File Utilities

File Utilities — various file-related functions

Types and Values

enum GFileError
#define G_FILE_ERROR
enum GFileTest
  GDir
  GMappedFile
typedef GStatBuf

Includes

#include <glib.h>
#include <glib/gstdio.h>

Description

There is a group of functions which wrap the common POSIX functions dealing with filenames (g_open(), g_rename(), g_mkdir(), g_stat(), g_unlink(), g_remove(), g_fopen(), g_freopen()). The point of these wrappers is to make it possible to handle file names with any Unicode characters in them on Windows without having to use ifdefs and the wide character API in the application code.

The pathname argument should be in the GLib file name encoding. On POSIX this is the actual on-disk encoding which might correspond to the locale settings of the process (or the G_FILENAME_ENCODING environment variable), or not.

On Windows the GLib file name encoding is UTF-8. Note that the Microsoft C library does not use UTF-8, but has separate APIs for current system code page and wide characters (UTF-16). The GLib wrappers call the wide character API if present (on modern Windows systems), otherwise convert to/from the system code page.

Another group of functions allows to open and read directories in the GLib file name encoding. These are g_dir_open(), g_dir_read_name(), g_dir_rewind(), g_dir_close().

Functions

g_file_error_from_errno ()

GFileError
g_file_error_from_errno (gint err_no);

Gets a GFileError constant based on the passed-in err_no . For example, if you pass in EEXIST this function returns G_FILE_ERROR_EXIST. Unlike errno values, you can portably assume that all GFileError values will exist.

Normally a GFileError value goes into a GError returned from a function that manipulates files. So you would use g_file_error_from_errno() when constructing a GError.

Parameters

err_no

an "errno" value

 

Returns

GFileError corresponding to the given errno


g_file_get_contents ()

gboolean
g_file_get_contents (const gchar *filename,
                     gchar **contents,
                     gsize *length,
                     GError **error);

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

If the call was successful, it returns TRUE and sets contents to the file contents and length to the length of the file contents in bytes. The string stored in contents will be nul-terminated, so for text files you can pass NULL for the length argument. If the call was not successful, it returns FALSE and sets error . The error domain is G_FILE_ERROR. Possible error codes are those in the GFileError enumeration. In the error case, contents is set to NULL and length is set to zero.

Parameters

filename

name of a file to read contents from, in the GLib file name encoding.

[type filename]

contents

location to store an allocated string, use g_free() to free the returned string.

[out][array length=length][element-type guint8]

length

location to store length in bytes of the contents, or NULL.

[allow-none]

error

return location for a GError, or NULL

 

Returns

TRUE on success, FALSE if an error occurred


g_file_set_contents ()

gboolean
g_file_set_contents (const gchar *filename,
                     const gchar *contents,
                     gssize length,
                     GError **error);

Writes all of contents to a file named filename , with good error checking. If a file called filename already exists it will be overwritten.

This write is atomic in the sense that it is first written to a temporary file which is then renamed to the final name. Notes:

  • On UNIX, if filename already exists hard links to filename will break. Also since the file is recreated, existing permissions, access control lists, metadata etc. may be lost. If filename is a symbolic link, the link itself will be replaced, not the linked file.

  • On Windows renaming a file will not remove an existing file with the new name, so on Windows there is a race condition between the existing file being removed and the temporary file being renamed.

  • On Windows there is no way to remove a file that is open to some process, or mapped into memory. Thus, this function will fail if filename already exists and is open.

If the call was successful, it returns TRUE. If the call was not successful, it returns FALSE and sets error . The error domain is G_FILE_ERROR. Possible error codes are those in the GFileError enumeration.

Note that the name for the temporary file is constructed by appending up to 7 characters to filename .

Parameters

filename

name of a file to write contents to, in the GLib file name encoding.

[type filename]

contents

string to write to the file.

[array length=length][element-type guint8]

length

length of contents , or -1 if contents is a nul-terminated string

 

error

return location for a GError, or NULL

 

Returns

TRUE on success, FALSE if an error occurred

Since: 2.8


g_file_test ()

gboolean
g_file_test (const gchar *filename,
             GFileTest test);

Returns TRUE if any of the tests in the bitfield test are 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 g_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 g_file_test() will return TRUE for G_FILE_TEST_IS_SYMLINK and FALSE for all other flags.

