{string};
size_t s = view.find_first('=');
if(s == size_t(-1))
__ensure(!"Environment strings need to contain an equals sign");
update_vector();
assign_variable(view.sub_string(0, s), string, true);
return 0;
}
} // namespace mlibc
#if __MLIBC_POSIX_OPTION
int putenv(char *string) {
return mlibc::putenv(string);
}
int setenv(const char *name, const char *value, int overwrite) {
frg::string_view view{name};
size_t s = view.find_first('=');
if(s != size_t(-1)) {
mlibc::infoLogger() << "mlibc: environment variable \""
<< frg::escape_fmt{view.data(), view.size()} << "\" contains an equals sign"
<< frg::endlog;
errno = EINVAL;
return -1;
}
// We never free strings here. TODO: Reuse them?
char *string;
__ensure(asprintf(&string, "%s=%s", name, value) > 0);
__ensure(string);
update_vector();
assign_variable(name, string, overwrite);
return 0;
}
int unsetenv(const char *name) {
update_vector();
unassign_variable(name);
return 0;
}
int clearenv(void) {
auto vector = get_vector();
vector.clear();
update_vector();
return 0;
}
#endif /* __MLIBC_POSIX_OPTION */
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