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Diffstat (limited to 'm4/ftello.m4')
| -rw-r--r-- | m4/ftello.m4 | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/m4/ftello.m4 b/m4/ftello.m4 new file mode 100644 index 0000000..e13fcd9 --- /dev/null +++ b/m4/ftello.m4 @@ -0,0 +1,162 @@ +# ftello.m4 serial 15 +dnl Copyright (C) 2007-2023 Free Software Foundation, Inc. +dnl This file is free software; the Free Software Foundation +dnl gives unlimited permission to copy and/or distribute it, +dnl with or without modifications, as long as this notice is preserved. + +AC_DEFUN([gl_FUNC_FTELLO], +[ + AC_REQUIRE([gl_STDIO_H_DEFAULTS]) + AC_REQUIRE([AC_PROG_CC]) + AC_REQUIRE([gl_STDIN_LARGE_OFFSET]) + AC_REQUIRE([gl_SYS_TYPES_H]) + + dnl Persuade glibc <stdio.h> to declare ftello(). + AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS]) + + AC_CHECK_DECLS_ONCE([ftello]) + if test $ac_cv_have_decl_ftello = no; then + HAVE_DECL_FTELLO=0 + fi + + AC_CACHE_CHECK([for ftello], [gl_cv_func_ftello], + [ + AC_LINK_IFELSE( + [AC_LANG_PROGRAM( + [[#include <stdio.h>]], + [[ftello (stdin);]])], + [gl_cv_func_ftello=yes], + [gl_cv_func_ftello=no]) + ]) + if test $gl_cv_func_ftello = no; then + HAVE_FTELLO=0 + else + if test $WINDOWS_64_BIT_OFF_T = 1; then + REPLACE_FTELLO=1 + fi + if test $gl_cv_var_stdin_large_offset = no; then + REPLACE_FTELLO=1 + fi + AC_REQUIRE([AC_CANONICAL_HOST]) + if test $REPLACE_FTELLO = 0; then + dnl On native Windows, in some circumstances, ftell(), ftello(), + dnl fgetpos(), lseek(), _lseeki64() all succeed on devices of type + dnl FILE_TYPE_PIPE. However, to match POSIX behaviour, we want + dnl ftell(), ftello(), fgetpos(), lseek() to fail when the argument fd + dnl designates a pipe. See also + dnl https://github.com/python/cpython/issues/78961#issuecomment-1093800325 + case "$host_os" in + mingw*) REPLACE_FTELLO=1 ;; + esac + fi + if test $REPLACE_FTELLO = 0; then + dnl Detect bug on Solaris. + dnl ftell and ftello produce incorrect results after putc that followed a + dnl getc call that reached EOF on Solaris. This is because the _IOREAD + dnl flag does not get cleared in this case, even though _IOWRT gets set, + dnl and ftell and ftello look whether the _IOREAD flag is set. + AC_CACHE_CHECK([whether ftello works], + [gl_cv_func_ftello_works], + [ + dnl Initial guess, used when cross-compiling or when /dev/tty cannot + dnl be opened. +changequote(,)dnl + case "$host_os" in + # Guess no on Solaris. + solaris*) gl_cv_func_ftello_works="guessing no" ;; + # Guess yes on native Windows. + mingw*) gl_cv_func_ftello_works="guessing yes" ;; + # Guess yes otherwise. + *) gl_cv_func_ftello_works="guessing yes" ;; + esac +changequote([,])dnl + AC_RUN_IFELSE( + [AC_LANG_SOURCE([[ +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#define TESTFILE "conftest.tmp" +int +main (void) +{ + FILE *fp; + + /* Create a file with some contents. */ + fp = fopen (TESTFILE, "w"); + if (fp == NULL) + return 70; + if (fwrite ("foogarsh", 1, 8, fp) < 8) + { fclose (fp); return 71; } + if (fclose (fp)) + return 72; + + /* The file's contents is now "foogarsh". */ + + /* Try writing after reading to EOF. */ + fp = fopen (TESTFILE, "r+"); + if (fp == NULL) + return 73; + if (fseek (fp, -1, SEEK_END)) + { fclose (fp); return 74; } + if (!(getc (fp) == 'h')) + { fclose (fp); return 1; } + if (!(getc (fp) == EOF)) + { fclose (fp); return 2; } + if (!(ftell (fp) == 8)) + { fclose (fp); return 3; } + if (!(ftell (fp) == 8)) + { fclose (fp); return 4; } + if (!(putc ('!', fp) == '!')) + { fclose (fp); return 5; } + if (!(ftell (fp) == 9)) + { fclose (fp); return 6; } + if (!(fclose (fp) == 0)) + return 7; + fp = fopen (TESTFILE, "r"); + if (fp == NULL) + return 75; + { + char buf[10]; + if (!(fread (buf, 1, 10, fp) == 9)) + { fclose (fp); return 10; } + if (!(memcmp (buf, "foogarsh!", 9) == 0)) + { fclose (fp); return 11; } + } + if (!(fclose (fp) == 0)) + return 12; + + /* The file's contents is now "foogarsh!". */ + + return 0; +}]])], + [gl_cv_func_ftello_works=yes], + [gl_cv_func_ftello_works=no], [:]) + ]) + case "$gl_cv_func_ftello_works" in + *yes) ;; + *) + REPLACE_FTELLO=1 + AC_DEFINE([FTELLO_BROKEN_AFTER_SWITCHING_FROM_READ_TO_WRITE], [1], + [Define to 1 if the system's ftello function has the Solaris bug.]) + ;; + esac + fi + if test $REPLACE_FTELLO = 0; then + dnl Detect bug on macOS >= 10.15. + gl_FUNC_UNGETC_WORKS + if test $gl_ftello_broken_after_ungetc = yes; then + REPLACE_FTELLO=1 + AC_DEFINE([FTELLO_BROKEN_AFTER_UNGETC], [1], + [Define to 1 if the system's ftello function has the macOS bug.]) + fi + fi + fi +]) + +# Prerequisites of lib/ftello.c. +AC_DEFUN([gl_PREREQ_FTELLO], +[ + dnl Native Windows has the function _ftelli64. mingw hides it, but mingw64 + dnl makes it usable again. + AC_CHECK_FUNCS([_ftelli64]) +]) |