t/test-lib-functions.sh

   1 #!/bin/sh
   2 #
   3 # Copyright (c) 2005 Junio C Hamano
   4 #
   5 # This program is free software: you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation, either version 2 of the License, or
   8 # (at your option) any later version.
   9 #
  10 # This program is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 # GNU General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU General Public License
  16 # along with this program.  If not, see http://www.gnu.org/licenses/ .
  17
  18 # The semantics of the editor variables are that of invoking
  19 # sh -c "$EDITOR \"$@\"" files ...
  20 #
  21 # If our trash directory contains shell metacharacters, they will be
  22 # interpreted if we just set $EDITOR directly, so do a little dance with
  23 # environment variables to work around this.
  24 #
  25 # In particular, quoting isn't enough, as the path may contain the same quote
  26 # that we're using.
  27 test_set_editor () {
  28         FAKE_EDITOR="$1"
  29         export FAKE_EDITOR
  30         EDITOR='"$FAKE_EDITOR"'
  31         export EDITOR
  32 }
  33
  34 test_decode_color () {
  35         awk '
  36                 function name(n) {
  37                         if (n == 0) return "RESET";
  38                         if (n == 1) return "BOLD";
  39                         if (n == 30) return "BLACK";
  40                         if (n == 31) return "RED";
  41                         if (n == 32) return "GREEN";
  42                         if (n == 33) return "YELLOW";
  43                         if (n == 34) return "BLUE";
  44                         if (n == 35) return "MAGENTA";
  45                         if (n == 36) return "CYAN";
  46                         if (n == 37) return "WHITE";
  47                         if (n == 40) return "BLACK";
  48                         if (n == 41) return "BRED";
  49                         if (n == 42) return "BGREEN";
  50                         if (n == 43) return "BYELLOW";
  51                         if (n == 44) return "BBLUE";
  52                         if (n == 45) return "BMAGENTA";
  53                         if (n == 46) return "BCYAN";
  54                         if (n == 47) return "BWHITE";
  55                 }
  56                 {
  57                         while (match($0, /\033\[[0-9;]*m/) != 0) {
  58                                 printf "%s<", substr($0, 1, RSTART-1);
  59                                 codes = substr($0, RSTART+2, RLENGTH-3);
  60                                 if (length(codes) == 0)
  61                                         printf "%s", name(0)
  62                                 else {
  63                                         n = split(codes, ary, ";");
  64                                         sep = "";
  65                                         for (i = 1; i <= n; i++) {
  66                                                 printf "%s%s", sep, name(ary[i]);
  67                                                 sep = ";"
  68                                         }
  69                                 }
  70                                 printf ">";
  71                                 $0 = substr($0, RSTART + RLENGTH, length($0) - RSTART - RLENGTH + 1);
  72                         }
  73                         print
  74                 }
  75         '
  76 }
  77
  78 nul_to_q () {
  79         perl -pe 'y/\000/Q/'
  80 }
  81
  82 q_to_nul () {
  83         perl -pe 'y/Q/\000/'
  84 }
  85
  86 q_to_cr () {
  87         tr Q '\015'
  88 }
  89
  90 q_to_tab () {
  91         tr Q '\011'
  92 }
  93
  94 qz_to_tab_space () {
  95         tr QZ '\011\040'
  96 }
  97
  98 append_cr () {
  99         sed -e 's/$/Q/' | tr Q '\015'
 100 }
 101
 102 remove_cr () {
 103         tr '\015' Q | sed -e 's/Q$//'
 104 }
 105
 106 # In some bourne shell implementations, the "unset" builtin returns
 107 # nonzero status when a variable to be unset was not set in the first
 108 # place.
 109 #
 110 # Use sane_unset when that should not be considered an error.
