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Compaq C

Compaq C
Run-Time Library Reference Manual for OpenVMS Systems
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setlocale

Selects the appropriate portion of the program's locale as specified by the category and locale arguments. You can use this function to change or query one category or the program's entire current locale.

Format

#include <locale.h>

char *setlocale (int category, const char *locale);

Arguments

category

The name of the category. Specify LC_ALL to change or query the entire locale. Other valid category names are:

locale

Pointer to a string that specifies the locale.

Description

This function sets or queries the appropriate portion of the program's locale as specified by the category and locale arguments. Specifying LC_ALL for the category argument names the entire locale; specifying the other values name only a portion of the program's locale.

The locale argument points to a character string that identifies the locale to be used. This argument can be one of the following:

Return Values

x Pointer to a string describing the locale.
NULL Indicates an error occurred; errno is set.

Example


#include <errno.h> 
#include <stdio.h> 
#include <locale.h> 
 
/* This program calls setlocale() three times. The second call  */ 
/* is for a nonexistent locale. The third call is for an        */ 
/* existing file that is not a locale file.                     */ 
 
main() 
{ 
    char *ret_str; 
 
    errno = 0; 
    printf("setlocale (LC_ALL, \"POSIX\")"); 
    ret_str = (char *) setlocale(LC_ALL, "POSIX"); 
 
    if (ret_str == NULL) 
        perror("setlocale error"); 
    else 
        printf(" call was succesfull\n"); 
                                            
    errno = 0; 
    printf("\n\nsetlocale (LC_ALL, \"junk.junk_codeset\")"); 
    ret_str = (char *) setlocale(LC_ALL, "junk.junk_codeset"); 
 
    if (ret_str == NULL) 
        perror(" returned error"); 
    else 
        printf(" call was succesfull\n"); 
 
    errno = 0; 
    printf("\n\nsetlocale (LC_ALL, \"sys$login:login.com\")"); 
    ret_str = (char *) setlocale(LC_ALL, "sys$login:login.com"); 
 
    if (ret_str == NULL) 
        perror(" returned error"); 
    else 
        printf(" call was succesfull\n"); 
}

Running the example program produces the following result: 


setlocale (LC_ALL, "POSIX") call was succesfull 
 
setlocale (LC_ALL, "junk.junk_codeset") 
returned error: no such file or directory 
 
setlocale (LC_ALL, "sys$login:login.com") 
returned error: non-translatable vms error code: 0x35C07C 
%c-f-localebad, not a locale file

setstate

Restarts, and changes random number generators.

Format

char *setstate (char *state;)

Arguments

state

Points to the array of state information.

Description

This function handles restarting and changing random number generators.

Once you initialize a state, the setstate function allows rapid switching between state arrays. The array defined by state is used for further random number generation until the initstate function is called or the setstate function is called again. The setstate function returns a pointer to the previous state array.

After initialization, you can restart a state array at a different point in one of two ways:

See also initstate , srandom , and random , in this section.

Return Values

x A pointer to the previous state array information.
0 Indicates an error. The state information is damaged. Further specified in the following errno value:
  • EINVAL---The state argument is invalid.

setuid

Implemented for program portability and serves no function. It returns 0 (to indicate success).

Format

#include <unistd.h>

int setuid (__uid_t member_number); (_DECC_V4_SOURCE)

uid_t setuid (uid_t member_number); (NOT _DECC_V4_SOURCE)

Argument

member_number

The member number.

Description

This function is implemented for program portability only and serves no function. It returns 0 to indicate success.

Note (ALPHA ONLY)
On OpenVMS Alpha systems, this function has been enhanced to take advantage of the new OpenVMS support for POSIX-style user, group, and session IDs available on a version of OpenVMS Alpha after Version 7.3.

The new functionality, based on PERSONA VMS services, is the default on those versions of OpenVMS Alpha where the underlying operating system support is available.

If the process has appropriate privileges, the setuid function sets the real user ID, effective user ID, and the saved set-user-ID to uid.

If the process does not have appropriate privileges but uid is equal to the real user ID or to the saved set-user-ID, then the setuid function sets the effective user ID to uid. The real user ID and saved set-user-ID remain unchanged.

To request the old behavior, define the DECC$GETJPI_BASED_UID logical name to "ENABLE": 


$ DEFINE DECC$GETJPI_BASED_UID ENABLE

setvbuf

Associates a buffer with an input or output file and potentially modifies the buffering behavior.

Format

#include <stdio.h>

int setvbuf (FILE *file_ptr, char *buffer, int type, size_t size);

Arguments

file_ptr

A pointer to a file.

buffer

A pointer to a character array, or a NULL pointer.

type

The buffering type. Use one of the following values defined in <stdio.h> : _IONBF, _IOFBF, _IOLBF.

size

The number of bytes to be used in buffer by the Compaq C RTL for buffering this file. The buffer size must be a minimum of 8192 bytes and a maximum of 32767 bytes.

Description

You can use this function after the file is opened but before any I/O operations are performed.

The ANSI C standard defines the following types of file buffering. In unbuffered I/O, each I/O operation is performed immediately. Output characters or lines are written to the output device before control is returned to the program. Input characters or lines are sent directly to the program without read-ahead by the Compaq C RTL.

In line-buffered I/O, characters are buffered in an area of memory until a new-line character is seen, at which point the appropriate RMS routine is called to transmit the entire buffer. Line buffering is more efficient than unbuffered I/O since it reduces the system overhead, but it delays the availability of the data to the user or disk on output.

In fully buffered I/O, characters are buffered in an area of memory until the buffer is full, regardless of the presence of break characters. Full buffering is more efficient than line buffering or unbuffered I/O, but it delays the availability of output data even longer than line buffering.