You should never use g_file_test() to test whether it is safe to perform an operation, 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 safe to write to a file without being tricked into writing into a different location. It doesn't work!

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// DON'T DO THIS
if (!g_file_test (filename, G_FILE_TEST_IS_SYMLINK)) 
  {
    fd = g_open (filename, O_WRONLY);
    // write to fd
  }

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.

On Windows, there are no symlinks, so testing for G_FILE_TEST_IS_SYMLINK will always return FALSE. Testing for G_FILE_TEST_IS_EXECUTABLE will just check that the file exists and its name indicates that it is executable, checking for well-known extensions and those listed in the PATHEXT environment variable.

Parameters

filename

a filename to test in the GLib file name encoding

 

test

bitfield of GFileTest flags

 

Returns

whether a test was TRUE


g_mkstemp ()

gint
g_mkstemp (gchar *tmpl);

Opens a temporary file. See the mkstemp() documentation on most UNIX-like systems.

The parameter is a string that should follow the rules for mkstemp() templates, i.e. contain the string "XXXXXX". g_mkstemp() is slightly more flexible than mkstemp() in that the sequence does not have to occur at the very end of the template. The X string will be modified to form the name of a file that didn't exist. The string should be in the GLib file name encoding. Most importantly, on Windows it should be in UTF-8.

Parameters

tmpl

template filename.

[type filename]

Returns

A file handle (as from open()) to the file opened for reading and writing. The file is opened in binary mode on platforms where there is a difference. The file handle should be closed with close(). In case of errors, -1 is returned and errno will be set.


g_mkstemp_full ()

gint
g_mkstemp_full (gchar *tmpl,
                gint flags,
                gint mode);

Opens a temporary file. See the mkstemp() documentation on most UNIX-like systems.

The parameter is a string that should follow the rules for mkstemp() templates, i.e. contain the string "XXXXXX". g_mkstemp_full() is slightly more flexible than mkstemp() in that the sequence does not have to occur at the very end of the template and you can pass a mode and additional flags . The X string will be modified to form the name of a file that didn't exist. The string should be in the GLib file name encoding. Most importantly, on Windows it should be in UTF-8.

Parameters

tmpl

template filename.

[type filename]

flags

flags to pass to an open() call in addition to O_EXCL and O_CREAT, which are passed automatically

 

mode

permissions to create the temporary file with

 

Returns

A file handle (as from open()) to the file opened for reading and writing. The file handle should be closed with close(). In case of errors, -1 is returned and errno will be set.

Since: 2.22


g_file_open_tmp ()

gint
g_file_open_tmp (const gchar *tmpl,
                 gchar **name_used,
                 GError **error);

Opens a file for writing in the preferred directory for temporary files (as returned by g_get_tmp_dir()).

tmpl should be a string in the GLib file name encoding containing a sequence of six 'X' characters, as the parameter to g_mkstemp(). However, unlike these functions, the template should only be a basename, no directory components are allowed. If template is NULL, a default template is used.

Note that in contrast to g_mkstemp() (and mkstemp()) tmpl is not modified, and might thus be a read-only literal string.

Upon success, and if name_used is non-NULL, the actual name used is returned in name_used . This string should be freed with g_free() when not needed any longer. The returned name is in the GLib file name encoding.

Parameters

tmpl

Template for file name, as in g_mkstemp(), basename only, or NULL for a default template.

[type filename][allow-none]

name_used

location to store actual name used, or NULL.

[out][type filename]

error

return location for a GError

 

Returns

A file handle (as from open()) to the file opened for reading and writing. The file is opened in binary mode on platforms where there is a difference. The file handle should be closed with close(). In case of errors, -1 is returned and error will be set.


g_file_read_link ()

gchar *
g_file_read_link (const gchar *filename,
                  GError **error);

Reads the contents of the symbolic link filename like the POSIX readlink() function. The returned string is in the encoding used for filenames. Use g_filename_to_utf8() to convert it to UTF-8.

Parameters

filename

the symbolic link

 

error

return location for a GError

 

Returns

A newly-allocated string with the contents of the symbolic link, or NULL if an error occurred.

Since: 2.4


g_mkdir_with_parents ()

gint
g_mkdir_with_parents (const gchar *pathname,
                      gint mode);

Create a directory if it doesn't already exist. Create intermediate parent directories as needed, too.

