mirror of
https://github.com/NixOS/nix
synced 2025-07-07 01:51:47 +02:00
nix-channel: implement in c++
This commit is contained in:
Shea Levy
parent
a6eed133c5
commit
59124228b3
8 changed files with 304 additions and 233 deletions
7
src/nix-channel/local.mk
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7
src/nix-channel/local.mk
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@ -0,0 +1,7 @@
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programs += nix-channel
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nix-channel_DIR := $(d)
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nix-channel_LIBS = libmain libutil libformat libstore
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nix-channel_SOURCES := $(d)/nix-channel.cc
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270
src/nix-channel/nix-channel.cc
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270
src/nix-channel/nix-channel.cc
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#include "shared.hh"
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#include "globals.hh"
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#include "download.hh"
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#include <fcntl.h>
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#include <regex>
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#include "store-api.hh"
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#include <pwd.h>
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using namespace nix;
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typedef std::map<string,string> Channels;
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static auto channels = Channels{};
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static auto channelsList = Path{};
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// Reads the list of channels.
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static void readChannels()
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{
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if (!pathExists(channelsList)) return;
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auto channelsFile = readFile(channelsList);
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for (const auto & line : tokenizeString<std::vector<string>>(channelsFile, "\n")) {
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chomp(line);
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if (std::regex_search(line, std::regex("^\\s*\\#")))
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continue;
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auto split = tokenizeString<std::vector<string>>(line, " ");
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auto url = std::regex_replace(split[0], std::regex("/*$"), "");
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auto name = split.size() > 1 ? split[1] : baseNameOf(url);
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channels[name] = url;
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}
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}
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// Writes the list of channels.
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static void writeChannels()
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{
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auto channelsFD = AutoCloseFD{open(channelsList.c_str(), O_WRONLY | O_CLOEXEC | O_CREAT | O_TRUNC, 0644)};
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if (!channelsFD)
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throw SysError(format("opening ‘%1%’ for writing") % channelsList);
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for (const auto & channel : channels)
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writeFull(channelsFD.get(), channel.second + " " + channel.first + "\n");
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}
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// Adds a channel.
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static void addChannel(const string & url, const string & name)
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{
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if (!regex_search(url, std::regex("^(file|http|https)://")))
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throw Error(format("invalid channel URL ‘%1%’") % url);
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if (!regex_search(name, std::regex("^[a-zA-Z0-9_][a-zA-Z0-9_\\.-]*$")))
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throw Error(format("invalid channel identifier ‘%1%’") % name);
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readChannels();
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channels[name] = url;
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writeChannels();
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}
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static auto profile = Path{};
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// Remove a channel.
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static void removeChannel(const string & name)
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{
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readChannels();
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channels.erase(name);
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writeChannels();
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runProgram(settings.nixBinDir + "/nix-env", true, { "--profile", profile, "--uninstall", name });
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}
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static auto nixDefExpr = Path{};
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// Fetch Nix expressions and binary cache URLs from the subscribed channels.
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static void update(const StringSet & channelNames)
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{
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readChannels();
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auto store = openStore();
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// Download each channel.
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auto exprs = Strings{};
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for (const auto & channel : channels) {
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if (!channelNames.empty() && channelNames.find(channel.first) != channelNames.end())
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continue;
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auto name = channel.first;
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auto url = channel.second;
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// We want to download the url to a file to see if it's a tarball while also checking if we
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// got redirected in the process, so that we can grab the various parts of a nix channel
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// definition from a consistent location if the redirect changes mid-download.
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auto effectiveUrl = string{};
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auto dl = makeDownloader();
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auto filename = dl->downloadCached(store, url, false, effectiveUrl);
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url = chomp(std::move(effectiveUrl));
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// If the URL contains a version number, append it to the name
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// attribute (so that "nix-env -q" on the channels profile
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// shows something useful).
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auto cname = name;
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std::smatch match;
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auto urlBase = baseNameOf(url);
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if (std::regex_search(urlBase, match, std::regex("(-\\d.*)$"))) {
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cname = cname + (string) match[1];
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}
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auto extraAttrs = string{};
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auto unpacked = false;
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if (std::regex_search(filename, std::regex("\\.tar\\.(gz|bz2|xz)$"))) {
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try {
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runProgram(settings.nixBinDir + "/nix-build", false, { "--no-out-link", "--expr", "import <nix/unpack-channel.nix> "
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"{ name = \"" + cname + "\"; channelName = \"" + name + "\"; src = builtins.storePath \"" + filename + "\"; }" });
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unpacked = true;
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} catch (ExecError & e) {
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}
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}
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if (!unpacked) {
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// The URL doesn't unpack directly, so let's try treating it like a full channel folder with files in it
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// Check if the channel advertises a binary cache.
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DownloadOptions opts;
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opts.showProgress = DownloadOptions::no;
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try {
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auto dlRes = dl->download(url + "/binary-cache-url", opts);
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extraAttrs = "binaryCacheURL = \"" + *dlRes.data + "\";";
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} catch (DownloadError & e) {
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}
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// Download the channel tarball.
