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libstand ()
  • >> libstand (3) ( FreeBSD man: Библиотечные вызовы )

  • BSD mandoc
     

    NAME

    
    
    libstand
    
     - support library for standalone executables
    
     
    

    SYNOPSIS

       #include <stand.h>
     

    DESCRIPTION

    The library provides a set of supporting functions for standalone applications, mimicking where possible the standard BSD programming environment. The following sections group these functions by kind. Unless specifically described here, see the corresponding section 3 manpages for the given functions.  

    STRING FUNCTIONS

    String functions are available as documented in string(3) and bstring(3).  

    MEMORY ALLOCATION

    void * malloc (size_t size);

    Allocate Fa size bytes of memory from the heap using a best-fit algorithm.
    void free (void *ptr);

    Free the allocated object at Fa ptr .
    void setheap (void *start void *limit);

    Initialise the heap. This function must be called before calling alloc ();
    for the first time. The region between Fa start and Fa limit will be used for the heap; attempting to allocate beyond this will result in a panic.
    char * sbrk (int junk);

    Provides the behaviour of sbrk (0 ,);
    i.e., returns the highest point that the heap has reached. This value can be used during testing to determine the actual heap usage. The Fa junk argument is ignored.

     

    ENVIRONMENT

    A set of functions are provided for manipulating a flat variable space similar to the traditional shell-supported environment. Major enhancements are support for set/unset hook functions.

    char * getenv (const char *name);
    int setenv (const char *name const char *value int overwrite);
    int putenv (const char *string);
    int unsetenv (const char *name);

    These functions behave similarly to their standard library counterparts.
    struct env_var * env_getenv (const char *name);

    Looks up a variable in the environment and returns its entire data structure.
    int env_setenv (const char *name int flags const void *value ev_sethook_t sethook ev_unsethook_t unsethook);

    Creates a new or sets an existing environment variable called Fa name . If creating a new variable, the Fa sethook and Fa unsethook arguments may be specified.

    The set hook is invoked whenever an attempt is made to set the variable, unless the EV_NOHOOK flag is set. Typically a set hook will validate the Fa value argument, and then call env_setenv ();
    again with EV_NOHOOK set to actually save the value. The predefined function env_noset ();
    may be specified to refuse all attempts to set a variable.

    The unset hook is invoked when an attempt is made to unset a variable. If it returns zero, the variable will be unset. The predefined function Fa env_nounset may be used to prevent a variable being unset.

     

    STANDARD LIBRARY SUPPORT

    int getopt (int argc char * const *argv const char *optstring);
    long strtol (const char *nptr char **endptr int base);
    void srandom (unsigned long seed);
    unsigned long random (void);
    char * strerror (int error);

    Returns error messages for the subset of errno values supported by .
    Fn assert expression

    Requires In assert.h .

    int setjmp (jmp_buf env);
    void longjmp (jmp_buf env int val);

    Defined as _setjmp ();
    and _longjmp ();
    respectively as there is no signal state to manipulate. Requires In setjmp.h .

     

    CHARACTER I/O

    void gets (char *buf);

    Read characters from the console into Fa buf . All of the standard cautions apply to this function.
    void ngets (char *buf int size);

    Read at most Fa size - 1 characters from the console into Fa buf . If Fa size is less than 1, the function's behaviour is as for gets (.);
    int fgetstr (char *buf int size int fd);

    Read a line of at most Fa size characters into Fa buf . Line terminating characters are stripped, and the buffer is always NUL terminated. Returns the number of characters in Fa buf if successful, or -1 if a read error occurs.
    int printf (const char *fmt ...);
    void vprintf (const char *fmt va_list ap);
    int sprintf (char *buf const char *fmt ...);
    void vsprintf (char *buf const char *fmt va_list ap);

    The *printf functions implement a subset of the standard printf ();
    family functionality and some extensions. The following standard conversions are supported: c,d,n,o,p,s,u,x. The following modifiers are supported: +,-,#,*,0,field width,precision,l.

    The b conversion is provided to decode error registers. Its usage is:

    printf( Qq reg=%b\n , regval, Qq <base><arg>* );

    where <base> is the output expressed as a control character, e.g. \10 gives octal, \20 gives hex. Each <arg> is a sequence of characters, the first of which gives the bit number to be inspected (origin 1) and the next characters (up to a character less than 32) give the text to be displayed if the bit is set. Thus

    printf( Qq reg=%b\n , 3, Qq \10\2BITTWO\1BITONE\n );

    would give the output

    reg=3<BITTWO,BITONE>

    The D conversion provides a hexdump facility, e.g.

    printf( Qq %6D , ptr, Qq : ); gives Qq XX:XX:XX:XX:XX:XX
    printf( Qq %*D , len, ptr, Qq   ); gives Qq XX XX XX ...