 111
 112 sane_unset () {
 113         unset "$@"
 114         return 0
 115 }
 116
 117 test_tick () {
 118         if test -z "${test_tick+set}"
 119         then
 120                 test_tick=1112911993
 121         else
 122                 test_tick=$(($test_tick + 60))
 123         fi
 124         GIT_COMMITTER_DATE="$test_tick -0700"
 125         GIT_AUTHOR_DATE="$test_tick -0700"
 126         export GIT_COMMITTER_DATE GIT_AUTHOR_DATE
 127 }
 128
 129 # Stop execution and start a shell. This is useful for debugging tests and
 130 # only makes sense together with "-v".
 131 #
 132 # Be sure to remove all invocations of this command before submitting.
 133
 134 test_pause () {
 135         if test "$verbose" = t; then
 136                 "$SHELL_PATH" <&6 >&3 2>&4
 137         else
 138                 error >&5 "test_pause requires --verbose"
 139         fi
 140 }
 141
 142 # Call test_commit with the arguments "<message> [<file> [<contents> [<tag>]]]"
 143 #
 144 # This will commit a file with the given contents and the given commit
 145 # message, and tag the resulting commit with the given tag name.
 146 #
 147 # <file>, <contents>, and <tag> all default to <message>.
 148
 149 test_commit () {
 150         notick= &&
 151         signoff= &&
 152         while test $# != 0
 153         do
 154                 case "$1" in
 155                 --notick)
 156                         notick=yes
 157                         ;;
 158                 --signoff)
 159                         signoff="$1"
 160                         ;;
 161                 *)
 162                         break
 163                         ;;
 164                 esac
 165                 shift
 166         done &&
 167         file=${2:-"$1.t"} &&
 168         echo "${3-$1}" > "$file" &&
 169         git add "$file" &&
 170         if test -z "$notick"
 171         then
 172                 test_tick
 173         fi &&
 174         git commit $signoff -m "$1" &&
 175         git tag "${4:-$1}"
 176 }
 177
 178 # Call test_merge with the arguments "<message> <commit>", where <commit>
 179 # can be a tag pointing to the commit-to-merge.
 180
 181 test_merge () {
 182         test_tick &&
 183         git merge -m "$1" "$2" &&
 184         git tag "$1"
 185 }
 186
 187 # This function helps systems where core.filemode=false is set.
 188 # Use it instead of plain 'chmod +x' to set or unset the executable bit
 189 # of a file in the working directory and add it to the index.
 190
 191 test_chmod () {
 192         chmod "$@" &&
 193         git update-index --add "--chmod=$@"
 194 }
 195
 196 # Unset a configuration variable, but don't fail if it doesn't exist.
 197 test_unconfig () {
 198         git config --unset-all "$@"
 199         config_status=$?
 200         case "$config_status" in
 201         5) # ok, nothing to unset
 202                 config_status=0
 203                 ;;
 204         esac
 205         return $config_status
 206 }
 207
 208 # Set git config, automatically unsetting it after the test is over.
 209 test_config () {
 210         test_when_finished "test_unconfig '$1'" &&
 211         git config "$@"
 212 }
 213
 214 test_config_global () {
 215         test_when_finished "test_unconfig --global '$1'" &&
 216         git config --global "$@"
 217 }
 218
 219 write_script () {
 220         {
 221                 echo "#!${2-"$SHELL_PATH"}" &&
 222                 cat
 223         } >"$1" &&
 224         chmod +x "$1"
 225 }
 226
 227 # Use test_set_prereq to tell that a particular prerequisite is available.
 228 # The prerequisite can later be checked for in two ways:
 229 #
 230 # - Explicitly using test_have_prereq.
 231 #
 232 # - Implicitly by specifying the prerequisite tag in the calls to
 233 #   test_expect_{success,failure,code}.
 234 #
 235 # The single parameter is the prerequisite tag (a simple word, in all
 236 # capital letters by convention).
