mirror of
https://github.com/privatevoid-net/nix-super.git
synced 2024-11-09 15:58:05 +02:00
libutil: add C bindings
This commit is contained in:
parent
c0b6907ccd
commit
4702317506
5 changed files with 437 additions and 1 deletions
2
local.mk
2
local.mk
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@ -2,7 +2,7 @@ GLOBAL_CXXFLAGS += -Wno-deprecated-declarations -Werror=switch
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# Allow switch-enum to be overridden for files that do not support it, usually because of dependency headers.
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ERROR_SWITCH_ENUM = -Werror=switch-enum
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$(foreach i, config.h $(wildcard src/lib*/*.hh), \
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$(foreach i, config.h $(wildcard src/lib*/*.hh) $(wildcard src/lib*/*.h), \
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$(eval $(call install-file-in, $(i), $(includedir)/nix, 0644)))
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$(GCH): src/libutil/util.hh config.h
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@ -137,6 +137,10 @@ public:
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: err(e)
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{ }
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std::string message() {
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return err.msg.str();
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}
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const char * what() const noexcept override { return calcWhat().c_str(); }
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const std::string & msg() const { return calcWhat(); }
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const ErrorInfo & info() const { calcWhat(); return err; }
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148
src/libutil/nix_api_util.cc
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148
src/libutil/nix_api_util.cc
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@ -0,0 +1,148 @@
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#include "nix_api_util.h"
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#include "config.hh"
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#include "error.hh"
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#include "nix_api_util_internal.h"
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#include "util.hh"
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#include <cxxabi.h>
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#include <typeinfo>
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nix_c_context *nix_c_context_create() { return new nix_c_context(); }
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void nix_c_context_free(nix_c_context *context) { delete context; }
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nix_err nix_context_error(nix_c_context *context) {
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if (context == nullptr) {
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throw;
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}
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try {
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throw;
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} catch (nix::Error &e) {
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/* Storing this exception is annoying, take what we need here */
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context->last_err = e.what();
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context->info = e.info();
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int status;
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const char *demangled =
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abi::__cxa_demangle(typeid(e).name(), 0, 0, &status);
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if (demangled) {
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context->name = demangled;
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// todo: free(demangled);
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} else {
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context->name = typeid(e).name();
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}
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context->last_err_code = NIX_ERR_NIX_ERROR;
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return context->last_err_code;
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} catch (const std::exception &e) {
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context->last_err = e.what();
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context->last_err_code = NIX_ERR_UNKNOWN;
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return context->last_err_code;
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}
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// unreachable
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}
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nix_err nix_set_err_msg(nix_c_context *context, nix_err err, const char *msg) {
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if (context == nullptr) {
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// todo last_err_code
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throw new nix::Error("Nix C api error", msg);
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}
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context->last_err_code = err;
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context->last_err = msg;
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return err;
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}
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const char *nix_version_get() { return PACKAGE_VERSION; }
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// Implementations
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nix_err nix_setting_get(nix_c_context *context, const char *key, char *value,
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int n) {
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if (context)
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context->last_err_code = NIX_OK;
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try {
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std::map<std::string, nix::AbstractConfig::SettingInfo> settings;
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nix::globalConfig.getSettings(settings);
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if (settings.contains(key))
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return nix_export_std_string(context, settings[key].value, value, n);
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else {
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return nix_set_err_msg(context, NIX_ERR_KEY, "Setting not found");
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}
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}
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NIXC_CATCH_ERRS
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}
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nix_err nix_setting_set(nix_c_context *context, const char *key,
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const char *value) {
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if (context)
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context->last_err_code = NIX_OK;
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if (nix::globalConfig.set(key, value))
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return NIX_OK;
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else {
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return nix_set_err_msg(context, NIX_ERR_KEY, "Setting not found");
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}
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}
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nix_err nix_libutil_init(nix_c_context *context) {
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if (context)
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context->last_err_code = NIX_OK;
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try {
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nix::initLibUtil();
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return NIX_OK;
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}
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NIXC_CATCH_ERRS
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}
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const char *nix_err_msg(nix_c_context *context,
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const nix_c_context *read_context, unsigned int *n) {
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if (context)
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context->last_err_code = NIX_OK;
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if (read_context->last_err) {
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if (n)
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*n = read_context->last_err->size();
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return read_context->last_err->c_str();
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}
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nix_set_err_msg(context, NIX_ERR_UNKNOWN, "No error message");
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return nullptr;
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}
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nix_err nix_err_name(nix_c_context *context, const nix_c_context *read_context,
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char *value, int n) {
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if (context)
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context->last_err_code = NIX_OK;
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if (read_context->last_err_code != NIX_ERR_NIX_ERROR) {
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return nix_set_err_msg(context, NIX_ERR_UNKNOWN,
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"Last error was not a nix error");
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}
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return nix_export_std_string(context, read_context->name, value, n);
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}
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nix_err nix_err_info_msg(nix_c_context *context,
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const nix_c_context *read_context, char *value,
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int n) {
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if (context)
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context->last_err_code = NIX_OK;
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if (read_context->last_err_code != NIX_ERR_NIX_ERROR) {
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return nix_set_err_msg(context, NIX_ERR_UNKNOWN,
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"Last error was not a nix error");
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}
