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https://github.com/darlinghq/darlingserver.git
synced 2024-11-26 22:00:26 +00:00
fix: Workaround for systems without overlayfs
Darling now be used without overlayfs by enabling the environment "DARLING_NOOVERLAYFS". Darling also disables overlayfs when it detects itself running in a WSL1 environment. Without overlayfs, Darling will have to recursively copy all files and folders from LIBEXEC_PATH to DPREFIX.
This commit is contained in:
Trung Nguyen
parent
94c375886b
commit
12aa182f51
@ -37,6 +37,7 @@
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#include <linux/sched.h>
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#include <sys/syscall.h>
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#include <sys/signal.h>
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#include <filesystem>
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#include <darling-config.h>
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@ -285,6 +286,153 @@ static bool testEnvVar(const char* var_name) {
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return false;
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};
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static bool shouldUseOverlayFs() {
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bool shouldUse = true;
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bool explicitlySet = false;
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if (testEnvVar("DARLING_NOOVERLAYFS")) {
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shouldUse = false;
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explicitlySet = true;
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} else if (getenv("DARLING_NOOVERLAYFS")) {
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shouldUse = true;
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explicitlySet = true;
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}
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// https://github.com/microsoft/WSL/issues/8748
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// Microsoft is being dumb with its overlayfs implementation and they don't seem to be willing to be fix WSL1-related bugs.
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// We therefore have to enable this hack on WSL1.
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// All WSL systems have WSLENV set by default, while WSL_INTEROP is WSL2-specific.
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if (!explicitlySet && getenv("WSLENV") && !getenv("WSL_INTEROP")) {
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shouldUse = false;
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}
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return shouldUse;
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}
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static int compareTimespec(const timespec& a, const timespec& b) {
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if (a.tv_sec != b.tv_sec) {
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return (a.tv_sec > b.tv_sec) ? 1 : -1;
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} else if (a.tv_nsec != b.tv_nsec) {
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return (a.tv_nsec > b.tv_nsec) ? 1 : -1;
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} else {
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return 0;
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}
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}
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static void copyAndSetAttributes(std::string& fromPath, std::string& toPath) {
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struct stat fromStat, toStat;
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if (lstat(fromPath.c_str(), &fromStat) == -1) {
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fprintf(stderr, "Failed to stat file %s: %s\n", fromPath.c_str(), strerror(errno));
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abort();
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}
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bool destinationExists = true;
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bool updateAttributes = false;
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if (lstat(toPath.c_str(), &toStat) == -1) {
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if (errno != ENOENT) {
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fprintf(stderr, "Failed to stat file %s: %s\n", toPath.c_str(), strerror(errno));
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abort();
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}
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destinationExists = false;
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}
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if (S_ISDIR(fromStat.st_mode)) {
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if (destinationExists && !S_ISDIR(toStat.st_mode)) {
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return;
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} else {
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if (!destinationExists) {
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if (mkdir(toPath.c_str(), fromStat.st_mode & ALLPERMS) == -1) {
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fprintf(stderr, "Failed to create directory %s: %s\n", toPath.c_str(), strerror(errno));
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abort();
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}
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updateAttributes = true;
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}
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DIR* fromDir = opendir(fromPath.c_str());
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if (fromDir == NULL) {
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fprintf(stderr, "Failed to open directory %s: %s\n", fromPath.c_str(), strerror(errno));
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abort();
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}
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struct dirent* entry = NULL;
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while ((errno = 0) || ((entry = readdir(fromDir)) != NULL)) {
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if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) {
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continue;
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}
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size_t oldFromSize = fromPath.size();
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size_t oldToSize = toPath.size();
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fromPath.push_back('/');
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toPath.push_back('/');
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fromPath.append(entry->d_name);
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toPath.append(entry->d_name);
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copyAndSetAttributes(fromPath, toPath);
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fromPath.resize(oldFromSize);
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toPath.resize(oldToSize);
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}
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if (errno) {
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fprintf(stderr, "Failed to read directory %s: %s\n", fromPath.c_str(), strerror(errno));
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abort();
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}
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if (closedir(fromDir) == -1) {
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fprintf(stderr, "Failed to close directory %s: %s\n", fromPath.c_str(), strerror(errno));
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}
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}
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} else {
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if (destinationExists) {
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if ((fromStat.st_mode & S_IFMT) != (toStat.st_mode & S_IFMT)) {
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return;
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} else {
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int compareResult = compareTimespec(fromStat.st_mtim, toStat.st_mtim);
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// the lower file is older, don't touch the newer file.
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if (compareResult == -1) {
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return;
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// the lower file and the newer files should be the same.
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// we still update the attributes though, in case ownership or permission changes.
