@c @c COPYRIGHT (c) 1988-2002. @c On-Line Applications Research Corporation (OAR). @c All rights reserved. @c @c $Id$ @c @chapter Files and Directories Manager @section Introduction The files and directories manager is ... The directives provided by the files and directories manager are: @itemize @bullet @item @code{opendir} - Open a Directory @item @code{readdir} - Reads a directory @item @code{rewinddir} - Resets the @code{readdir()} pointer @item @code{scandir} - Scan a directory for matching entries @item @code{telldir} - Return current location in directory stream @item @code{closedir} - Ends directory read operation @item @code{getdents} - Get directory entries @item @code{chdir} - Changes the current working directory @item @code{fchdir} - Changes the current working directory @item @code{getcwd} - Gets current working directory @item @code{open} - Opens a file @item @code{creat} - Create a new file or rewrite an existing one @item @code{umask} - Sets a file creation mask @item @code{link} - Creates a link to a file @item @code{symlink} - Creates a symbolic link to a file @item @code{readlink} - Obtain the name of the link destination @item @code{mkdir} - Makes a directory @item @code{mkfifo} - Makes a FIFO special file @item @code{unlink} - Removes a directory entry @item @code{rmdir} - Delete a directory @item @code{rename} - Renames a file @item @code{stat} - Gets information about a file. @item @code{fstat} - Gets file status @item @code{lstat} - Gets file status @item @code{access} - Check permissions for a file. @item @code{chmod} - Changes file mode @item @code{fchmod} - Changes permissions of a file @item @code{chown} - Changes the owner and/ or group of a file @item @code{utime} - Change access and/or modification times of an inode @item @code{ftruncate} - Truncate a file to a specified length @item @code{truncate} - Truncate a file to a specified length @item @code{pathconf} - Gets configuration values for files @item @code{fpathconf} - Get configuration values for files @item @code{mknod} - Create a directory @end itemize @section Background @subsection Path Name Evaluation A pathname is a string that consists of no more than @code{PATH_MAX} bytes, including the terminating null character. A pathname has an optional beginning slash, followed by zero or more filenames separated by slashes. If the pathname refers to a directory, it may also have one or more trailing slashes. Multiple successive slahes are considered to be the same as one slash. POSIX allows a pathname that begins with precisely two successive slashes to be interpreted in an implementation-defined manner. RTEMS does not currently recognize this as a special condition. Any number of successive slashes is treated the same as a single slash. POSIX requires that an implementation treat more than two leading slashes as a single slash. @section Operations There is currently no text in this section. @section Directives This section details the files and directories manager's directives. A subsection is dedicated to each of this manager's directives and describes the calling sequence, related constants, usage, and status codes. @c @c @c @page @subsection opendir - Open a Directory @findex opendir @cindex open a directory @subheading CALLING SEQUENCE: @ifset is-C @example #include #include int opendir( const char *dirname ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission was denied on a component of the path prefix of @code{dirname}, or read permission is denied @item EMFILE Too many file descriptors in use by process @item ENFILE Too many files are currently open in the system. @item ENOENT Directory does not exist, or @code{name} is an empty string. @item ENOMEM Insufficient memory to complete the operation. @item ENOTDIR @code{name} is not a directory. @end table @subheading DESCRIPTION: This routine opens a directory stream corresponding to the directory specified by the @code{dirname} argument. The directory stream is positioned at the first entry. @subheading NOTES: The routine is implemented in Cygnus newlib. @c @c @c @page @subsection readdir - Reads a directory @findex readdir @cindex reads a directory @subheading CALLING SEQUENCE: @ifset is-C @example #include #include int readdir( DIR *dirp ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EBADF Invalid file descriptor @end table @subheading DESCRIPTION: The @code{readdir()} function returns a pointer to a structure @code{dirent} representing the next directory entry from the directory stream pointed to by @code{dirp}. On end-of-file, NULL is returned. The @code{readdir()} function may (or may not) return entries for . or .. Your program should tolerate reading dot and dot-dot but not require them. The data pointed to be @code{readdir()} may be overwritten by another call to @code{readdir()} for the same directory stream. It will not be overwritten by a call for another directory. @subheading NOTES: If @code{ptr} is not a pointer returned by @code{malloc()}, @code{calloc()}, or @code{realloc()} or has been deallocated with @code{free()} or @code{realloc()}, the results are not portable and are probably disastrous. The routine is implemented in Cygnus newlib. @c @c @c @page @subsection rewinddir - Resets the readdir() pointer @findex rewinddir @cindex resets the readdir() pointer @subheading CALLING SEQUENCE: @ifset is-C @example #include #include void rewinddir( DIR *dirp ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: No value is returned. @subheading DESCRIPTION: The @code{rewinddir()} function resets the position associated with the directory stream pointed to by @code{dirp}. It also causes the directory stream to refer to the current state of the directory. @subheading NOTES: NONE If @code{dirp} is not a pointer by @code{opendir()}, the results are undefined. The routine is implemented in Cygnus newlib. @c @c @c @page @subsection scandir - Scan a directory for matching entries @findex scandir @cindex scan a directory for matching entries @subheading CALLING SEQUENCE: @ifset is-C @example #include int scandir( const char *dir, struct dirent ***namelist, int (*select)(const struct dirent *), int (*compar)(const struct dirent **, const struct dirent **) ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item ENOMEM Insufficient memory to complete the operation. @end table @subheading DESCRIPTION: The @code{scandir()} function scans the directory @code{dir}, calling @code{select()} on each directory entry. Entries for which @code{select()} returns non-zero are stored in strings allocated via @code{malloc()}, sorted using @code{qsort()} with the comparison function @code{compar()}, and collected in array @code{namelist} which is allocated via @code{malloc()}. If @code{select} is NULL, all entries are selected. @subheading NOTES: The routine is implemented in Cygnus newlib. @c @c @c @page @subsection telldir - Return current location in directory stream @findex telldir @cindex return current location in directory stream @subheading CALLING SEQUENCE: @ifset is-C @example #include off_t telldir( DIR *dir ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EBADF Invalid directory stream descriptor @code{dir}. @end table @subheading DESCRIPTION: The @code{telldir()} function returns the current location associated with the directory stream @code{dir}. @subheading NOTES: The routine is implemented in Cygnus newlib. @c @c @c @page @subsection closedir - Ends directory read operation @findex closedir @cindex ends directory read operation @subheading CALLING SEQUENCE: @ifset is-C @example #include #include int closedir( DIR *dirp ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EBADF Invalid file descriptor @end table @subheading DESCRIPTION: The directory stream associated with @code{dirp} is closed. The value in @code{dirp} may not be usable after a call to @code{closedir()}. @subheading NOTES: NONE The argument to @code{closedir()} must be a pointer returned by @code{opendir()}. If it is not, the results are not portable and most likely unpleasant. The routine is implemented in Cygnus newlib. @c @c @c @page @subsection chdir - Changes the current working directory @findex chdir @cindex changes the current working directory @subheading CALLING SEQUENCE: @ifset is-C @example #include int chdir( const char *path ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: On error, this routine returns -1 and sets @code{errno} to one of the following: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix. @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist. @item ENOTDIR A component of the specified pathname was not a directory when directory was expected. @end table @subheading DESCRIPTION: The @code{chdir()} function causes the directory named by @code{path} to become the current working directory; that is, the starting point for searches of pathnames not beginning with a slash. If @code{chdir()} detects an error, the current working directory is not changed. @subheading NOTES: NONE @c @c @c @page @subsection fchdir - Changes the current working directory @findex fchdir @cindex changes the current working directory @subheading CALLING SEQUENCE: @ifset is-C @example #include int fchdir( int fd ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: On error, this routine returns -1 and sets @code{errno} to one of the following: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix. @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist. @item ENOTDIR A component of the specified pathname was not a directory when directory was expected. @end table @subheading DESCRIPTION: The @code{fchdir()} function causes the directory named by @code{fd} to become the current working directory; that is, the starting point for searches of pathnames not beginning with a slash. If @code{fchdir()} detects an error, the current working directory is not changed. @subheading NOTES: NONE @c @c @c @page @subsection getcwd - Gets current working directory @findex getcwd @cindex gets current working directory @subheading CALLING SEQUENCE: @ifset is-C @example #include int getcwd( void ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EINVAL Invalid argument @item ERANGE Result is too large @item EACCES Search permission is denied for a directory in a file's path prefix. @end table @subheading DESCRIPTION: The @code{getcwd()} function copies the absolute pathname of the current working directory to the character array pointed to by @code{buf}. The @code{size} argument is the number of bytes available in @code{buf} @subheading NOTES: There is no way to determine the maximum string length that @code{fetcwd()} may need to return. Applications should tolerate getting @code{ERANGE} and allocate a larger buffer. It is possible for @code{getcwd()} to return EACCES if, say, @code{login} puts the process into a directory without read access. The 1988 standard uses @code{int} instead of @code{size_t} for the second parameter. @c @c @c @page @subsection open - Opens a file @findex open @cindex opens a file @subheading CALLING SEQUENCE: @ifset is-C @example #include #include #include int open( const char *path, int oflag, mode_t mode ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix. @item EEXIST The named file already exists. @item EINTR Function was interrupted by a signal. @item EISDIR Attempt to open a directory for writing or to rename a file to be a directory. @item EMFILE Too many file descriptors are in use by this process. @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENFILE Too many files are currently open in the system. @item ENOENT A file or directory does not exist. @item ENOSPC No space left on disk. @item ENOTDIR A component of the specified pathname was not a directory when a directory was expected. @item ENXIO No such device. This error may also occur when a device is not ready, for example, a tape drive is off-line. @item EROFS Read-only file system. @end table @subheading DESCRIPTION: The @code{open} function establishes a connection between a file and a file descriptor. The file descriptor is a small integer that is used by I/O functions to reference the file. The @code{path} argument points to the pathname for the file. The @code{oflag} argument is the bitwise inclusive OR of the values of symbolic constants. The programmer must specify exactly one of the following three symbols: @table @b @item O_RDONLY Open for reading only. @item O_WRONLY Open for writing only. @item O_RDWR Open for reading and writing. @end table Any combination of the following symbols may also be used. @table @b @item O_APPEND Set the file offset to the end-of-file prior to each write. @item O_CREAT If the file does not exist, allow it to be created. This flag indicates that the @code{mode} argument is present in the call to @code{open}. @item O_EXCL This flag may be used only if O_CREAT is also set. It causes the call to @code{open} to fail if the file already exists. @item O_NOCTTY If @code{path} identifies a terminal, this flag prevents that teminal from becoming the controlling terminal for thi9s process. See Chapter 8 for a description of terminal I/O. @item O_NONBLOCK Do no wait for the device or file to be ready or available. After the file is open, the @code{read} and @code{write} calls return immediately. If the process would be delayed in the read or write opermation, -1 is returned and @code{errno} is set to @code{EAGAIN} instead of blocking the caller. @item O_TRUNC This flag should be used only on ordinary files opened for writing. It causes the file to be tuncated to zero length.. @end table Upon successful completion, @code{open} returns a non-negative file descriptor. @subheading NOTES: NONE @c @c @c @page @subsection creat - Create a new file or rewrite an existing one @findex creat @cindex create a new file or rewrite an existing one @subheading CALLING SEQUENCE: @ifset is-C @example #include #include #include int creat( const char *path, mode_t mode ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EEXIST @code{path} already exists and O_CREAT and O_EXCL were used. @item EISDIR @code{path} refers to a directory and the access requested involved writing @item ETXTBSY @code{path} refers to an executable image which is currently being executed and write access was requested @item EFAULT @code{path} points outside your accessible address space @item EACCES The requested access to the file is not allowed, or one of the directories in @code{path} did not allow search (execute) permission. @item ENAMETOOLONG @code{path} was too long. @item ENOENT A directory component in @code{path} does not exist or is a dangling symbolic link. @item ENOTDIR A component used as a directory in @code{path} is not, in fact, a directory. @item EMFILE The process alreadyh has the maximum number of files open. @item ENFILE The limit on the total number of files open on the system has been reached. @item ENOMEM Insufficient kernel memory was available. @item EROFS @code{path} refers to a file on a read-only filesystem and write access was requested @end table @subheading DESCRIPTION: @code{creat} attempts to create a file and return a file descriptor for use in read, write, etc. @subheading NOTES: NONE The routine is implemented in Cygnus newlib. @c @c @c @page @subsection umask - Sets a file creation mask. @findex umask @cindex sets a file creation mask. @subheading CALLING SEQUENCE: @ifset is-C @example #include #include mode_t umask( mode_t cmask ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @subheading DESCRIPTION: The @code{umask()} function sets the process file creation mask to @code{cmask}. The file creation mask is used during @code{open()}, @code{creat()}, @code{mkdir()}, @code{mkfifo()} calls to turn off permission bits in the @code{mode} argument. Bit positions that are set in @code{cmask} are cleared in the mode of the created file. @subheading NOTES: NONE The @code{cmask} argument should have only permission bits set. All other bits should be zero. In a system which supports multiple processes, the file creation mask is inherited across @code{fork()} and @code{exec()} calls. This makes it possible to alter the default permission bits of created files. RTEMS does not support multiple processes so this behavior is not possible. @c @c @c @page @subsection link - Creates a link to a file @findex link @cindex creates a link to a file @subheading CALLING SEQUENCE: @ifset is-C @example #include int link( const char *existing, const char *new ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix @item EEXIST The named file already exists. @item