t/test-lib-functions.sh

   1 # Library of functions shared by all tests scripts, included by
   2 # test-lib.sh.
   3 #
   4 # Copyright (c) 2005 Junio C Hamano
   5 #
   6 # This program is free software: you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation, either version 2 of the License, or
   9 # (at your option) any later version.
  10 #
  11 # This program is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 # GNU General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU General Public License
  17 # along with this program.  If not, see http://www.gnu.org/licenses/ .
  18
  19 # The semantics of the editor variables are that of invoking
  20 # sh -c "$EDITOR \"$@\"" files ...
  21 #
  22 # If our trash directory contains shell metacharacters, they will be
  23 # interpreted if we just set $EDITOR directly, so do a little dance with
  24 # environment variables to work around this.
  25 #
  26 # In particular, quoting isn't enough, as the path may contain the same quote
  27 # that we're using.
  28 test_set_editor () {
  29         FAKE_EDITOR="$1"
  30         export FAKE_EDITOR
  31         EDITOR='"$FAKE_EDITOR"'
  32         export EDITOR
  33 }
  34
  35 test_decode_color () {
  36         awk '
  37                 function name(n) {
  38                         if (n == 0) return "RESET";
  39                         if (n == 1) return "BOLD";
  40                         if (n == 30) return "BLACK";
  41                         if (n == 31) return "RED";
  42                         if (n == 32) return "GREEN";
  43                         if (n == 33) return "YELLOW";
  44                         if (n == 34) return "BLUE";
  45                         if (n == 35) return "MAGENTA";
  46                         if (n == 36) return "CYAN";
  47                         if (n == 37) return "WHITE";
  48                         if (n == 40) return "BLACK";
  49                         if (n == 41) return "BRED";
  50                         if (n == 42) return "BGREEN";
  51                         if (n == 43) return "BYELLOW";
  52                         if (n == 44) return "BBLUE";
  53                         if (n == 45) return "BMAGENTA";
  54                         if (n == 46) return "BCYAN";
  55                         if (n == 47) return "BWHITE";
  56                 }
  57                 {
  58                         while (match($0, /\033\[[0-9;]*m/) != 0) {
  59                                 printf "%s<", substr($0, 1, RSTART-1);
  60                                 codes = substr($0, RSTART+2, RLENGTH-3);
  61                                 if (length(codes) == 0)
  62                                         printf "%s", name(0)
  63                                 else {
  64                                         n = split(codes, ary, ";");
  65                                         sep = "";
  66                                         for (i = 1; i <= n; i++) {
  67                                                 printf "%s%s", sep, name(ary[i]);
  68                                                 sep = ";"
  69                                         }
  70                                 }
  71                                 printf ">";
  72                                 $0 = substr($0, RSTART + RLENGTH, length($0) - RSTART - RLENGTH + 1);
  73                         }
  74                         print
  75                 }
  76         '
  77 }
  78
  79 nul_to_q () {
  80         perl -pe 'y/\000/Q/'
  81 }
  82
  83 q_to_nul () {
  84         perl -pe 'y/Q/\000/'
  85 }
  86
  87 q_to_cr () {
  88         tr Q '\015'
  89 }
  90
  91 q_to_tab () {
  92         tr Q '\011'
  93 }
  94
  95 qz_to_tab_space () {
  96         tr QZ '\011\040'
  97 }
  98
  99 append_cr () {
 100         sed -e 's/$/Q/' | tr Q '\015'
 101 }
 102
 103 remove_cr () {
 104         tr '\015' Q | sed -e 's/Q$//'
 105 }
 106
 107 # In some bourne shell implementations, the "unset" builtin returns
 108 # nonzero status when a variable to be unset was not set in the first
 109 # place.
 110 #
 111 # Use sane_unset when that should not be considered an error.