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return nix_export_std_string(context, read_context->info->msg.str(), value,
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n);
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}
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nix_err nix_err_code(nix_c_context *context,
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const nix_c_context *read_context) {
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if (context)
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context->last_err_code = NIX_OK;
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return read_context->last_err_code;
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}
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// internal
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nix_err nix_export_std_string(nix_c_context *context,
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const std::string_view str, char *dest,
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unsigned int n) {
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size_t i = str.copy(dest, n - 1);
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dest[i] = 0;
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if (i == n - 1) {
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return nix_set_err_msg(context, NIX_ERR_OVERFLOW,
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"Provided buffer too short");
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} else
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return NIX_OK;
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}
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223
src/libutil/nix_api_util.h
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223
src/libutil/nix_api_util.h
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@ -0,0 +1,223 @@
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#ifndef NIX_API_UTIL_H
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#define NIX_API_UTIL_H
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/** @file
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* @brief Main entry for the libutil C bindings
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*
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* Also contains error handling utilities
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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// cffi start
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// Error codes
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/**
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* @brief Type for error codes in the NIX system
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*
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* This type can have one of several predefined constants:
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* - NIX_OK: No error occurred (0)
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* - NIX_ERR_UNKNOWN: An unknown error occurred (-1)
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* - NIX_ERR_OVERFLOW: An overflow error occurred (-2)
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* - NIX_ERR_KEY: A key error occurred (-3)
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* - NIX_ERR_NIX_ERROR: A generic Nix error occurred (-4)
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*/
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typedef int nix_err;
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/**
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* @brief No error occurred.
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*
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* This error code is returned when no error has occurred during the function
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* execution.
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*/
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#define NIX_OK 0
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/**
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* @brief An unknown error occurred.
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*
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* This error code is returned when an unknown error occurred during the
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* function execution.
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*/
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#define NIX_ERR_UNKNOWN -1
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/**
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* @brief An overflow error occurred.
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*
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* This error code is returned when an overflow error occurred during the
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* function execution.
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*/
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#define NIX_ERR_OVERFLOW -2
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/**
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* @brief A key error occurred.
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*
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* This error code is returned when a key error occurred during the function
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* execution.
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*/
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#define NIX_ERR_KEY -3
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/**
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* @brief A generic Nix error occurred.
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*
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* This error code is returned when a generic Nix error occurred during the
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* function execution.
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*/
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#define NIX_ERR_NIX_ERROR -4
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/**
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* @brief This object stores error state.
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*
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* Passed as a first parameter to C functions that can fail, will store error
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* information. Optional wherever it is used, passing NULL will throw a C++
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* exception instead. The first field is a nix_err, that can be read directly to
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* check for errors.
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* @note These can be reused between different function calls,
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* but make sure not to use them for multiple calls simultaneously (which can
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* happen in callbacks).
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*/
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typedef struct nix_c_context nix_c_context;
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// Function prototypes
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/**
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* @brief Allocate a new nix_c_context.
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* @throws std::bad_alloc
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* @return allocated nix_c_context, owned by the caller. Free using
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* `nix_c_context_free`.
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*/
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nix_c_context *nix_c_context_create();
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/**
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* @brief Free a nix_c_context. Does not fail.
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* @param[out] context The context to free, mandatory.
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*/
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void nix_c_context_free(nix_c_context *context);
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/**
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* @brief Initializes nix_libutil and its dependencies.
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*
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* This function can be called multiple times, but should be called at least
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* once prior to any other nix function.
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*
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* @param[out] context Optional, stores error information
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* @return NIX_OK if the initialization is successful, or an error code
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* otherwise.
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*/
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nix_err nix_libutil_init(nix_c_context *context);
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/**
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* @brief Retrieves a setting from the nix global configuration.
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*
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* This function requires nix_libutil_init() to be called at least once prior to
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* its use.
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*
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* @param[out] context optional, Stores error information
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* @param[in] key The key of the setting to retrieve.
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* @param[out] value A pointer to a buffer where the value of the setting will
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* be stored.
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* @param[in] n The size of the buffer pointed to by value.
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* @return NIX_ERR_KEY if the setting is unknown, NIX_ERR_OVERFLOW if the
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* provided buffer is too short, or NIX_OK if the setting was retrieved
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* successfully.
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*/
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nix_err nix_setting_get(nix_c_context *context, const char *key, char *value,
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int n);
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/**
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* @brief Sets a setting in the nix global configuration.
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*
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* Use "extra-<setting name>" to append to the setting's value.