     

    CHARACTER TESTS AND CONVERSIONS

    int isupper (int c);
    int islower (int c);
    int isspace (int c);
    int isdigit (int c);
    int isxdigit (int c);
    int isascii (int c);
    int isalpha (int c);
    int toupper (int c);
    int tolower (int c);

     

    FILE I/O

    int open (const char *path int flags);

    Similar to the behaviour as specified in open(2), except that file creation is not supported, so the mode parameter is not required. The Fa flags argument may be one of O_RDONLY, O_WRONLY and O_RDWR (although no file systems currently support writing).
    int close (int fd);
    void closeall (void);

    Close all open files.
    ssize_t read (int fd void *buf size_t len);
    ssize_t write (int fd void *buf size_t len);

    (No file systems currently support writing.)

    off_t lseek (int fd off_t offset int whence);

    Files being automatically uncompressed during reading cannot seek backwards from the current point.
    int stat (const char *path struct stat *sb);
    int fstat (int fd struct stat *sb);

    The stat ();
    and fstat ();
    functions only fill out the following fields in the Fa sb structure: st_mode,st_nlink,st_uid,st_gid,st_size. The tftp file system cannot provide meaningful values for this call, and the cd9660 file system always reports files having uid/gid of zero.

     

    PAGER

    The library supplies a simple internal pager to ease reading the output of large commands.

    void pager_open ();

    Initialises the pager and tells it that the next line output will be the top of the display. The environment variable LINES is consulted to determine the number of lines to be displayed before pausing.
    void pager_close (void);

    Closes the pager.
    int pager_output (const char *lines);

    Sends the lines in the NUL -terminated buffer at Fa lines to the pager. Newline characters are counted in order to determine the number of lines being output (wrapped lines are not accounted for). The pager_output ();
    function will return zero when all of the lines have been output, or nonzero if the display was paused and the user elected to quit.
    int pager_file (const char *fname);

    Attempts to open and display the file Fa fname . Returns -1 on error, 0 at EOF, or 1 if the user elects to quit while reading.

     

    MISC

    void twiddle (void);

    Successive calls emit the characters in the sequence |,/,-,\ followed by a backspace in order to provide reassurance to the user.

     

    REQUIRED LOW-LEVEL SUPPORT

    The following resources are consumed by - stack, heap, console and devices.

    The stack must be established before functions can be invoked. Stack requirements vary depending on the functions and file systems used by the consumer and the support layer functions detailed below.

    The heap must be established before calling alloc ();
    or open ();
    by calling setheap (.);
    Heap usage will vary depending on the number of simultaneously open files, as well as client behaviour. Automatic decompression will allocate more than 64K of data per open file.

    Console access is performed via the getchar (,);
    putchar ();
    and ischar ();
    functions detailed below.

    Device access is initiated via devopen ();
    and is performed through the dv_strategy (,);
    dv_ioctl ();
    and dv_close ();
    functions in the device switch structure that devopen ();
    returns.

    The consumer must provide the following support functions:

    int getchar (void);

    Return a character from the console, used by gets (,);
    ngets ();
    and pager functions.
    int ischar (void);

    Returns nonzero if a character is waiting from the console.
    void putchar (int);

    Write a character to the console, used by gets (,);
    ngets (,);
    Fn *printf , panic ();
    and twiddle ();
    and thus by many other functions for debugging and informational output.
    int devopen (struct open_file *of const char *name const char **file);

    Open the appropriate device for the file named in Fa name , returning in Fa file a pointer to the remaining body of Fa name which does not refer to the device. The f_dev field in Fa of will be set to point to the Vt devsw structure for the opened device if successful. Device identifiers must always precede the path component, but may otherwise be arbitrarily formatted. Used by open ();
    and thus for all device-related I/O.
    int devclose (struct open_file *of);

    Close the device allocated for Fa of . The device driver itself will already have been called for the close; this call should clean up any allocation made by devopen only.
    void panic (const char *msg ...);

    Signal a fatal and unrecoverable error condition. The Fa msg ... arguments are as for printf (.);

     

    INTERNAL FILE SYSTEMS

    Internal file systems are enabled by the consumer exporting the array Vt struct fs_ops *file_system[] , which should be initialised with pointers to Vt struct fs_ops structures. The following file system handlers are supplied by , the consumer may supply other file systems of their own:

    ufs_fsops
    The BSD UFS.
    ext2fs_fsops
    Linux ext2fs file system.
    tftp_fsops
    File access via TFTP.
    nfs_fsops
    File access via NFS.
    cd9660_fsops
    ISO 9660 (CD-ROM) file system.
    gzipfs_fsops
    Stacked file system supporting gzipped files. When trying the gzipfs file system, appends .gz to the end of the filename, and then tries to locate the file using the other file systems. Placement of this file system in the file_system[] array determines whether gzipped files will be opened in preference to non-gzipped files. It is only possible to seek a gzipped file forwards, and stat ();
    and fstat ();
    on gzipped files will report an invalid length.
    bzipfs_fsops
    The same as gzipfs_fsops but for bzip2(1)Ns-compressed files.

    The array of Vt struct fs_ops pointers should be terminated with a NULL.  

    DEVICES

    Devices are exported by the supporting code via the array Vt struct devsw *devsw[] which is a NULL terminated array of pointers to device switch structures.  

    HISTORY

    The library contains contributions from many sources, including:

    The reorganisation and port to Fx 3.0 , the environment functions and this manpage were written by An Mike Smith Aq msmith@FreeBSD.org .  

    BUGS

    The lack of detailed memory usage data is unhelpful.


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    STRING FUNCTIONS
    MEMORY ALLOCATION
    ENVIRONMENT
    STANDARD LIBRARY SUPPORT
    CHARACTER I/O
    CHARACTER TESTS AND CONVERSIONS
    FILE I/O
    PAGER
    MISC
    REQUIRED LOW-LEVEL SUPPORT
    INTERNAL FILE SYSTEMS
    DEVICES
    HISTORY
    BUGS


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