From 3058029fbafb53563fcc31401546edce258d65ca Mon Sep 17 00:00:00 2001 From: Artemis Tosini Date: Sat, 27 Jul 2024 19:40:40 +0000 Subject: [PATCH] libutil: Add bindPath function from libstore bindPath/doBind is a useful function in build that is used in several parts of LocalDerivationGoal. Moving this function makes it easier to split LocalDerivationGoal implementation between several files. Change-Id: Ic5a0768479c153c1aa3ed425f12604b20bbf0f42 --- src/libstore/build/local-derivation-goal.cc | 44 +++------------------ src/libutil/meson.build | 2 + src/libutil/mount.cc | 43 ++++++++++++++++++++ src/libutil/mount.hh | 16 ++++++++ 4 files changed, 67 insertions(+), 38 deletions(-) create mode 100644 src/libutil/mount.cc create mode 100644 src/libutil/mount.hh diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc index 2f1f338c1..665840856 100644 --- a/src/libstore/build/local-derivation-goal.cc +++ b/src/libstore/build/local-derivation-goal.cc @@ -17,6 +17,7 @@ #include "namespaces.hh" #include "child.hh" #include "unix-domain-socket.hh" +#include "mount.hh" #include #include @@ -386,39 +387,6 @@ void LocalDerivationGoal::cleanupPostOutputsRegisteredModeNonCheck() cleanupPostOutputsRegisteredModeCheck(); } -#if __linux__ -static void doBind(const Path & source, const Path & target, bool optional = false) { - debug("bind mounting '%1%' to '%2%'", source, target); - - auto bindMount = [&]() { - if (mount(source.c_str(), target.c_str(), "", MS_BIND | MS_REC, 0) == -1) - throw SysError("bind mount from '%1%' to '%2%' failed", source, target); - }; - - auto maybeSt = maybeLstat(source); - if (!maybeSt) { - if (optional) - return; - else - throw SysError("getting attributes of path '%1%'", source); - } - auto st = *maybeSt; - - if (S_ISDIR(st.st_mode)) { - createDirs(target); - bindMount(); - } else if (S_ISLNK(st.st_mode)) { - // Symlinks can (apparently) not be bind-mounted, so just copy it - createDirs(dirOf(target)); - copyFile(source, target, {}); - } else { - createDirs(dirOf(target)); - writeFile(target, ""); - bindMount(); - } -}; -#endif - void LocalDerivationGoal::startBuilder() { if ((buildUser && buildUser->getUIDCount() != 1) @@ -1321,7 +1289,7 @@ void LocalDerivationGoal::addDependency(const StorePath & path) Path target = chrootRootDir + worker.store.printStorePath(path); if (pathExists(target)) { - // There is a similar debug message in doBind, so only run it in this block to not have double messages. + // There is a similar debug message in bindPath, so only run it in this block to not have double messages. debug("bind-mounting %s -> %s", target, source); throw Error("store path '%s' already exists in the sandbox", worker.store.printStorePath(path)); } @@ -1338,7 +1306,7 @@ void LocalDerivationGoal::addDependency(const StorePath & path) if (setns(sandboxMountNamespace.get(), 0) == -1) throw SysError("entering sandbox mount namespace"); - doBind(source, target); + bindPath(source, target); _exit(0); }); @@ -2117,7 +2085,7 @@ void LocalDerivationGoal::runChild() chmodPath(dst, 0555); } else #endif - doBind(i.second.source, chrootRootDir + i.first, i.second.optional); + bindPath(i.second.source, chrootRootDir + i.first, i.second.optional); } /* Bind a new instance of procfs on /proc. */ @@ -2156,8 +2124,8 @@ void LocalDerivationGoal::runChild() } else { if (errno != EINVAL) throw SysError("mounting /dev/pts"); - doBind("/dev/pts", chrootRootDir + "/dev/pts"); - doBind("/dev/ptmx", chrootRootDir + "/dev/ptmx"); + bindPath("/dev/pts", chrootRootDir + "/dev/pts"); + bindPath("/dev/ptmx", chrootRootDir + "/dev/ptmx"); } } diff --git a/src/libutil/meson.build b/src/libutil/meson.build index c860e7e00..731521bbb 100644 --- a/src/libutil/meson.build +++ b/src/libutil/meson.build @@ -21,6 +21,7 @@ libutil_sources = files( 'hilite.cc', 'json-utils.cc', 'logging.cc', + 'mount.cc', 'namespaces.cc', 'position.cc', 'print-elided.cc', @@ -84,6 +85,7 @@ libutil_headers = files( 'logging-json.hh', 'lru-cache.hh', 'monitor-fd.hh', + 'mount.hh', 'namespaces.hh', 'pool.hh', 'position.hh', diff --git a/src/libutil/mount.cc b/src/libutil/mount.cc new file mode 100644 index 000000000..025ced5b9 --- /dev/null +++ b/src/libutil/mount.cc @@ -0,0 +1,43 @@ +#include "mount.hh" +#include "error.hh" +#include "file-system.hh" +#include "logging.hh" +#if __linux__ +#include + +namespace nix { + +void bindPath(const Path & source, const Path & target, bool optional) { + debug("bind mounting '%1%' to '%2%'", source, target); + + auto bindMount = [&]() { + if (mount(source.c_str(), target.c_str(), "", MS_BIND | MS_REC, 0) == -1) + throw SysError("bind mount from '%1%' to '%2%' failed", source, target); + }; + + auto maybeSt = maybeLstat(source); + if (!maybeSt) { + if (optional) + return; + else + throw SysError("getting attributes of path '%1%'", source); + } + auto st = *maybeSt; + + if (S_ISDIR(st.st_mode)) { + createDirs(target); + bindMount(); + } else if (S_ISLNK(st.st_mode)) { + // Symlinks can (apparently) not be bind-mounted, so just copy it + createDirs(dirOf(target)); + copyFile(source, target, {}); + } else { + createDirs(dirOf(target)); + writeFile(target, ""); + bindMount(); + } +} + +} + +#endif diff --git a/src/libutil/mount.hh b/src/libutil/mount.hh new file mode 100644 index 000000000..59e2218be --- /dev/null +++ b/src/libutil/mount.hh @@ -0,0 +1,16 @@ +#pragma once +///@file + +#include "types.hh" + +#if __linux__ +namespace nix { + +/** + * Bind-mount file or directory from `source` to `destination`. + * If source does not exist this will fail unless `optional` is set + */ +void bindPath(const Path & source, const Path & target, bool optional = false); + +} +#endif