xnu-3248.20.55.tar.gz

[apple/xnu.git] / bsd / man / man2 / stat.2

diff --git a/bsd/man/man2/stat.2 b/bsd/man/man2/stat.2
index 53704ece88aea98009ed92e37c4279377c130d08..7282de5a91b76f2c131cf970d42c87cab042ff70 100644 (file)
--- a/bsd/man/man2/stat.2
+++ b/bsd/man/man2/stat.2
@@ -33,13 +33,17 @@
 .\"
 .\"     @(#)stat.2     8.3 (Berkeley) 4/19/94
 .\"
 .\"
 .\"     @(#)stat.2     8.3 (Berkeley) 4/19/94
 .\"

-.Dd April 19, 1994
+.Dd May 15, 2008

 .Dt STAT 2
 .Os BSD 4
 .Sh NAME
 .Nm fstat ,
 .Dt STAT 2
 .Os BSD 4
 .Sh NAME
 .Nm fstat ,

+.Nm fstat64 ,

 .Nm lstat ,
 .Nm lstat ,

-.Nm stat
+.Nm lstat64 ,
+.Nm stat ,
+.Nm stat64 ,
+.Nm fstatat

 .Nd get file status
 .Sh SYNOPSIS
 .Fd #include <sys/stat.h>
 .Nd get file status
 .Sh SYNOPSIS
 .Fd #include <sys/stat.h>


@@ -58,10 +62,31 @@
 .Fa "const char *restrict path"
 .Fa "struct stat *restrict buf"
 .Fc
 .Fa "const char *restrict path"
 .Fa "struct stat *restrict buf"
 .Fc

+.Ft int
+.Fn fstatat "int fd" "const char *path" "struct stat *buf" "int flag"
+.Sh TRANSITIIONAL SYNOPSIS (NOW DEPRECATED)
+.Ft int
+.br
+.Fo fstat64
+.Fa "int fildes"
+.Fa "struct stat64 *buf"
+.Fc ;
+.sp
+.Ft int
+.br
+.Fo lstat64
+.Fa "const char *restrict path"
+.Fa "struct stat64 *restrict buf"
+.Fc ;
+.sp
+.Ft int
+.br
+.Fo stat64
+.Fa "const char *restrict path"
+.Fa "struct stat64 *restrict buf"
+.Fc ;

 .Sh DESCRIPTION
 .Sh DESCRIPTION

-The
-.Fn stat
-family of functions obtain information about a file. The 
+The 

 .Fn stat 
 function obtains information about the file pointed to by
 .Fa path .
 .Fn stat 
 function obtains information about the file pointed to by
 .Fa path .


@@ -69,21 +94,19 @@ 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.
 .Pp
 permission of the named file is not required, but all directories
 listed in the path name leading to the file must be searchable.
 .Pp

-.Fn Lstat
+The
+.Fn lstat
+function

 is like
 .Fn stat
 is like
 .Fn stat

-except in the case where the named file is a symbolic link,
-in which case
+except in the case where the named file is a symbolic link;

 .Fn lstat
 returns information about the link,
 while
 .Fn stat
 returns information about the file the link references.
 .Fn lstat
 returns information about the link,
 while
 .Fn 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
+The attributes cannot be relied on in case of symbolic links.
+In this case, the only attributes returned from an

 .Fn lstat
 that refer to the symbolic link itself are the file type (S_IFLNK),
 size, blocks, and link count (always 1).
 .Fn lstat
 that refer to the symbolic link itself are the file type (S_IFLNK),
 size, blocks, and link count (always 1).