EMLINK The number of links would exceed @code{LINK_MAX}. @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist. @item ENOSPC No space left on disk. @item ENOTDIR A component of the specified pathname was not a directory when a directory was expected. @item EPERM Operation is not permitted. Process does not have the appropriate priviledges or permissions to perform the requested operations. @item EROFS Read-only file system. @item EXDEV Attempt to link a file to another file system. @end table @subheading DESCRIPTION: The @code{link()} function atomically creates a new link for an existing file and increments the link count for the file. If the @code{link()} function fails, no directories are modified. The @code{existing} argument should not be a directory. The caller may (or may not) need permission to access the existing file. @subheading NOTES: NONE @c @c @c @page @subsection symlink - Creates a symbolic link to a file @findex symlink @cindex creates a symbolic link to a file @subheading CALLING SEQUENCE: @ifset is-C @example #include int symlink( const char *topath, const char *frompath ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix @item EEXIST The named file already exists. @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist. @item ENOSPC No space left on disk. @item ENOTDIR A component of the specified pathname was not a directory when a directory was expected. @item EPERM Operation is not permitted. Process does not have the appropriate priviledges or permissions to perform the requested operations. @item EROFS Read-only file system. @end table @subheading DESCRIPTION: The @code{symlink()} function creates a symbolic link from the frombath to the topath. The symbolic link will be interpreted at run-time. If the @code{symlink()} function fails, no directories are modified. The caller may (or may not) need permission to access the existing file. @subheading NOTES: NONE @c @c @c @page @subsection readlink - Obtain the name of a symbolic link destination @findex readlink @cindex obtain the name of a symbolic link destination @subheading CALLING SEQUENCE: @ifset is-C @example #include int readlink( const char *path, char *buf, size_t bufsize ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist. @item ENOTDIR A component of the prefix pathname was not a directory when a directory was expected. @item ELOOP Too many symbolic links were encountered in the pathname. @item EINVAL The pathname does not refer to a symbolic link @item EFAULT An invalid pointer was passed into the @code{readlink()} routine. @end table @subheading DESCRIPTION: The @code{readlink()} function places the symbolic link destination into @code{buf} argument and returns the number of characters copied. If the symbolic link destination is longer than bufsize characters the name will be truncated. @subheading NOTES: NONE @c @c @c @page @subsection mkdir - Makes a directory @findex mkdir @cindex makes a directory @subheading CALLING SEQUENCE: @ifset is-C @example #include #include int mkdir( const char *path, mode_t mode ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix @item EEXIST The name file already exist. @item EMLINK The number of links would exceed LINK_MAX @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist. @item ENOSPC No space left on disk. @item ENOTDIR A component of the specified pathname was not a directory when a directory was expected. @item EROFS Read-only file system. @end table @subheading DESCRIPTION: The @code{mkdir()} function creates a new diectory named @code{path}. The permission bits (modified by the file creation mask) are set from @code{mode}. The owner and group IDs for the directory are set from the effective user ID and group ID. The new directory may (or may not) contain entries for.. and .. but is otherwise empty. @subheading NOTES: NONE @c @c @c @page @subsection mkfifo - Makes a FIFO special file @findex mkfifo @cindex makes a fifo special file @subheading CALLING SEQUENCE: @ifset is-C @example #include #include int mkfifo( const char *path, mode_t mode ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix @item EEXIST The named file already exists. @item ENOENT A file or directory does not exist. @item ENOSPC No space left on disk. @item ENOTDIR A component of the specified @code{path} was not a directory when a directory was expected. @item EROFS Read-only file system. @end table @subheading DESCRIPTION: The @code{mkfifo()} function creates a new FIFO special file named @code{path}. The permission bits (modified by the file creation mask) are set from @code{mode}. The owner and group IDs for the FIFO are set from the efective user ID and group ID. @subheading NOTES: NONE @c @c @c @page @subsection unlink - Removes a directory entry @findex unlink @cindex removes a directory entry @subheading CALLING SEQUENCE: @ifset is-C @example #include int unlink( const char path ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix @item EBUSY The directory is in use. @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist. @item ENOTDIR A component of the specified @code{path} was not a directory when a directory was expected. @item EPERM Operation is not permitted. Process does not have the appropriate priviledges or permissions to perform the requested operations. @item EROFS Read-only file system. @end table @subheading DESCRIPTION: The @code{unlink} function removes the link named by @code{path} and decrements the link count of the file referenced by the link. When the link count goes to zero