 237
 238 test_set_prereq () {
 239         satisfied_prereq="$satisfied_prereq$1 "
 240 }
 241 satisfied_prereq=" "
 242 lazily_testable_prereq= lazily_tested_prereq=
 243
 244 # Usage: test_lazy_prereq PREREQ 'script'
 245 test_lazy_prereq () {
 246         lazily_testable_prereq="$lazily_testable_prereq$1 "
 247         eval test_prereq_lazily_$1=\$2
 248 }
 249
 250 test_run_lazy_prereq_ () {
 251         script='
 252 mkdir -p "$TRASH_DIRECTORY/prereq-test-dir" &&
 253 (
 254         cd "$TRASH_DIRECTORY/prereq-test-dir" &&'"$2"'
 255 )'
 256         say >&3 "checking prerequisite: $1"
 257         say >&3 "$script"
 258         test_eval_ "$script"
 259         eval_ret=$?
 260         rm -rf "$TRASH_DIRECTORY/prereq-test-dir"
 261         if test "$eval_ret" = 0; then
 262                 say >&3 "prerequisite $1 ok"
 263         else
 264                 say >&3 "prerequisite $1 not satisfied"
 265         fi
 266         return $eval_ret
 267 }
 268
 269 test_have_prereq () {
 270         # prerequisites can be concatenated with ','
 271         save_IFS=$IFS
 272         IFS=,
 273         set -- $*
 274         IFS=$save_IFS
 275
 276         total_prereq=0
 277         ok_prereq=0
 278         missing_prereq=
 279
 280         for prerequisite
 281         do
 282                 case "$prerequisite" in
 283                 !*)
 284                         negative_prereq=t
 285                         prerequisite=${prerequisite#!}
 286                         ;;
 287                 *)
 288                         negative_prereq=
 289                 esac
 290
 291                 case " $lazily_tested_prereq " in
 292                 *" $prerequisite "*)
 293                         ;;
 294                 *)
 295                         case " $lazily_testable_prereq " in
 296                         *" $prerequisite "*)
 297                                 eval "script=\$test_prereq_lazily_$prerequisite" &&
 298                                 if test_run_lazy_prereq_ "$prerequisite" "$script"
 299                                 then
 300                                         test_set_prereq $prerequisite
 301                                 fi
 302                                 lazily_tested_prereq="$lazily_tested_prereq$prerequisite "
 303                         esac
 304                         ;;
 305                 esac
 306
 307                 total_prereq=$(($total_prereq + 1))
 308                 case "$satisfied_prereq" in
 309                 *" $prerequisite "*)
 310                         satisfied_this_prereq=t
 311                         ;;
 312                 *)
 313                         satisfied_this_prereq=
 314                 esac
 315
 316                 case "$satisfied_this_prereq,$negative_prereq" in
 317                 t,|,t)
 318                         ok_prereq=$(($ok_prereq + 1))
 319                         ;;
 320                 *)
 321                         # Keep a list of missing prerequisites; restore
 322                         # the negative marker if necessary.
