Sync with Git 2.30.2 for CVE-2021-21300

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --cc cache.h
Simple merge

diff --cc git-compat-util.h
Simple merge

diff --cc run-command.c
Simple merge

diff --cc t/t0021-conversion.sh
Simple merge

diff --cc t/t2006-checkout-index-basic.sh
index 7ff3edab05aec604b740608a29e54b4f257f8f8f,7b25a3572e2f0823fa74b126d87d0cf8777cb36a..7705e3a31708355c05271aa9d5eafa5af359043f
--- 1/t/t2006-checkout-index-basic.sh
--- 2/t/t2006-checkout-index-basic.sh
+++ b/t/t2006-checkout-index-basic.sh
@@@ -31,28 -31,50 +31,73 @@@ test_expect_success 'checkout-index rep
        test_must_fail git checkout-index --stdin 2>stderr &&
        test_i18ngrep not.in.the.cache stderr
  '
+ for mode in 'case' 'utf-8'
+ do
+       case "$mode" in
+       case)   dir='A' symlink='a' mode_prereq='CASE_INSENSITIVE_FS' ;;
+       utf-8)
+               dir=$(printf "\141\314\210") symlink=$(printf "\303\244")
+               mode_prereq='UTF8_NFD_TO_NFC' ;;
+       esac
+ 
+       test_expect_success SYMLINKS,$mode_prereq \
+       "checkout-index with $mode-collision don't write to the wrong place" '
+               git init $mode-collision &&
+               (
+                       cd $mode-collision &&
+                       mkdir target-dir &&
+ 
+                       empty_obj_hex=$(git hash-object -w --stdin </dev/null) &&
+                       symlink_hex=$(printf "%s" "$PWD/target-dir" | git hash-object -w --stdin) &&
+ 
+                       cat >objs <<-EOF &&
+                       100644 blob ${empty_obj_hex}    ${dir}/x
+                       100644 blob ${empty_obj_hex}    ${dir}/y
+                       100644 blob ${empty_obj_hex}    ${dir}/z
+                       120000 blob ${symlink_hex}      ${symlink}
+                       EOF
+ 
+                       git update-index --index-info <objs &&
+ 
+                       # Note: the order is important here to exercise the
+                       # case where the file at ${dir} has its type changed by
+                       # the time Git tries to check out ${dir}/z.
+                       #
+                       # Also, we use core.precomposeUnicode=false because we
+                       # want Git to treat the UTF-8 paths transparently on
+                       # Mac OS, matching what is in the index.
+                       #
+                       git -c core.precomposeUnicode=false checkout-index -f \
+                               ${dir}/x ${dir}/y ${symlink} ${dir}/z &&
+ 
+                       # Should not create ${dir}/z at ${symlink}/z
+                       test_path_is_missing target-dir/z
+ 
+               )
+       '
+ done
  
 +test_expect_success 'checkout-index --temp correctly reports error on missing blobs' '
 +      test_when_finished git reset --hard &&
 +      missing_blob=$(echo "no such blob here" | git hash-object --stdin) &&
 +      cat >objs <<-EOF &&
 +      100644 $missing_blob    file
 +      120000 $missing_blob    symlink
 +      EOF
 +      git update-index --index-info <objs &&
 +
 +      test_must_fail git checkout-index --temp symlink file 2>stderr &&
 +      test_i18ngrep "unable to read sha1 file of file ($missing_blob)" stderr &&
 +      test_i18ngrep "unable to read sha1 file of symlink ($missing_blob)" stderr
 +'
 +
 +test_expect_success 'checkout-index --temp correctly reports error for submodules' '
 +      git init sub &&
 +      test_commit -C sub file &&
 +      git submodule add ./sub &&
 +      git commit -m sub &&
 +      test_must_fail git checkout-index --temp sub 2>stderr &&
 +      test_i18ngrep "cannot create temporary submodule sub" stderr
 +'
 +
  test_done

diff --cc unpack-trees.c
Simple merge