bdls::FilesystemUtil_UnixImpUtil< UNIX_INTERFACE > Struct Template Reference

#include <bdls_filesystemutil_uniximputil.h>

Public Types
typedef int	FileDescriptor
typedef UNIX_INTERFACE::off_t	Offset

Static Public Member Functions
static Offset	getFileSize (FileDescriptor descriptor)
static int	getLastModificationTime (bdlt::Datetime *time, FileDescriptor descriptor)

Detailed Description

template<class UNIX_INTERFACE>
struct bdls::FilesystemUtil_UnixImpUtil< UNIX_INTERFACE >

This component-private utility struct provides a namespace for a suite of functions that FilesystemUtil uses as implementation details. These functions have a UNIX_INTERFACE template parameter, which provides access to the entities that large-file environment Unix systems declare, and that the function implementations need.

Note that, on some Unix platforms and some build configurations, the stat struct does not have an st_mtime field, and st_mtime is a macro that emulates the access of the field. Similarly, on some Unix platforms and some build configurations, the stat structure does not have an st_mtim field or the st_mtim struct does not have a tv_nsec (or, for some versions of Solaris, __tv_nsec) field, in which case the get_st_mtim_nsec function returns zero. For more information, please see the specification of the sys/stat.h header from IEEE Std 1003.1-2017, which provides information about the evolution of the stat struct in the POSIX specification (https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/).

The program is ill-formed unless the specified UNIX_INTERFACE is a class type that meets the following requirements:

• UNIX_INTERFACE::off_t is a type alias to the off_t type provided by the sys/types.h header.
• UNIX_INTERFACE::stat is a type alias to the stat type provided by the sys/stat.h header.
• UNIX_INTERFACE::time_t is a type alias to the time_t type provided by the sys/types.h header.
• UNIX_INTERFACE::get_st_mtim_nsec is a public, static member function that has long (const stat& stat) type and whose contract is to return the value of the st_mtim.tv_nsec field of the specified stat struct.
• UNIX_INTERFACE::get_st_mtime is a public, static member function that has time_t (const stat& stat) type and whose contract is to return the value of the st_mtime field of the specified stat struct.
• UNIX_INTERFACE::get_st_size is a public, static member function that has off_t (const stat& stat) type and whose contract is to return the value of the st_size field of the specified stat struct. Note that this function is required in order to access the data members of a stat struct in a manner consistent with the requirements of get_st_mtime.
• UNIX_INTERFACE::fstat is a public, static member function that has int (int fildes, stat *buf) type and whose contract is to return the result of ::fstat(fildes, buf), where fstat is the function provided by the sys/stat.h header.

Member Typedef Documentation

FileDescriptor

template<class UNIX_INTERFACE >

typedef int bdls::FilesystemUtil_UnixImpUtil< UNIX_INTERFACE >::FileDescriptor

FileDescriptor is an alias for the operating system's native file descriptor / file handle type.

Offset

template<class UNIX_INTERFACE >

typedef UNIX_INTERFACE::off_t bdls::FilesystemUtil_UnixImpUtil< UNIX_INTERFACE >::Offset

Offset is an alias for a signed integral type, and represents the offset of a location in a file.

Member Function Documentation

getFileSize()

template<class UNIX_INTERFACE >

FilesystemUtil_UnixImpUtil< UNIX_INTERFACE >::Offset bdls::FilesystemUtil_UnixImpUtil< UNIX_INTERFACE >::getFileSize ( FileDescriptor  descriptor )

static

Return the size, in bytes, of the file with the specified descriptor, or a negative value if an error occurs.

getLastModificationTime()

template<class UNIX_INTERFACE >

int bdls::FilesystemUtil_UnixImpUtil< UNIX_INTERFACE >::getLastModificationTime ( bdlt::Datetime *  time, FileDescriptor  descriptor  )

static

Load into the specified time the last modification time of the file with the specified descriptor, as reported by the filesystem. Return 0 on success, and a non-zero value otherwise. Note that the time is reported in UTC.

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The documentation for this struct was generated from the following file:

• bdls_filesystemutil_uniximputil.h