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} else if (compareResult == 0) {
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updateAttributes = true;
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} else if (compareResult == 1) {
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if (unlink(toPath.c_str()) == -1) {
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fprintf(stderr, "Failed to delete old destination file %s: %s\n", toPath.c_str(), strerror(errno));
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abort();
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}
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std::filesystem::copy(fromPath, toPath, std::filesystem::copy_options::copy_symlinks);
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updateAttributes = true;
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}
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}
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} else {
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std::filesystem::copy(fromPath, toPath, std::filesystem::copy_options::copy_symlinks);
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updateAttributes = true;
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}
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}
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if (updateAttributes) {
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struct timespec times[] = {
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fromStat.st_atim,
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fromStat.st_mtim
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};
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if (utimensat(-1, toPath.c_str(), times, AT_SYMLINK_NOFOLLOW) == -1) {
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fprintf(stderr, "Failed to set timestamp for %s: %s\n", toPath.c_str(), strerror(errno));
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abort();
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}
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if (fchownat(-1, toPath.c_str(), fromStat.st_uid, fromStat.st_gid, AT_SYMLINK_NOFOLLOW) == -1) {
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fprintf(stderr, "Failed to set owner for %s: %s\n", toPath.c_str(), strerror(errno));
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abort();
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}
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// POSIX said that AT_SYMLINK_NOFOLLOW is acceptable for links, but on Linux all calls with AT_SYMLINK_NOFOLLOW fails with ENOTSUP.
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if (fchmodat(-1, toPath.c_str(), fromStat.st_mode & ALLPERMS, S_ISLNK(fromStat.st_mode) ? AT_SYMLINK_NOFOLLOW : 0) == -1) {
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if (!(S_ISLNK(fromStat.st_mode) && (errno == ENOTSUP))) {
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fprintf(stderr, "Failed to set permissions for %s: %s\n", toPath.c_str(), strerror(errno));
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abort();
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}
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}
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}
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}
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static void temp_drop_privileges(uid_t uid, gid_t gid) {
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// it's important to drop GID first, because non-root users can't change their GID
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if (setresgid(gid, gid, 0) < 0) {
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@ -440,14 +588,6 @@ int main(int argc, char** argv) {
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exit(1);
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}
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// Because systemd marks / as MS_SHARED and we would inherit this into the overlay mount,
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// causing it not to be unmounted once the init process dies.
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if (mount(NULL, "/", NULL, MS_REC | MS_SLAVE, NULL) != 0)
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{
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fprintf(stderr, "Cannot remount / as slave: %s\n", strerror(errno));
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exit(1);
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}
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umount("/dev/shm");
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if (mount("tmpfs", "/dev/shm", "tmpfs", MS_NOSUID | MS_NOEXEC | MS_NODEV, NULL) != 0)
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{
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@ -455,28 +595,42 @@ int main(int argc, char** argv) {
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exit(1);
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}
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opts = (char*) malloc(strlen(prefix)*2 + sizeof(LIBEXEC_PATH) + 100);
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const char* opts_fmt = "lowerdir=%s,upperdir=%s,workdir=%s.workdir,index=off";
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sprintf(opts, opts_fmt, LIBEXEC_PATH, prefix, prefix);
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// Mount overlay onto our prefix
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if (mount("overlay", prefix, "overlay", 0, opts) != 0)
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{
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if (errno == EINVAL) {
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opts_fmt = "lowerdir=%s,upperdir=%s,workdir=%s.workdir";
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sprintf(opts, opts_fmt, LIBEXEC_PATH, prefix, prefix);
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if (mount("overlay", prefix, "overlay", 0, opts) == 0) {
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goto mount_ok;
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}
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if (shouldUseOverlayFs()) {
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// Because systemd marks / as MS_SHARED and we would inherit this into the overlay mount,
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// causing it not to be unmounted once the init process dies.
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if (mount(NULL, "/", NULL, MS_REC | MS_SLAVE, NULL) != 0)
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{
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fprintf(stderr, "Cannot remount / as slave: %s\n", strerror(errno));
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exit(1);
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}
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fprintf(stderr, "Cannot mount overlay: %s\n", strerror(errno));
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exit(1);
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}
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mount_ok:
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free(opts);
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opts = (char*) malloc(strlen(prefix)*2 + sizeof(LIBEXEC_PATH) + 100);
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const char* opts_fmt = "lowerdir=%s,upperdir=%s,workdir=%s.workdir,index=off";
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sprintf(opts, opts_fmt, LIBEXEC_PATH, prefix, prefix);
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// Mount overlay onto our prefix
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if (mount("overlay", prefix, "overlay", 0, opts) != 0)
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{
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if (errno == EINVAL) {
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opts_fmt = "lowerdir=%s,upperdir=%s,workdir=%s.workdir";
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sprintf(opts, opts_fmt, LIBEXEC_PATH, prefix, prefix);
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if (mount("overlay", prefix, "overlay", 0, opts) == 0) {
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goto mount_ok;
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}
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}
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fprintf(stderr, "Cannot mount overlay: %s\n", strerror(errno));
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exit(1);
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}
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mount_ok:
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free(opts);
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} else {
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std::string fromPath = LIBEXEC_PATH;
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std::string toPath = prefix;
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copyAndSetAttributes(fromPath, toPath);
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}
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// This is executed once at prefix creation
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if (fix_permissions) {
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