Man page - error_message_count(3)

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Manual

error

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
ATTRIBUTES
STANDARDS
SEE ALSO

NAME

error, error_at_line, error_message_count, error_one_per_line, error_print_progname - glibc error reporting functions

LIBRARY

Standard C library ( libc , -lc )

SYNOPSIS

#include <error.h>

void error(int status , int errnum , const char * format , ...);
void error_at_line(int status , int errnum , const char * filename ,
unsigned int linenum , const char * format , ...);

extern unsigned int error_message_count ;
extern int error_one_per_line ;

extern void (* error_print_progname )(void);

DESCRIPTION

error () is a general error-reporting function. It flushes stdout , and then outputs to stderr the program name, a colon and a space, the message specified by the printf (3)-style format string format , and, if errnum is nonzero, a second colon and a space followed by the string given by strerror(errnum) . Any arguments required for format should follow format in the argument list. The output is terminated by a newline character.

The program name printed by error () is the value of the global variable program_invocation_name (3). program_invocation_name initially has the same value as main ()’s argv[0] . The value of this variable can be modified to change the output of error ().

If status has a nonzero value, then error () calls exit (3) to terminate the program using the given value as the exit status; otherwise it returns after printing the error message.

The error_at_line () function is exactly the same as error (), except for the addition of the arguments filename and linenum . The output produced is as for error (), except that after the program name are written: a colon, the value of filename , a colon, and the value of linenum . The preprocessor values __LINE__ and __FILE__ may be useful when calling error_at_line (), but other values can also be used. For example, these arguments could refer to a location in an input file.

If the global variable error_one_per_line is set nonzero, a sequence of error_at_line () calls with the same value of filename and linenum will result in only one message (the first) being output.

The global variable error_message_count counts the number of messages that have been output by error () and error_at_line ().

If the global variable error_print_progname is assigned the address of a function (i.e., is not NULL), then that function is called instead of prefixing the message with the program name and colon. The function should print a suitable string to stderr .

ATTRIBUTES

For an explanation of the terms used in this section, see attributes (7).

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The internal error_one_per_line variable is accessed (without any form of synchronization, but since it’s an int used once, it should be safe enough) and, if error_one_per_line is set nonzero, the internal static variables (not exposed to users) used to hold the last printed filename and line number are accessed and modified without synchronization; the update is not atomic and it occurs before disabling cancelation, so it can be interrupted only after one of the two variables is modified. After that, error_at_line () is very much like error ().

STANDARDS

GNU.

SEE ALSO

err (3), errno (3), exit (3), perror (3), program_invocation_name (3), strerror (3)