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libXFCcore / xfc / glib

fileutils.hh File Reference

C++ interface for GDir and the various GLib file-related functions. More...

#include <xfc/stackobject.hh>
#include <xfc/utfstring.hh>
#include <glib/gdir.h>
#include <glib/gfileutils.h>
#include <vector>
#include <xfc/glib/inline/fileutils.inl>

Namespaces

Classes

File Methods

Typedefs

Enumerations

Detailed Description

C++ interface for GDir and the various GLib file-related functions.

Enumeration Type Documentation

enum FileError
 

Values corresponding to errno codes returned from file operations on UNIX.

Unlike errno codes, FileError values are available on all systems. The exact meaning of each code depends on what sort of file operation you were performing; the UNIX documentation gives more details. The following error code descriptions come from the GNU C Library manual, and are under the copyright of that manual.

It's not very portable to make detailed assumptions about exactly which errors will be returned from a given operation. Some errors don't occur on some systems, etc., sometimes there are subtle differences in when a system will report a given error, etc.

Enumeration values:
FILE_ERROR_EXIST  Operation not permitted; only the owner of the file (or other resource) or processes with special privileges can perform the operation.
FILE_ERROR_ISDIR  File is a directory; you cannot open a directory for writing, or create or remove hard links to it.
FILE_ERROR_ACCES  Permission denied; the file permissions do not allow the attempted operation.
FILE_ERROR_NAMETOOLONG  Filename is too long.
FILE_ERROR_NOENT  No such file or directory; This is a "file doesn't exist" error for ordinary files that are referenced in contexts where they are expected to already exist.
FILE_ERROR_NOTDIR  A file that isn't a directory was specified when a directory is required.
FILE_ERROR_NXIO  No such device or address; The system tried to use the device represented by a file you specified, and it couldn't find the device; This can mean that the device file was installed incorrectly, or that the physical device is missing or not correctly attached to the computer.
FILE_ERROR_NODEV  This file is of a type that doesn't support mapping.
FILE_ERROR_ROFS  The directory containing the new link can't be modified because it's on a read-only file system.
FILE_ERROR_TXTBSY  Text file busy.
FILE_ERROR_FAULT  You passed in a pointer to bad memory (GLib won't reliably return this, don't pass in pointers to bad memory).
FILE_ERROR_LOOP  Too many levels of symbolic links were encountered in looking up a file name; This often indicates a cycle of symbolic links.
FILE_ERROR_NOSPC  No space left on device; write operation on a file failed because the disk is full.
FILE_ERROR_NOMEM  No memory available; The system cannot allocate more virtual memory because its capacity is full.
FILE_ERROR_MFILE  The current process has too many files open and can't open any more; Duplicate descriptors do count toward this limit.
FILE_ERROR_NFILE  There are too many distinct file openings in the entire system.
FILE_ERROR_BADF  Bad file descriptor; for example, I/O on a descriptor that has been closed or reading from a descriptor open only for writing (or vice versa).
FILE_ERROR_INVAL  Invalid argument; This is used to indicate various kinds of problems with passing the wrong argument to a library function.
FILE_ERROR_PIPE  Broken pipe; there is no process reading from the other end of a pipe (Every library function that returns this error code also generates a `SIGPIPE' signal; this signal terminates the program if not handled or blocked; Thus, your program will never actually see this code unless it has handled or blocked `SIGPIPE').
FILE_ERROR_AGAIN  Resource temporarily unavailable; the call might work if you try again later.
FILE_ERROR_INTR  Interrupted function call; an asynchronous signal occurred and prevented completion of the call (When this happens, you should try the call again).
FILE_ERROR_IO  Input/output error; usually used for physical read or write errors, that is, the disk or other physical device hardware is returning errors.
FILE_ERROR_PERM  Operation not permitted; only the owner of the file (or other resource) or processes with special privileges can perform the operation.
FILE_ERROR_NOSYS  Function not implemented; this indicates that the system is missing some functionality.
FILE_ERROR_FAILED  Does not correspond to a UNIX error code; this is the standard "failed for unspecified reason" error code present in all GError error code enumerations (Returned if no specific code applies).

enum FileTest
 

Specifies a test to perform on a file using G::file_test().

Enumeration values:
FILE_TEST_IS_REGULAR  Tests true if the file is a regular file (not a symlink or directory).
FILE_TEST_IS_SYMLINK  Tests true if the file is a symlink.
FILE_TEST_IS_DIR  Tests true if the file is a directory.
FILE_TEST_IS_EXECUTABLE  Tests true if the file is executable.
FILE_TEST_EXISTS  Tests true if the file exists. It may or may not be a regular file.

Function Documentation

FileError file_error_from_errno (  int  err_no  ) 
 

Gets a FileError constant based on the passed-in errno, for example, if you pass in EEXIST this function returns G_FILE_ERROR_EXIST.

Parameters:
err_no An "errno" value
Returns:
A FileError corresponding to the given errno.
Unlike errno values, you can portably assume that all FileError values will exist. Normally a FileError value goes into a G::Error returned from a method that manipulates files. So you would use G::file_error_from_errno() when constructing a G::Error.

bool file_get_contents (  const std::string &  filename,
std::string &  contents,
G::Error *  error
) 
 

Reads an entire file into allocated memory, with good error checking.

Parameters:
filename A file to read the contents from.
contents The location to store the file contents.
error The return location for a G::Error.
Returns:
true on success, false if error is set.
If error is set, false is returned, and contents is set to an empty string. If true is returned, error will not be set, and contents will be set to the file contents. The error domain is G_FILE_ERROR. Possible error codes are those in the FileError enumeration.

bool file_test (  const std::string &  filename,
FileTestField  test
) 
 

Determines whether any of the tests in the bitfield test are true.

Parameters:
filename A filename to test.
test A bitfield of G::FileTest flags.
Returns:
true if a test was true.
For example, (G::FILE_TEST_EXISTS | G::FILE_TEST_IS_DIR) will return true if the file exists; the check whether it's a directory doesn't matter since the existence test is true. With the current set of available tests, there's no point passing in more than one test at a time.

Apart from G::FILE_TEST_IS_SYMLINK all tests follow symbolic links, so for a symbolic link to a regular file file_test() will return true for both G::FILE_TEST_IS_SYMLINK and G::FILE_TEST_IS_REGULAR. Note, that for a dangling symbolic link file_test() will return true for G::FILE_TEST_IS_SYMLINK and false for all other flags.

You should never use file_test() to test whether it is safe to perform an operaton, because there is always the possibility of the condition changing before you actually perform the operation. For example, you might think you could use G::FILE_TEST_IS_SYMLINK to know whether it is is safe to write to a file without being tricked into writing into a different location. It doesn't work!

Example: DON'T DO THIS. 

     if (!file_test(filename, FILE_TEST_IS_SYMLINK))
     {
        TempFile file(filename);
        if (file.is_open())
        // write to file
     }

Another thing to note is that G::FILE_TEST_EXISTS and G::FILE_TEST_IS_EXECUTABLE are implemented using the access() system call. This usually doesn't matter, but if your program is setuid or setgid it means that these tests will give you the answer for the real user ID and group ID , rather than the effective user ID and group ID.

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