 323                         prerequisite=${negative_prereq:+!}$prerequisite
 324                         if test -z "$missing_prereq"
 325                         then
 326                                 missing_prereq=$prerequisite
 327                         else
 328                                 missing_prereq="$prerequisite,$missing_prereq"
 329                         fi
 330                 esac
 331         done
 332
 333         test $total_prereq = $ok_prereq
 334 }
 335
 336 test_declared_prereq () {
 337         case ",$test_prereq," in
 338         *,$1,*)
 339                 return 0
 340                 ;;
 341         esac
 342         return 1
 343 }
 344
 345 test_expect_failure () {
 346         test_start_
 347         test "$#" = 3 && { test_prereq=$1; shift; } || test_prereq=
 348         test "$#" = 2 ||
 349         error "bug in the test script: not 2 or 3 parameters to test-expect-failure"
 350         export test_prereq
 351         if ! test_skip "$@"
 352         then
 353                 say >&3 "checking known breakage: $2"
 354                 if test_run_ "$2" expecting_failure
 355                 then
 356                         test_known_broken_ok_ "$1"
 357                 else
 358                         test_known_broken_failure_ "$1"
 359                 fi
 360         fi
 361         test_finish_
 362 }
 363
 364 test_expect_success () {
 365         test_start_
 366         test "$#" = 3 && { test_prereq=$1; shift; } || test_prereq=
 367         test "$#" = 2 ||
 368         error "bug in the test script: not 2 or 3 parameters to test-expect-success"
 369         export test_prereq
 370         if ! test_skip "$@"
 371         then
 372                 say >&3 "expecting success: $2"
 373                 if test_run_ "$2"
 374                 then
 375                         test_ok_ "$1"
 376                 else
 377                         test_failure_ "$@"
 378                 fi
 379         fi
 380         test_finish_
 381 }
 382
 383 # test_external runs external test scripts that provide continuous
 384 # test output about their progress, and succeeds/fails on
 385 # zero/non-zero exit code.  It outputs the test output on stdout even
 386 # in non-verbose mode, and announces the external script with "# run
 387 # <n>: ..." before running it.  When providing relative paths, keep in
 388 # mind that all scripts run in "trash directory".
 389 # Usage: test_external description command arguments...
 390 # Example: test_external 'Perl API' perl ../path/to/test.pl
 391 test_external () {
 392         test "$#" = 4 && { test_prereq=$1; shift; } || test_prereq=
 393         test "$#" = 3 ||
 394         error >&5 "bug in the test script: not 3 or 4 parameters to test_external"
 395         descr="$1"
 396         shift
 397         export test_prereq
 398         if ! test_skip "$descr" "$@"
 399         then
 400                 # Announce the script to reduce confusion about the
 401                 # test output that follows.
 402                 say_color "" "# run $test_count: $descr ($*)"
 403                 # Export TEST_DIRECTORY, TRASH_DIRECTORY and GIT_TEST_LONG
 404                 # to be able to use them in script
 405                 export TEST_DIRECTORY TRASH_DIRECTORY GIT_TEST_LONG
 406                 # Run command; redirect its stderr to &4 as in
 407                 # test_run_, but keep its stdout on our stdout even in
 408                 # non-verbose mode.
 409                 "$@" 2>&4
 410                 if [ "$?" = 0 ]
 411                 then
 412                         if test $test_external_has_tap -eq 0; then
 413                                 test_ok_ "$descr"
 414                         else
 415                                 say_color "" "# test_external test $descr was ok"
 416                                 test_success=$(($test_success + 1))
 417                         fi
 418                 else
 419                         if test $test_external_has_tap -eq 0; then
 420                                 test_failure_ "$descr" "$@"
 421                         else
 422                                 say_color error "# test_external test $descr failed: $@"
 423                                 test_failure=$(($test_failure + 1))
 424                         fi
 425                 fi
 426         fi
 427 }
 428
 429 # Like test_external, but in addition tests that the command generated
 430 # no output on stderr.
 431 test_external_without_stderr () {
 432         # The temporary file has no (and must have no) security
 433         # implications.
 434         tmp=${TMPDIR:-/tmp}
 435         stderr="$tmp/git-external-stderr.$$.tmp"
 436         test_external "$@" 4> "$stderr"
 437         [ -f "$stderr" ] || error "Internal error: $stderr disappeared."
 438         descr="no stderr: $1"
 439         shift
 440         say >&3 "# expecting no stderr from previous command"
 441         if [ ! -s "$stderr" ]; then
 442                 rm "$stderr"
 443
 444                 if test $test_external_has_tap -eq 0; then
 445                         test_ok_ "$descr"
 446                 else
 447                         say_color "" "# test_external_without_stderr test $descr was ok"
 448                         test_success=$(($test_success + 1))
 449                 fi
 450         else
 451                 if [ "$verbose" = t ]; then
 452                         output=`echo; echo "# Stderr is:"; cat "$stderr"`
 453                 else
 454                         output=
 455                 fi
 456                 # rm first in case test_failure exits.
