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Move plugins infra to libnixmain

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They are not actually part of the store layer, but instead part of the
Nix executable infra (libraries don't need plugins, executables do).

This is part of a larger project of moving all of our legacy settings
infra to libmain, and having the underlying libraries just have plain
configuration structs detached from any settings infra / UI layer.

Progress on #5638
This commit is contained in:
John Ericson 2024-07-02 15:15:17 -04:00
parent 1a273a623f
commit 0feeab755a
18 changed files with 361 additions and 126 deletions
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55
src/libstore/globals.cc
View file

@ -15,7 +15,6 @@
#include <nlohmann/json.hpp>
#ifndef _WIN32
# include <dlfcn.h>
# include <sys/utsname.h>
#endif
@ -335,60 +334,6 @@ unsigned int MaxBuildJobsSetting::parse(const std::string & str) const
}
Paths PluginFilesSetting::parse(const std::string & str) const
{
if (pluginsLoaded)
throw UsageError("plugin-files set after plugins were loaded, you may need to move the flag before the subcommand");
return BaseSetting<Paths>::parse(str);
}
void initPlugins()
{
assert(!settings.pluginFiles.pluginsLoaded);
for (const auto & pluginFile : settings.pluginFiles.get()) {
std::vector<std::filesystem::path> pluginFiles;
try {
auto ents = std::filesystem::directory_iterator{pluginFile};
for (const auto & ent : ents) {
checkInterrupt();
pluginFiles.emplace_back(ent.path());
}
} catch (std::filesystem::filesystem_error & e) {
if (e.code() != std::errc::not_a_directory)
throw;
pluginFiles.emplace_back(pluginFile);
}
for (const auto & file : pluginFiles) {
checkInterrupt();
/* handle is purposefully leaked as there may be state in the
DSO needed by the action of the plugin. */
#ifndef _WIN32 // TODO implement via DLL loading on Windows
void *handle =
dlopen(file.c_str(), RTLD_LAZY | RTLD_LOCAL);
if (!handle)
throw Error("could not dynamically open plugin file '%s': %s", file, dlerror());
/* Older plugins use a statically initialized object to run their code.
Newer plugins can also export nix_plugin_entry() */
void (*nix_plugin_entry)() = (void (*)())dlsym(handle, "nix_plugin_entry");
if (nix_plugin_entry)
nix_plugin_entry();
#else
throw Error("could not dynamically open plugin file '%s'", file);
#endif
}
}
/* Since plugins can add settings, try to re-apply previously
unknown settings. */
globalConfig.reapplyUnknownSettings();
globalConfig.warnUnknownSettings();
/* Tell the user if they try to set plugin-files after we've already loaded */
settings.pluginFiles.pluginsLoaded = true;
}
static void preloadNSS()
{
/* builtin:fetchurl can trigger a DNS lookup, which with glibc can trigger a dynamic library load of

50
src/libstore/globals.hh
View file

@ -31,23 +31,6 @@ struct MaxBuildJobsSetting : public BaseSetting<unsigned int>
unsigned int parse(const std::string & str) const override;
};
struct PluginFilesSetting : public BaseSetting<Paths>
{
bool pluginsLoaded = false;
PluginFilesSetting(Config * options,
const Paths & def,
const std::string & name,
const std::string & description,
const std::set<std::string> & aliases = {})
: BaseSetting<Paths>(def, true, name, description, aliases)
{
options->addSetting(this);
}
Paths parse(const std::string & str) const override;
};
const uint32_t maxIdsPerBuild =
#if __linux__
1 << 16
@ -1158,33 +1141,6 @@ public:
Setting<uint64_t> minFreeCheckInterval{this, 5, "min-free-check-interval",
"Number of seconds between checking free disk space."};
PluginFilesSetting pluginFiles{
this, {}, "plugin-files",
R"(
A list of plugin files to be loaded by Nix. Each of these files will
be dlopened by Nix. If they contain the symbol `nix_plugin_entry()`,
this symbol will be called. Alternatively, they can affect execution
through static initialization. In particular, these plugins may construct
static instances of RegisterPrimOp to add new primops or constants to the
expression language, RegisterStoreImplementation to add new store
implementations, RegisterCommand to add new subcommands to the `nix`
command, and RegisterSetting to add new nix config settings. See the
constructors for those types for more details.
Warning! These APIs are inherently unstable and may change from
release to release.
Since these files are loaded into the same address space as Nix
itself, they must be DSOs compatible with the instance of Nix
running at the time (i.e. compiled against the same headers, not
linked to any incompatible libraries). They should not be linked to
any Nix libs directly, as those will be available already at load
time.
If an entry in the list is a directory, all files in the directory
are loaded as plugins (non-recursively).
)"};
Setting<size_t> narBufferSize{this, 32 * 1024 * 1024, "nar-buffer-size",
"Maximum size of NARs before spilling them to disk."};
@ -1278,12 +1234,6 @@ public:
// FIXME: don't use a global variable.
extern Settings settings;
/**
* This should be called after settings are initialized, but before
* anything else
*/
void initPlugins();
/**
* Load the configuration (from `nix.conf`, `NIX_CONFIG`, etc.) into the
* given configuration object.