If you having trouble with certificate verification like this:
PHP Warning: svn_log(): svn error(s) occured 175002 (RA layer request failed) OPTIONS of 'https://example.com/your/repos/path': Server certificate verification failed: issuer is not trusted
Try this two steps:
1. Run
"svn log https://example.com/your/repos/path"
on the commandline and permanent accept the certificate by typing "p" when asked.
2. Use the following settings for svn_auth_set_parameter() before calling other svn functions:
<?php
svn_auth_set_parameter(SVN_AUTH_PARAM_DEFAULT_USERNAME, 'your svn user');
svn_auth_set_parameter(SVN_AUTH_PARAM_DEFAULT_PASSWORD, 'your svn users password');
svn_auth_set_parameter(PHP_SVN_AUTH_PARAM_IGNORE_SSL_VERIFY_ERRORS, true); // <--- Important for certificate issues!
svn_auth_set_parameter(SVN_AUTH_PARAM_NON_INTERACTIVE, true);
svn_auth_set_parameter(SVN_AUTH_PARAM_NO_AUTH_CACHE, true);
var_dump(svn_log('https://example.com/your/repos/path'));
?>
This will work for SVN client libraries below 1.6!