 457                 rm "$stderr"
 458                 if test $test_external_has_tap -eq 0; then
 459                         test_failure_ "$descr" "$@" "$output"
 460                 else
 461                         say_color error "# test_external_without_stderr test $descr failed: $@: $output"
 462                         test_failure=$(($test_failure + 1))
 463                 fi
 464         fi
 465 }
 466
 467 # debugging-friendly alternatives to "test [-f|-d|-e]"
 468 # The commands test the existence or non-existence of $1. $2 can be
 469 # given to provide a more precise diagnosis.
 470 test_path_is_file () {
 471         if ! [ -f "$1" ]
 472         then
 473                 echo "File $1 doesn't exist. $*"
 474                 false
 475         fi
 476 }
 477
 478 test_path_is_dir () {
 479         if ! [ -d "$1" ]
 480         then
 481                 echo "Directory $1 doesn't exist. $*"
 482                 false
 483         fi
 484 }
 485
 486 test_path_is_missing () {
 487         if [ -e "$1" ]
 488         then
 489                 echo "Path exists:"
 490                 ls -ld "$1"
 491                 if [ $# -ge 1 ]; then
 492                         echo "$*"
 493                 fi
 494                 false
 495         fi
 496 }
 497
 498 # test_line_count checks that a file has the number of lines it
 499 # ought to. For example:
 500 #
 501 #       test_expect_success 'produce exactly one line of output' '
 502 #               do something >output &&
 503 #               test_line_count = 1 output
 504 #       '
 505 #
 506 # is like "test $(wc -l <output) = 1" except that it passes the
 507 # output through when the number of lines is wrong.
 508
 509 test_line_count () {
 510         if test $# != 3
 511         then
 512                 error "bug in the test script: not 3 parameters to test_line_count"
 513         elif ! test $(wc -l <"$3") "$1" "$2"
 514         then
 515                 echo "test_line_count: line count for $3 !$1 $2"
 516                 cat "$3"
 517                 return 1
 518         fi
 519 }
 520
 521 # This is not among top-level (test_expect_success | test_expect_failure)
 522 # but is a prefix that can be used in the test script, like:
 523 #
 524 #       test_expect_success 'complain and die' '
 525 #           do something &&
 526 #           do something else &&
 527 #           test_must_fail git checkout ../outerspace
 528 #       '
 529 #
 530 # Writing this as "! git checkout ../outerspace" is wrong, because
 531 # the failure could be due to a segv.  We want a controlled failure.
 532
 533 test_must_fail () {
 534         "$@"
 535         exit_code=$?
 536         if test $exit_code = 0; then
 537                 echo >&2 "test_must_fail: command succeeded: $*"
 538                 return 1
 539         elif test $exit_code -gt 129 -a $exit_code -le 192; then
 540                 echo >&2 "test_must_fail: died by signal: $*"
 541                 return 1
 542         elif test $exit_code = 127; then
 543                 echo >&2 "test_must_fail: command not found: $*"
 544                 return 1
 545         elif test $exit_code = 126; then
 546                 echo >&2 "test_must_fail: valgrind error: $*"
 547                 return 1
 548         fi
 549         return 0
 550 }
 551
 552 # Similar to test_must_fail, but tolerates success, too.  This is
 553 # meant to be used in contexts like:
 554 #
 555 #       test_expect_success 'some command works without configuration' '
 556 #               test_might_fail git config --unset all.configuration &&
 557 #               do something
 558 #       '
 559 #
 560 # Writing "git config --unset all.configuration || :" would be wrong,
 561 # because we want to notice if it fails due to segv.
 562
 563 test_might_fail () {
 564         "$@"
 565         exit_code=$?