and no process has the file open, the space occupied by the file is freed and the file is no longer accessible. @subheading NOTES: NONE @c @c @c @page @subsection rmdir - Delete a directory @findex rmdir @cindex delete a directory @subheading CALLING SEQUENCE: @ifset is-C @example #include int rmdir( const char *pathname ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EPERM The filesystem containing @code{pathname} does not support the removal of directories. @item EFAULT @code{pathname} points ouside your accessible address space. @item EACCES Write access to the directory containing @code{pathname} was not allowed for the process's effective uid, or one of the directories in @code{pathname} did not allow search (execute) permission. @item EPERM The directory containing @code{pathname} has the stickybit (S_ISVTX) set and the process's effective uid is neither the uid of the file to be delected nor that of the director containing it. @item ENAMETOOLONG @code{pathname} was too long. @item ENOENT A dirctory component in @code{pathname} does not exist or is a dangling symbolic link. @item ENOTDIR @code{pathname}, or a component used as a directory in @code{pathname}, is not, in fact, a directory. @item ENOTEMPTY @code{pathname} contains entries other than . and .. . @item EBUSY @code{pathname} is the current working directory or root directory of some process @item EBUSY @code{pathname} is the current directory or root directory of some process. @item ENOMEM Insufficient kernel memory was available @item EROGS @code{pathname} refers to a file on a read-only filesystem. @item ELOOP @code{pathname} contains a reference to a circular symbolic link @end table @subheading DESCRIPTION: @code{rmdir} deletes a directory, which must be empty @subheading NOTES: NONE @c @c @c @page @subsection rename - Renames a file @findex rename @cindex renames a file @subheading CALLING SEQUENCE: @ifset is-C @example #include int rename( const char *old, const char *new ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix. @item EBUSY The directory is in use. @item EEXIST The named file already exists. @item EINVAL Invalid argument. @item EISDIR Attempt to open a directory for writing or to rename a file to be a directory. @item EMLINK The number of links would exceed LINK_MAX. @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does no exist. @item ENOSPC No space left on disk. @item ENOTDIR A component of the specified pathname was not a directory when a directory was expected. @item ENOTEMPTY Attempt to delete or rename a non-empty directory. @item EROFS Read-only file system @item EXDEV Attempt to link a file to another file system. @end table @subheading DESCRIPTION: The @code{rename()} function causes the file known bo @code{old} to now be known as @code{new}. Ordinary files may be renamed to ordinary files, and directories may be renamed to directories; however, files cannot be converted using @code{rename()}. The @code{new} pathname may not contain a path prefix of @code{old}. @subheading NOTES: If a file already exists by the name @code{new}, it is removed. The @code{rename()} function is atomic. If the @code{rename()} detects an error, no files are removed. This guarantees that the @code{rename("x", "x")} does not remove @code{x}. You may not rename dot or dot-dot. The routine is implemented in Cygnus newlib using @code{link()} and @code{unlink()}. @c @c @c @page @subsection stat - Gets information about a file @findex stat @cindex gets information about a file @subheading CALLING SEQUENCE: @ifset is-C @example #include #include int stat( const char *path, struct stat *buf ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix. @item EBADF Invalid file descriptor. @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist. @item ENOTDIR A component of the specified pathname was not a directory when a directory was expected. @end table @subheading DESCRIPTION: The @code{path} argument points to a pathname for a file. Read, write, or execute permission for the file is not required, but all directories listed in @code{path} must be searchable. The @code{stat()} function obtains information about the named file and writes it to the area pointed to by @code{buf}. @subheading NOTES: NONE @c @c @c @page @subsection fstat - Gets file status @findex fstat @cindex gets file status @subheading CALLING SEQUENCE: @ifset is-C @example #include #include int fstat( int fildes, struct stat *buf ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EBADF Invalid file descriptor @end table @subheading DESCRIPTION: The @code{fstat()} function obtains information about the file associated with @code{fildes} and writes it to the area pointed to by the @code{buf} argument. @subheading NOTES: If the filesystem object referred to by @code{fildes} is a link, then the information returned in @code{buf} refers to the destination of that link. This is in contrast to @code{lstat()} which does not follow the link. @c @c @c @page @subsection lstat - Gets file status @findex lstat @cindex gets file status @subheading CALLING SEQUENCE: @ifset is-C @example #include #include int lstat( int fildes, struct stat *buf ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EBADF Invalid file descriptor @end table @subheading DESCRIPTION: The @code{lstat()} function obtains information about the file associated with @code{fildes} and writes it to the area pointed to by the @code{buf} argument. @subheading NOTES: If the filesystem object referred to by @code{fildes} is a link, then