 112
 113 sane_unset () {
 114         unset "$@"
 115         return 0
 116 }
 117
 118 test_tick () {
 119         if test -z "${test_tick+set}"
 120         then
 121                 test_tick=1112911993
 122         else
 123                 test_tick=$(($test_tick + 60))
 124         fi
 125         GIT_COMMITTER_DATE="$test_tick -0700"
 126         GIT_AUTHOR_DATE="$test_tick -0700"
 127         export GIT_COMMITTER_DATE GIT_AUTHOR_DATE
 128 }
 129
 130 # Stop execution and start a shell. This is useful for debugging tests and
 131 # only makes sense together with "-v".
 132 #
 133 # Be sure to remove all invocations of this command before submitting.
 134
 135 test_pause () {
 136         if test "$verbose" = t; then
 137                 "$SHELL_PATH" <&6 >&3 2>&4
 138         else
 139                 error >&5 "test_pause requires --verbose"
 140         fi
 141 }
 142
 143 # Call test_commit with the arguments "<message> [<file> [<contents> [<tag>]]]"
 144 #
 145 # This will commit a file with the given contents and the given commit
 146 # message, and tag the resulting commit with the given tag name.
 147 #
 148 # <file>, <contents>, and <tag> all default to <message>.
 149
 150 test_commit () {
 151         notick= &&
 152         signoff= &&
 153         while test $# != 0
 154         do
 155                 case "$1" in
 156                 --notick)
 157                         notick=yes
 158                         ;;
 159                 --signoff)
 160                         signoff="$1"
 161                         ;;
 162                 *)
 163                         break
 164                         ;;
 165                 esac
 166                 shift
 167         done &&
 168         file=${2:-"$1.t"} &&
 169         echo "${3-$1}" > "$file" &&
 170         git add "$file" &&
 171         if test -z "$notick"
 172         then
 173                 test_tick
 174         fi &&
 175         git commit $signoff -m "$1" &&
 176         git tag "${4:-$1}"
 177 }
 178
 179 # Call test_merge with the arguments "<message> <commit>", where <commit>
 180 # can be a tag pointing to the commit-to-merge.
 181
 182 test_merge () {
 183         test_tick &&
 184         git merge -m "$1" "$2" &&
 185         git tag "$1"
 186 }
 187
 188 # This function helps systems where core.filemode=false is set.
 189 # Use it instead of plain 'chmod +x' to set or unset the executable bit
 190 # of a file in the working directory and add it to the index.
 191
 192 test_chmod () {
 193         chmod "$@" &&
 194         git update-index --add "--chmod=$@"
 195 }
 196
 197 # Unset a configuration variable, but don't fail if it doesn't exist.
 198 test_unconfig () {
 199         git config --unset-all "$@"
 200         config_status=$?
 201         case "$config_status" in
 202         5) # ok, nothing to unset
 203                 config_status=0
 204                 ;;
 205         esac
 206         return $config_status
 207 }
 208
 209 # Set git config, automatically unsetting it after the test is over.
 210 test_config () {
 211         test_when_finished "test_unconfig '$1'" &&
 212         git config "$@"
 213 }
 214
 215 test_config_global () {
 216         test_when_finished "test_unconfig --global '$1'" &&
 217         git config --global "$@"
 218 }
 219
 220 write_script () {
 221         {
 222                 echo "#!${2-"$SHELL_PATH"}" &&
 223                 cat
 224         } >"$1" &&
 225         chmod +x "$1"
 226 }
 227
 228 # Use test_set_prereq to tell that a particular prerequisite is available.
 229 # The prerequisite can later be checked for in two ways:
 230 #
 231 # - Explicitly using test_have_prereq.
 232 #
 233 # - Implicitly by specifying the prerequisite tag in the calls to
 234 #   test_expect_{success,failure,code}.
 235 #
 236 # The single parameter is the prerequisite tag (a simple word, in all
 237 # capital letters by convention).
