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Compaq C

Compaq C
Run-Time Library Reference Manual for OpenVMS Systems
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decc$set_reentrancy

Controls the type of reentrancy that reentrant Compaq C RTL routines will exhibit.

Format

#include <reentrancy.h>

int decc$set_reentrancy (int type);

Argument

type

The type of reentrancy desired. Use one of the following values:

The reentrancy type can be raised but never lowered. The ordering of reentrancy types from low to high is C$C_NONE, C$C_TOLERANT, C$C_AST and C$C_MULTITHREAD. For example, once an application is set to multithread, a call to set the reentrancy to AST is ignored. A call to decc$set_reentrancy that attempts to lower the reentrancy type returns a value of --1.

Description

Use this function to change the type of reentrancy exhibited by reentrant routines.

decc$set_reentrancy must be called exclusively at the non-AST level.

In an application using DECthreads, DECthreads automatically sets the reentrancy to multithread.

Return Value

type The type of reentrancy used before this call.
--1 The reentrancy was set to a lower type.

decc$to_vms

Converts UNIX style file specifications to OpenVMS file specifications.

Format

#include <unixlib.h>

int decc$to_vms (const char *unix_style_filespec, int (*action_routine)(char *unix_style_filespec, int type_of_file), int allow_wild, int no_directory);

Arguments

unix_style_filespec

The address of a null-terminated string containing a name in UNIX style file specification format.

action_routine

The address of a routine that accepts the following arguments:

If action_routine returns a nonzero value (TRUE), file translation continues. If it returns a 0 value (FALSE), no further file translation takes place.

allow_wild

Either 0 or 1, passed by value. If a 0 is specified, wildcards found in unix_style_filespec are not expanded. Otherwise, wildcards are expanded and each one is passed to action_routine. Only expanded file names that correspond to existing OpenVMS files are included.

no_directory

An integer that has one of the following values:
Value Translation
0 Directory is not allowed.
1 Prevent expansion of the string as a directory name.
2 Forced to be a directory name.

Description

This routine converts the given UNIX style file specification into the equivalent OpenVMS file specification (in all uppercase letters). It allows you to specify UNIX style wildcards, which are translated into a list of corresponding OpenVMS files.

Return Value

x The number of file names that result from the specified UNIX style file specification.

Example


/* Translate "Unix" wildcard file names to VMS names    */ 
/* Define as a foreign command and provide the name     */ 
/* as an argument.                                      */ 
 
#include <unixlib.h> 
#include <stdio.h> 
int print_name(char *, int); 
int main(int argc, char *argv[]) 
{ 
    int number_found;           /* number of files found */ 
 
    printf("Translating: %s\n", argv[1]); 
 
    number_found = decc$to_vms(argv[1], print_name, 1, 0); 
    printf("%d files found\n", number_found); 
} 
 
/* action routine that prints name and type on each line */ 
 
int print_name(char *name, int type) 
{ 
    if (type == DECC$K_DIRECTORY) 
        printf("directory: %s\n", name); 
    else if (type == DECC$K_FOREIGN) 
        printf("remote non-VMS: %s\n", name); 
    else 
        printf("file:        %s\n", name); 
 
    /* Translation continues as long as success status is returned */ 
    return (1); 
}

This example shows how to use the decc$to_vms routine in Compaq C. It takes a UNIX style file specification argument and displays, in OpenVMS file specification format, the name of each existing file that matches it.

decc$translate_vms

Translates OpenVMS file specifications to UNIX style file specifications.

Format

#include <unixlib.h>

char *decc$translate_vms (const char *vms_filespec);

Argument

vms_filespec

The address of a null-terminated string containing a name in OpenVMS file specification format.

Description

This function translates the given OpenVMS file specification into the equivalent UNIX style file specification, whether or not the file exists. The translated name string is stored in a thread-specific memory, which is overwritten by each call to decc$translate_vms from the same thread.

This function differs from the decc$from_vms function, which does the conversion for existing files only.

Return Values

x The address of a null-terminated string containing a name in UNIX style file specification format.
0 Indicates that the file name is null or syntactically incorrect.
--1 Indicates that the file specification contains an ellipsis (for example, [...]a.dat), but is otherwise correct. You cannot translate the OpenVMS ellipsis syntax into a valid UNIX style file specification.