Parameters

pathname

a pathname in the GLib file name encoding

 

mode

permissions to use for newly created directories

 

Returns

0 if the directory already exists, or was successfully created. Returns -1 if an error occurred, with errno set.

Since: 2.8


g_mkdtemp ()

gchar *
g_mkdtemp (gchar *tmpl);

Creates a temporary directory. See the mkdtemp() documentation on most UNIX-like systems.

The parameter is a string that should follow the rules for mkdtemp() templates, i.e. contain the string "XXXXXX". g_mkdtemp() is slightly more flexible than mkdtemp() in that the sequence does not have to occur at the very end of the template and you can pass a mode and additional flags . The X string will be modified to form the name of a directory that didn't exist. The string should be in the GLib file name encoding. Most importantly, on Windows it should be in UTF-8.

Parameters

tmpl

template directory name.

[type filename]

Returns

A pointer to tmpl , which has been modified to hold the directory name. In case of errors, NULL is returned and errno will be set.

Since: 2.30


g_mkdtemp_full ()

gchar *
g_mkdtemp_full (gchar *tmpl,
                gint mode);

Creates a temporary directory. See the mkdtemp() documentation on most UNIX-like systems.

The parameter is a string that should follow the rules for mkdtemp() templates, i.e. contain the string "XXXXXX". g_mkdtemp() is slightly more flexible than mkdtemp() in that the sequence does not have to occur at the very end of the template and you can pass a mode . The X string will be modified to form the name of a directory that didn't exist. The string should be in the GLib file name encoding. Most importantly, on Windows it should be in UTF-8.

Parameters

tmpl

template directory name.

[type filename]

mode

permissions to create the temporary directory with

 

Returns

A pointer to tmpl , which has been modified to hold the directory name. In case of errors, NULL is returned, and errno will be set.

Since: 2.30


g_dir_make_tmp ()

gchar *
g_dir_make_tmp (const gchar *tmpl,
                GError **error);

Creates a subdirectory in the preferred directory for temporary files (as returned by g_get_tmp_dir()).

tmpl should be a string in the GLib file name encoding containing a sequence of six 'X' characters, as the parameter to g_mkstemp(). However, unlike these functions, the template should only be a basename, no directory components are allowed. If template is NULL, a default template is used.

Note that in contrast to g_mkdtemp() (and mkdtemp()) tmpl is not modified, and might thus be a read-only literal string.

Parameters

tmpl

Template for directory name, as in g_mkdtemp(), basename only, or NULL for a default template.

[type filename][allow-none]

error

return location for a GError

 

Returns

The actual name used. This string should be freed with g_free() when not needed any longer and is is in the GLib file name encoding. In case of errors, NULL is returned and error will be set.

[type filename]

Since: 2.30


g_dir_open ()

GDir *
g_dir_open (const gchar *path,
            guint flags,
            GError **error);

Opens a directory for reading. The names of the files in the directory can then be retrieved using g_dir_read_name(). Note that the ordering is not defined.

Parameters

path

the path to the directory you are interested in. On Unix in the on-disk encoding. On Windows in UTF-8

 

flags

Currently must be set to 0. Reserved for future use.

 

error

return location for a GError, or NULL. If non-NULL, an error will be set if and only if g_dir_open() fails.

 

Returns

a newly allocated GDir on success, NULL on failure. If non-NULL, you must free the result with g_dir_close() when you are finished with it.


g_dir_read_name ()

const gchar *
g_dir_read_name (GDir *dir);

Retrieves the name of another entry in the directory, or NULL. The order of entries returned from this function is not defined, and may vary by file system or other operating-system dependent factors.

NULL may also be returned in case of errors. On Unix, you can check errno to find out if NULL was returned because of an error.

On Unix, the '.' and '..' entries are omitted, and the returned name is in the on-disk encoding.

On Windows, as is true of all GLib functions which operate on filenames, the returned name is in UTF-8.

Parameters

dir

a GDir* created by g_dir_open()

 

Returns

The entry's name or NULL if there are no more entries. The return value is owned by GLib and must not be modified or freed.


g_dir_rewind ()

void
g_dir_rewind (GDir *dir);

Resets the given directory. The next call to g_dir_read_name() will return the first entry again.

