Coverage Report

Created: 2020-11-21 08:34

/src/botan/build/include/botan/internal/os_utils.h
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/*
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* OS specific utility functions
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* (C) 2015,2016,2017,2018 Jack Lloyd
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*
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* Botan is released under the Simplified BSD License (see license.txt)
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*/
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#ifndef BOTAN_OS_UTILS_H_
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#define BOTAN_OS_UTILS_H_
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#include <botan/types.h>
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#include <functional>
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#include <string>
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#include <vector>
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namespace Botan {
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namespace OS {
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/*
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* This header is internal (not installed) and these functions are not
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* intended to be called by applications. However they are given public
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* visibility (using BOTAN_TEST_API macro) for the tests. This also probably
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* allows them to be overridden by the application on ELF systems, but
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* this hasn't been tested.
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*/
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/**
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* @return process ID assigned by the operating system.
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* On Unix and Windows systems, this always returns a result
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* On IncludeOS it returns 0 since there is no process ID to speak of
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* in a unikernel.
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*/
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uint32_t BOTAN_TEST_API get_process_id();
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/**
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* Test if we are currently running with elevated permissions
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* eg setuid, setgid, or with POSIX caps set.
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*/
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bool running_in_privileged_state();
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/**
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* @return CPU processor clock, if available
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*
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* On Windows, calls QueryPerformanceCounter.
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*
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* Under GCC or Clang on supported platforms the hardware cycle counter is queried.
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* Currently supported processors are x86, PPC, Alpha, SPARC, IA-64, S/390x, and HP-PA.
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* If no CPU cycle counter is available on this system, returns zero.
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*/
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uint64_t BOTAN_TEST_API get_cpu_cycle_counter();
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size_t BOTAN_TEST_API get_cpu_total();
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size_t BOTAN_TEST_API get_cpu_available();
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/**
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* Return the ELF auxiliary vector cooresponding to the given ID.
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* This only makes sense on Unix-like systems and is currently
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* only supported on Linux, Android, and FreeBSD.
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*
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* Returns zero if not supported on the current system or if
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* the id provided is not known.
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*/
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unsigned long get_auxval(unsigned long id);
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/*
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* @return best resolution timestamp available
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*
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* The epoch and update rate of this clock is arbitrary and depending
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* on the hardware it may not tick at a constant rate.
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*
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* Uses hardware cycle counter, if available.
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* On POSIX platforms clock_gettime is used with a monotonic timer
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* As a final fallback std::chrono::high_resolution_clock is used.
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*/
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uint64_t BOTAN_TEST_API get_high_resolution_clock();
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/**
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* @return system clock (reflecting wall clock) with best resolution
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* available, normalized to nanoseconds resolution.
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*/
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uint64_t BOTAN_TEST_API get_system_timestamp_ns();
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/**
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* @return maximum amount of memory (in bytes) Botan could/should
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* hyptothetically allocate for the memory poool. Reads environment
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* variable "BOTAN_MLOCK_POOL_SIZE", set to "0" to disable pool.
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*/
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size_t get_memory_locking_limit();
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/**
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* Return the size of a memory page, if that can be derived on the
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* current system. Otherwise returns some default value (eg 4096)
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*/
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size_t system_page_size();
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/**
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* Read the value of an environment variable, setting it to value_out if it
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* exists.  Returns false and sets value_out to empty string if no such variable
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* is set. If the process seems to be running in a privileged state (such as
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* setuid) then always returns false and does not examine the environment.
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*/
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bool read_env_variable(std::string& value_out, const std::string& var_name);
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/**
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* Read the value of an environment variable and convert it to an
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* integer. If not set or conversion fails, returns the default value.
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*
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* If the process seems to be running in a privileged state (such as setuid)
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* then always returns nullptr, similiar to glibc's secure_getenv.
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*/
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size_t read_env_variable_sz(const std::string& var_name, size_t def_value = 0);
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/**
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* Request count pages of RAM which are locked into memory using mlock,
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* VirtualLock, or some similar OS specific API. Free it with free_locked_pages.
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*
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* Returns an empty list on failure. This function is allowed to return fewer
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* than count pages.
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*
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* The contents of the allocated pages are undefined.
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*
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* Each page is preceded by and followed by a page which is marked
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* as noaccess, such that accessing it will cause a crash. This turns
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* out of bound reads/writes into crash events.
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*
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* @param count requested number of locked pages
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*/
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std::vector<void*> allocate_locked_pages(size_t count);
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/**
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* Free memory allocated by allocate_locked_pages
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* @param pages a list of pages returned by allocate_locked_pages
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*/
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void free_locked_pages(const std::vector<void*>& pages);
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/**
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* Set the MMU to prohibit access to this page
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*/
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void page_prohibit_access(void* page);
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/**
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* Set the MMU to allow R/W access to this page
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*/
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void page_allow_access(void* page);
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/**
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* Run a probe instruction to test for support for a CPU instruction.
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* Runs in system-specific env that catches illegal instructions; this
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* function always fails if the OS doesn't provide this.
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* Returns value of probe_fn, if it could run.
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* If error occurs, returns negative number.
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* This allows probe_fn to indicate errors of its own, if it wants.
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* For example the instruction might not only be only available on some
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* CPUs, but also buggy on some subset of these - the probe function
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* can test to make sure the instruction works properly before
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* indicating that the instruction is available.
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*
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* @warning on Unix systems uses signal handling in a way that is not
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* thread safe. It should only be called in a single-threaded context
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* (ie, at static init time).
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*
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* If probe_fn throws an exception the result is undefined.
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*
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* Return codes:
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* -1 illegal instruction detected
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*/
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int BOTAN_TEST_API run_cpu_instruction_probe(std::function<int ()> probe_fn);
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/**
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* Represents a terminal state
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*/
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class BOTAN_UNSTABLE_API Echo_Suppression
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   {
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   public:
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      /**
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      * Reenable echo on this terminal. Can be safely called
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      * multiple times. May throw if an error occurs.
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      */
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      virtual void reenable_echo() = 0;
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      /**
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      * Implicitly calls reenable_echo, but swallows/ignored all
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      * errors which would leave the terminal in an invalid state.
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      */
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      virtual ~Echo_Suppression() = default;
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   };
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/**
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* Suppress echo on the terminal
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* Returns null if this operation is not supported on the current system.
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*/
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std::unique_ptr<Echo_Suppression> BOTAN_UNSTABLE_API suppress_echo_on_terminal();
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}
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}
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#endif