@@ -95,6 +118,48 @@ known by the file descriptor
 .Fa fildes .
 .Pp
 The
 .Fa fildes .
 .Pp
 The

+.Fn fstatat
+system call is equivalent to
+.Fn stat
+and
+.Fn lstat
+except in the case where the
+.Fa path
+specifies a relative path.
+In this case the status is retrieved from a file relative to
+the directory associated with the file descriptor
+.Fa fd
+instead of the current working directory.
+.Pp
+The values for the
+.Fa flag
+are constructed by a bitwise-inclusive OR of flags from the following list,
+defined in
+.In fcntl.h :
+.Bl -tag -width indent
+.It Dv AT_SYMLINK_NOFOLLOW
+If
+.Fa path
+names a symbolic link, the status of the symbolic link is returned.
+.El
+.Pp
+If
+.Fn fstatat
+is passed the special value
+.Dv AT_FDCWD
+in the
+.Fa fd
+parameter, the current working directory is used and the behavior is
+identical to a call to
+.Fn stat
+or
+.Fn lstat
+respectively, depending on whether or not the
+.Dv AT_SYMLINK_NOFOLLOW
+bit is set in
+.Fa flag .
+.Pp
+The

 .Fa buf
 argument is a pointer to a
 .Fa stat
 .Fa buf
 argument is a pointer to a
 .Fa stat


@@ -102,8 +167,38 @@ structure
 as defined by
 .Aq Pa sys/stat.h
 and into which information is placed concerning the file.
 as defined by
 .Aq Pa sys/stat.h
 and into which information is placed concerning the file.

+When the macro
+.Dv _DARWIN_FEATURE_64_BIT_INODE
+is not defined (see below for more information about this macro), the
+.Fa stat
+structure is defined as:
+.Bd -literal
+struct stat { /* when _DARWIN_FEATURE_64_BIT_INODE is NOT defined */
+    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 of 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 */
+    struct timespec st_atimespec;  /* time of last access */
+    struct timespec st_mtimespec;  /* time of last data modification */
+    struct timespec st_ctimespec;  /* time of last file status change */
+    off_t    st_size;   /* file size, in bytes */
+    quad_t   st_blocks; /* blocks allocated for file */
+    u_long   st_blksize;/* optimal file sys I/O ops blocksize */
+    u_long   st_flags;  /* user defined flags for file */
+    u_long   st_gen;    /* file generation number */
+};
+.Ed
+.Pp
+However, when the macro
+.Dv _DARWIN_FEATURE_64_BIT_INODE
+is defined, the
+.Fa stat
+structure will now be defined as:

 .Bd -literal
 .Bd -literal

-struct stat {
+struct stat { /* when _DARWIN_FEATURE_64_BIT_INODE is defined */

     dev_t           st_dev;           /* ID of device containing file */
     mode_t          st_mode;          /* Mode of file (see below) */
     nlink_t         st_nlink;         /* Number of hard links */
     dev_t           st_dev;           /* ID of device containing file */
     mode_t          st_mode;          /* Mode of file (see below) */
     nlink_t         st_nlink;         /* Number of hard links */


@@ -123,8 +218,6 @@ struct stat {
     int32_t         st_lspare;        /* RESERVED: DO NOT USE! */
     int64_t         st_qspare[2];     /* RESERVED: DO NOT USE! */
 };
     int32_t         st_lspare;        /* RESERVED: DO NOT USE! */
     int64_t         st_qspare[2];     /* RESERVED: DO NOT USE! */
 };

-
-

 .Ed
 .Pp
 The time-related fields of
 .Ed
 .Pp
 The time-related fields of


@@ -161,10 +254,9 @@ and
 .Xr write 2
 system calls.
 .It st_birthtime
 .Xr write 2
 system calls.
 .It st_birthtime

-Time of file creation. Only set once when the file is created.
-On filesystems where birthtime is not available, this field holds the
-.Fa ctime
-instead.
+Time of file creation. Only set once when the file is created. This field is 
+only available in the 64 bit inode variants. On filesystems where birthtime is 
+not available, this field is set to 0 (i.e. epoch).

 .El
 .Pp
 The size-related fields of the structures are as follows:
 .El
 .Pp
 The size-related fields of the structures are as follows:


@@ -210,6 +302,141 @@ field, see
 .Aq Pa sys/stat.h
 and
 .Xr chflags 2 .
 .Aq Pa sys/stat.h
 and
 .Xr chflags 2 .