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*
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* Settings only apply for new States. Call nix_plugins_init() when you are done
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* with the settings to load any plugins.
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*
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* @param[out] context optional, Stores error information
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* @param[in] key The key of the setting to set.
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* @param[in] value The value to set for the setting.
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* @return NIX_ERR_KEY if the setting is unknown, or NIX_OK if the setting was
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* set successfully.
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*/
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nix_err nix_setting_set(nix_c_context *context, const char *key,
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const char *value);
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// todo: nix_plugins_init()
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/**
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* @brief Retrieves the nix library version.
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*
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* Does not fail.
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* @return A static string representing the version of the nix library.
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*/
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const char *nix_version_get();
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/**
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* @brief Retrieves the most recent error message from a context.
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*
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* @pre This function should only be called after a previous nix function has
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* returned an error.
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*
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* @param[out] context optional, the context to store errors in if this function
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* fails
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* @param[in] ctx the context to retrieve the error message from
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* @param[out] n optional: a pointer to an unsigned int that is set to the
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* length of the error.
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* @return nullptr if no error message was ever set,
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* a borrowed pointer to the error message otherwise.
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*/
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const char *nix_err_msg(nix_c_context *context, const nix_c_context *ctx,
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unsigned int *n);
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/**
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* @brief Retrieves the error message from errorInfo in a context.
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*
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* Used to inspect nix Error messages.
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*
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* @pre This function should only be called after a previous nix function has
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* returned a NIX_ERR_NIX_ERROR
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*
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* @param[out] context optional, the context to store errors in if this function
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* fails
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* @param[in] read_context the context to retrieve the error message from
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* @param[out] value The allocated area to write the error string to.
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* @param[in] n Maximum size of the returned string.
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* @return NIX_OK if there were no errors, an error code otherwise.
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*/
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nix_err nix_err_info_msg(nix_c_context *context,
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const nix_c_context *read_context, char *value, int n);
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/**
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* @brief Retrieves the error name from a context.
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*
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* Used to inspect nix Error messages.
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*
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* @pre This function should only be called after a previous nix function has
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* returned a NIX_ERR_NIX_ERROR
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*
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* @param context optional, the context to store errors in if this function
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* fails
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* @param[in] read_context the context to retrieve the error message from
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* @param[out] value The allocated area to write the error string to.
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* @param[in] n Maximum size of the returned string.
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* @return NIX_OK if there were no errors, an error code otherwise.
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*/
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nix_err nix_err_name(nix_c_context *context, const nix_c_context *read_context,
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char *value, int n);
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/**
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* @brief Retrieves the most recent error code from a nix_c_context
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*
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* Equivalent to reading the first field of the context.
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*
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* @param[out] context optional, the context to store errors in if this function
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* fails
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* @param[in] read_context the context to retrieve the error message from
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* @return most recent error code stored in the context.
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*/
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nix_err nix_err_code(nix_c_context *context, const nix_c_context *read_context);
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// cffi end
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#ifdef __cplusplus
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}
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#endif
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#endif // NIX_API_UTIL_H
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61
src/libutil/nix_api_util_internal.h
Normal file
61
src/libutil/nix_api_util_internal.h
Normal file
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#ifndef NIX_API_UTIL_INTERNAL_H
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#define NIX_API_UTIL_INTERNAL_H
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#include <string>
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// forward declaration
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namespace nix {
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class Error;
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};
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struct nix_c_context {
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nix_err last_err_code = NIX_OK;
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std::optional<std::string> last_err = {};
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std::optional<nix::ErrorInfo> info = {};
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std::string name = "";
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};
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nix_err nix_context_error(nix_c_context *context);
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/**
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* Internal use only.
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*
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* Sets the most recent error message.
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*
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* @param context context to write the error message to, or NULL
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* @param err The error code to set and return
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* @param msg The error message to set.
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* @returns the error code set
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*/
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nix_err nix_set_err_msg(nix_c_context *context, nix_err err, const char *msg);
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/**
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* Internal use only.
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*
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* Export a std::string across the C api boundary
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* @param context optional, the context to store errors in if this function
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* fails
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* @param str The string to export
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* @param value The allocated area to write the string to.
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* @param n Maximum size of the returned string.
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* @return NIX_OK if there were no errors, NIX_ERR_OVERFLOW if the string length
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* exceeds `n`.
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*/
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nix_err nix_export_std_string(nix_c_context *context,
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const std::string_view str, char *dest,
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unsigned int n);
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#define NIXC_CATCH_ERRS \
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catch (...) { \
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return nix_context_error(context); \
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} \
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return NIX_OK;
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#define NIXC_CATCH_ERRS_RES(def) \
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catch (...) { \
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nix_context_error(context); \
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return def; \
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}
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#define NIXC_CATCH_ERRS_NULL NIXC_CATCH_ERRS_RES(nullptr)
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#endif // NIX_API_UTIL_INTERNAL_H
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