Parameters

dir

a GDir* created by g_dir_open()

 

g_dir_close ()

void
g_dir_close (GDir *dir);

Closes the directory and deallocates all related resources.

Parameters

dir

a GDir* created by g_dir_open()

 

g_mapped_file_new ()

GMappedFile *
g_mapped_file_new (const gchar *filename,
                   gboolean writable,
                   GError **error);

Maps a file into memory. On UNIX, this is using the mmap() function.

If writable is TRUE, the mapped buffer may be modified, otherwise it is an error to modify the mapped buffer. Modifications to the buffer are not visible to other processes mapping the same file, and are not written back to the file.

Note that modifications of the underlying file might affect the contents of the GMappedFile. Therefore, mapping should only be used if the file will not be modified, or if all modifications of the file are done atomically (e.g. using g_file_set_contents()).

If filename is the name of an empty, regular file, the function will successfully return an empty GMappedFile. In other cases of size 0 (e.g. device files such as /dev/null), error will be set to the GFileError value G_FILE_ERROR_INVAL.

Parameters

filename

The path of the file to load, in the GLib filename encoding

 

writable

whether the mapping should be writable

 

error

return location for a GError, or NULL

 

Returns

a newly allocated GMappedFile which must be unref'd with g_mapped_file_unref(), or NULL if the mapping failed.

Since: 2.8


g_mapped_file_new_from_fd ()

GMappedFile *
g_mapped_file_new_from_fd (gint fd,
                           gboolean writable,
                           GError **error);

Maps a file into memory. On UNIX, this is using the mmap() function.

If writable is TRUE, the mapped buffer may be modified, otherwise it is an error to modify the mapped buffer. Modifications to the buffer are not visible to other processes mapping the same file, and are not written back to the file.

Note that modifications of the underlying file might affect the contents of the GMappedFile. Therefore, mapping should only be used if the file will not be modified, or if all modifications of the file are done atomically (e.g. using g_file_set_contents()).

Parameters

fd

The file descriptor of the file to load

 

writable

whether the mapping should be writable

 

error

return location for a GError, or NULL

 

Returns

a newly allocated GMappedFile which must be unref'd with g_mapped_file_unref(), or NULL if the mapping failed.

Since: 2.32


g_mapped_file_ref ()

GMappedFile *
g_mapped_file_ref (GMappedFile *file);

Increments the reference count of file by one. It is safe to call this function from any thread.

Parameters

file

a GMappedFile

 

Returns

the passed in GMappedFile.

Since: 2.22


g_mapped_file_unref ()

void
g_mapped_file_unref (GMappedFile *file);

Decrements the reference count of file by one. If the reference count drops to 0, unmaps the buffer of file and frees it.

It is safe to call this function from any thread.

Since 2.22

Parameters

file

a GMappedFile

 

g_mapped_file_free ()

void
g_mapped_file_free (GMappedFile *file);

g_mapped_file_free has been deprecated since version 2.22 and should not be used in newly-written code.

Use g_mapped_file_unref() instead.

This call existed before GMappedFile had refcounting and is currently exactly the same as g_mapped_file_unref().

Parameters

file

a GMappedFile

 

Since: 2.8


g_mapped_file_get_length ()

gsize
g_mapped_file_get_length (GMappedFile *file);

Returns the length of the contents of a GMappedFile.

Parameters

file

a GMappedFile

 

Returns

the length of the contents of file .

Since: 2.8


g_mapped_file_get_contents ()

gchar *
g_mapped_file_get_contents (GMappedFile *file);

Returns the contents of a GMappedFile.

Note that the contents may not be zero-terminated, even if the GMappedFile is backed by a text file.

If the file is empty then NULL is returned.

Parameters

file

a GMappedFile

 

Returns

the contents of file , or NULL.

Since: 2.8


g_mapped_file_get_bytes ()

GBytes *
g_mapped_file_get_bytes (GMappedFile *file);

Creates a new GBytes which references the data mapped from file . The mapped contents of the file must not be modified after creating this bytes object, because a GBytes should be immutable.

Parameters

file

a GMappedFile

 

Returns

A newly allocated GBytes referencing data from file .

