open overloads
Declared in <bdls_filesystemutil.h>
Open the file at the specified path, using the specified openPolicy to determine whether to open an existing file or create a new file, and using the specified ioPolicy to determine whether the file will be opened for reading, writing, or both. Optionally specify a truncatePolicy to determine whether any contents of the file will be deleted before open returns. If truncatePolicy is not supplied, the value e_KEEP will be used. Return a valid FileDescriptor for the file on success, or k_INVALID_FD otherwise. If openPolicy is e_OPEN, the file will be opened if it exists, and open will fail otherwise. If openPolicy is e_CREATE or e_CREATE_PRIVATE, and no file exists at path, a new file will be created, and open will fail otherwise. If openPolicy is e_CREATE_PRIVATE, the file will be created with access restricted to the same userid as the caller in environments where that is supported (which does not necessarily include Windows) otherwise the system default access policy is used (e.g. '0777 & ~umask'). If openPolicy is e_OPEN_OR_CREATE, the file will be opened if it exists, and a new file will be created otherwise. If ioPolicy is e_READ_ONLY, the returned FileDescriptor will allow only read operations on the file. If ioPolicy is e_WRITE_ONLY or e_APPEND_ONLY, the returned FileDescriptor will allow only write operations on the file. If ioPolicy is e_READ_WRITE or e_READ_APPEND, the returned FileDescriptor will allow both read and write operations on the file. Additionally, if ioPolicy is e_APPEND_ONLY or e_READ_APPEND all writes will be made to the end of the file ("append mode"). If truncatePolicy is e_TRUNCATE, the file will have zero length when open returns. If truncatePolicy is e_KEEP, the file will be opened with its existing contents, if any. Note that when a file is opened in append mode, all writes will go to the end of the file, even if there has been seeking on the file descriptor or another process has changed the length of the file. Append-mode writes are not atomic except in limited cases; another thread, or even another process, operating on the file may cause output not to be written, unbroken, to the end of the file. (Unix environments writing to local file systems may promise more.) Note that open will fail to open a file with a truncatePolicy of e_TRUNCATE unless at least one of the following policies is specified for openPolicy or ioPolicy: * e_CREATE * e_CREATE_PRIVATE * e_OPEN_OR_CREATE * 'e_WRITE_ONLY * e_READ_WRITE The parameterized STRING_TYPE must be one of bsl::string, std::string, std::pmr::string (if supported), bsl::string_view, or bslstl::StringRef.
static
FileDescriptor
open(
char const* path,
FileOpenPolicy openPolicy,
FileIOPolicy ioPolicy,
FileTruncatePolicy truncatePolicy = e_KEEP);Same as the overload taking const char *.
template<class STRING_TYPE>
static
FilesystemUtil::FileDescriptor
open(
STRING_TYPE const& path,
FileOpenPolicy openPolicy,
FileIOPolicy ioPolicy,
FileTruncatePolicy truncatePolicy = e_KEEP);