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auto fullURL = url + "/nixexprs.tar.xz";
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try {
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filename = dl->downloadCached(store, fullURL, false);
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} catch (DownloadError & e) {
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fullURL = url + "/nixexprs.tar.bz2";
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filename = dl->downloadCached(store, fullURL, false);
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}
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chomp(filename);
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}
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// Regardless of where it came from, add the expression representing this channel to accumulated expression
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exprs.push_back("f: f { name = \"" + cname + "\"; channelName = \"" + name + "\"; src = builtins.storePath \"" + filename + "\"; " + extraAttrs + " }");
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}
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// Unpack the channel tarballs into the Nix store and install them
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// into the channels profile.
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std::cerr << "unpacking channels...\n";
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auto envArgs = Strings{ "--profile", profile, "--file", "<nix/unpack-channel.nix>", "--install", "--from-expression" };
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for (auto & expr : exprs)
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envArgs.push_back(std::move(expr));
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envArgs.push_back("--quiet");
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runProgram(settings.nixBinDir + "/nix-env", false, envArgs);
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// Make the channels appear in nix-env.
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struct stat st;
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if (lstat(nixDefExpr.c_str(), &st) == 0) {
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if (S_ISLNK(st.st_mode))
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// old-skool ~/.nix-defexpr
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if (unlink(nixDefExpr.c_str()) == -1)
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throw SysError(format("unlinking %1%") % nixDefExpr);
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} else if (errno != ENOENT) {
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throw SysError(format("getting status of %1%") % nixDefExpr);
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}
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createDirs(nixDefExpr);
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auto channelLink = nixDefExpr + "/channels";
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replaceSymlink(profile, channelLink);
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}
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int main(int argc, char ** argv)
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{
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return handleExceptions(argv[0], [&]() {
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initNix();
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// Turn on caching in nix-prefetch-url.
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auto channelCache = settings.nixStateDir + "/channel-cache";
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createDirs(channelCache);
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setenv("NIX_DOWNLOAD_CACHE", channelCache.c_str(), 1);
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// Figure out the name of the `.nix-channels' file to use
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auto home = getEnv("HOME");
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if (home.empty())
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throw Error("$HOME not set");
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channelsList = home + "/.nix-channels";
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nixDefExpr = home + "/.nix-defexpr";
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// Figure out the name of the channels profile.
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auto name = string{};
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auto pw = getpwuid(getuid());
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if (!pw)
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name = getEnv("USER", "");
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else
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name = pw->pw_name;
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if (name.empty())
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throw Error("cannot figure out user name");
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profile = settings.nixStateDir + "/profiles/per-user/" + name + "/channels";
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createDirs(dirOf(profile));
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enum {
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cNone,
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cAdd,
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cRemove,
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cList,
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cUpdate,
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cRollback
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} cmd = cNone;
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auto args = std::vector<string>{};
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parseCmdLine(argc, argv, [&](Strings::iterator & arg, const Strings::iterator & end) {
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if (*arg == "--help") {
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showManPage("nix-channel");
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} else if (*arg == "--version") {
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printVersion("nix-channel");
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} else if (*arg == "--add") {
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cmd = cAdd;
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} else if (*arg == "--remove") {
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cmd = cRemove;
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} else if (*arg == "--list") {
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cmd = cList;
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} else if (*arg == "--update") {
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cmd = cUpdate;
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} else if (*arg == "--rollback") {
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cmd = cRollback;
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} else {
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args.push_back(std::move(*arg));
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}
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return true;
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});
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switch (cmd) {
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case cNone:
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throw UsageError("no command specified");
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case cAdd:
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if (args.size() < 1 || args.size() > 2)
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throw UsageError("‘--add’ requires one or two arguments");
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{
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auto url = args[0];
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auto name = string{};
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if (args.size() == 2) {
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name = args[1];
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} else {
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name = baseNameOf(url);
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name = std::regex_replace(name, std::regex("-unstable$"), "");
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name = std::regex_replace(name, std::regex("-stable$"), "");
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}
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addChannel(url, name);
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}
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break;
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case cRemove:
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if (args.size() != 1)
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throw UsageError("‘--remove’ requires one argument");
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removeChannel(args[0]);
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break;
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case cList:
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if (!args.empty())
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throw UsageError("‘--list’ expects no arguments");
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readChannels();
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for (const auto & channel : channels)
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std::cout << channel.first << ' ' << channel.second << '\n';
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break;
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case cUpdate:
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update(StringSet(args.begin(), args.end()));
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break;
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case cRollback:
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if (args.size() > 1)
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throw UsageError("‘--rollback’ has at most one argument");
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auto envArgs = Strings{"--profile", profile};
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if (args.size() == 1) {
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envArgs.push_back("--switch-generation");
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envArgs.push_back(args[0]);
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} else {
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envArgs.push_back("--rollback");
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}
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runProgram(settings.nixBinDir + "/nix-env", false, envArgs);
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break;
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}
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});
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}
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