path resolution support links (40b06b22) · Commits · hpc / gekkofs

ifs/src/preload/resolve.cpp

+71 −14

Original line number	Diff line number	Diff line
		@@ -7,19 +7,58 @@
		#include "preload/passthrough.hpp"
		#include "preload/preload.hpp"

		/* Match components in path
		*
		* Returns the number of consecutive components at start of `path`
		* that match the ones in `components` vector.
		*
		* `path_components` will be set to the total number of components found in `path`
		*
		* Example:
		* ```
		* unsigned int tot_comp;
		* path_match_components("/matched/head/with/tail", &tot_comp, ["matched", "head", "no"]) == 2;
		* tot_comp == 4;
		* ```
		*/
		unsigned int path_match_components(const std::string& path, unsigned int &path_components, const std::vector<std::string>& components) {
		unsigned int matched = 0;
		unsigned int processed_components = 0;
		std::string::size_type comp_size = 0; // size of current component
		std::string::size_type start = 0; // start index of curr component
		std::string::size_type end = 0; // end index of curr component (last processed Path Separator "PSP")

		while(++end < path.size()) {
		start = end;

		// Find next component
		end = path.find(PSP, start);
		if(end == std::string::npos) {
		end = path.size();
		}

		comp_size = end - start;
		if (matched == processed_components &&
		path.compare(start, comp_size, components.at(matched)) == 0) {
		++matched;
		}
		++processed_components;
		}
		path_components = processed_components;
		return matched;
		}

		bool resolve_path (const std::string& path, std::string& resolved) {
		CTX->log()->debug("{}() path: '{}'", __func__, path);

		struct stat st;
		const std::vector<std::string>& mnt_components = CTX->mountdir_components();
		unsigned int mnt_matched = 0; // matched number of component in mountdir
		unsigned int matched_components = 0; // matched number of component in mountdir
		unsigned int resolved_components = 0;
		std::string::size_type comp_size = 0; // size of current component
		std::string::size_type start = 0; // start index of curr component
		std::string::size_type end = 0; // end index of curr component (last processed PSP)
		std::string::size_type end = 0; // end index of curr component (last processed Path Separator "PSP")
		std::string::size_type last_slash_pos = 0; // index of last slash in resolved path
		std::string component;
		resolved.clear();
		resolved.reserve(path.size());

		@@ -54,8 +93,11 @@ bool resolve_path (const std::string& path, std::string& resolved) {
		if (resolved.size() > 0) {
		resolved.erase(last_slash_pos);
		}
		if(mnt_matched > 0) {
		--mnt_matched;
		if (resolved_components > 0) {
		--resolved_components;
		}
		if (matched_components > 0) {
		--matched_components;
		}
		continue;
		}
		@@ -65,28 +107,43 @@ bool resolve_path (const std::string& path, std::string& resolved) {
		last_slash_pos = resolved.size() - 1;
		resolved.append(path, start, comp_size);

		if (mnt_matched < mnt_components.size()) {
		if (matched_components < mnt_components.size()) {
		// Outside GekkoFS
		if (path.compare(start, comp_size, mnt_components.at(mnt_matched)) == 0) {
		++mnt_matched;
		}
		if (LIBC_FUNC(__xstat, _STAT_VER, resolved.c_str(), &st) < 0) {
		if (matched_components == resolved_components &&
		path.compare(start, comp_size, mnt_components.at(matched_components)) == 0) {
		++matched_components;
		}
		if (LIBC_FUNC(__lxstat, _STAT_VER, resolved.c_str(), &st) < 0) {
		#ifndef NDEBUG
		CTX->log()->debug("{}() path does not exists: '{}'", __func__, resolved.c_str());
		#endif
		resolved.append(path, end, std::string::npos);
		return false;
		}
		if (S_ISLNK(st.st_mode)) {
		CTX->log()->error("{}() encountered link: {}", __func__, resolved);
		throw std::runtime_error("Readlink encoutered: '" + resolved + "'");
		char link_resolved[PATH_MAX_LEN];
		if (LIBC_FUNC(realpath, resolved.c_str(), link_resolved) == nullptr) {
		CTX->log()->error("{}() Failed to get realpath for link '{}'. Error: {}", __func__, resolved, strerror(errno));
		throw std::runtime_error("Failed to get realpath for link '" + resolved + "'. Error: " + strerror(errno));
		}
		// substituute resolved with new link path
		resolved = link_resolved;
		matched_components = path_match_components(resolved, resolved_components, mnt_components);
		// set matched counter to value coherent with the new path
		last_slash_pos = resolved.find_last_of(PSP);
		continue;
		} else if ((!S_ISDIR(st.st_mode)) && (end != path.size())) {
		resolved.append(path, end, std::string::npos);
		return false;
		}
		} else {
		// Inside GekkoFS
		++mnt_matched;
		++matched_components;
		}
		++resolved_components;
		}
		if (mnt_matched >= mnt_components.size()) {

		if (matched_components >= mnt_components.size()) {
		resolved.erase(1, CTX->mountdir().size());
		CTX->log()->debug("{}() internal: '{}'", __func__, resolved);
		return true;