What is a pre-revprop-change hook in SVN, and how do I create it?

Question

I wanted to edit a log comment in the repository browser and received an error message that no pre-revprop-change hook exists for the repository. Besides having a scary name, what is a pre-revprop-change hook, and how do I create it?

Answer 1

For Windows, here's a link to an example batch file that only allows changes to the log message (not other properties):

http://ayria.livejournal.com/33438.html

Basically copy the code below into a text file and name it pre-revprop-change.bat and save it in the \hooks subdirectory for your repository.

@ECHO OFF
:: Set all parameters. Even though most are not used, in case you want to add
:: changes that allow, for example, editing of the author or addition of log messages.
set repository=%1
set revision=%2
set userName=%3
set propertyName=%4
set action=%5

:: Only allow the log message to be changed, but not author, etc.
if /I not "%propertyName%" == "svn:log" goto ERROR_PROPNAME

:: Only allow modification of a log message, not addition or deletion.
if /I not "%action%" == "M" goto ERROR_ACTION

:: Make sure that the new svn:log message is not empty.
set bIsEmpty=true
for /f "tokens=*" %%g in ('find /V ""') do (
set bIsEmpty=false
)
if "%bIsEmpty%" == "true" goto ERROR_EMPTY

goto :eof

:ERROR_EMPTY
echo Empty svn:log messages are not allowed. >&2
goto ERROR_EXIT

:ERROR_PROPNAME
echo Only changes to svn:log messages are allowed. >&2
goto ERROR_EXIT

:ERROR_ACTION
echo Only modifications to svn:log revision properties are allowed. >&2
goto ERROR_EXIT

:ERROR_EXIT
exit /b 1