+.Sh _DARWIN_FEATURE_64_BIT_INODE
+In order to accommodate advanced capabilities of newer file systems, the 
+.Fa struct stat ,
+.Fa struct statfs ,
+and
+.Fa struct dirent
+data structures were updated in Mac OSX 10.5.
+.Pp
+The most obvious change is the increased size of
+.Fa ino_t
+from 32 bits to 64 bits.  As a consequence, storing an ino_t in an int is
+no longer safe, and file formats storing ino_t as 32-bit values may need to
+be updated.  There are other changes as well, such as the widening of
+.Fa f_fstypename ,
+.Fa f_mntonname ,
+and
+.Fa f_mntfromname
+in
+.Fa struct statfs .
+Please refer to
+.Xr stat 2
+and
+.Xr dir 5
+for more detail on the specific changes to the other affected data structures.
+.Pp
+On platforms that existed before these updates were available, ABI
+compatibility is achieved by providing two implementations for related
+functions: one using the legacy data structures and one using the updated
+data structures.  Variants which make use of the newer structures have their
+symbols suffixed with $INODE64.  These $INODE64 suffixes are automatically
+appended by the compiler tool-chain and should not be used directly.
+.Pp
+Platforms that were released after these updates only have the newer variants
+available to them.  These platforms have the macro
+.Dv _DARWIN_FEATURE_ONLY_64_BIT_INODE
+defined.
+.Pp
+The
+.Dv _DARWIN_FEATURE_64_BIT_INODE
+macro should not be set directly.  Instead, developers should make use of the
+.Dv _DARWIN_NO_64_BIT_INODE
+or
+.Dv _DARWIN_USE_64_BIT_INODE
+macros when the default variant is not desired.  The following table details
+the effects of defining these macros for different deployment targets.
+.Pp
+.TS
+center;
+c s s s
+l | c s s
+c | c c c
+c | c c c
+l | c c c.
+T{
+.Dv _DARWIN_FEATURE_ONLY_64_BIT_INODE Sy not defined
+T}
+=
+       Deployment Target
+user defines:  < 10.5  10.5    > 10.5
+_
+T{
+.Em (none)
+T}     32-bit  32-bit  64-bit
+T{
+.Dv _DARWIN_NO_64_BIT_INODE
+T}     32-bit  32-bit  32-bit
+T{
+.Dv _DARWIN_USE_64_BIT_INODE
+T}     32-bit  64-bit  64-bit
+_
+.T&
+c s s s
+c s s s
+c | l s s
+c | c c c
+l | c c c.
+
+T{
+.Dv _DARWIN_FEATURE_ONLY_64_BIT_INODE Sy defined
+T}
+=
+user defines:  Any Deployment Target
+_
+T{
+.Em (none)
+T}     64-bit-only
+T{
+.Dv _DARWIN_NO_64_BIT_INODE
+T}     T{
+.Em (error)
+T}
+T{
+.Dv _DARWIN_USE_64_BIT_INODE
+T}     64-bit-only
+_
+.TE
+.Pp
+.Bl -tag -width 64-bit-only -offset indent
+.It 32-bit
+32-bit inode values are enabled, and the legacy structures involving the
+.Vt ino_t
+type are in use.
+The macro
+.Dv _DARWIN_FEATURE_64_BIT_INODE
+is not defined.
+.It 64-bit
+64-bit inode values are enabled, and the expanded structures involving the
+.Vt ino_t
+type are in use.
+The macro
+.Dv _DARWIN_FEATURE_64_BIT_INODE
+is defined, and loader symbols will contain the
+.Li $INODE64
+suffix.
+.It 64-bit-only
+Like 64-bit, except loader symbols do not have the
+.Li $INODE64
+suffix.
+.It Em (error)
+A compile time error is generated.
+.El
+.Pp
+Due to the increased benefits of the larger structure, it is highly
+recommended that developers not define
+.Dv _DARWIN_NO_64_BIT_INODE
+and make use of
+.Dv _DARWIN_USE_64_BIT_INODE
+when targeting Mac OSX 10.5.
+.Pp
+In addition to the $INODE64 suffixed symbols, variants suffixed with 64 are
+also available for related functions.  These functions were provided as a way
+for developers to use the updated structures in code that also made use of
+the legacy structures.  The enlarged stat structures were also prefixed with
+64 to distinguish them from their legacy variants.  These functions have been
+deprecated and should be avoided.