 238
 239 test_set_prereq () {
 240         satisfied_prereq="$satisfied_prereq$1 "
 241 }
 242 satisfied_prereq=" "
 243 lazily_testable_prereq= lazily_tested_prereq=
 244
 245 # Usage: test_lazy_prereq PREREQ 'script'
 246 test_lazy_prereq () {
 247         lazily_testable_prereq="$lazily_testable_prereq$1 "
 248         eval test_prereq_lazily_$1=\$2
 249 }
 250
 251 test_run_lazy_prereq_ () {
 252         script='
 253 mkdir -p "$TRASH_DIRECTORY/prereq-test-dir" &&
 254 (
 255         cd "$TRASH_DIRECTORY/prereq-test-dir" &&'"$2"'
 256 )'
 257         say >&3 "checking prerequisite: $1"
 258         say >&3 "$script"
 259         test_eval_ "$script"
 260         eval_ret=$?
 261         rm -rf "$TRASH_DIRECTORY/prereq-test-dir"
 262         if test "$eval_ret" = 0; then
 263                 say >&3 "prerequisite $1 ok"
 264         else
 265                 say >&3 "prerequisite $1 not satisfied"
 266         fi
 267         return $eval_ret
 268 }
 269
 270 test_have_prereq () {
 271         # prerequisites can be concatenated with ','
 272         save_IFS=$IFS
 273         IFS=,
 274         set -- $*
 275         IFS=$save_IFS
 276
 277         total_prereq=0
 278         ok_prereq=0
 279         missing_prereq=
 280
 281         for prerequisite
 282         do
 283                 case "$prerequisite" in
 284                 !*)
 285                         negative_prereq=t
 286                         prerequisite=${prerequisite#!}
 287                         ;;
 288                 *)
 289                         negative_prereq=
 290                 esac
 291
 292                 case " $lazily_tested_prereq " in
 293                 *" $prerequisite "*)
 294                         ;;
 295                 *)
 296                         case " $lazily_testable_prereq " in
 297                         *" $prerequisite "*)
 298                                 eval "script=\$test_prereq_lazily_$prerequisite" &&
 299                                 if test_run_lazy_prereq_ "$prerequisite" "$script"
 300                                 then
 301                                         test_set_prereq $prerequisite
 302                                 fi
 303                                 lazily_tested_prereq="$lazily_tested_prereq$prerequisite "
 304                         esac
 305                         ;;
 306                 esac
 307
 308                 total_prereq=$(($total_prereq + 1))
 309                 case "$satisfied_prereq" in
 310                 *" $prerequisite "*)
 311                         satisfied_this_prereq=t
 312                         ;;
 313                 *)
 314                         satisfied_this_prereq=
 315                 esac
 316
 317                 case "$satisfied_this_prereq,$negative_prereq" in
 318                 t,|,t)
 319                         ok_prereq=$(($ok_prereq + 1))
 320                         ;;
 321                 *)
 322                         # Keep a list of missing prerequisites; restore
 323                         # the negative marker if necessary.