the information returned in @code{buf} refers to the link itself. This is in contrast to @code{fstat()} which follows the link. The @code{lstat()} routine is defined by BSD 4.3 and SVR4 and not included in POSIX 1003.1b-1996. @c @c @c @page @subsection access - Check permissions for a file @findex access @cindex check permissions for a file @subheading CALLING SEQUENCE: @ifset is-C @example #include int access( const char *pathname, int mode ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES The requested access would be denied, either to the file itself or one of the directories in @code{pathname}. @item EFAULT @code{pathname} points outside your accessible address space. @item EINVAL @code{Mode} was incorrectly specified. @item ENAMETOOLONG @code{pathname} is too long. @item ENOENT A directory component in @code{pathname} would have been accessible but does not exist or was a dangling symbolic link. @item ENOTDIR A component used as a directory in @code{pathname} is not, in fact, a directory. @item ENOMEM Insufficient kernel memory was available. @end table @subheading DESCRIPTION: @code{Access} checks whether the process would be allowed to read, write or test for existence of the file (or other file system object) whose name is @code{pathname}. If @code{pathname} is a symbolic link permissions of the file referred by this symbolic link are tested. @code{Mode} is a mask consisting of one or more of R_OK, W_OK, X_OK and F_OK. @subheading NOTES: NONE @c @c @c @page @subsection chmod - Changes file mode. @findex chmod @cindex changes file mode. @subheading CALLING SEQUENCE: @ifset is-C @example #include #include int chmod( const char *path, mode_t mode ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist. @item ENOTDIR A component of the specified pathname was not a directory when a directory was expected. @item EPERM Operation is not permitted. Process does not have the appropriate priviledges or permissions to perform the requested operations. @item EROFS Read-only file system. @end table @subheading DESCRIPTION: Set the file permission bits, the set user ID bit, and the set group ID bit for the file named by @code{path} to @code{mode}. If the effective user ID does not match the owner of the file and the calling process does not have the appropriate privileges, @code{chmod()} returns -1 and sets @code{errno} to @code{EPERM}. @subheading NOTES: NONE @c @c @c @page @subsection fchmod - Changes permissions of a file @findex fchmod @cindex changes permissions of a file @subheading CALLING SEQUENCE: @ifset is-C @example #include #include int fchmod( int fildes, mode_t mode ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix. @item EBADF The descriptor is not valid. @item EFAULT @code{path} points outside your accessible address space. @item EIO A low-level I/o error occurred while modifying the inode. @item ELOOP @code{path} contains a circular reference @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does no exist. @item ENOMEM Insufficient kernel memory was avaliable. @item ENOTDIR A component of the specified pathname was not a directory when a directory was expected. @item EPERM The effective UID does not match the owner of the file, and is not zero @item EROFS Read-only file system @end table @subheading DESCRIPTION: The mode of the file given by @code{path} or referenced by @code{filedes} is changed. @subheading NOTES: NONE @c @c @c @page @subsection getdents - Get directory entries @findex getdents @cindex get directory entries @subheading CALLING SEQUENCE: @ifset is-C @example #include #include #include long getdents( int dd_fd, char *dd_buf, int dd_len ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: A successful call to @code{getdents} returns th the number of bytes read. On end of directory, 0 is returned. When an error occurs, -1 is returned, and @code{errno} is set appropriately. @table @b @item EBADF Invalid file descriptor @code{fd}. @item EFAULT Argument points outside the calling process's address space. @item EINVAL Result buffer is too small. @item ENOENT No such directory. @item ENOTDIR File descriptor does not refer to a directory. @end table @subheading DESCRIPTION: @code{getdents} reads several @code{dirent} structures from the directory pointed by @code{fd} into the memory area pointed to by @code{dirp}. The parameter @code{count} is the size of the memory area. @subheading NOTES: NONE @c @c @c @page @subsection chown - Changes the owner and/or group of a file. @findex chown @cindex changes the owner and/or group of a file. @subheading CALLING SEQUENCE: @ifset is-C @example #include #include int chown( const char *path, uid_t owner, gid_t group ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Search permission is denied for a directory in a file's path prefix @item EINVAL Invalid argument @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist. @item ENOTDIR A component of the specified pathname was not a directory when a directory was expected. @item EPERM Operation is not permitted. Process does not have the appropriate priviledges or permissions to perform the requested operations. @item EROFS Read-only file system. @end table @subheading DESCRIPTION: The user ID and group ID of the file named by @code{path} are set to @code{owner} and @code{path}, respectively. For regular files, the set group ID (S_ISGID) and set user ID (S_ISUID) bits are cleared. Some systems consider it a security violation to allow the owner of a file to be changed, If users are billed for disk space