 .Sh RETURN VALUES
 Upon successful completion a value of 0 is returned.
 Otherwise, a value of -1 is returned and
 .Sh RETURN VALUES
 Upon successful completion a value of 0 is returned.
 Otherwise, a value of -1 is returned and


@@ -296,16 +523,75 @@ or the file serial number cannot be represented correctly
 in the structure pointed to by
 .Fa buf .
 .El
 in the structure pointed to by
 .Fa buf .
 .El

+.Pp
+In addition to the errors returned by the
+.Fn stat
+and
+.Fn lstat ,
+.Fn fstatat
+may fail if:
+.Bl -tag -width Er
+.It Bq Er EBADF
+The
+.Fa path
+argument does not specify an absolute path and the
+.Fa fd
+argument is neither
+.Dv AT_FDCWD
+nor a valid file descriptor open for searching.
+.It Bq Er EINVAL
+The value of the
+.Fa flag
+argument is not valid.
+.It Bq Er ENOTDIR
+The
+.Fa path
+argument is not an absolute path and
+.Fa fd
+is neither
+.Dv AT_FDCWD
+nor a file descriptor associated with a directory.
+.El

 .Sh CAVEATS
 The file generation number,
 .Fa st_gen ,
 is only available to the super-user.
 .Sh CAVEATS
 The file generation number,
 .Fa st_gen ,
 is only available to the super-user.

+.br
+The fields in the stat structure currently marked
+.Fa st_spare1 ,
+.Fa st_spare2 ,
+and
+.Fa st_spare3
+are present in preparation for inode time stamps expanding
+to 64 bits.  This, however, can break certain programs that
+depend on the time stamps being contiguous (in calls to
+.Xr utimes 2 ) .
+.Sh TRANSITIONAL DESCRIPTION (NOW DEPRECATED)
+The
+.Fa fstat64 ,
+.Fa lstat64
+and
+.Fa stat64
+routines are equivalent to their corresponding non-64-suffixed routine,
+when 64-bit inodes are in effect.
+They were added before there was support for the symbol variants, and so are
+now deprecated.
+Instead of using these, set the
+.Dv _DARWIN_USE_64_BIT_INODE
+macro before including header files to force 64-bit inode support.
+.Pp
+The
+.Fa stat64
+structure used by these deprecated routines is the same as the
+.Fa stat
+structure when 64-bit inodes are in effect (see above).

 .Sh SEE ALSO
 .Xr chflags 2 ,
 .Xr chmod 2 ,
 .Xr chown 2 ,
 .Xr utimes 2 ,
 .Xr compat 5 ,
 .Sh SEE ALSO
 .Xr chflags 2 ,
 .Xr chmod 2 ,
 .Xr chown 2 ,
 .Xr utimes 2 ,
 .Xr compat 5 ,

+.Xr statfs 2 ,

 .Xr symlink 7
 .Sh BUGS
 Applying
 .Xr symlink 7
 .Sh BUGS
 Applying


@@ -321,8 +607,21 @@ and
 .Fn fstat
 function calls are expected to conform to 
 .St -p1003.1-88 .
 .Fn fstat
 function calls are expected to conform to 
 .St -p1003.1-88 .

+The
+.Fn fstatat
+system call is expected to conform to POSIX.1-2008 .

 .Sh HISTORY
 An
 .Fn lstat
 function call appeared in
 .Bx 4.2 .
 .Sh HISTORY
 An
 .Fn lstat
 function call appeared in
 .Bx 4.2 .

+The 
+.Fn stat64 ,
+.Fn fstat64 ,
+and
+.Fn lstat64
+system calls first appeared in Mac OS X 10.5 (Leopard) and are now deprecated
+in favor of the corresponding symbol variants.
+The
+.Fn fstatat
+system call appeared in OS X 10.10