man7.org > tlpi > code > online code > lib/error_functions.c

lib/error_functions.c

This is lib/error_functions.c (Listing 3-3, page 54), an example program file from the book The Linux Programming Interface.

The source code file is copyright 2010, Michael Kerrisk, and is licensed under the GNU Lesser General Public License, version 3.

This page shows the "distribution" or "book" version of the file (why are there two versions?), or the differences between the two versions. You can switch between the views using the tabs below.

In the listing below, the names of Linux system calls and C library functions are hyperlinked to manual pages from the Linux man-pages project, and the names of functions implemented in the book are hyperlinked to the implementations of those functions.

Function list (Bold in this list means a function is non-static)

#include <stdarg.h>
#include "error_functions.h"
#include "tlpi_hdr.h"
#include "ename.c.inc"          /* Defines ename and MAX_ENAME */

#ifdef __GNUC__
__attribute__ ((__noreturn__))
#endif
static void
terminate(Boolean useExit3)
{
    char *s;

    /* Dump core if EF_DUMPCORE environment variable is defined and
       is a nonempty string; otherwise call exit(3) or _exit(2),
       depending on the value of 'useExit3'. */

    s = getenv("EF_DUMPCORE");

    if (s != NULL && *s != '\0')
        abort();
    else if (useExit3)
        exit(EXIT_FAILURE);
    else
        _exit(EXIT_FAILURE);
}

static void
outputError(Boolean useErr, int err, Boolean flushStdout,
        const char *format, va_list ap)
{
#define BUF_SIZE 500
    char buf[BUF_SIZE], userMsg[BUF_SIZE], errText[BUF_SIZE];

    vsnprintf(userMsg, BUF_SIZE, format, ap);

    if (useErr)
        snprintf(errText, BUF_SIZE, " [%s %s]",
                (err > 0 && err <= MAX_ENAME) ?
                ename[err] : "?UNKNOWN?", strerror(err));
    else
        snprintf(errText, BUF_SIZE, ":");

    snprintf(buf, BUF_SIZE, "ERROR%s %s\n", errText, userMsg);

    if (flushStdout)
        fflush(stdout);       /* Flush any pending stdout */
    fputs(buf, stderr);
    fflush(stderr);           /* In case stderr is not line-buffered */
}

void
errMsg(const char *format, ...)
{
    va_list argList;
    int savedErrno;

    savedErrno = errno;       /* In case we change it here */

    va_start(argList, format);
    outputError(TRUE, errno, TRUE, format, argList);
    va_end(argList);

    errno = savedErrno;
}

void
errExit(const char *format, ...)
{
    va_list argList;

    va_start(argList, format);
    outputError(TRUE, errno, TRUE, format, argList);
    va_end(argList);

    terminate(TRUE);
}

void
err_exit(const char *format, ...)
{
    va_list argList;

    va_start(argList, format);
    outputError(TRUE, errno, FALSE, format, argList);
    va_end(argList);

    terminate(FALSE);
}

void
errExitEN(int errnum, const char *format, ...)
{
    va_list argList;

    va_start(argList, format);
    outputError(TRUE, errnum, TRUE, format, argList);
    va_end(argList);

    terminate(TRUE);
}

void
fatal(const char *format, ...)
{
    va_list argList;

    va_start(argList, format);
    outputError(FALSE, 0, TRUE, format, argList);
    va_end(argList);

    terminate(TRUE);
}

void
usageErr(const char *format, ...)
{
    va_list argList;

    fflush(stdout);           /* Flush any pending stdout */

    fprintf(stderr, "Usage: ");
    va_start(argList, format);
    vfprintf(stderr, format, argList);
    va_end(argList);

    fflush(stderr);           /* In case stderr is not line-buffered */
    exit(EXIT_FAILURE);
}

void
cmdLineErr(const char *format, ...)
{
    va_list argList;

    fflush(stdout);           /* Flush any pending stdout */

    fprintf(stderr, "Command-line usage error: ");
    va_start(argList, format);
    vfprintf(stderr, format, argList);
    va_end(argList);

    fflush(stderr);           /* In case stderr is not line-buffered */
    exit(EXIT_FAILURE);
}

 

Download lib/error_functions.c

This page copyright (C) 2013, Michael Kerrisk,   mtk AT man7.org