 324                         prerequisite=${negative_prereq:+!}$prerequisite
 325                         if test -z "$missing_prereq"
 326                         then
 327                                 missing_prereq=$prerequisite
 328                         else
 329                                 missing_prereq="$prerequisite,$missing_prereq"
 330                         fi
 331                 esac
 332         done
 333
 334         test $total_prereq = $ok_prereq
 335 }
 336
 337 test_declared_prereq () {
 338         case ",$test_prereq," in
 339         *,$1,*)
 340                 return 0
 341                 ;;
 342         esac
 343         return 1
 344 }
 345
 346 test_expect_failure () {
 347         test_start_
 348         test "$#" = 3 && { test_prereq=$1; shift; } || test_prereq=
 349         test "$#" = 2 ||
 350         error "bug in the test script: not 2 or 3 parameters to test-expect-failure"
 351         export test_prereq
 352         if ! test_skip "$@"
 353         then
 354                 say >&3 "checking known breakage: $2"
 355                 if test_run_ "$2" expecting_failure
 356                 then
 357                         test_known_broken_ok_ "$1"
 358                 else
 359                         test_known_broken_failure_ "$1"
 360                 fi
 361         fi
 362         test_finish_
 363 }
 364
 365 test_expect_success () {
 366         test_start_
 367         test "$#" = 3 && { test_prereq=$1; shift; } || test_prereq=
 368         test "$#" = 2 ||
 369         error "bug in the test script: not 2 or 3 parameters to test-expect-success"
 370         export test_prereq
 371         if ! test_skip "$@"
 372         then
 373                 say >&3 "expecting success: $2"
 374                 if test_run_ "$2"
 375                 then
 376                         test_ok_ "$1"
 377                 else
 378                         test_failure_ "$@"
 379                 fi
 380         fi
 381         test_finish_
 382 }
 383
 384 # test_external runs external test scripts that provide continuous
 385 # test output about their progress, and succeeds/fails on
 386 # zero/non-zero exit code.  It outputs the test output on stdout even
 387 # in non-verbose mode, and announces the external script with "# run
 388 # <n>: ..." before running it.  When providing relative paths, keep in
 389 # mind that all scripts run in "trash directory".
 390 # Usage: test_external description command arguments...
 391 # Example: test_external 'Perl API' perl ../path/to/test.pl
 392 test_external () {
 393         test "$#" = 4 && { test_prereq=$1; shift; } || test_prereq=
 394         test "$#" = 3 ||
 395         error >&5 "bug in the test script: not 3 or 4 parameters to test_external"
 396         descr="$1"
 397         shift
 398         export test_prereq
 399         if ! test_skip "$descr" "$@"
 400         then
 401                 # Announce the script to reduce confusion about the
 402                 # test output that follows.
 403                 say_color "" "# run $test_count: $descr ($*)"
 404                 # Export TEST_DIRECTORY, TRASH_DIRECTORY and GIT_TEST_LONG
 405                 # to be able to use them in script
 406                 export TEST_DIRECTORY TRASH_DIRECTORY GIT_TEST_LONG
 407                 # Run command; redirect its stderr to &4 as in
 408                 # test_run_, but keep its stdout on our stdout even in
 409                 # non-verbose mode.
 410                 "$@" 2>&4
 411                 if [ "$?" = 0 ]
 412                 then
 413                         if test $test_external_has_tap -eq 0; then
 414                                 test_ok_ "$descr"
 415                         else
 416                                 say_color "" "# test_external test $descr was ok"
 417                                 test_success=$(($test_success + 1))
 418                         fi
 419                 else
 420                         if test $test_external_has_tap -eq 0; then
 421                                 test_failure_ "$descr" "$@"
 422                         else
 423                                 say_color error "# test_external test $descr failed: $@"
 424                                 test_failure=$(($test_failure + 1))
 425                         fi
 426                 fi
 427         fi
 428 }
 429
 430 # Like test_external, but in addition tests that the command generated
 431 # no output on stderr.
 432 test_external_without_stderr () {
 433         # The temporary file has no (and must have no) security
 434         # implications.
 435         tmp=${TMPDIR:-/tmp}
 436         stderr="$tmp/git-external-stderr.$$.tmp"
 437         test_external "$@" 4> "$stderr"
 438         [ -f "$stderr" ] || error "Internal error: $stderr disappeared."
 439         descr="no stderr: $1"
 440         shift
 441         say >&3 "# expecting no stderr from previous command"
 442         if [ ! -s "$stderr" ]; then
 443                 rm "$stderr"
 444
 445                 if test $test_external_has_tap -eq 0; then
 446                         test_ok_ "$descr"
 447                 else
 448                         say_color "" "# test_external_without_stderr test $descr was ok"
 449                         test_success=$(($test_success + 1))
 450                 fi
 451         else
 452                 if [ "$verbose" = t ]; then
 453                         output=`echo; echo "# Stderr is:"; cat "$stderr"`
 454                 else
 455                         output=
 456                 fi
 457                 # rm first in case test_failure exits.
