Fix random segfaults in pack-objects.

diff --git a/git-merge-one-file.sh b/git-merge-one-file.sh
index 906098dda5a2e9f4490b518eadbdaa4332e8793b..7d62d7902cb1d7cd2749091b86d532306bea89b3 100755 (executable)
--- a/git-merge-one-file.sh
+++ b/git-merge-one-file.sh
@@ -8,7 +8,7 @@
 #   $2 - file in branch1 SHA1 (or empty)
 #   $3 - file in branch2 SHA1 (or empty)
 #   $4 - pathname in repository
-#   $5 - orignal file mode (or empty)
+#   $5 - original file mode (or empty)
 #   $6 - file in branch1 mode (or empty)
 #   $7 - file in branch2 mode (or empty)
 #
@@ -23,10 +23,16 @@ case "${1:-.}${2:-.}${3:-.}" in
 "$1.." | "$1.$1" | "$1$1.")
        if [ "$2" ]; then
                echo "Removing $4"
+       else
+               # read-tree checked that index matches HEAD already,
+               # so we know we do not have this path tracked.
+               # there may be an unrelated working tree file here,
+               # which we should just leave unmolested.
+               exit 0
        fi
        if test -f "$4"; then
                rm -f -- "$4" &&
-               rmdir -p "$(expr "$4" : '\(.*\)/')" 2>/dev/null || :
+               rmdir -p "$(expr "z$4" : 'z\(.*\)/')" 2>/dev/null || :
        fi &&
                exec git-update-index --remove -- "$4"
        ;;
@@ -34,8 +40,16 @@ case "${1:-.}${2:-.}${3:-.}" in
 #
 # Added in one.
 #
-".$2." | "..$3" )
+".$2.")
+       # the other side did not add and we added so there is nothing
+       # to be done.
+       ;;
+"..$3")
        echo "Adding $4"
+       test -f "$4" || {
+               echo "ERROR: untracked $4 is overwritten by the merge."
+               exit 1
+       }
        git-update-index --add --cacheinfo "$6$7" "$2$3" "$4" &&
                exec git-checkout-index -u -f -- "$4"
        ;;
@@ -58,6 +72,14 @@ case "${1:-.}${2:-.}${3:-.}" in
 # Modified in both, but differently.
 #
 "$1$2$3" | ".$2$3")
+
+       case ",$6,$7," in
+       *,120000,*)
+               echo "ERROR: $4: Not merging symbolic link changes."
+               exit 1
+               ;;
+       esac
+
        src2=`git-unpack-file $3`
        case "$1" in
        '')
@@ -74,20 +96,21 @@ case "${1:-.}${2:-.}${3:-.}" in
                expr "$sz0" \< "$sz1" \* 2 >/dev/null || : >$orig
                ;;
        *)
-               echo "Auto-merging $4."
+               echo "Auto-merging $4"
                orig=`git-unpack-file $1`
                ;;
        esac
 
-       # Create the working tree file, with the correct permission bits.
-       # we can not rely on the fact that our tree has the path, because
-       # we allow the merge to be done in an unchecked-out working tree.
-       rm -f "$4" &&
-               git-cat-file blob "$2" >"$4" &&
-               case "$6" in *7??) chmod +x "$4" ;; esac &&
-               merge "$4" "$orig" "$src2"
+       # Be careful for funny filename such as "-L" in "$4", which
+       # would confuse "merge" greatly.
+       src1=`git-unpack-file $2`
+       git-merge-file "$src1" "$orig" "$src2"
        ret=$?
-       rm -f -- "$orig" "$src2"
+
+       # Create the working tree file, using "our tree" version from the
+       # index, and then store the result of the merge.
+       git-checkout-index -f --stage=2 -- "$4" && cat "$src1" >"$4"
+       rm -f -- "$orig" "$src1" "$src2"
 
        if [ "$6" != "$7" ]; then
                echo "ERROR: Permissions conflict: $5->$6,$7."
@@ -98,7 +121,7 @@ case "${1:-.}${2:-.}${3:-.}" in
        fi
 
        if [ $ret -ne 0 ]; then
-               echo "ERROR: Merge conflict in $4."
+               echo "ERROR: Merge conflict in $4"
                exit 1
        fi
        exec git-update-index -- "$4"