warn.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/* $Source: /u/mark/src/pax/RCS/warn.c,v $
 *
 * $Revision: 1.2 $
 *
 * warn.c - miscellaneous user warning routines 
 *
 * DESCRIPTION
 *
 *	These routines provide the user with various forms of warning
 *	and informational messages.
 *
 * AUTHOR
 *
 *     Mark H. Colburn, NAPS International ([e-mail])
 *
 * Sponsored by The USENIX Association for public distribution. 
 *
 * Copyright (c) 1989 Mark H. Colburn.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice is duplicated in all such 
 * forms and that any documentation, advertising materials, and other 
 * materials related to such distribution and use acknowledge that the 
 * software was developed * by Mark H. Colburn and sponsored by The 
 * USENIX Association. 
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * $Log:	warn.c,v $
 * Revision 1.2  89/02/12  10:06:15  mark
 * 1.2 release fixes
 * 
 * Revision 1.1  88/12/23  18:02:40  mark
 * Initial revision
 * 
 */

#ifndef lint
static char *ident = "$Id: warn.c,v 1.2 89/02/12 10:06:15 mark Exp $";
static char *copyright = "Copyright (c) 1989 Mark H. Colburn.\nAll rights reserved.\n";
#endif /* ! lint */


/* Headers */

#include "pax.h"


/* Function Prototypes */

#ifdef __STDC__

static void prsize(FILE *, OFFSET);

#else /* !__STDC__ */

static void prsize();

#endif /* __STDC__ */


/* warnarch - print an archive-related warning message and offset
 *
 * DESCRIPTION
 *
 *	Present the user with an error message and an archive offset at
 *	which the error occured.   This can be useful for diagnosing or
 *	fixing damaged archives.
 *
 * PARAMETERS
 *
 *	char 	*msg	- A message string to be printed for the user.
 *	OFFSET 	adjust	- An adjustment which is added to the current 
 *			  archive position to tell the user exactly where 
 *			  the error occurred.
 */

#ifdef __STDC__

void warnarch(char *msg, OFFSET adjust)

#else 

void warnarch(msg, adjust)
char           *msg;
OFFSET          adjust;

#endif
{
    fprintf(stderr, "%s: [offset ", myname);
    prsize(stderr, total - adjust);
    fprintf(stderr, "]: %s\n", msg);
}


/* strerror - return pointer to appropriate system error message
 *
 * DESCRIPTION
 *
 *	Get an error message string which is appropriate for the setting
 *	of the errno variable.
 *
 * RETURNS
 *
 *	Returns a pointer to a string which has an appropriate error
 *	message for the present value of errno.  The error message
 *	strings are taken from sys_errlist[] where appropriate.  If an
 *	appropriate message is not available in sys_errlist, then a
 *	pointer to the string "Unknown error (errno <errvalue>)" is 
 *	returned instead.
 */

#ifdef __STDC__

char *strerror(void)

#else

char *strerror()

#endif
{
#ifdef _POSIX_SOURCE
#undef strerror
    return (strerror(errno));
#else
    static char     msg[40];		/* used for "Unknown error" messages */

    if (errno > 0 && errno < sys_nerr) {
	return (sys_errlist[errno]);
    }
    sprintf(msg, "Unknown error (errno %d)", errno);
    return (msg);
#endif
}


/* prsize - print a file offset on a file stream
 *
 * DESCRIPTION
 *
 *	Prints a file offset to a specific file stream.  The file offset is
 *	of the form "%dm+%dk+%d", where the number preceeding the "m" and
 *	the "k" stand for the number of Megabytes and the number of
 *	Kilobytes, respectivley, which have been processed so far.
 *
 * PARAMETERS
 *
 *	FILE  *stream	- Stream which is to be used for output 
 *	OFFSET size	- Current archive position to be printed on the output 
 *			  stream in the form: "%dm+%dk+%d".
 *
 */

#ifdef __STDC__

static void prsize(FILE *stream, OFFSET size)

#else

static void prsize(stream, size)
FILE           *stream;		/* stream which is used for output */
OFFSET          size;		/* current archive position to be printed */

#endif

{
    OFFSET          n;

    if (n = (size / (1024L * 1024L))) {
	fprintf(stream, "%ldm+", n);
	size -= n * 1024L * 1024L;
    }
    if (n = (size / 1024L)) {
	fprintf(stream, "%ldk+", n);
	size -= n * 1024L;
    }
    fprintf(stream, "%ld", size);
}


/* fatal - print fatal message and exit
 *
 * DESCRIPTION
 *
 *	Fatal prints the program's name along with an error message, then
 *	exits the program with a non-zero return code.
 *
 * PARAMETERS
 *
 *	char 	*why	- description of reason for termination 
 *		
 * RETURNS
 *
 *	Returns an exit code of 1 to the parent process.
 */

#ifdef __STDC__

void fatal(char *why)

#else

void fatal(why)
char           *why;		/* description of reason for termination */

#endif
{
    fprintf(stderr, "%s: %s\n", myname, why);
    exit(1);
}



/* warn - print a warning message
 *
 * DESCRIPTION
 *
 *	Print an error message listing the program name, the actual error
 *	which occurred and an informational message as to why the error
 *	occurred on the standard error device.  The standard error is
 *	flushed after the error is printed to assure that the user gets
 *	the message in a timely fasion.
 *
 * PARAMETERS
 *
 *	char *what	- Pointer to string describing what failed.
 *	char *why	- Pointer to string describing why did it failed.
 */

#ifdef __STDC__

void warn(char *what, char *why)

#else

void warn(what, why)
char           *what;		/* message as to what the error was */
char           *why;		/* explanation why the error occurred */

#endif
{
    fprintf(stderr, "%s: %s : %s\n", myname, what, why);
    fflush(stderr);
}