Example


/* Demonstrate translation of a "UNIX" name to VMS form */ 
/* define a foreign command and pass the name as the    */ 
/* argument.                                            */ 
            
#include <unixlib.h> 
#include <stdio.h> 
 
int main(int argc, char *argv[]) 
{ 
    char *ptr;                      /* translation result */ 
 
    ptr = decc$translate_vms( argv[1] ); 
 
    if ((int) ptr == 0 || (int) ptr == -1) 
 
        printf( "could not translate %s\n", argv[1]); 
    else 
        printf( "%s is translated to %s\n", argv[1], ptr ); 
}

decc$validate_wchar

Confirms that its argument is a valid wide character in the current program's locale.

Format

#include <unistd.h>

int decc$validate_wchar (wchar_t wc);

Argument

wc

Wide character to be validated.

Description

This function provides a convenient way to verify whether a specified argument of wchar_t type is a valid wide character in the current program's locale.

One reason to call decc$validate_wchar is that the isw * wide-character classification functions and macros do not validate their argument before dereferencing the classmask array describing character properties. Passing an isw * function a value that exceeds the maximum wide-character value for the current program's locale can result in an attempt to access memory beyond the allocated classmask array.

A standard way to validate a wide character is to call the wctomb function, but this way is less convenient because it requires declaring a multibyte character array of sufficient size and passing it to wctomb .

Return Values

1 Indicates that the specified wide character is a valid wide character in the current program's locale.
0 Indicates that the specified wide character is not a valid wide character in the current program's locale. errno is not set.

decc$write_eof_to_mbx

Writes an end-of-file message to the mailbox.

Format

#include <unistd.h>

int decc$write_eof_to_mbx (int fd);

Argument

fd

File descriptor associated with the mailbox.

Description

This function writes end-of-file message to the mailbox.

For a mailbox that is not a pipe, the write function called with an nbytes parameter value of 0 sends an end-of-file message to the mailbox. For a pipe, however, the only way to write an end-of-file message to the mailbox is to close the pipe.

If the child's standard input is redirected to a pipe through a call to the decc$set_child_standard_streams function, the parent process can call decc$write_eof_to_mbx for this pipe to send an EOF message to the child. It has the same effect as if the child read the data from a terminal, and Ctrl/Z was pressed.

After a call to decc$write_eof_to_mbx , the pipe can be reused for communication with another child, for example. This is the purpose of decc$write_eof_to_mbx : to allow reuse of the pipe instead of having to close it just to send an end-of-file message.

Return Values

0 Indicates success
--1 Indicates failure; errno and vaxc$errno are set according to the failure status returned by SYS$QIOW.

Example


/*      decc$write_eof_to_mbx_example.c         */ 
 
#include <errno.h> 
#include <stdio.h> 
#include <string.h> 
 
#include <fcntl.h> 
#include <unistd.h> 
#include <unixio.h> 
 
#include <descrip.h> 
#include <ssdef.h> 
#include <starlet.h> 
 
 
int decc$write_eof_to_mbx( int ); 
 
main() 
{ 
    int status, nbytes, failed = 0; 
    int fd, fd2[2]; 
    short int channel; 
    $DESCRIPTOR(mbxname_dsc, "TEST_MBX"); 
    char c; 
 
    /* first try a mailbox created by SYS$CREMBX        */ 
 
    status = sys$crembx(0, &channel, 0, 0, 0, 0, &mbxname_dsc, 0, 0); 
    if ( status != SS$_NORMAL ) { 
        printf("sys$crembx failed: %s\n",strerror(EVMSERR, status)); 
        failed = 1; 
    } 
 
    if ( (fd = open(mbxname_dsc.dsc$a_pointer, O_RDWR, 0)) == -1 ) { 
        perror("? open mailbox"); 
        failed = 1; 
    } 
 
    if ( decc$write_eof_to_mbx(fd) == -1 ) { 
        perror("?  decc$write_eof_to_mbx to mailbox"); 
        failed = 1; 
    } 
 
    if ( (nbytes = read(fd, &c, 1)) != 0 || errno != 0 ) { 
        perror("? read mailbox"); 
        printf("? nbytes = %d\n", nbytes); 
        failed = 1; 
    } 
 
    if ( close(fd) == -1 ) { 
        perror("? close mailbox"); 
        failed = 1; 
    } 
 
    /* Now do the same thing with a pipe                */ 
 
    errno = 0;                  /* Clear errno for consistency */ 
 
    if ( pipe(fd2) == -1 ) { 
        perror("? opening pipe"); 
        failed = 1; 
    } 
 
    if ( decc$write_eof_to_mbx(fd2[1]) == -1 ) { 
        perror("? decc$write_eof_to_mbx to pipe"); 
        failed = 1; 
    } 
 
    if ( (nbytes = read(fd2[0], &c, 1)) != 0 || errno != 0 ) { 
        perror("? read pipe"); 
        printf("? nbytes = %d\n", nbytes); 
        failed = 1; 
    } 
 
