src/PEAR/Dependency2.php
function validatePackageUninstall(&$dl)
    {
        if (PEAR::isError($this->_dependencydb)) {
            return $this->_dependencydb;
        }

        $params = array();
        // construct an array of "downloaded" packages to fool the package dependency checker
        // into using these to validate uninstalls of circular dependencies
        $downloaded = &$dl->getUninstallPackages();
        foreach ($downloaded as $i => $pf) {
            if (!class_exists('PEAR_Downloader_Package')) {
                require_once 'PEAR/Downloader/Package.php';
            }
            $dp = &new PEAR_Downloader_Package($dl);
            $dp->setPackageFile($downloaded[$i]);
            $params[$i] = &$dp;
        }

        // check cache
        $memyselfandI = strtolower($this->_currentPackage['channel']) . '/' .
            strtolower($this->_currentPackage['package']);
        if (isset($dl->___uninstall_package_cache)) {
            $badpackages = $dl->___uninstall_package_cache;
            if (isset($badpackages[$memyselfandI]['warnings'])) {
                foreach ($badpackages[$memyselfandI]['warnings'] as $warning) {
                    $dl->log(0, $warning[0]);
                }
            }

            if (isset($badpackages[$memyselfandI]['errors'])) {
                foreach ($badpackages[$memyselfandI]['errors'] as $error) {
                    if (is_array($error)) {
                        $dl->log(0, $error[0]);
                    } else {
                        $dl->log(0, $error->getMessage());
                    }
                }

                if (isset($this->_options['nodeps']) || isset($this->_options['force'])) {
                    return $this->warning(
                        'warning: %s should not be uninstalled, other installed packages depend ' .
                        'on this package');
                }

                return $this->raiseError(
                    '%s cannot be uninstalled, other installed packages depend on this package');
            }

            return true;
        }

        // first, list the immediate parents of each package to be uninstalled
        $perpackagelist = array();
        $allparents = array();
        foreach ($params as $i => $param) {
            $a = array(
                'channel' => strtolower($param->getChannel()),
                'package' => strtolower($param->getPackage())
            );

            $deps = $this->_dependencydb->getDependentPackages($a);
            if ($deps) {
                foreach ($deps as $d) {
                    $pardeps = $this->_dependencydb->getDependencies($d);
                    foreach ($pardeps as $dep) {
                        if (strtolower($dep['dep']['channel']) == $a['channel'] &&
                              strtolower($dep['dep']['name']) == $a['package']) {
                            if (!isset($perpackagelist[$a['channel'] . '/' . $a['package']])) {
                                $perpackagelist[$a['channel'] . '/' . $a['package']] = array();
                            }
                            $perpackagelist[$a['channel'] . '/' . $a['package']][]
                                = array($d['channel'] . '/' . $d['package'], $dep);
                            if (!isset($allparents[$d['channel'] . '/' . $d['package']])) {
                                $allparents[$d['channel'] . '/' . $d['package']] = array();
                            }
                            if (!isset($allparents[$d['channel'] . '/' . $d['package']][$a['channel'] . '/' . $a['package']])) {
                                $allparents[$d['channel'] . '/' . $d['package']][$a['channel'] . '/' . $a['package']] = array();
                            }
                            $allparents[$d['channel'] . '/' . $d['package']]
                                       [$a['channel'] . '/' . $a['package']][]
                                = array($d, $dep);
                        }
                    }
                }
            }
        }

        // next, remove any packages from the parents list that are not installed
        $remove = array();
        foreach ($allparents as $parent => $d1) {
            foreach ($d1 as $d) {
                if ($this->_registry->packageExists($d[0][0]['package'], $d[0][0]['channel'])) {
                    continue;
                }
                $remove[$parent] = true;
            }
        }

        // next remove any packages from the parents list that are not passed in for
        // uninstallation
        foreach ($allparents as $parent => $d1) {
            foreach ($d1 as $d) {
                foreach ($params as $param) {
                    if (strtolower($param->getChannel()) == $d[0][0]['channel'] &&
                          strtolower($param->getPackage()) == $d[0][0]['package']) {
                        // found it
                        continue 3;
                    }
                }
                $remove[$parent] = true;
            }
        }

        // remove all packages whose dependencies fail
        // save which ones failed for error reporting
        $badchildren = array();
        do {
            $fail = false;
            foreach ($remove as $package => $unused) {
                if (!isset($allparents[$package])) {
                    continue;
                }

                foreach ($allparents[$package] as $kid => $d1) {
                    foreach ($d1 as $depinfo) {
                        if ($depinfo[1]['type'] != 'optional') {
                            if (isset($badchildren[$kid])) {
                                continue;
                            }
                            $badchildren[$kid] = true;
                            $remove[$kid] = true;
                            $fail = true;
                            continue 2;
                        }
                    }
                }
                if ($fail) {
                    // start over, we removed some children
                    continue 2;
                }
            }
        } while ($fail);

