f90_unix_file: Unix File Operations Module

Table of Contents

1 Name

f90_unix_file — Module of Unix file operations

2 Usage

USE F90_UNIX_FILE

This module contains part of a Fortran API to functions detailed in ISO/IEC 9945-1:1990 Portable Operating System Interface (POSIX) - Part 1: System Application Program Interface (API) [C Language].

The functions in this module are from Section 5.6 File Characteristics.

Error handling is described in F90_UNIX_ERRNO. Note that for procedures with an optional ERRNO argument, if an error occurs and ERRNO is not present, the program will be terminated.

All the procedures in this module are generic; some may be specific but this is subject to change in a future release.

3 Synopsis

Parameters
F_OK, ID_KIND (from F90_UNIX_ENV), MODE_KIND (from F90_UNIX_DIR), R_OK, S_IRGRP, S_IROTH, S_IRUSR, S_IRWXG, S_IRWXO, S_IRWXU, S_ISGID, S_ISUID, S_IWGRP, S_IWOTH, S_IWUSR, S_IXGRP, S_IXOTH, S_IXUSR, TIME_KIND (from F90_UNIX_ENV), W_OK, X_OK.
Derived Types
STAT_T, UTIMBUF.
Generic Procedures
ACCESS, CHMOD, CHOWN, FSTAT, STAT, S_ISBLK, S_ISCHR, S_ISDIR, S_ISFIFO, S_ISREG, UTIME.

Note that some of these generic procedures might also be specific; these characteristics could change in a future release.

4 Parameter Description

INTEGER(int32),PARAMETER :: F_OK
Flag for requesting file existence check (see ACCESS).

USE F90_UNIX_ENV,ONLY:ID_KIND
See F90_UNIX_ENV for a description of this parameter.

USE F90_UNIX_DIR,ONLY:MODE_KIND
See F90_UNIX_DIR for a description of this parameter.

INTEGER(int32),PARAMETER :: R_OK
Flag for requesting file readability check (see ACCESS).

INTEGER(MODE_KIND),PARAMETER :: S_IRGRP
File mode bit indicating group read permission (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_IROTH
File mode bit indicating other read permission (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_IRUSR
File mode bit indicating user read permission (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_IRWXG
Mask to select the group accessibility bits from a file mode (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_IRWXO
Mask to select the other accessibility bits from a file mode (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_IRWXU
Mask to select the user accessibility bits from a file mode (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_ISGID
File mode bit indicating that the file is set-group-ID (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_ISUID
File mode bit indicating that the file is set-user-ID (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_IWGRP
File mode bit indicating group write permission (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_IWOTH
File mode bit indicating other write permission (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_IWUSR
File mode bit indicating user write permission (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_IXGRP
File mode bit indicating group execute permission (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_IXOTH
File mode bit indicating other execute permission (see STAT_T).

INTEGER(MODE_KIND),PARAMETER :: S_IXUSR
File mode bit indicating user execute permission (see STAT_T).

USE F90_UNIX_ENV,ONLY :: TIME_KIND
See F90_UNIX_ENV for a description of this parameter.

INTEGER(int32),PARAMETER :: W_OK
Flag for requesting file writability check (see ACCESS).

INTEGER(int32),PARAMETER :: X_OK
Flag for requesting file executability check (see ACCESS).

5 Derived-Type Description

TYPE stat_t
    INTEGER(MODE_KIND) st_mode
    INTEGER(...) st_ino
    INTEGER(...) st_dev
    INTEGER(...) st_nlink
    INTEGER(id_kind) st_uid
    INTEGER(id_kind) st_gid
    INTEGER(...) st_size
    INTEGER(TIME_KIND) st_atime, st_mtime, st_ctime
END TYPE
Derived type holding file characteristics.
ST_MODE
File mode (read/write/execute permission for user/group/other, plus set-group-ID and set-user-ID bits).
ST_INO
File serial number.
ST_DEV
ID for the device on which the file resides.
ST_NLINK
The number of links (see F90_UNIX_DIR, LINK operation) to the file.
ST_UID
User number of the file's owner.
ST_GID
Group number of the file.
ST_SIZE
File size in bytes (regular files only).
ST_ATIME
Time of last access.
ST_MTIME
Time of last modification.
ST_CTIME
Time of last file status change.

TYPE UTIMBUF
    INTEGER(time_kind) actime, modtime
END TYPE
Data type holding time values for communication to UTIME. ACTIME is the new value for ST_ATIME, MODTIME is the new value for ST_MTIME.

6 Procedure Description

PURE SUBROUTINE access(path,amode,errno)
    CHARACTER(*),INTENT(IN) :: path
    INTEGER(*),INTENT(IN) :: amode
    INTEGER(error_kind),INTENT(OUT) :: errno
Checks file accessibility according to the value of AMODE; this should be F_OK or a combination of R_OK, W_OK and X_OK. In the latter case the values may be combined by addition or the intrinsic function IOR.

The result of the accessibility check is returned in ERRNO, which receives zero for success (i.e. the file exists for F_OK, or all the accesses requested by the R_OK et al combination are allowed) or an error code indicating the reason for access rejection. Possible rejection codes include EACCES, ENAMETOOLONG, ENOENT, ENOTDIR and EROFS (see F90_UNIX_ERRNO).

