[dpkg] 12/24: dpkg-divert: Warn when using --rename on a file from an Essential package

[Guillem Jover]

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guillem pushed a commit to branch master
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commit c2715071aa64807c9b95edd7c6e4cd8c3eb4ad8c
Author: Guillem Jover <guil...@debian.org>
Date:   Wed Apr 4 02:48:32 2018 +0200

    dpkg-divert: Warn when using --rename on a file from an Essential package
    
    Renaming a file from dpkg-divert for an Essential package is very
    dangerous, because that file will not be available until dpkg has
    unpacked the diverting package, which might render the system
    non-functional.
---
 debian/changelog |  1 +
 src/divertcmd.c  | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index f6ad3a5..123ef67 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -50,6 +50,7 @@ dpkg (1.19.1) UNRELEASED; urgency=medium
   * Add a new --no-rename option to dpkg-divert. This is the current default
     behavior, but it will make it possible to do a default switch in 1.20.x.
   * Warn when using dpkg-divert --add or --remove w/o --rename or --no-rename.
+  * Warn when using dpkg-divert --rename on a file from an Essential package.
   * Architecture support:
     - Add support for riscv64 CPU. Closes: #822914
       Thanks to Manuel A. Fernandez Montecelo <m...@debian.org>
diff --git a/src/divertcmd.c b/src/divertcmd.c
index d46331f..e7bb5ad 100644
--- a/src/divertcmd.c
+++ b/src/divertcmd.c
@@ -399,6 +399,33 @@ divertdb_write(void)
 }
 
 static bool
+diversion_is_essential(struct filenamenode *namenode)
+{
+       struct pkginfo *pkg;
+       struct pkgiterator *pkg_iter;
+       struct filepackages_iterator *iter;
+       bool essential = false;
+
+       pkg_iter = pkg_db_iter_new();
+       while ((pkg = pkg_db_iter_next_pkg(pkg_iter))) {
+               if (pkg->installed.essential)
+                       ensure_packagefiles_available(pkg);
+       }
+       pkg_db_iter_free(pkg_iter);
+
+       iter = filepackages_iter_new(namenode);
+       while ((pkg = filepackages_iter_next(iter))) {
+               if (pkg->installed.essential) {
+                       essential = true;
+                       break;
+               }
+       }
+       filepackages_iter_free(iter);
+
+       return essential;
+}
+
+static bool
 diversion_is_owned_by_self(struct pkgset *set, struct filenamenode *namenode)
 {
        struct pkginfo *pkg;
@@ -514,6 +541,9 @@ diversion_add(const char *const *argv)
                               filename, pkgset->name);
                opt_rename = false;
        }
+       if (opt_rename && diversion_is_essential(fnn_from))
+               warning(_("diverting file '%s' from an Essential package with "
+                         "rename is dangerous, use --no-rename"), filename);
        if (!opt_test) {
                divertdb_write();
                if (opt_rename)

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