 458                 rm "$stderr"
 459                 if test $test_external_has_tap -eq 0; then
 460                         test_failure_ "$descr" "$@" "$output"
 461                 else
 462                         say_color error "# test_external_without_stderr test $descr failed: $@: $output"
 463                         test_failure=$(($test_failure + 1))
 464                 fi
 465         fi
 466 }
 467
 468 # debugging-friendly alternatives to "test [-f|-d|-e]"
 469 # The commands test the existence or non-existence of $1. $2 can be
 470 # given to provide a more precise diagnosis.
 471 test_path_is_file () {
 472         if ! [ -f "$1" ]
 473         then
 474                 echo "File $1 doesn't exist. $*"
 475                 false
 476         fi
 477 }
 478
 479 test_path_is_dir () {
 480         if ! [ -d "$1" ]
 481         then
 482                 echo "Directory $1 doesn't exist. $*"
 483                 false
 484         fi
 485 }
 486
 487 test_path_is_missing () {
 488         if [ -e "$1" ]
 489         then
 490                 echo "Path exists:"
 491                 ls -ld "$1"
 492                 if [ $# -ge 1 ]; then
 493                         echo "$*"
 494                 fi
 495                 false
 496         fi
 497 }
 498
 499 # test_line_count checks that a file has the number of lines it
 500 # ought to. For example:
 501 #
 502 #       test_expect_success 'produce exactly one line of output' '
 503 #               do something >output &&
 504 #               test_line_count = 1 output
 505 #       '
 506 #
 507 # is like "test $(wc -l <output) = 1" except that it passes the
 508 # output through when the number of lines is wrong.
 509
 510 test_line_count () {
 511         if test $# != 3
 512         then
 513                 error "bug in the test script: not 3 parameters to test_line_count"
 514         elif ! test $(wc -l <"$3") "$1" "$2"
 515         then
 516                 echo "test_line_count: line count for $3 !$1 $2"
 517                 cat "$3"
 518                 return 1
 519         fi
 520 }
 521
 522 # This is not among top-level (test_expect_success | test_expect_failure)
 523 # but is a prefix that can be used in the test script, like:
 524 #
 525 #       test_expect_success 'complain and die' '
 526 #           do something &&
 527 #           do something else &&
 528 #           test_must_fail git checkout ../outerspace
 529 #       '
 530 #
 531 # Writing this as "! git checkout ../outerspace" is wrong, because
 532 # the failure could be due to a segv.  We want a controlled failure.
 533
 534 test_must_fail () {
 535         "$@"
 536         exit_code=$?
 537         if test $exit_code = 0; then
 538                 echo >&2 "test_must_fail: command succeeded: $*"
 539                 return 1
 540         elif test $exit_code -gt 129 -a $exit_code -le 192; then
 541                 echo >&2 "test_must_fail: died by signal: $*"
 542                 return 1
 543         elif test $exit_code = 127; then
 544                 echo >&2 "test_must_fail: command not found: $*"
 545                 return 1
 546         elif test $exit_code = 126; then
 547                 echo >&2 "test_must_fail: valgrind error: $*"
 548                 return 1
 549         fi
 550         return 0
 551 }
 552
 553 # Similar to test_must_fail, but tolerates success, too.  This is
 554 # meant to be used in contexts like:
 555 #
 556 #       test_expect_success 'some command works without configuration' '
 557 #               test_might_fail git config --unset all.configuration &&
 558 #               do something
 559 #       '
 560 #
 561 # Writing "git config --unset all.configuration || :" would be wrong,
 562 # because we want to notice if it fails due to segv.
 563
 564 test_might_fail () {
 565         "$@"
 566         exit_code=$?
