intercept chdir,fchdir,getcwd (6930d8e3) · Commits · David Auer / gekkofs

ifs/include/preload/hooks.hpp

+3 −0

Original line number	Diff line number	Diff line
		@@ -20,6 +20,9 @@ int hook_dup2(unsigned int oldfd, unsigned int newfd);
		int hook_dup3(unsigned int oldfd, unsigned int newfd, int flags);
		int hook_getdents(unsigned int fd, struct linux_dirent *dirp, unsigned int count);
		int hook_mkdirat(int dirfd, const char * cpath, mode_t mode);
		int hook_chdir(const char* path);
		int hook_fchdir(unsigned int fd);
		int hook_getcwd(char * buf, unsigned long size);


		#endif

ifs/src/preload/hooks.cpp

+78 −1

Original line number	Diff line number	Diff line
		@@ -8,7 +8,7 @@
		#include <libsyscall_intercept_hook_point.h>
		#include <sys/stat.h>
		#include <fcntl.h>

		#include <memory>

		static inline int with_errno(int ret) {
		return (ret < 0)? -errno : ret;
		@@ -264,3 +264,80 @@ int hook_mkdirat(int dirfd, const char * cpath, mode_t mode) {
		}
		return syscall_no_intercept(SYS_mkdirat, dirfd, resolved.c_str(), mode);
		}

		int hook_chdir(const char * path) {
		CTX->log()->trace("{}() called with path '{}'", __func__, path);
		std::string rel_path;
		bool internal = CTX->relativize_path(path, rel_path);
		if (internal) {
		//path falls in our namespace
		struct stat st;
		if(adafs_stat(rel_path, &st) != 0) {
		CTX->log()->error("{}() path does not exists", __func__);
		return -ENOENT;
		}
		if(!S_ISDIR(st.st_mode)) {
		CTX->log()->error("{}() path is not a directory", __func__);
		return -ENOTDIR;
		}
		//TODO get complete path from relativize_path instead of
		// removing mountdir and then adding again here
		rel_path.insert(0, CTX->mountdir());
		if (has_trailing_slash(rel_path)) {
		// open_dir is '/'
		rel_path.pop_back();
		}
		}
		try {
		set_cwd(rel_path, internal);
		} catch (const std::system_error& se) {
		return -1;
		}
		return 0;
		}

		int hook_fchdir(unsigned int fd) {
		CTX->log()->trace("{}() called with fd {}", __func__, fd);
		if (CTX->file_map()->exist(fd)) {
		auto open_file = CTX->file_map()->get(fd);
		auto open_dir = std::static_pointer_cast<OpenDir>(open_file);
		if(!open_dir){
		//Cast did not succeeded: open_file is a regular file
		CTX->log()->error("{}() file descriptor refers to a normal file: '{}'",
		__func__, open_dir->path());
		return -EBADF;
		}

		std::string new_path = CTX->mountdir() + open_dir->path();
		if (has_trailing_slash(new_path)) {
		// open_dir is '/'
		new_path.pop_back();
		}
		try {
		set_cwd(new_path, true);
		} catch (const std::system_error& se) {
		return -1;
		}
		} else {
		long ret = syscall_no_intercept(SYS_fchdir, fd);
		if (ret < 0) {
		throw std::system_error(syscall_error_code(ret),
		std::system_category(),
		"Failed to change directory (fchdir syscall)");
		}
		unset_env_cwd();
		CTX->cwd(get_sys_cwd());
		}
		return 0;
		}

		int hook_getcwd(char * buf, unsigned long size) {
		CTX->log()->trace("{}() called with size {}", __func__, size);
		if(CTX->cwd().size() + 1 > size) {
		CTX->log()->error("{}() buffer too small to host current working dir", __func__);
		return -ERANGE;
		}

		strcpy(buf, CTX->cwd().c_str());
		return (CTX->cwd().size() + 1);
		}

ifs/src/preload/intercept.cpp

+13 −0

Original line number	Diff line number	Diff line
		@@ -122,6 +122,19 @@ static inline int hook(long syscall_number,
		static_cast<mode_t>(arg1));
		break;

		case SYS_chdir:
		result = hook_chdir(reinterpret_cast<const char >(arg0));
		break;

		case SYS_fchdir:
		*result = hook_fchdir(static_cast<unsigned int>(arg0));
		break;

		case SYS_getcwd:
		result = hook_getcwd(reinterpret_cast<char >(arg0),
		static_cast<unsigned long>(arg1));
		break;

		default:
		/*
		* Ignore any other syscalls