[transfer full]

Since: 2.34


g_open ()

int
g_open (const gchar *filename,
        int flags,
        int mode);

A wrapper for the POSIX open() function. The open() function is used to convert a pathname into a file descriptor.

On POSIX systems file descriptors are implemented by the operating system. On Windows, it's the C library that implements open() and file descriptors. The actual Win32 API for opening files is quite different, see MSDN documentation for CreateFile(). The Win32 API uses file handles, which are more randomish integers, not small integers like file descriptors.

Because file descriptors are specific to the C library on Windows, the file descriptor returned by this function makes sense only to functions in the same C library. Thus if the GLib-using code uses a different C library than GLib does, the file descriptor returned by this function cannot be passed to C library functions like write() or read().

See your C library manual for more details about open().

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

flags

as in open()

 

mode

as in open()

 

Returns

a new file descriptor, or -1 if an error occurred. The return value can be used exactly like the return value from open().

Since: 2.6


g_rename ()

int
g_rename (const gchar *oldfilename,
          const gchar *newfilename);

A wrapper for the POSIX rename() function. The rename() function renames a file, moving it between directories if required.

See your C library manual for more details about how rename() works on your system. It is not possible in general on Windows to rename a file that is open to some process.

Parameters

oldfilename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

newfilename

a pathname in the GLib file name encoding

 

Returns

0 if the renaming succeeded, -1 if an error occurred

Since: 2.6


g_mkdir ()

int
g_mkdir (const gchar *filename,
         int mode);

A wrapper for the POSIX mkdir() function. The mkdir() function attempts to create a directory with the given name and permissions. The mode argument is ignored on Windows.

See your C library manual for more details about mkdir().

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

mode

permissions to use for the newly created directory

 

Returns

0 if the directory was successfully created, -1 if an error occurred

Since: 2.6


g_stat ()

int
g_stat (const gchar *filename,
        GStatBuf *buf);

A wrapper for the POSIX stat() function. The stat() function returns information about a file. On Windows the stat() function in the C library checks only the FAT-style READONLY attribute and does not look at the ACL at all. Thus on Windows the protection bits in the st_mode field are a fabrication of little use.

On Windows the Microsoft C libraries have several variants of the stat struct and stat() function with names like _stat(), _stat32(), _stat32i64() and _stat64i32(). The one used here is for 32-bit code the one with 32-bit size and time fields, specifically called _stat32().

In Microsoft's compiler, by default struct stat means one with 64-bit time fields while in MinGW struct stat is the legacy one with 32-bit fields. To hopefully clear up this messs, the gstdio.h header defines a type GStatBuf which is the appropriate struct type depending on the platform and/or compiler being used. On POSIX it is just struct stat, but note that even on POSIX platforms, stat() might be a macro.

See your C library manual for more details about stat().

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

buf

a pointer to a stat struct, which will be filled with the file information

 

Returns

0 if the information was successfully retrieved, -1 if an error occurred

Since: 2.6


g_lstat ()

int
g_lstat (const gchar *filename,
         GStatBuf *buf);

A wrapper for the POSIX lstat() function. The lstat() function is like stat() except that in the case of symbolic links, it returns information about the symbolic link itself and not the file that it refers to. If the system does not support symbolic links g_lstat() is identical to g_stat().

See your C library manual for more details about lstat().

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

buf

a pointer to a stat struct, which will be filled with the file information

 

Returns

0 if the information was successfully retrieved, -1 if an error occurred

Since: 2.6


g_unlink ()

int
g_unlink (const gchar *filename);

A wrapper for the POSIX unlink() function. The unlink() function deletes a name from the filesystem. If this was the last link to the file and no processes have it opened, the diskspace occupied by the file is freed.

See your C library manual for more details about unlink(). Note that on Windows, it is in general not possible to delete files that are open to some process, or mapped into memory.

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

Returns

0 if the name was successfully deleted, -1 if an error occurred

Since: 2.6


g_remove ()

int
g_remove (const gchar *filename);

A wrapper for the POSIX remove() function. The remove() function deletes a name from the filesystem.

See your C library manual for more details about how remove() works on your system. On Unix, remove() removes also directories, as it calls unlink() for files and rmdir() for directories. On Windows, although remove() in the C library only works for files, this function tries first remove() and then if that fails rmdir(), and thus works for both files and directories. Note however, that on Windows, it is in general not possible to remove a file that is open to some process, or mapped into memory.

