gno/usr.man/man2/stat.2

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.\"     @(#)stat.2	8.3 (Berkeley) 4/19/94
.\"
.TH STAT 2 "19 January 1997" "BSD 4" "System Calls"
.SH NAME
.BR stat ,
.BR lstat ,
.BR fstat
\- get file status
.SH SYNOPSIS
#include <sys/types.h>
.br
#include <sys/stat.h>
.sp 1
int
\fBstat\fR (const char *\fIpath\fR, struct stat *\fIsb\fR);
.br
int
\fBlstat\fR (const char *\fIpath\fR, struct stat *\fIsb\fR);
.br
int
\fBfstat\fR (int \fIfd\fR, struct stat *\fIsb\fR);
.SH DESCRIPTION
These calls are used to retrieve status information about files.
They do much the same think as the GS/OS call
.BR GetFileInfoGS ,
except that they return the information in a format compatible with
Unix's
.BR stat
calls, and also provide information about sockets and GNO character
devices.
.LP
The
.BR stat 
function obtains information about the file pointed to by
.IR path .
Read, write or execute
permission of the named file is not required, but all directories
listed in the path name leading to the file must be searchable.
.LP
.BR lstat 
is like
.BR stat 
except in the case where the named file is a symbolic link,
in which case
.BR lstat 
returns information about the link,
while
.BR stat 
returns information about the file the link references.
Unlike other filesystem objects,
symbolic links do not have an owner, group, access mode, times, etc.
Instead, these attributes are taken from the directory that
contains the link.
The only attributes returned from an
.BR lstat 
that refer to the symbolic link itself are the file type (S_IFLNK),
size, blocks, and link count (always 1).
.LP
The
.BR fstat 
obtains the same information about an open file
known by the file descriptor
.IR fd .
.LP
The
.I sb
argument is a pointer to a
.BR stat 
structure
as defined by <sys/stat.h>
(shown below)
and into which information is placed concerning the file.
.nf
struct stat {
    dev_t    st_dev;    /* device inode resides on */
    ino_t    st_ino;    /* inode's number */
    mode_t   st_mode;   /* inode protection mode */
    nlink_t  st_nlink;  /* number or hard links to the file */
    uid_t    st_uid;    /* user-id of owner */
    gid_t    st_gid;    /* group-id of owner */
    dev_t    st_rdev;   /* device type, for special file inode */
    off_t    st_size;   /* file size, in bytes */
    time_t   st_atime;  /* time of last access (GNO: same as st_mtime) */
    int      st_spare1; /* reserved */
    time_t   st_mtime;  /* time of last data modification */
    int      st_spare2; /* reserved */
    time_t   st_ctime;  /* time of last file status change */
    int      st_spare3; /* reserved */
    long     st_blksize;/* size in bytes of blocks on filesystem */
    long     st_blocks; /* blocks allocated for file */
    long     st_spare4[2]; /* reserved */
}
.fi
.LP
The items marked 'reserved' are not currently used but are reserved
for future expansion; do not use these fields for any reason.
.BR st_dev
is the number of the device on which the file resides.  This number
is the same as the GS/OS device ID number.
.BR st_rdev
is not currently used, but may in the future designate a device type
code.
.LP
As short symbolic links are stored in the inode, 
.IR st_blocks
may be zero.
.LP
The status information word
.I st_mode
has the following bits:
.nf
#define S_IFCHR  0020000  /* character special */
#define S_IFDIR  0040000  /* directory */
#define S_IFBLK  0060000  /* block special */
#define S_IFREG  0100000  /* regular */
#define S_IFLNK  0120000  /* symbolic link */
#define S_IFSOCK 0140000  /* socket */
#define S_IRUSR  0000400  /* read permission, owner */
#define S_IWUSR  0000200  /* write permission, owner */
#define S_IXUSR  0000100  /* execute/search permission, owner */
.fi
.LP
For a list of access modes, see <sys/stat.h>,
.BR access (2)
and
.BR chmod (2).
.SH RETURN VALUES
Upon successful completion a value of 0 is returned.
Otherwise, a value of -1 is returned and
.IR errno
is set to indicate the error.
.SH COMPATIBILITY
BSD uses a larger set of defined fields than does GNO.  The types
of the fields also, in general, differ.
.LP
The
.BR stat
man page for GNO v2.0.4 documented the macros
.BR S_IREAD ,
.BR S_IWRITE ,
and 
.BR S_IEXEC .
These macros are still available in <sys/stat.h> provided that
.BR _POSIX_SOURCE
is not defined.
.SH ERRORS
.BR Stat 
and
.BR lstat 
will fail if:
.RS
.IP \fBENOTDIR\fR
A component of the path prefix is not a directory.
.IP \fBENOENT\fR
The named file does not exist.
.IP \fBEBADF\fR
.IR fd
does not refer to an open file.
.RE
.LP
.RS
.BR Fstat 
will fail if:
.IP \fBEBADF\fR
.I fd
is not a valid open file descriptor.
.IP \fBEIO\fR
An I/O error occurred while reading from or writing to the file system.
.RE
.SH SEE ALSO
.BR chmod (2),
.BR chown (2),
.BR utimes (2)
.BR symlink (7)
.SH BUGS
GNO does not yet support hard or symbolic file links on the IIgs.  Therefore,
.BR lstat
operates exactly like
.BR stat .
If there's a case where
.BR lstat 
might be more appropriate at a time when links are supported, then use
.BR lstat
instead and be ready for the future.
.LP
.BR fstat
doesn't do anything clever with all the unused fields when its argument is
a pipe or terminal.
.SH STANDARDS
The
.BR stat 
and
.BR fstat 
function calls are close, but do not conform, to IEEE Std 1003.1-1988 (POSIX).
In particular, 
.RS
.LP
\- this implementation does not make the distinction of file ownership;
.LP
\- not all the required error return codes are implemented; and
.LP
\- file access time mirrors modification time.
.RE
.SH HISTORY
An
.BR lstat
function call appeared in 4.2BSD.