usage, loaning a file to another user could result in incorrect billing. The @code{chown()} function may be restricted to privileged users for some or all files. The group ID can still be changed to one of the supplementary group IDs. @subheading NOTES: This function may be restricted for some file. The @code{pathconf} function can be used to test the @code{_PC_CHOWN_RESTRICTED} flag. @c @c @c @page @subsection utime - Change access and/or modification times of an inode @findex utime @cindex change access and/or modification times of an inode @subheading CALLING SEQUENCE: @ifset is-C @example #include int utime( const char *filename, struct utimbuf *buf ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EACCES Permission to write the file is denied @item ENOENT @code{Filename} does not exist @end table @subheading DESCRIPTION: @code{Utime} changes the access and modification times of the inode specified by @code{filename} to the @code{actime} and @code{modtime} fields of @code{buf} respectively. If @code{buf} is NULL, then the access and modification times of the file are set to the current time. @subheading NOTES: NONE @c @c @c @page @subsection ftruncate - truncate a file to a specified length @findex ftruncate @cindex truncate a file to a specified length @subheading CALLING SEQUENCE: @ifset is-C @example #include int ftrunctate( int fd, size_t length ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item ENOTDIR A component of the path prefix is not a directory. @item EINVAL The pathname contains a character with the high-order bit set. @item ENAMETOOLONG A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters. @item ENOENT The named file does not exist. @item EACCES The named file is not writable by the user. @item EACCES Search permission is denied for a component of the path prefix. @item ELOOP Too many symbolic links were encountered in translating the pathname @item EISDIR The named file is a directory. @item EROFS The named file resides on a read-only file system @item ETXTBSY The file is a pure procedure (shared text) file that is being executed @item EIO An I/O error occurred updating the inode. @item EFAULT @code{Path} points outside the process's allocated address space. @item EBADF The @code{fd} is not a valid descriptor. @end table @subheading DESCRIPTION: @code{truncate()} causes the file named by @code{path} or referenced by @code{fd} to be truncated to at most @code{length} bytes in size. If the file previously was larger than this size, the extra data is lost. With @code{ftruncate()}, the file must be open for writing. @subheading NOTES: NONE @c @c @c @page @subsection truncate - truncate a file to a specified length @findex truncate @cindex truncate a file to a specified length @subheading CALLING SEQUENCE: @ifset is-C @example #include int trunctate( const char *path, size_t length ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item ENOTDIR A component of the path prefix is not a directory. @item EINVAL The pathname contains a character with the high-order bit set. @item ENAMETOOLONG A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters. @item ENOENT The named file does not exist. @item EACCES The named file is not writable by the user. @item EACCES Search permission is denied for a component of the path prefix. @item ELOOP Too many symbolic links were encountered in translating the pathname @item EISDIR The named file is a directory. @item EROFS The named file resides on a read-only file system @item ETXTBSY The file is a pure procedure (shared text) file that is being executed @item EIO An I/O error occurred updating the inode. @item EFAULT @code{Path} points outside the process's allocated address space. @item EBADF The @code{fd} is not a valid descriptor. @end table @subheading DESCRIPTION: @code{truncate()} causes the file named by @code{path} or referenced by @code{fd} to be truncated to at most @code{length} bytes in size. If the file previously was larger than this size, the extra data is lost. With @code{ftruncate()}, the file must be open for writing. @subheading NOTES: NONE @c @c @c @page @subsection pathconf - Gets configuration values for files @findex pathconf @cindex gets configuration values for files @subheading CALLING SEQUENCE: @ifset is-C @example #include int pathconf( const char *path, int name ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EINVAL Invalid argument @item EACCES Permission to write the file is denied @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist @item ENOTDIR A component of the specified @code{path} was not a directory whan a directory was expected. @end table @subheading DESCRIPTION: @code{pathconf()} gets a value for the configuration option @code{name} for the open file descriptor @code{filedes}. The possible values for @code{name} are: @table @b @item _PC_LINK_MAX returns the maximum number of links to the file. If @code{filedes} or @code{path} refer to a directory, then the value applies to the whole directory. The corresponding macro is @code{_POSIX_LINK_MAX}. @item _PC_MAX_CANON returns the maximum length of a formatted input line, where @code{filedes} or @code{path} must refer to a terminal. The corresponding macro is @code{_POSIX_MAX_CANON}. @item _PC_MAX_INPUT returns the maximum length of an input line, where @code{filedes} or @code{path} must refer to a terminal. The corresponding macro is @code{_POSIX_MAX_INPUT}. @item _PC_NAME_MAX returns the maximum length of a filename in the directory @code{path} or @code{filedes}. The