Creating Gekko API example

examples/gfind/CMakeLists.txt

@@ -28,9 +28,17 @@
 
 set (CMAKE_CXX_STANDARD 14)
 add_executable(sfind sfind.cpp)
+add_executable(gkfs_lib_example gkfs_lib_example.cpp)
+
+target_link_libraries(gkfs_lib_example
+  PRIVATE gkfs_intercept
+)
 
 if(GKFS_INSTALL_TESTS)
     install(TARGETS sfind 
         DESTINATION ${CMAKE_INSTALL_BINDIR}
     )
+    install(TARGETS gkfs_lib_example
+        DESTINATION ${CMAKE_INSTALL_BINDIR}
+    )
 endif()

examples/gfind/gkfs_lib_example.cpp

+/*
+  Copyright 2018-2022, Barcelona Supercomputing Center (BSC), Spain
+  Copyright 2015-2022, Johannes Gutenberg Universitaet Mainz, Germany
+
+  This software was partially supported by the
+  EC H2020 funded project NEXTGenIO (Project ID: 671951, www.nextgenio.eu).
+
+  This software was partially supported by the
+  ADA-FS project under the SPPEXA project funded by the DFG.
+
+  This file is part of GekkoFS.
+
+  GekkoFS is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  GekkoFS is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with GekkoFS.  If not, see <https://www.gnu.org/licenses/>.
+
+  SPDX-License-Identifier: GPL-3.0-or-later
+*/
+
+
+#include <cmath>
+#include <cstring>
+#include <getopt.h>
+#include <iostream>
+#include <queue>
+#include <regex.h>
+#include <stdio.h>
+#include <string>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <limits>
+#include <cstdint>
+#include <client/gkfs_functions.hpp>
+
+using namespace std;
+
+/* Function exported from GekkoFS LD_PRELOAD, code needs to be compiled with
+ * -fPIC */
+extern "C" int gkfs_init()
+    __attribute__((weak));
+
+extern "C" int gkfs_end()
+    __attribute__((weak));
+
+void init_preload() {};
+void destroy_preload() {};
+
+
+
+void write_file(std::string filename){
+  // Opem File
+  int fd = gkfs::syscall::gkfs_open(filename,S_IRWXU,O_RDWR|O_CREAT);
+
+  cout << "FD open  " << fd << endl;
+  char *buf = "testing";
+  
+  // int size = gkfs::syscall::gkfs_write(fd, buf, 7);
+
+ //  cout << "FD size" << size << endl;
+
+  gkfs::syscall::gkfs_close(fd);
+
+}
+
+
+void read_file(std::string filename){
+  int fdread = gkfs::syscall::gkfs_open(filename,S_IRWXU,O_RDONLY);
+  char *bufread = "TESTING\0";
+  int sizeread = gkfs::syscall::gkfs_read(fdread, bufread, 7);
+
+  cout << "Reading : "  << sizeread << " --> " << bufread << endl;
+
+  gkfs::syscall::gkfs_close(fdread);
+
+}
+int main(int argc, char **argv) {
+  cout << "GekkoFS Client library test" << endl;
+
+  auto res = gkfs_init();
+
+  cout << "Init result " << res << endl;
+
+  //write_file ("/test.tmp"); 
+  
+  read_file("/test.tmp");
+
+  res = gkfs_end();
+
+  cout << "End result " << res << endl;
+
+}

include/client/gkfs_functions.hpp

@@ -149,6 +149,9 @@ gkfs_getdents64(unsigned int fd, struct linux_dirent64* dirp,
 int
 gkfs_rmdir(const std::string& path);
 
+int
+gkfs_close(unsigned int fd);
+
 #ifdef HAS_RENAME
 int
 gkfs_rename(const std::string& old_path, const std::string& new_path);

include/client/preload.hpp

@@ -47,5 +47,10 @@ init_preload() __attribute__((constructor));
 void
 destroy_preload() __attribute__((destructor));
 
+extern "C" int
+gkfs_init();
+
+extern "C" int
+gkfs_end();
 
 #endif // IOINTERCEPT_PRELOAD_HPP

src/client/gkfs_functions.cpp

@@ -1394,6 +1394,27 @@ gkfs_getdents64(unsigned int fd, struct linux_dirent64* dirp,
     return written;
 }
 
+/**
+ * @brief Closes an fd. To be used externally
+ * 
+ * @param fd 
+ * @return int 
+ */
+int gkfs_close(unsigned int fd) {
+    if(CTX->file_map()->exist(fd)) {
+        // No call to the daemon is required
+        CTX->file_map()->remove(fd);
+        return 0;
+    }
+
+    if(CTX->is_internal_fd(fd)) {
+        // the client application (for some reason) is trying to close an
+        // internal fd: ignore it
+        return 0;
+    }
+    
+    return -1;
+}
 
 #ifdef HAS_SYMLINKS
 #ifdef GKFS_ENABLE_UNUSED_FUNCTIONS

src/client/hooks.cpp

@@ -91,17 +91,10 @@ hook_close(int fd) {
 
     LOG(DEBUG, "{}() called with fd: {}", __func__, fd);
 
-    if(CTX->file_map()->exist(fd)) {
-        // No call to the daemon is required
-        CTX->file_map()->remove(fd);
+    auto ret = gkfs::syscall::gkfs_close(fd);
+    
+    if (ret == 0) 
         return 0;
-    }
-
-    if(CTX->is_internal_fd(fd)) {
-        // the client application (for some reason) is trying to close an
-        // internal fd: ignore it
-        return 0;
-    }
 
     return syscall_no_intercept_wrapper(SYS_close, fd);
 }

src/client/preload.cpp

@@ -65,8 +65,10 @@ exit_error_msg(int errcode, const string& msg) {
     // if we don't disable interception before calling ::exit()
     // syscall hooks may find an inconsistent in shared state
     // (e.g. the logger) and thus, crash
-    gkfs::preload::stop_interception();
-    CTX->disable_interception();
+    if(CTX->interception_enabled()) { 
+        gkfs::preload::stop_interception();
+        CTX->disable_interception();
+    }
     ::exit(errcode);
 }
 
@@ -310,9 +312,39 @@ destroy_preload() {
     ld_network_service.reset();
     LOG(DEBUG, "RPC subsystem shut down");
 
-    gkfs::preload::stop_interception();
-    CTX->disable_interception();
-    LOG(DEBUG, "Syscall interception stopped");
+    if(CTX->interception_enabled()) { 
+        gkfs::preload::stop_interception();
+        CTX->disable_interception();
+        LOG(DEBUG, "Syscall interception stopped");
+    }
 
     LOG(INFO, "All subsystems shut down. Client shutdown complete.");
 }
+
+
+
+/**
+ * @brief External functions to call linking the library
+ * 
+ */
+extern "C" int
+gkfs_init() {
+    CTX->init_logging();
+    // from here ownwards it is safe to print messages
+    LOG(DEBUG, "Logging subsystem initialized");
+    gkfs::preload::init_environment();
+    return 4;
+}
+
+
+extern "C" int
+gkfs_end() {
+   CTX->clear_hosts();
+    LOG(DEBUG, "Peer information deleted");
+
+    ld_network_service.reset();
+    LOG(DEBUG, "RPC subsystem shut down");
+
+    LOG(INFO, "All subsystems shut down. Client shutdown complete.");
+    return 4;
+}
\ No newline at end of file