 566         if test $exit_code -gt 129 -a $exit_code -le 192; then
 567                 echo >&2 "test_might_fail: died by signal: $*"
 568                 return 1
 569         elif test $exit_code = 127; then
 570                 echo >&2 "test_might_fail: command not found: $*"
 571                 return 1
 572         fi
 573         return 0
 574 }
 575
 576 # Similar to test_must_fail and test_might_fail, but check that a
 577 # given command exited with a given exit code. Meant to be used as:
 578 #
 579 #       test_expect_success 'Merge with d/f conflicts' '
 580 #               test_expect_code 1 git merge "merge msg" B master
 581 #       '
 582
 583 test_expect_code () {
 584         want_code=$1
 585         shift
 586         "$@"
 587         exit_code=$?
 588         if test $exit_code = $want_code
 589         then
 590                 return 0
 591         fi
 592
 593         echo >&2 "test_expect_code: command exited with $exit_code, we wanted $want_code $*"
 594         return 1
 595 }
 596
 597 # test_cmp is a helper function to compare actual and expected output.
 598 # You can use it like:
 599 #
 600 #       test_expect_success 'foo works' '
 601 #               echo expected >expected &&
 602 #               foo >actual &&
 603 #               test_cmp expected actual
 604 #       '
 605 #
 606 # This could be written as either "cmp" or "diff -u", but:
 607 # - cmp's output is not nearly as easy to read as diff -u
 608 # - not all diff versions understand "-u"
 609
 610 test_cmp() {
 611         $GIT_TEST_CMP "$@"
 612 }
 613
 614 # Check if the file expected to be empty is indeed empty, and barfs
 615 # otherwise.
 616
 617 test_must_be_empty () {
 618         if test -s "$1"
 619         then
 620                 echo "'$1' is not empty, it contains:"
 621                 cat "$1"
 622                 return 1
 623         fi
 624 }
 625
 626 # Tests that its two parameters refer to the same revision
 627 test_cmp_rev () {
 628         git rev-parse --verify "$1" >expect.rev &&
 629         git rev-parse --verify "$2" >actual.rev &&
 630         test_cmp expect.rev actual.rev
 631 }
 632
 633 # Print a sequence of numbers or letters in increasing order.  This is
 634 # similar to GNU seq(1), but the latter might not be available
 635 # everywhere (and does not do letters).  It may be used like:
 636 #
 637 #       for i in `test_seq 100`; do
 638 #               for j in `test_seq 10 20`; do
 639 #                       for k in `test_seq a z`; do
 640 #                               echo $i-$j-$k
 641 #                       done
 642 #               done
 643 #       done
 644
 645 test_seq () {
 646         case $# in
 647         1)      set 1 "$@" ;;
 648         2)      ;;
 649         *)      error "bug in the test script: not 1 or 2 parameters to test_seq" ;;
 650         esac
 651         perl -le 'print for $ARGV[0]..$ARGV[1]' -- "$@"
 652 }
 653
 654 # This function can be used to schedule some commands to be run
 655 # unconditionally at the end of the test to restore sanity:
 656 #
 657 #       test_expect_success 'test core.capslock' '
 658 #               git config core.capslock true &&
 659 #               test_when_finished "git config --unset core.capslock" &&
 660 #               hello world
 661 #       '
 662 #
 663 # That would be roughly equivalent to
 664 #
 665 #       test_expect_success 'test core.capslock' '
 666 #               git config core.capslock true &&
 667 #               hello world
 668 #               git config --unset core.capslock
 669 #       '
 670 #
 671 # except that the greeting and config --unset must both succeed for
 672 # the test to pass.
 673 #
 674 # Note that under --immediate mode, no clean-up is done to help diagnose
 675 # what went wrong.
 676
 677 test_when_finished () {
 678         test_cleanup="{ $*
 679                 } && (exit \"\$eval_ret\"); eval_ret=\$?; $test_cleanup"
 680 }
 681
 682 # Most tests can use the created repository, but some may need to create more.