        // next, construct the list of packages that can't be uninstalled
        $badpackages = array();
        $save = $this->_currentPackage;
        foreach ($perpackagelist as $package => $packagedeps) {
            foreach ($packagedeps as $parent) {
                if (!isset($remove[$parent[0]])) {
                    continue;
                }

                $packagename = $this->_registry->parsePackageName($parent[0]);
                $packagename['channel'] = $this->_registry->channelAlias($packagename['channel']);
                $pa = $this->_registry->getPackage($packagename['package'], $packagename['channel']);
                $packagename['package'] = $pa->getPackage();
                $this->_currentPackage = $packagename;
                // parent is not present in uninstall list, make sure we can actually
                // uninstall it (parent dep is optional)
                $parentname['channel'] = $this->_registry->channelAlias($parent[1]['dep']['channel']);
                $pa = $this->_registry->getPackage($parent[1]['dep']['name'], $parent[1]['dep']['channel']);
                $parentname['package'] = $pa->getPackage();
                $parent[1]['dep']['package'] = $parentname['package'];
                $parent[1]['dep']['channel'] = $parentname['channel'];
                if ($parent[1]['type'] == 'optional') {
                    $test = $this->_validatePackageUninstall($parent[1]['dep'], false, $dl);
                    if ($test !== true) {
                        $badpackages[$package]['warnings'][] = $test;
                    }
                } else {
                    $test = $this->_validatePackageUninstall($parent[1]['dep'], true, $dl);
                    if ($test !== true) {
                        $badpackages[$package]['errors'][] = $test;
                    }
                }
            }
        }

        $this->_currentPackage          = $save;
        $dl->___uninstall_package_cache = $badpackages;
        if (isset($badpackages[$memyselfandI])) {
            if (isset($badpackages[$memyselfandI]['warnings'])) {
                foreach ($badpackages[$memyselfandI]['warnings'] as $warning) {
                    $dl->log(0, $warning[0]);
                }
            }

            if (isset($badpackages[$memyselfandI]['errors'])) {
                foreach ($badpackages[$memyselfandI]['errors'] as $error) {
                    if (is_array($error)) {
                        $dl->log(0, $error[0]);
                    } else {
                        $dl->log(0, $error->getMessage());
                    }
                }

                if (isset($this->_options['nodeps']) || isset($this->_options['force'])) {
                    return $this->warning(
                        'warning: %s should not be uninstalled, other installed packages depend ' .
                        'on this package');
                }

                return $this->raiseError(
                    '%s cannot be uninstalled, other installed packages depend on this package');
            }
        }

        return true;
    }
function validatePackageUninstall(&$dl)
    {
        if (PEAR::isError($this->_dependencydb)) {
            return $this->_dependencydb;
        }

        $params = array();
        // construct an array of "downloaded" packages to fool the package dependency checker
        // into using these to validate uninstalls of circular dependencies
        $downloaded = &$dl->getUninstallPackages();
        foreach ($downloaded as $i => $pf) {
            if (!class_exists('PEAR_Downloader_Package')) {
                require_once 'PEAR/Downloader/Package.php';
            }
            $dp = &new PEAR_Downloader_Package($dl);
            $dp->setPackageFile($downloaded[$i]);
            $params[$i] = &$dp;
        }

        // check cache
        $memyselfandI = strtolower($this->_currentPackage['channel']) . '/' .
            strtolower($this->_currentPackage['package']);
        if (isset($dl->___uninstall_package_cache)) {
            $badpackages = $dl->___uninstall_package_cache;
            if (isset($badpackages[$memyselfandI]['warnings'])) {
                foreach ($badpackages[$memyselfandI]['warnings'] as $warning) {
                    $dl->log(0, $warning[0]);
                }
            }

            if (isset($badpackages[$memyselfandI]['errors'])) {
                foreach ($badpackages[$memyselfandI]['errors'] as $error) {
                    if (is_array($error)) {
                        $dl->log(0, $error[0]);
                    } else {
                        $dl->log(0, $error->getMessage());
                    }
                }

                if (isset($this->_options['nodeps']) || isset($this->_options['force'])) {
                    return $this->warning(
                        'warning: %s should not be uninstalled, other installed packages depend ' .
                        'on this package');
                }

                return $this->raiseError(
                    '%s cannot be uninstalled, other installed packages depend on this package');
            }

            return true;
        }

        // first, list the immediate parents of each package to be uninstalled
        $perpackagelist = array();
        $allparents = array();
        foreach ($params as $i => $param) {
            $a = array(
                'channel' => strtolower($param->getChannel()),
                'package' => strtolower($param->getPackage())
            );

