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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