 683 # Usage: test_create_repo <directory>
 684 test_create_repo () {
 685         test "$#" = 1 ||
 686         error "bug in the test script: not 1 parameter to test-create-repo"
 687         repo="$1"
 688         mkdir -p "$repo"
 689         (
 690                 cd "$repo" || error "Cannot setup test environment"
 691                 "$GIT_EXEC_PATH/git-init" "--template=$GIT_BUILD_DIR/templates/blt/" >&3 2>&4 ||
 692                 error "cannot run git init -- have you built things yet?"
 693                 mv .git/hooks .git/hooks-disabled
 694         ) || exit
 695 }
 696
 697 # This function helps on symlink challenged file systems when it is not
 698 # important that the file system entry is a symbolic link.
 699 # Use test_ln_s_add instead of "ln -s x y && git add y" to add a
 700 # symbolic link entry y to the index.
 701
 702 test_ln_s_add () {
 703         if test_have_prereq SYMLINKS
 704         then
 705                 ln -s "$1" "$2" &&
 706                 git update-index --add "$2"
 707         else
 708                 printf '%s' "$1" >"$2" &&
 709                 ln_s_obj=$(git hash-object -w "$2") &&
 710                 git update-index --add --cacheinfo 120000 $ln_s_obj "$2"
 711         fi
 712 }
 713
 714 perl () {
 715         command "$PERL_PATH" "$@"
 716 }
 717
 718 # The following mingw_* functions obey POSIX shell syntax, but are actually
 719 # bash scripts, and are meant to be used only with bash on Windows.
 720
 721 # A test_cmp function that treats LF and CRLF equal and avoids to fork
 722 # diff when possible.
 723 mingw_test_cmp () {
 724         # Read text into shell variables and compare them. If the results
 725         # are different, use regular diff to report the difference.
 726         local test_cmp_a= test_cmp_b=
 727
 728         # When text came from stdin (one argument is '-') we must feed it
 729         # to diff.
 730         local stdin_for_diff=
 731
 732         # Since it is difficult to detect the difference between an
 733         # empty input file and a failure to read the files, we go straight
 734         # to diff if one of the inputs is empty.
 735         if test -s "$1" && test -s "$2"
 736         then
 737                 # regular case: both files non-empty
 738                 mingw_read_file_strip_cr_ test_cmp_a <"$1"
 739                 mingw_read_file_strip_cr_ test_cmp_b <"$2"
 740         elif test -s "$1" && test "$2" = -
 741         then
 742                 # read 2nd file from stdin
 743                 mingw_read_file_strip_cr_ test_cmp_a <"$1"
 744                 mingw_read_file_strip_cr_ test_cmp_b
 745                 stdin_for_diff='<<<"$test_cmp_b"'
 746         elif test "$1" = - && test -s "$2"
 747         then
 748                 # read 1st file from stdin
 749                 mingw_read_file_strip_cr_ test_cmp_a
 750                 mingw_read_file_strip_cr_ test_cmp_b <"$2"
 751                 stdin_for_diff='<<<"$test_cmp_a"'
 752         fi
 753         test -n "$test_cmp_a" &&
 754         test -n "$test_cmp_b" &&
 755         test "$test_cmp_a" = "$test_cmp_b" ||
 756         eval "diff -u \"\$@\" $stdin_for_diff"
 757 }
 758
 759 # $1 is the name of the shell variable to fill in
 760 mingw_read_file_strip_cr_ () {
 761         # Read line-wise using LF as the line separator
 762         # and use IFS to strip CR.
 763         local line
 764         while :
 765         do
 766                 if IFS=$'\r' read -r -d $'\n' line
 767                 then
 768                         # good
 769                         line=$line$'\n'
 770                 else
 771                         # we get here at EOF, but also if the last line
 772                         # was not terminated by LF; in the latter case,
 773                         # some text was read
 774                         if test -z "$line"
 775                         then
 776                                 # EOF, really
 777                                 break
 778                         fi
 779                 fi
 780                 eval "$1=\$$1\$line"
 781         done
 782 }