git-merge-one-file.shon commit Documentation: add "Fighting regressions with git bisect" article (69a9cd3)
   1#!/bin/sh
   2#
   3# Copyright (c) Linus Torvalds, 2005
   4#
   5# This is the git per-file merge script, called with
   6#
   7#   $1 - original file SHA1 (or empty)
   8#   $2 - file in branch1 SHA1 (or empty)
   9#   $3 - file in branch2 SHA1 (or empty)
  10#   $4 - pathname in repository
  11#   $5 - original file mode (or empty)
  12#   $6 - file in branch1 mode (or empty)
  13#   $7 - file in branch2 mode (or empty)
  14#
  15# Handle some trivial cases.. The _really_ trivial cases have
  16# been handled already by git read-tree, but that one doesn't
  17# do any merges that might change the tree layout.
  18
  19case "${1:-.}${2:-.}${3:-.}" in
  20#
  21# Deleted in both or deleted in one and unchanged in the other
  22#
  23"$1.." | "$1.$1" | "$1$1.")
  24        if [ "$2" ]; then
  25                echo "Removing $4"
  26        else
  27                # read-tree checked that index matches HEAD already,
  28                # so we know we do not have this path tracked.
  29                # there may be an unrelated working tree file here,
  30                # which we should just leave unmolested.  Make sure
  31                # we do not have it in the index, though.
  32                exec git update-index --remove -- "$4"
  33        fi
  34        if test -f "$4"; then
  35                rm -f -- "$4" &&
  36                rmdir -p "$(expr "z$4" : 'z\(.*\)/')" 2>/dev/null || :
  37        fi &&
  38                exec git update-index --remove -- "$4"
  39        ;;
  40
  41#
  42# Added in one.
  43#
  44".$2.")
  45        # the other side did not add and we added so there is nothing
  46        # to be done, except making the path merged.
  47        exec git update-index --add --cacheinfo "$6" "$2" "$4"
  48        ;;
  49"..$3")
  50        echo "Adding $4"
  51        if test -f "$4"
  52        then
  53                echo "ERROR: untracked $4 is overwritten by the merge."
  54                exit 1
  55        fi
  56        git update-index --add --cacheinfo "$7" "$3" "$4" &&
  57                exec git checkout-index -u -f -- "$4"
  58        ;;
  59
  60#
  61# Added in both, identically (check for same permissions).
  62#
  63".$3$2")
  64        if [ "$6" != "$7" ]; then
  65                echo "ERROR: File $4 added identically in both branches,"
  66                echo "ERROR: but permissions conflict $6->$7."
  67                exit 1
  68        fi
  69        echo "Adding $4"
  70        git update-index --add --cacheinfo "$6" "$2" "$4" &&
  71                exec git checkout-index -u -f -- "$4"
  72        ;;
  73
  74#
  75# Modified in both, but differently.
  76#
  77"$1$2$3" | ".$2$3")
  78
  79        case ",$6,$7," in
  80        *,120000,*)
  81                echo "ERROR: $4: Not merging symbolic link changes."
  82                exit 1
  83                ;;
  84        *,160000,*)
  85                echo "ERROR: $4: Not merging conflicting submodule changes."
  86                exit 1
  87                ;;
  88        esac
  89
  90        src2=`git-unpack-file $3`
  91        case "$1" in
  92        '')
  93                echo "Added $4 in both, but differently."
  94                # This extracts OUR file in $orig, and uses git apply to
  95                # remove lines that are unique to ours.
  96                orig=`git-unpack-file $2`
  97                sz0=`wc -c <"$orig"`
  98                diff -u -La/$orig -Lb/$orig $orig $src2 | git apply --no-add
  99                sz1=`wc -c <"$orig"`
 100
 101                # If we do not have enough common material, it is not
 102                # worth trying two-file merge using common subsections.
 103                expr "$sz0" \< "$sz1" \* 2 >/dev/null || : >$orig
 104                ;;
 105        *)
 106                echo "Auto-merging $4"
 107                orig=`git-unpack-file $1`
 108                ;;
 109        esac
 110
 111        # Be careful for funny filename such as "-L" in "$4", which
 112        # would confuse "merge" greatly.
 113        src1=`git-unpack-file $2`
 114        git merge-file "$src1" "$orig" "$src2"
 115        ret=$?
 116        msg=
 117        if [ $ret -ne 0 ]; then
 118                msg='content conflict'
 119        fi
 120
 121        # Create the working tree file, using "our tree" version from the
 122        # index, and then store the result of the merge.
 123        git checkout-index -f --stage=2 -- "$4" && cat "$src1" >"$4"
 124        rm -f -- "$orig" "$src1" "$src2"
 125
 126        if [ "$6" != "$7" ]; then
 127                if [ -n "$msg" ]; then
 128                        msg="$msg, "
 129                fi
 130                msg="${msg}permissions conflict: $5->$6,$7"
 131                ret=1
 132        fi
 133        if [ "$1" = '' ]; then
 134                ret=1
 135        fi
 136
 137        if [ $ret -ne 0 ]; then
 138                echo "ERROR: $msg in $4"
 139                exit 1
 140        fi
 141        exec git update-index -- "$4"
 142        ;;
 143
 144*)
 145        echo "ERROR: $4: Not handling case $1 -> $2 -> $3"
 146        ;;
 147esac
 148exit 1