process is allowed to create. The corresponding macro is @code{_POSIX_NAME_MAX}. @item _PC_PATH_MAX returns the maximum length of a relative pathname when @code{path} or @code{filedes} is the current working directory. The corresponding macro is @code{_POSIX_PATH_MAX}. @item _PC_PIPE_BUF returns the size of the pipe buffer, where @code{filedes} must refer to a pipe or FIFO and @code{path} must refer to a FIFO. The corresponding macro is @code{_POSIX_PIPE_BUF}. @item _PC_CHOWN_RESTRICTED returns nonzero if the chown(2) call may not be used on this file. If @code{filedes} or @code{path} refer to a directory, then this applies to all files in that directory. The corresponding macro is @code{_POSIX_CHOWN_RESTRICTED}. @end table @subheading NOTES: Files with name lengths longer than the value returned for @code{name} equal @code{_PC_NAME_MAX} may exist in the given directory. @c @c @c @page @subsection fpathconf - Gets configuration values for files @findex fpathconf @cindex gets configuration values for files @subheading CALLING SEQUENCE: @ifset is-C @example #include int fpathconf( int filedes, int name ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @table @b @item EINVAL Invalid argument @item EACCES Permission to write the file is denied @item ENAMETOOLONG Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in effect. @item ENOENT A file or directory does not exist @item ENOTDIR A component of the specified @code{path} was not a directory whan a directory was expected. @end table @subheading DESCRIPTION: @code{pathconf()} gets a value for the configuration option @code{name} for the open file descriptor @code{filedes}. The possible values for name are: @table @b @item _PC_LINK_MAX returns the maximum number of links to the file. If @code{filedes} or @code{path} refer to a directory, then the value applies to the whole directory. The corresponding macro is _POSIX_LINK_MAX. @item _PC_MAX_CANON returns the maximum length of a formatted input line, where @code{filedes} or @code{path} must refer to a terminal. The corresponding macro is @code{_POSIX_MAX_CANON}. @item _PC_MAX_INPUT returns the maximum length of an input line, where @code{filedes} or @code{path} must refer to a terminal. The corresponding macro is @code{_POSIX_MAX_INPUT}. @item _PC_NAME_MAX returns the maximum length of a filename in the directory @code{path} or @code{filedes}. The process is allowed to create. The corresponding macro is @code{_POSIX_NAME_MAX}. @item _PC_PATH_MAX returns the maximum length of a relative pathname when @code{path} or @code{filedes} is the current working directory. The corresponding macro is @code{_POSIX_PATH_MAX}. @item _PC_PIPE_BUF returns the size of the pipe buffer, where @code{filedes} must refer to a pipe or FIFO and @code{path} must refer to a FIFO. The corresponding macro is @code{_POSIX_PIPE_BUF}. @item _PC_CHOWN_RESTRICTED returns nonzero if the @code{chown()} call may not be used on this file. If @code{filedes} or @code{path} refer to a directory, then this applies to all files in that directory. The corresponding macro is @code{_POSIX_CHOWN_RESTRICTED}. @end table @subheading NOTES: NONE @c @c @c @page @subsection mknod - create a directory @findex mknod @cindex create a directory @subheading CALLING SEQUENCE: @ifset is-C @example #include #include #include #include long mknod( const char *pathname, mode_t mode, dev_t dev ); @end example @end ifset @ifset is-Ada @end ifset @subheading STATUS CODES: @code{mknod} returns zero on success, or -1 if an error occurred (in which case, errno is set appropriately). @table @b @item ENAMETOOLONG @code{pathname} was too long. @item ENOENT A directory component in @code{pathname} does not exist or is a dangling symbolic link. @item ENOTDIR A component used in the directory @code{pathname} is not, in fact, a directory. @item ENOMEM Insufficient kernel memory was available @item EROFS @code{pathname} refers to a file on a read-only filesystem. @item ELOOP @code{pathname} contains a reference to a circular symbolic link, ie a symbolic link whose expansion contains a reference to itself. @item ENOSPC The device containing @code{pathname} has no room for the new node. @end table @subheading DESCRIPTION: @code{mknod} attempts to create a filesystem node (file, device special file or named pipe) named @code{pathname}, specified by @code{mode} and @code{dev}. @code{mode} specifies both the permissions to use and the type of node to be created. It should be a combination (using bitwise OR) of one of the file types listed below and the permissions for the new node. The permissions are modified by the process's @code{umask} in the usual way: the permissions of the created node are @code{(mode & ~umask)}. The file type should be one of @code{S_IFREG}, @code{S_IFCHR}, @code{S_IFBLK} and @code{S_IFIFO} to specify a normal file (which will be created empty), character special file, block special file or FIFO (named pipe), respectively, or zero, which will create a normal file. If the file type is @code{S_IFCHR} or @code{S_IFBLK} then @code{dev} specifies the major and minor numbers of the newly created device special file; otherwise it is ignored. The newly created node will be owned by the effective uid of the process. If the directory containing the node has the set group id bit set, or if the filesystem is mounted with BSD group semantics, the new node will inherit the group ownership from its parent directory; otherwise it will be owned by the effective gid of the process. @subheading NOTES: NONE