If this function fails on Windows you can't infer too much from the errno value. rmdir() is tried regardless of what caused remove() to fail. Any errno value set by remove() will be overwritten by that set by rmdir().

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

Returns

0 if the file was successfully removed, -1 if an error occurred

Since: 2.6


g_rmdir ()

int
g_rmdir (const gchar *filename);

A wrapper for the POSIX rmdir() function. The rmdir() function deletes a directory from the filesystem.

See your C library manual for more details about how rmdir() works on your system.

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

Returns

0 if the directory was successfully removed, -1 if an error occurred

Since: 2.6


g_fopen ()

FILE *
g_fopen (const gchar *filename,
         const gchar *mode);

A wrapper for the stdio fopen() function. The fopen() function opens a file and associates a new stream with it.

Because file descriptors are specific to the C library on Windows, and a file descriptor is part of the FILE struct, the FILE* returned by this function makes sense only to functions in the same C library. Thus if the GLib-using code uses a different C library than GLib does, the FILE* returned by this function cannot be passed to C library functions like fprintf() or fread().

See your C library manual for more details about fopen().

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

mode

a string describing the mode in which the file should be opened

 

Returns

A FILE* if the file was successfully opened, or NULL if an error occurred

Since: 2.6


g_freopen ()

FILE *
g_freopen (const gchar *filename,
           const gchar *mode,
           FILE *stream);

A wrapper for the POSIX freopen() function. The freopen() function opens a file and associates it with an existing stream.

See your C library manual for more details about freopen().

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

mode

a string describing the mode in which the file should be opened

 

stream

an existing stream which will be reused, or NULL.

[allow-none]

Returns

A FILE* if the file was successfully opened, or NULL if an error occurred.

Since: 2.6


g_chmod ()

int
g_chmod (const gchar *filename,
         int mode);

A wrapper for the POSIX chmod() function. The chmod() function is used to set the permissions of a file system object.

On Windows the file protection mechanism is not at all POSIX-like, and the underlying chmod() function in the C library just sets or clears the FAT-style READONLY attribute. It does not touch any ACL. Software that needs to manage file permissions on Windows exactly should use the Win32 API.

See your C library manual for more details about chmod().

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

mode

as in chmod()

 

Returns

0 if the operation succeeded, -1 on error

Since: 2.8


g_access ()

int
g_access (const gchar *filename,
          int mode);

A wrapper for the POSIX access() function. This function is used to test a pathname for one or several of read, write or execute permissions, or just existence.

On Windows, the file protection mechanism is not at all POSIX-like, and the underlying function in the C library only checks the FAT-style READONLY attribute, and does not look at the ACL of a file at all. This function is this in practise almost useless on Windows. Software that needs to handle file permissions on Windows more exactly should use the Win32 API.

See your C library manual for more details about access().

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

mode

as in access()

 

Returns

zero if the pathname refers to an existing file system object that has all the tested permissions, or -1 otherwise or on error.

Since: 2.8


g_creat ()

int
g_creat (const gchar *filename,
         int mode);

A wrapper for the POSIX creat() function. The creat() function is used to convert a pathname into a file descriptor, creating a file if necessary.

On POSIX systems file descriptors are implemented by the operating system. On Windows, it's the C library that implements creat() and file descriptors. The actual Windows API for opening files is different, see MSDN documentation for CreateFile(). The Win32 API uses file handles, which are more randomish integers, not small integers like file descriptors.

Because file descriptors are specific to the C library on Windows, the file descriptor returned by this function makes sense only to functions in the same C library. Thus if the GLib-using code uses a different C library than GLib does, the file descriptor returned by this function cannot be passed to C library functions like write() or read().

See your C library manual for more details about creat().

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

mode

as in creat()

 

Returns

a new file descriptor, or -1 if an error occurred. The return value can be used exactly like the return value from creat().

Since: 2.8


g_chdir ()

int
g_chdir (const gchar *path);

A wrapper for the POSIX chdir() function. The function changes the current directory of the process to path .

See your C library manual for more details about chdir().

Parameters

path

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

Returns

0 on success, -1 if an error occurred.