If the value of AMODE is invalid, error EINVAL is returned.

Note that most ACCESS enquiries are equivalent to an INQUIRE statement, in particular:

CALL ACCESS(PATH,F_OK,ERRNO)
returns success (ERRNO==0) if and only if
INQUIRE(FILE=PATH,EXIST=LVAR) would set LVAR to .TRUE.;
CALL ACCESS(PATH,R_OK,ERRNO)
returns success (ERRNO==0) if and only if
INQUIRE(FILE=PATH,READ=CHVAR) would set CHVAR to 'YES';
CALL ACCESS(PATH,W_OK,ERRNO)
returns success (ERRNO==0) if and only if
INQUIRE(FILE=PATH,WRITE=CHVAR) would set CHVAR to 'YES';
CALL ACCESS(PATH,IOR(W_OK,R_OK),ERRNO)
returns success (ERRNO==0) if and only if
INQUIRE(FILE=PATH,READWRITE=CHVAR) would set CHVAR to 'YES'.
The only differences being that ACCESS returns a reason for rejection, and can test file executability.

SUBROUTINE CHMOD(PATH,MODE,ERRNO)
    CHARACTER(*),INTENT(IN) :: PATH
    INTEGER(*),INTENT(IN) :: MODE
    INTEGER(error_kind),OPTIONAL,INTENT(OUT) :: ERRNO
Sets the file mode (ST_MODE) to MODE.

Possible errors include EACCES, ENAMETOOLONG, ENOTDIR, EPERM and EROFS (see F90_UNIX_ERRNO).

SUBROUTINE CHOWN(PATH,OWNER,GROUP,ERRNO)
    CHARACTER(*),INTENT(IN) :: PATH
    INTEGER(id_kind),INTENT(IN) :: OWNER, GROUP
    INTEGER(error_kind),OPTIONAL,INTENT(OUT) :: ERRNO
Changes the owner (ST_UID) of file PATH to OWNER, and the group number (ST_GID) of the file to GROUP.

Possible errors include EACCES, EINVAL, ENAMETOOLONG, ENOTDIR, ENOENT, EPERM and EROFS (see F90_UNIX_ERRNO).

SUBROUTINE FSTAT(LUNIT,BUF,ERRNO)
    INTEGER(*),INTENT(IN) :: LUNIT
    TYPE(stat_t),INTENT(OUT) :: BUF
    INTEGER(error_kind),OPTIONAL,INTENT(OUT) :: ERRNO
BUF receives the characteristics of the file connected to logical unit LUNIT.

If LUNIT is not a valid logical unit number or is not connected to a file, error EBADF is raised (see F90_UNIX_ERRNO).

PURE LOGICAL(word) FUNCTION s_isblk(mode)
    INTEGER(mode_kind),INTENT(IN) :: mode

Returns .TRUE. if and only if the MODE value indicates that the file is a “block device”.

PURE LOGICAL(word) FUNCTION s_ischr(mode)
    INTEGER(mode_kind),INTENT(IN) :: mode

Returns .TRUE. if and only if the MODE value indicates that the file is a “character device”.

PURE LOGICAL(word) FUNCTION s_isdir(mode)
    INTEGER(mode_kind),INTENT(IN) :: mode

Returns .TRUE. if and only if the MODE value indicates that the file is a directory (or folder).

PURE LOGICAL(word) FUNCTION s_isfifo(mode)
    INTEGER(mode_kind),INTENT(IN) :: mode

Returns .TRUE. if and only if the MODE value indicates that the file is a “FIFO” (named or unnamed pipe).

PURE LOGICAL(word) FUNCTION s_isreg(mode)
    INTEGER(mode_kind),INTENT(IN) :: mode

Returns .TRUE. if and only if the MODE value indicates that the file is a “regular” (i.e. normal) file.

SUBROUTINE STAT(PATH,BUF,ERRNO)
    CHARACTER(*),INTENT(IN) :: PATH
    TYPE(stat_t),INTENT(OUT) :: BUF
    INTEGER(error_kind),OPTIONAL,INTENT(OUT) :: ERRNO
BUF receives the characteristics of the file PATH.

Possible errors include EACCES, ENAMETOOLONG, ENOENT and ENOTDIR (see F90_UNIX_ERRNO).

SUBROUTINE utime(path,times,errno)
    CHARACTER(*),INTENT(IN) :: path
    TYPE(utimbuf),OPTIONAL,INTENT(IN) :: times
    INTEGER(error_kind),OPTIONAL,INTENT(OUT) :: errno

Set the access and modification times of the file named by PATH to those specified by the ACTIME and MODTIME components of TIMES respectively.

Possible errors include EACCES, ENAMETOOLONG, ENOENT, ENOTDIR, EPERM and EROFS (see F90_UNIX_ERRNO).

7 See Also

f90_unix_dir(3), f90_unix_env(3), f90_unix_errno(3), intro(3), nag_modules(3), nagfor(1).

8 Bugs

Please report any bugs found to ‘support@nag.co.uk’ or ‘support@nag.com’, along with any suggestions for improvements.