Use the values _IONBF, _IOLBF, and _IOFBF defined in <stdio.h> for the type argument to specify unbuffered, line-buffered, and fully buffered I/O, respectively.

If _IONBF is specified for type, I/O will be unbuffered and the buffer and size arguments are ignored.

If _IOLBF or _IOFBF is specified for type, the Compaq C RTL will use line-buffered I/O if file_ptr specifies a terminal device; otherwise, it will use fully buffered I/O.

The Compaq C RTL automatically allocates a buffer to use for each I/O stream. So there are several buffer allocation possibilities:

User programs must not depend on the contents of buffer once I/O has been performed on the stream. The Compaq C RTL might or might not use buffer for any given I/O operation.

Generally, it is unnecessary to use setvbuf or setbuf to control the buffer size used by the Compaq C RTL. The automatically allocated buffer sizes are chosen for efficiency based on the kind of I/O operations performed and the device characteristics (such as terminal, disk, or socket).

The setvbuf and setbuf functions are useful to introduce buffering for improved performance when writing a large amount of text to the stdout stream. This stream is unbuffered by default when bound to a terminal device (the normal case), and therefore incurs a large number of OpenVMS buffered I/O operations unless Compaq C RTL buffering is introduced by a call to setvbuf or setbuf .

The setvbuf function is used only to control the buffering used by the Compaq C RTL, not the buffering used by the underlying RMS I/O operations. You can modify RMS default buffering behavior by specifying various values for the ctx, fop, rat, gbc, mbc, mbf, rfm, and rop RMS keywords when the file is opened by the creat , freopen or open functions.

Return Values

0 Indicates success.
nonzero value Indicates that an invalid input value was specifed for type or file_ptr, or because file_ptr is being used by another thread (see Section 1.7.1).

sigaction

Specifies the action to take upon delivery of a signal.

Format

#include <signal.h>

int sigaction (int sig, const struct sigaction *action, struct sigaction *o_action);

Arguments

sig

The signal for which the action is to be taken.

action

A pointer to a sigaction structure that describes the action to take when you receive the signal specified by the sig argument.

o_action

A pointer to a sigaction structure. When the sigaction function returns from a call, the action previously attached to the specified signal is stored in this structure.

Description

When a process requests the sigaction function, the process can both examine and specify what action to perform when the specified signal is delivered. The arguments determine the behavior of the sigaction function as follows:

The sigaction structure consists of the following members: 


  void        (*sa_handler)(int); 
  sigset_t    sa_mask; 
  int         sa_flags;

The sigaction structure members are defined as follows:
sa_handler This member can contain the following values:
  • SIG_DFL -- Specifies the default action taken when the signal is delivered.
  • SIG_IGN -- Specifies that the signal has no effect on the receiving process.
  • Function pointer -- Requests to catch the signal. The signal causes the function call.
sa_mask This member can request that individual signals, in addition to those in the process signal mask, are blocked from delivery while the signal handler function specified by the sa_handler member is executing.
sa_flags This member can set the flags to enable further control over the actions taken when a signal is delivered.

The sa_flags member of the sigaction structure has the following values:
SA_ONSTACK Setting this bit causes the system to run the signal catching function on the signal stack specified by the sigstack function. If this bit is not set, the function runs on the stack of the process where the signal is delivered.
SA_RESETHAND Setting this bit resets the signal to SIG_DFL. Be aware that you cannot automatically reset SIGILL and SIGTRAP.
SA_NODEFER Setting this bit does not automatically block the signal as it is caught.
SA_NOCLDSTOP If this bit is set and the sig argument is equal to SIGCHLD and a child process of the calling process stops, then a SIGCHLD signal is sent to the calling process only if SA_NOCLDSTOP is not set for SIGCHLD.

When a signal is caught by a signal-catching function installed by sigaction , a new signal mask is calculated and installed for the duration of the signal-catching function (or until a call to either sigprocmask or sigsuspend is made. This mask is formed by taking the union of the current signal mask and the value of the sa_mask for the signal being delivered unless SA_NODEFER or SA_RESETHAND is set, and then including the signal being delivered. If and when the user's signal handler returns normally, the original signal mask is restored.

Once an action is installed for a specific signal, it remains installed until another action is explicitly requested (by another call to sigaction ), until the SA_RESETHAND flag causes resetting of the handler, or until one of the exec functions is called.

If the previous action for a specified signal had been established by signal , the values of the fields returned in the structure pointed to by the o_action argument of sigaction are unspecified, and in particular o_action->sa_handler is not necessarily the same value passed to signal . However, if a pointer to the same structure or a copy thereof is passed to a subsequent call to sigaction by means of the action argument of sigaction ), the signal is handled as if the original call to signal were repeated.

If sigaction fails, no new signal handler is installed.

It is unspecified whether an attempt to set the action for a signal that cannot be caught or ignored to SIG_DFL is ignored or causes an error to be returned with errno set to EINVAL.

See Section 4.2 for more information on signal handling.

Note
The sigvec and signal functions are provided for compatibility to old UNIX systems; their function is a subset of that available with the sigaction function.

See also sigstack , sigvec , signal , wait , read , and write , in this section.

Return Values

0 Indicates success.
--1 Indicates an error; A new signal handler is not installed. errno is set to one of the following values:
  • EFAULT -- The action or o_action argument points to a location outside of the allocated address space of the process.
  • EINVAL -- The sig argument is not a valid signal number. Or an attempt was made to ignore or supply a handler for the SIGKILL, SIGSTOP, and SIGCONT signals.

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