 567         if test $exit_code -gt 129 -a $exit_code -le 192; then
 568                 echo >&2 "test_might_fail: died by signal: $*"
 569                 return 1
 570         elif test $exit_code = 127; then
 571                 echo >&2 "test_might_fail: command not found: $*"
 572                 return 1
 573         fi
 574         return 0
 575 }
 576
 577 # Similar to test_must_fail and test_might_fail, but check that a
 578 # given command exited with a given exit code. Meant to be used as:
 579 #
 580 #       test_expect_success 'Merge with d/f conflicts' '
 581 #               test_expect_code 1 git merge "merge msg" B master
 582 #       '
 583
 584 test_expect_code () {
 585         want_code=$1
 586         shift
 587         "$@"
 588         exit_code=$?
 589         if test $exit_code = $want_code
 590         then
 591                 return 0
 592         fi
 593
 594         echo >&2 "test_expect_code: command exited with $exit_code, we wanted $want_code $*"
 595         return 1
 596 }
 597
 598 # test_cmp is a helper function to compare actual and expected output.
 599 # You can use it like:
 600 #
 601 #       test_expect_success 'foo works' '
 602 #               echo expected >expected &&
 603 #               foo >actual &&
 604 #               test_cmp expected actual
 605 #       '
 606 #
 607 # This could be written as either "cmp" or "diff -u", but:
 608 # - cmp's output is not nearly as easy to read as diff -u
 609 # - not all diff versions understand "-u"
 610
 611 test_cmp() {
 612         $GIT_TEST_CMP "$@"
 613 }
 614
 615 # Check if the file expected to be empty is indeed empty, and barfs
 616 # otherwise.
 617
 618 test_must_be_empty () {
 619         if test -s "$1"
 620         then
 621                 echo "'$1' is not empty, it contains:"
 622                 cat "$1"
 623                 return 1
 624         fi
 625 }
 626
 627 # Tests that its two parameters refer to the same revision
 628 test_cmp_rev () {
 629         git rev-parse --verify "$1" >expect.rev &&
 630         git rev-parse --verify "$2" >actual.rev &&
 631         test_cmp expect.rev actual.rev
 632 }
 633
 634 # Print a sequence of numbers or letters in increasing order.  This is
 635 # similar to GNU seq(1), but the latter might not be available
 636 # everywhere (and does not do letters).  It may be used like:
 637 #
 638 #       for i in `test_seq 100`; do
 639 #               for j in `test_seq 10 20`; do
 640 #                       for k in `test_seq a z`; do
 641 #                               echo $i-$j-$k
 642 #                       done
 643 #               done
 644 #       done
 645
 646 test_seq () {
 647         case $# in
 648         1)      set 1 "$@" ;;
 649         2)      ;;
 650         *)      error "bug in the test script: not 1 or 2 parameters to test_seq" ;;
 651         esac
 652         perl -le 'print for $ARGV[0]..$ARGV[1]' -- "$@"
 653 }
 654
 655 # This function can be used to schedule some commands to be run
 656 # unconditionally at the end of the test to restore sanity:
 657 #
 658 #       test_expect_success 'test core.capslock' '
 659 #               git config core.capslock true &&
 660 #               test_when_finished "git config --unset core.capslock" &&
 661 #               hello world
 662 #       '
 663 #
 664 # That would be roughly equivalent to
 665 #
 666 #       test_expect_success 'test core.capslock' '
 667 #               git config core.capslock true &&
 668 #               hello world
 669 #               git config --unset core.capslock
 670 #       '
 671 #
 672 # except that the greeting and config --unset must both succeed for
 673 # the test to pass.
 674 #
 675 # Note that under --immediate mode, no clean-up is done to help diagnose
 676 # what went wrong.
 677
 678 test_when_finished () {
 679         test_cleanup="{ $*
 680                 } && (exit \"\$eval_ret\"); eval_ret=\$?; $test_cleanup"
 681 }
 682
 683 # Most tests can use the created repository, but some may need to create more.
