| 1 | # ungetc.m4 serial 10
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| 2 | dnl Copyright (C) 2009-2022 Free Software Foundation, Inc.
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| 3 | dnl This file is free software; the Free Software Foundation
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| 4 | dnl gives unlimited permission to copy and/or distribute it,
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| 5 | dnl with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | AC_DEFUN_ONCE([gl_FUNC_UNGETC_WORKS],
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| 8 | [
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| 9 | AC_REQUIRE([AC_PROG_CC])
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| 10 | AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
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| 11 |
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| 12 | AC_CACHE_CHECK([whether ungetc works on arbitrary bytes],
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| 13 | [gl_cv_func_ungetc_works],
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| 14 | [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
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| 15 | #include <stdio.h>
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| 16 | ]], [[FILE *f;
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| 17 | if (!(f = fopen ("conftest.tmp", "w+")))
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| 18 | return 1;
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| 19 | if (fputs ("abc", f) < 0)
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| 20 | { fclose (f); return 2; }
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| 21 | rewind (f);
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| 22 | if (fgetc (f) != 'a')
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| 23 | { fclose (f); return 3; }
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| 24 | if (fgetc (f) != 'b')
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| 25 | { fclose (f); return 4; }
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| 26 | if (ungetc ('d', f) != 'd')
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| 27 | { fclose (f); return 5; }
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| 28 | if (ftell (f) != 1)
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| 29 | { fclose (f); return 6; }
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| 30 | if (fgetc (f) != 'd')
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| 31 | { fclose (f); return 7; }
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| 32 | if (ftell (f) != 2)
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| 33 | { fclose (f); return 8; }
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| 34 | if (fseek (f, 0, SEEK_CUR) != 0)
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| 35 | { fclose (f); return 9; }
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| 36 | if (ftell (f) != 2)
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| 37 | { fclose (f); return 10; }
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| 38 | if (fgetc (f) != 'c')
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| 39 | { fclose (f); return 11; }
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| 40 | fclose (f);
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| 41 | remove ("conftest.tmp");
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| 42 | ]])],
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| 43 | [gl_cv_func_ungetc_works=yes], [gl_cv_func_ungetc_works=no],
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| 44 | [case "$host_os" in
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| 45 | # Guess yes on glibc systems.
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| 46 | *-gnu* | gnu*) gl_cv_func_ungetc_works="guessing yes" ;;
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| 47 | # Guess yes on musl systems.
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| 48 | *-musl*) gl_cv_func_ungetc_works="guessing yes" ;;
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| 49 | # Guess yes on bionic systems.
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| 50 | *-android*) gl_cv_func_ungetc_works="guessing yes" ;;
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| 51 | # Guess yes on native Windows.
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| 52 | mingw*) gl_cv_func_ungetc_works="guessing yes" ;;
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| 53 | # If we don't know, obey --enable-cross-guesses.
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| 54 | *) gl_cv_func_ungetc_works="$gl_cross_guess_normal" ;;
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| 55 | esac
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| 56 | ])
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| 57 | ])
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| 58 | gl_ftello_broken_after_ungetc=no
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| 59 | case "$gl_cv_func_ungetc_works" in
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| 60 | *yes) ;;
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| 61 | *)
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| 62 | dnl On macOS >= 10.15, where the above program fails with exit code 6,
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| 63 | dnl we fix it through an ftello override.
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| 64 | case "$host_os" in
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| 65 | darwin*) gl_ftello_broken_after_ungetc=yes ;;
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| 66 | *)
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| 67 | AC_DEFINE([FUNC_UNGETC_BROKEN], [1],
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| 68 | [Define to 1 if ungetc is broken when used on arbitrary bytes.])
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| 69 | ;;
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| 70 | esac
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| 71 | ;;
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| 72 | esac
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| 73 | ])
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