            $deps = $this->_dependencydb->getDependentPackages($a);
            if ($deps) {
                foreach ($deps as $d) {
                    $pardeps = $this->_dependencydb->getDependencies($d);
                    foreach ($pardeps as $dep) {
                        if (strtolower($dep['dep']['channel']) == $a['channel'] &&
                              strtolower($dep['dep']['name']) == $a['package']) {
                            if (!isset($perpackagelist[$a['channel'] . '/' . $a['package']])) {
                                $perpackagelist[$a['channel'] . '/' . $a['package']] = array();
                            }
                            $perpackagelist[$a['channel'] . '/' . $a['package']][]
                                = array($d['channel'] . '/' . $d['package'], $dep);
                            if (!isset($allparents[$d['channel'] . '/' . $d['package']])) {
                                $allparents[$d['channel'] . '/' . $d['package']] = array();
                            }
                            if (!isset($allparents[$d['channel'] . '/' . $d['package']][$a['channel'] . '/' . $a['package']])) {
                                $allparents[$d['channel'] . '/' . $d['package']][$a['channel'] . '/' . $a['package']] = array();
                            }
                            $allparents[$d['channel'] . '/' . $d['package']]
                                       [$a['channel'] . '/' . $a['package']][]
                                = array($d, $dep);
                        }
                    }
                }
            }
        }

        // next, remove any packages from the parents list that are not installed
        $remove = array();
        foreach ($allparents as $parent => $d1) {
            foreach ($d1 as $d) {
                if ($this->_registry->packageExists($d[0][0]['package'], $d[0][0]['channel'])) {
                    continue;
                }
                $remove[$parent] = true;
            }
        }

        // next remove any packages from the parents list that are not passed in for
        // uninstallation
        foreach ($allparents as $parent => $d1) {
            foreach ($d1 as $d) {
                foreach ($params as $param) {
                    if (strtolower($param->getChannel()) == $d[0][0]['channel'] &&
                          strtolower($param->getPackage()) == $d[0][0]['package']) {
                        // found it
                        continue 3;
                    }
                }
                $remove[$parent] = true;
            }
        }

        // remove all packages whose dependencies fail
        // save which ones failed for error reporting
        $badchildren = array();
        do {
            $fail = false;
            foreach ($remove as $package => $unused) {
                if (!isset($allparents[$package])) {
                    continue;
                }

                foreach ($allparents[$package] as $kid => $d1) {
                    foreach ($d1 as $depinfo) {
                        if ($depinfo[1]['type'] != 'optional') {
                            if (isset($badchildren[$kid])) {
                                continue;
                            }
                            $badchildren[$kid] = true;
                            $remove[$kid] = true;
                            $fail = true;
                            continue 2;
                        }
                    }
                }
                if ($fail) {
                    // start over, we removed some children
                    continue 2;
                }
            }
        } while ($fail);

        // next, construct the list of packages that can't be uninstalled
        $badpackages = array();
        $save = $this->_currentPackage;
        foreach ($perpackagelist as $package => $packagedeps) {
            foreach ($packagedeps as $parent) {
                if (!isset($remove[$parent[0]])) {
                    continue;
                }

                $packagename = $this->_registry->parsePackageName($parent[0]);
                $packagename['channel'] = $this->_registry->channelAlias($packagename['channel']);
                $pa = $this->_registry->getPackage($packagename['package'], $packagename['channel']);
                $packagename['package'] = $pa->getPackage();
                $this->_currentPackage = $packagename;
                // parent is not present in uninstall list, make sure we can actually
                // uninstall it (parent dep is optional)
                $parentname['channel'] = $this->_registry->channelAlias($parent[1]['dep']['channel']);
                $pa = $this->_registry->getPackage($parent[1]['dep']['name'], $parent[1]['dep']['channel']);
                $parentname['package'] = $pa->getPackage();
                $parent[1]['dep']['package'] = $parentname['package'];
                $parent[1]['dep']['channel'] = $parentname['channel'];
                if ($parent[1]['type'] == 'optional') {
                    $test = $this->_validatePackageUninstall($parent[1]['dep'], false, $dl);
                    if ($test !== true) {
                        $badpackages[$package]['warnings'][] = $test;
                    }
                } else {
                    $test = $this->_validatePackageUninstall($parent[1]['dep'], true, $dl);
                    if ($test !== true) {
                        $badpackages[$package]['errors'][] = $test;
                    }
                }
            }
        }

        $this->_currentPackage          = $save;
        $dl->___uninstall_package_cache = $badpackages;
        if (isset($badpackages[$memyselfandI])) {
            if (isset($badpackages[$memyselfandI]['warnings'])) {
                foreach ($badpackages[$memyselfandI]['warnings'] as $warning) {
                    $dl->log(0, $warning[0]);
                }
            }

            if (isset($badpackages[$memyselfandI]['errors'])) {
                foreach ($badpackages[$memyselfandI]['errors'] as $error) {
                    if (is_array($error)) {
                        $dl->log(0, $error[0]);
                    } else {
                        $dl->log(0, $error->getMessage());
                    }
                }

                if (isset($this->_options['nodeps']) || isset($this->_options['force'])) {
                    return $this->warning(
                        'warning: %s should not be uninstalled, other installed packages depend ' .
                        'on this package');
                }

                return $this->raiseError(
                    '%s cannot be uninstalled, other installed packages depend on this package');
            }
        }

        return true;
    }
Verify that uninstalling packages passed in to command line is OK.

@param PEAR_Installer $dl
@return PEAR_Error|true