    /* Close both file descriptors involved with the pipe       */ 
 
    if ( close(fd2[0]) == -1 ) { 
        perror("close(fd2[0])"); 
        failed = 1; 
    } 
 
    if ( close(fd2[1]) == -1 ) { 
        perror("close(fd2[1])"); 
        failed = 1; 
    } 
 
    if ( failed ) 
        puts("?Example program failed"); 
    else 
        puts("Example ran to completion"); 
}

This example program produces the following result: 


Example ran to completion

[w]delch

Delete the character on the specified window at the current position of the cursor. The delch function operates on the stdscr window.

Format

#include <curses.h>

int delch();

int wdelch (WINDOW *win);

Argument

win

A pointer to the window.

Description

All of the characters to the right of the cursor on the same line are shifted to the left, and a blank character is appended to the end of the line.

Return Values

OK Indicates success.
ERR Indicates an error.

delete

Deletes a file.

Format

#include <unixio.h>

int delete (const char *file_spec);

Argument

file_spec

A pointer to the string that is an OpenVMS or UNIX style file specification. The file specification can include a wildcard in its version number (but not in any other part of the file spec). So, for example, files of the form filename.txt;* can be deleted.

Description

If you specify a directory in the file name and it is a search list that contains an error, Compaq C for OpenVMS Systems interprets it as a file error.

The remove and delete functions are functionally equivalent in the Compaq C RTL.

See also remove in this section.

Note
The delete routine is not available to C++ programmers because it conflicts with the C++ reserved word delete . C++ programmers should use the ANSI/ISO C standard function remove instead.

Return Values

0 Indicates success.
nonzero value Indicates that the operation has failed.

[w]deleteln

Delete the line at the current position of the cursor. The deleteln function acts on the stdscr window.

Format

#include <curses.h>

int deleteln();

int wdeleteln (WINDOW *win);

Argument

win

A pointer to the window.

Description

Every line below the deleted line moves up, and the bottom line becomes blank. The current (y,x) coordinates of the cursor remain unchanged.

Return Values

OK Indicates success.
ERR Indicates an error.

delwin

Deletes the specified window from memory.

Format

#include <curses.h>

int delwin (WINDOW *win);

Argument

win

A pointer to the window.

Description

If the window being deleted contains a subwindow, the subwindow is invalidated. Delete subwindows before deleting their parent. The delwin function refreshes all windows covered by the deleted window.

Return Values

OK Indicates success.
ERR Indicates an error.

difftime

Computes the difference, in seconds, between the two times specified by the time1 and time2 arguments.

Format

#include <time.h>

double difftime (time_t time2, time_t time1);

Arguments

time2

A time value of type time_t .

time1

A time value of type time_t .

Description

The type time_t is defined in the <time.h> header file as follows: 


typedef unsigned long int time_t

Return Value

n time2 -- time1 in seconds expressed as a double .

dirname

Reports the parent directory name of a file path name.

Format

#include <libgen.h>

char *dirname (char *path);

Function Variants This function also has variants named _dirname32 and _dirname64 for use with 32-bit and 64-bit pointer sizes, respectively. See Section 1.8 for more information on using pointer-size-specific functions.

Argument

path

The file path name.

Description

This function takes a pointer to a character string that contains a UNIX path name and returns a pointer to a string that is a path name of the parent directory of that file. Trailing '/' (slash) characters in the path are not counted as part of the path.

The dirname function returns a pointer to the string "." (dot), when the path argument:

The dirname function can modify the string pointed to by the path argument.

The dirname and basename functions together yield a complete path name. The expression dirname (path) obtains the path name of the directory where basename (path) is found.

See also basename in this section.

Return Values

x A pointer to a string that is the parent directory of the path argument.
"." The path argument:
  • Does not contain a '/' (slash).
  • Is a NULL pointer.
  • Points to an empty string.

Example

Using the dirname function, the following example reads a path name, changes the current working directory to the parent directory, and opens a file. 


    char path [MAXPATHLEN], *pathcopy; 
    int fd; 
 
    fgets(path, MAXPATHLEN, stdin); 
    pathcopy = strdup(path); 
    chdir(dirname(pathcopy)); 
    fd = open(basename(path), O_RDONLY);

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