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-rw-r--r--src/change_log.cc104
-rw-r--r--src/io.h61
-rw-r--r--src/utility.h28
3 files changed, 193 insertions, 0 deletions
diff --git a/src/change_log.cc b/src/change_log.cc
new file mode 100644
index 0000000..5ca0e8e
--- /dev/null
+++ b/src/change_log.cc
@@ -0,0 +1,104 @@
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include <memory>
+#include <functional>
+#include <unordered_set>
+
+#include "io.h"
+#include "utility.h"
+
+static std::unique_ptr<std::unordered_set<std::string>> tracked_files;
+static std::unique_ptr<io::FileDescriptorGuard> fd_guard;
+static std::unique_ptr<utility::Logger> log;
+
+template <class Result, typename... Arguments>
+std::function<Result(Arguments...)> get_real_function(
+ const std::string& symbol_name) {
+
+ Result (*real_function)(Arguments...) = nullptr;
+ const void* symbol_address = dlsym(RTLD_NEXT, symbol_name.c_str());
+
+ std::memcpy(&real_function, &symbol_address, sizeof(symbol_address));
+
+ return std::function<Result(Arguments...)>(real_function);
+}
+
+void init() __attribute__ ((constructor));
+void init() {
+ tracked_files = std::make_unique<std::unordered_set<std::string>>();
+
+ if ( getenv("CHANGE_LOG_TARGET") != NULL ) {
+ fd_guard = std::make_unique<io::FileDescriptorGuard>(
+ getenv("CHANGE_LOG_TARGET")
+ );
+ log = std::make_unique<utility::Logger>(*fd_guard);
+ } else {
+ log = std::make_unique<utility::Logger>(STDERR_FILENO);
+ }
+}
+
+void exit(int status) {
+ get_real_function<void, int>("exit")(status);
+}
+
+bool is_tracked_file(const std::string& file_name) {
+ return tracked_files->find(file_name) != tracked_files->end();
+}
+
+bool track_file(const std::string& file_name) {
+ return tracked_files->emplace(file_name).second;
+}
+
+ssize_t write(int fd, const void* buffer, size_t count) {
+ static auto real_write = get_real_function<ssize_t, int, const void*, size_t>("write");
+
+ if ( io::is_regular_file(fd) ) {
+ const std::string file_name{ io::get_file_name(fd) };
+
+ if ( !is_tracked_file(file_name) ) {
+ track_file(file_name);
+
+ log->append("wrote to '" + file_name + "'");
+ }
+ }
+
+ return real_write(fd, buffer, count);
+}
+
+int rename(const char* old_path, const char* new_path) {
+ static auto real_rename = get_real_function<int, const char*, const char*>("rename");
+
+ log->append("renamed '" + std::string(old_path) + "' to '" + std::string(new_path) + "'");
+
+ return real_rename(old_path, new_path);
+}
+
+int rmdir(const char* path) {
+ static auto real_rmdir = get_real_function<int, const char*>("rmdir");
+
+ log->append("removed directory '" + std::string(path) + "'");
+
+ return real_rmdir(path);
+}
+
+int unlink(const char* path) {
+ static auto real_unlink = get_real_function<int, const char*>("unlink");
+
+ log->append("removed '" + std::string(path) + "'");
+
+ return real_unlink(path);
+}
+
+int unlinkat(int dirfd, const char* path, int flags) {
+ static auto real_unlinkat = get_real_function<int, int, const char*, int>("unlinkat");
+
+ if ( dirfd == AT_FDCWD ) {
+ log->append("removed '" + std::string(path) + "'");
+ } else {
+ log->append("removed '" + io::get_file_name(dirfd) + path + "'");
+ }
+
+ return real_unlinkat(dirfd, path, flags);
+}
diff --git a/src/io.h b/src/io.h
new file mode 100644
index 0000000..87778ec
--- /dev/null
+++ b/src/io.h
@@ -0,0 +1,61 @@
+#ifndef CHANGE_IO_H_
+#define CHANGE_IO_H_
+
+#include <unistd.h>
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+
+#include <cstring>
+
+namespace io {
+
+class FileDescriptorGuard {
+ public:
+ FileDescriptorGuard(const std::string& path) {
+ this->fd = open(path.c_str(), O_WRONLY | O_APPEND);
+
+ if ( !this->fd ) {
+ this->fd = STDERR_FILENO;
+ }
+ }
+
+ ~FileDescriptorGuard() {
+ close(this->fd);
+ }
+
+ operator int() {
+ return this->fd;
+ }
+
+ private:
+ int fd;
+
+};
+
+std::string get_file_name(int fd) {
+ char proc_link[20];
+ char file_name[256];
+
+ snprintf(proc_link, sizeof(proc_link), "/proc/self/fd/%d", fd);
+ const ssize_t name_size = readlink(proc_link, file_name, sizeof(file_name));
+
+ if ( name_size > 0 ) {
+ file_name[name_size] = '\0';
+
+ return std::string(file_name);
+ } else {
+ return std::string();
+ }
+}
+
+bool is_regular_file(int fd) {
+ struct stat fd_stat;
+ fstat(fd, &fd_stat);
+
+ return S_ISREG(fd_stat.st_mode);
+}
+
+}
+
+#endif // CHANGE_IO_H_
diff --git a/src/utility.h b/src/utility.h
new file mode 100644
index 0000000..27ce8e9
--- /dev/null
+++ b/src/utility.h
@@ -0,0 +1,28 @@
+#ifndef CHANGE_UTILITY_H_
+#define CHANGE_UTILITY_H_
+
+#include <ext/stdio_filebuf.h>
+
+#include <iostream>
+
+namespace utility {
+
+class Logger {
+ public:
+ Logger(const int target_fd):
+ buffer(target_fd, std::ios::out),
+ stream(&this->buffer) { }
+
+ void append(const std::string& msg) {
+ this->stream << msg << std::endl;
+ }
+
+ private:
+ __gnu_cxx::stdio_filebuf<char> buffer;
+ std::ostream stream;
+
+};
+
+}
+
+#endif // CHANGE_UTILITY_H_