Since: 2.8


g_utime ()

int
g_utime (const gchar *filename,
         struct utimbuf *utb);

A wrapper for the POSIX utime() function. The utime() function sets the access and modification timestamps of a file.

See your C library manual for more details about how utime() works on your system.

Parameters

filename

a pathname in the GLib file name encoding (UTF-8 on Windows)

 

utb

a pointer to a struct utimbuf.

 

Returns

0 if the operation was successful, -1 if an error occurred

Since: 2.18


g_close ()

gboolean
g_close (gint fd,
         GError **error);

This wraps the close() call; in case of error, errno will be preserved, but the error will also be stored as a GError in error .

Besides using GError, there is another major reason to prefer this function over the call provided by the system; on Unix, it will attempt to correctly handle EINTR, which has platform-specific semantics.

Parameters

fd

A file descriptor

 

error

a GError

 

Returns

TRUE on success, FALSE if there was an error.

Since: 2.36

Types and Values

enum GFileError

Values corresponding to errno codes returned from file operations on UNIX. Unlike errno codes, GFileError values are available on all systems, even Windows. 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.

Members

G_FILE_ERROR_EXIST

Operation not permitted; only the owner of the file (or other resource) or processes with special privileges can perform the operation.

 

G_FILE_ERROR_ISDIR

File is a directory; you cannot open a directory for writing, or create or remove hard links to it.

 

G_FILE_ERROR_ACCES

Permission denied; the file permissions do not allow the attempted operation.

 

G_FILE_ERROR_NAMETOOLONG

Filename too long.

 

G_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.

 

G_FILE_ERROR_NOTDIR

A file that isn't a directory was specified when a directory is required.

 

G_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.

 

G_FILE_ERROR_NODEV

The underlying file system of the specified file does not support memory mapping.

 

G_FILE_ERROR_ROFS

The directory containing the new link can't be modified because it's on a read-only file system.

 

G_FILE_ERROR_TXTBSY

Text file busy.

 

G_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.)

 

G_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.

 

G_FILE_ERROR_NOSPC

No space left on device; write operation on a file failed because the disk is full.

 

G_FILE_ERROR_NOMEM

No memory available. The system cannot allocate more virtual memory because its capacity is full.

 

G_FILE_ERROR_MFILE

The current process has too many files open and can't open any more. Duplicate descriptors do count toward this limit.

 

G_FILE_ERROR_NFILE

There are too many distinct file openings in the entire system.

 

G_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).

 

G_FILE_ERROR_INVAL

Invalid argument. This is used to indicate various kinds of problems with passing the wrong argument to a library function.

 

G_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'.

 

G_FILE_ERROR_AGAIN

Resource temporarily unavailable; the call might work if you try again later.

 

G_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.

 

G_FILE_ERROR_IO

Input/output error; usually used for physical read or write errors. i.e. the disk or other physical device hardware is returning errors.

 

G_FILE_ERROR_PERM

Operation not permitted; only the owner of the file (or other resource) or processes with special privileges can perform the operation.

 

G_FILE_ERROR_NOSYS

Function not implemented; this indicates that the system is missing some functionality.

 

G_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.

 

G_FILE_ERROR

#define G_FILE_ERROR g_file_error_quark ()

Error domain for file operations. Errors in this domain will be from the GFileError enumeration. See GError for information on error domains.


enum GFileTest

A test to perform on a file using g_file_test().

Members

G_FILE_TEST_IS_REGULAR

TRUE if the file is a regular file (not a directory). Note that this test will also return TRUE if the tested file is a symlink to a regular file.

 

G_FILE_TEST_IS_SYMLINK

TRUE if the file is a symlink.

 

G_FILE_TEST_IS_DIR

TRUE if the file is a directory.

 

G_FILE_TEST_IS_EXECUTABLE

TRUE if the file is executable.

 

G_FILE_TEST_EXISTS

TRUE if the file exists. It may or may not be a regular file.

 

GDir

typedef struct _GDir GDir;

An opaque structure representing an opened directory.


GMappedFile

typedef struct _GMappedFile GMappedFile;

The GMappedFile represents a file mapping created with g_mapped_file_new(). It has only private members and should not be accessed directly.


GStatBuf

typedef struct _stat32 GStatBuf;

A type corresponding to the appropriate struct type for the stat() system call, depending on the platform and/or compiler being used.

See g_stat() for more information.