share/msysGit/post-checkout-hook

   1 #!/bin/sh
   2
   3 # This post-checkout hook is meant to be installed in msysGit's root repository.
   4 #
   5 # The problem:
   6 #       Windows does not allow deleting or overwriting files that are in use.
   7 #       Concretely, it does not allow msysGit's shell to call Git to update
   8 #       msys-1.0.dll, because the shell still uses it.
   9 #
  10 # The symptoms:
  11 #       Directly after a checkout (as is the case when this hook is called),
  12 #       some files that should have been changed (i.e. that are in the output
  13 #       of 'git diff --name-only $old..$new') are marked modified, i.e. the
  14 #       command 'git diff-files --quiet -- $files' fails.
  15 #
  16 # The solution:
  17 #       We copy a fresh /bin/sh.exe and /bin/msys-1.0.dll into a temporary
  18 #       directory, add a script to that directory that will add the PATH back
  19 #       so we can use the Git commands (which are unaffected by the issue, as
  20 #       they are neither MSys programs nor are they tracked), and then fixes
  21 #       the issue.
  22 #
  23 #       Finally, we add a shortcut on the desktop so that it is easy for the
  24 #       user to start after closing all msysGit windows.
  25
  26 die () {
  27         echo "$*" >&2
  28         exit 1
  29 }
  30
  31 test "$3" != 1 && exit
  32 test "$1" = "$2" && exit
  33 MODIFIED="$(cd / && git diff --ignore-submodules --name-only -z "$1".."$2" |
  34                 xargs -0r git ls-files --modified)"
  35 test -z "$MODIFIED" && exit
  36 cd /share/msysGit || exit 0 # called from tmproot
  37
  38 mkdir -p tmproot/bin tmproot/etc &&
  39 echo "$MODIFIED" > tmproot/etc/modifiedFiles &&
  40 make create-shortcut.exe > /dev/null &&
  41 cp /bin/{sh.exe,msys-1.0.dll,git.exe,cat.exe,rm.exe,xargs.exe} \
  42         /mingw/bin/{libcurl-4.dll,libiconv2.dll} tmproot/bin/ &&
  43 cat > tmproot/etc/profile << \EOF &&
  44 # cd to msysGit root
  45 cd "$(pwd -W)"/../../../..
  46
  47 # add original msysGit PATH
  48 export PATH=/bin:"$(pwd)/bin:$(pwd)/mingw/bin"
  49
  50 prompt_and_exit () {
  51         echo "<Press Enter to close this window>" >&2
  52         read line
  53         exit "$1"
  54 }
  55
  56 die () {
  57         printf '\n' >&2
  58         echo "$*" >&2
  59         prompt_and_exit 1
  60 }
  61
  62 # Try to update files marked 'modified'
  63 test -s /etc/modifiedFiles && {
  64         echo "Trying to finish checkout" >&2
  65         cat /etc/modifiedFiles |
  66         xargs git checkout -- ||
  67         die "Please close _all_ msysGit instances and run this shortcut again"
  68         test -z "$(cat /etc/modifiedFiles |
  69                         xargs git diff --ignore-submodules --name-only)" ||
  70         die "At least one file could not be updated; is msysGit still running?"
  71 }
  72
  73 echo "Everything up-to-date"
  74 test -f /etc/linkfile && rm -f "$(cat /etc/linkfile)"
  75 prompt_and_exit 0
  76 EOF
  77 echo "$USERPROFILE/Desktop/finish-checkout.lnk" > tmproot/etc/linkfile &&
  78 ./create-shortcut --work-dir "$(cd tmproot/bin && pwd -W)" \
  79         --icon-file "$(cd ../resources && pwd -W)/msysgitlogo.ico" \
  80         --arguments "--login -i" \
  81         "$(pwd -W)"/tmproot/bin/sh.exe \
  82         "$(cat tmproot/etc/linkfile)" &&
  83 cat << EOF ||
  84
  85 WARNING!
  86 --------
  87
  88 You appear to have modified files after switching branches.  As Windows has
  89 problems updating files that are in use, the most likely reason is that a
  90 .dll or a .exe file needs to be updated, but that was refused due to a process
  91 locking it.
  92
  93 A shortcut 'finish-checkout' was created on your desktop to help you: quit
  94 all msysGit programs, launch that shortcut, and all should be fixed.
  95 EOF
  96 die "Could not set up temporary MSys root"