 684 # Usage: test_create_repo <directory>
 685 test_create_repo () {
 686         test "$#" = 1 ||
 687         error "bug in the test script: not 1 parameter to test-create-repo"
 688         repo="$1"
 689         mkdir -p "$repo"
 690         (
 691                 cd "$repo" || error "Cannot setup test environment"
 692                 "$GIT_EXEC_PATH/git-init" "--template=$GIT_BUILD_DIR/templates/blt/" >&3 2>&4 ||
 693                 error "cannot run git init -- have you built things yet?"
 694                 mv .git/hooks .git/hooks-disabled
 695         ) || exit
 696 }
 697
 698 # This function helps on symlink challenged file systems when it is not
 699 # important that the file system entry is a symbolic link.
 700 # Use test_ln_s_add instead of "ln -s x y && git add y" to add a
 701 # symbolic link entry y to the index.
 702
 703 test_ln_s_add () {
 704         if test_have_prereq SYMLINKS
 705         then
 706                 ln -s "$1" "$2" &&
 707                 git update-index --add "$2"
 708         else
 709                 printf '%s' "$1" >"$2" &&
 710                 ln_s_obj=$(git hash-object -w "$2") &&
 711                 git update-index --add --cacheinfo 120000 $ln_s_obj "$2"
 712         fi
 713 }
 714
 715 perl () {
 716         command "$PERL_PATH" "$@"
 717 }
 718
 719 # The following mingw_* functions obey POSIX shell syntax, but are actually
 720 # bash scripts, and are meant to be used only with bash on Windows.
 721
 722 # A test_cmp function that treats LF and CRLF equal and avoids to fork
 723 # diff when possible.
 724 mingw_test_cmp () {
 725         # Read text into shell variables and compare them. If the results
 726         # are different, use regular diff to report the difference.
 727         local test_cmp_a= test_cmp_b=
 728
 729         # When text came from stdin (one argument is '-') we must feed it
 730         # to diff.
 731         local stdin_for_diff=
 732
 733         # Since it is difficult to detect the difference between an
 734         # empty input file and a failure to read the files, we go straight
 735         # to diff if one of the inputs is empty.
 736         if test -s "$1" && test -s "$2"
 737         then
 738                 # regular case: both files non-empty
 739                 mingw_read_file_strip_cr_ test_cmp_a <"$1"
 740                 mingw_read_file_strip_cr_ test_cmp_b <"$2"
 741         elif test -s "$1" && test "$2" = -
 742         then
 743                 # read 2nd file from stdin
 744                 mingw_read_file_strip_cr_ test_cmp_a <"$1"
 745                 mingw_read_file_strip_cr_ test_cmp_b
 746                 stdin_for_diff='<<<"$test_cmp_b"'
 747         elif test "$1" = - && test -s "$2"
 748         then
 749                 # read 1st file from stdin
 750                 mingw_read_file_strip_cr_ test_cmp_a
 751                 mingw_read_file_strip_cr_ test_cmp_b <"$2"
 752                 stdin_for_diff='<<<"$test_cmp_a"'
 753         fi
 754         test -n "$test_cmp_a" &&
 755         test -n "$test_cmp_b" &&
 756         test "$test_cmp_a" = "$test_cmp_b" ||
 757         eval "diff -u \"\$@\" $stdin_for_diff"
 758 }
 759
 760 # $1 is the name of the shell variable to fill in
 761 mingw_read_file_strip_cr_ () {
 762         # Read line-wise using LF as the line separator
 763         # and use IFS to strip CR.
 764         local line
 765         while :
 766         do
 767                 if IFS=$'\r' read -r -d $'\n' line
 768                 then
 769                         # good
 770                         line=$line$'\n'
 771                 else
 772                         # we get here at EOF, but also if the last line
 773                         # was not terminated by LF; in the latter case,
 774                         # some text was read
 775                         if test -z "$line"
 776                         then
 777                                 # EOF, really
 778                                 break
 779                         fi
 780                 fi
 781                 eval "$1=\$$1\$line"
 782         done
 783 }