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97 lines
2.4 KiB
C
97 lines
2.4 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* *printf implementations for busybox
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*
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* Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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/* Mar 12, 2003 Manuel Novoa III
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*
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* While fwrite(), fputc(), fputs(), etc. all set the stream error flag
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* on failure, the *printf functions are unique in that they can fail
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* for reasons not related to the actual output itself. Among the possible
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* reasons for failure which don't set the streams error indicator,
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* SUSv3 lists EILSEQ, EINVAL, and ENOMEM.
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*
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* In some cases, it would be desirable to have a group of *printf()
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* functions available that _always_ set the stream error indicator on
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* failure. That would allow us to defer error checking until applet
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* exit. Unfortunately, there is no standard way of setting a streams
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* error indicator... even though we can clear it with clearerr().
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*/
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/* Mar 22, 2006 Rich Felker III
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*
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* Actually there is a portable way to set the error indicator. See below.
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* It is not thread-safe as written due to a race condition with file
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* descriptors but since BB is not threaded that does not matter. It can be
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* made thread-safe at the expense of slightly more code, if this is ever
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* needed in the future.
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*/
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#include <stdio.h>
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#include <stdarg.h>
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#include <unistd.h>
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#include <errno.h>
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#include "libbb.h"
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int bb_vfprintf(FILE * __restrict stream,
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const char * __restrict format,
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va_list arg)
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{
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int rv;
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if ((rv = vfprintf(stream, format, arg)) < 0) {
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/* The following sequence portably sets the error flag for
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* stream on any remotely POSIX-compliant implementation. */
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int errno_save = errno;
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int fd = fileno(stream);
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int tmp = dup(fd);
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fflush(stream);
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close(fd);
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/* Force an attempted write to nonexistant fd => EBADF */
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fputc(0, stream);
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fflush(stream);
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/* Restore the stream's original fd */
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dup2(tmp, fd);
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close(tmp);
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errno = errno_save;
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}
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return rv;
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}
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int bb_vprintf(const char * __restrict format, va_list arg)
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{
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return bb_vfprintf(stdout, format, arg);
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}
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int bb_fprintf(FILE * __restrict stream,
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const char * __restrict format, ...)
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{
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va_list arg;
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int rv;
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va_start(arg, format);
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rv = bb_vfprintf(stream, format, arg);
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va_end(arg);
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return rv;
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}
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int bb_printf(const char * __restrict format, ...)
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{
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va_list arg;
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int rv;
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va_start(arg, format);
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rv = bb_vfprintf(stdout, format, arg);
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va_end(arg);
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return rv;
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}
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