[821] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * *printf implementations for busybox
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| 4 | *
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| 5 | * Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
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| 6 | *
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| 7 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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| 8 | */
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| 9 |
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| 10 | /* Mar 12, 2003 Manuel Novoa III
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| 11 | *
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| 12 | * While fwrite(), fputc(), fputs(), etc. all set the stream error flag
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| 13 | * on failure, the *printf functions are unique in that they can fail
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| 14 | * for reasons not related to the actual output itself. Among the possible
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| 15 | * reasons for failure which don't set the streams error indicator,
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| 16 | * SUSv3 lists EILSEQ, EINVAL, and ENOMEM.
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| 17 | *
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| 18 | * In some cases, it would be desirable to have a group of *printf()
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| 19 | * functions available that _always_ set the stream error indicator on
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| 20 | * failure. That would allow us to defer error checking until applet
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| 21 | * exit. Unfortunately, there is no standard way of setting a streams
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| 22 | * error indicator... even though we can clear it with clearerr().
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| 23 | */
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| 24 |
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| 25 | /* Mar 22, 2006 Rich Felker III
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| 26 | *
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| 27 | * Actually there is a portable way to set the error indicator. See below.
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| 28 | * It is not thread-safe as written due to a race condition with file
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| 29 | * descriptors but since BB is not threaded that does not matter. It can be
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| 30 | * made thread-safe at the expense of slightly more code, if this is ever
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| 31 | * needed in the future.
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| 32 | */
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| 33 |
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| 34 | #include <stdio.h>
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| 35 | #include <stdarg.h>
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| 36 | #include <unistd.h>
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| 37 | #include <errno.h>
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| 38 | #include "libbb.h"
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| 39 |
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| 40 | #ifdef L_bb_vfprintf
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| 41 | int bb_vfprintf(FILE * __restrict stream,
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| 42 | const char * __restrict format,
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| 43 | va_list arg)
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| 44 | {
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| 45 | int rv;
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| 46 |
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| 47 | if ((rv = vfprintf(stream, format, arg)) < 0) {
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| 48 | /* The following sequence portably sets the error flag for
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| 49 | * stream on any remotely POSIX-compliant implementation. */
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| 50 |
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| 51 | int errno_save = errno;
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| 52 | int fd = fileno(stream);
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| 53 | int tmp = dup(fd);
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| 54 |
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| 55 | fflush(stream);
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| 56 | close(fd);
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| 57 | /* Force an attempted write to nonexistant fd => EBADF */
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| 58 | fputc(0, stream);
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| 59 | fflush(stream);
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| 60 | /* Restore the stream's original fd */
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| 61 | dup2(tmp, fd);
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| 62 | close(tmp);
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| 63 | errno = errno_save;
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| 64 | }
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| 65 |
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| 66 | return rv;
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| 67 | }
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| 68 | #endif
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| 69 |
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| 70 | #ifdef L_bb_vprintf
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| 71 | int bb_vprintf(const char * __restrict format, va_list arg)
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| 72 | {
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| 73 | return bb_vfprintf(stdout, format, arg);
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| 74 | }
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| 75 | #endif
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| 76 |
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| 77 | #ifdef L_bb_fprintf
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| 78 | int bb_fprintf(FILE * __restrict stream,
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| 79 | const char * __restrict format, ...)
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| 80 | {
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| 81 | va_list arg;
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| 82 | int rv;
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| 83 |
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| 84 | va_start(arg, format);
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| 85 | rv = bb_vfprintf(stream, format, arg);
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| 86 | va_end(arg);
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| 87 |
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| 88 | return rv;
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| 89 | }
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| 90 | #endif
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| 91 |
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| 92 | #ifdef L_bb_printf
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| 93 | int bb_printf(const char * __restrict format, ...)
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| 94 | {
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| 95 | va_list arg;
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| 96 | int rv;
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| 97 |
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| 98 | va_start(arg, format);
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| 99 | rv = bb_vfprintf(stdout, format, arg);
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| 100 | va_end(arg);
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| 101 |
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| 102 | return rv;
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| 103 | }
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| 104 | #endif
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