dpkg-query: Add new --control-list and --control-show commands

These replace the now deprecated --control-path command, as these do
not rely on any specific database layout.

debian/changelog

@@ -32,6 +32,8 @@ dpkg (1.16.5) UNRELEASED; urgency=low
   * Switch source compression to xz.
   * Detect ar header fields truncation due to too long member names or too
     large member sizes. Closes: #678933
+  * Add new dpkg-query --control-list and --control-show commands, which
+    replace the now deprecated --control-path.
 
   [ Updated dpkg translations ]
   * Swedish (Peter Krefting).

doc/README.feature-removal-schedule

@@ -54,6 +54,14 @@ Why:
  support compressing new .deb files with that format, although unpacking
  will be kept being supported to handle existing compressed files.
 
+What: --control-path (dpkg-query option)
+Status: deprecated
+When: 1.18.x
+Warning: man page
+ This was a semi-public interface now superceded by --control-list and
+ --control-show, which are a better interface as they do not rely on any
+ specific database layout.
+
 History of feature removals
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

man/dpkg-query.1

@@ -107,13 +107,19 @@ by an empty line, with the same order as specified on the argument list.
 However, note that files created by package-specific installation-scripts
 are not listed.
 .TP
+.BR \-\-control\-list " \fIpackage-name\fP
+List control files installed to your system from \fIpackage-name\fP.
+These can be used as input arguments to \fB\-\-control\-show\fP.
+.TP
+.BR \-\-control\-show " \fIpackage-name\fP \fIcontrol-file\fP"
+Print the \fIcontrol-file\fP installed to your system from \fIpackage-name\fP
+to the standard output.
+.TP
 .BR \-c ", " \-\-control\-path " \fIpackage-name\fP [\fIcontrol-file\fP]"
 List paths for control files installed to your system from \fIpackage-name\fP.
 If \fIcontrol-file\fP is specified then only list the path for that control
-file if it is present. \fBWarning\fP: this command is semi-public, it should
-be used only as a last resort solution, and if no other interface is
-available. It might get deprecated later on if better interfaces or the
-current architectural deficiencies have been solved.
+file if it is present. \fBWarning\fP: this command is deprecated, please
+switch to use \fB\-\-control\-list\fP and \fB\-\-control\-show\fP instead.
 .TP
 .BR \-S ", " \-\-search " \fIfilename-search-pattern\fP..."
 Search for packages that own files corresponding to the given pattern.

src/main.h

@@ -75,6 +75,8 @@ enum action {
 	act_listfiles,
 	act_searchfiles,
 	act_controlpath,
+	act_controllist,
+	act_controlshow,
 
 	act_cmpversions,
 

src/querycmd.c

@@ -50,6 +50,7 @@
 #include <dpkg/pkg-show.h>
 #include <dpkg/string.h>
 #include <dpkg/path.h>
+#include <dpkg/file.h>
 #include <dpkg/options.h>
 
 #include "filesdb.h"
@@ -600,6 +601,15 @@ pkg_infodb_print_filename(const char *filename, const char *filetype)
   printf("%s\n", filename);
 }
 
+static void
+pkg_infodb_print_filetype(const char *filename, const char *filetype)
+{
+  if (pkg_infodb_is_internal(filetype))
+    return;
+
+  printf("%s\n", filetype);
+}
+
 static void
 control_path_file(struct pkginfo *pkg, const char *control_file)
 {
@@ -656,6 +666,76 @@ control_path(const char *const *argv)
   return 0;
 }
 
+static int
+control_list(const char *const *argv)
+{
+  struct dpkg_error err;
+  struct pkginfo *pkg;
+  const char *pkgname;
+
+  pkgname = *argv++;
+  if (!pkgname || *argv)
+    badusage(_("--%s takes one package name argument"), cipaction->olong);
+
+  modstatdb_open(msdbrw_readonly);
+
+  pkg = pkg_spec_parse_pkg(pkgname, &err);
+  if (pkg == NULL)
+    badusage(_("--%s needs a valid package name but '%.250s' is not: %s"),
+             cipaction->olong, pkgname, err.str);
+
+  if (pkg->status == stat_notinstalled)
+    ohshit(_("package '%s' is not installed"), pkg_name(pkg, pnaw_nonambig));
+
+  pkg_infodb_foreach(pkg, &pkg->installed, pkg_infodb_print_filetype);
+
+  modstatdb_shutdown();
+
+  return 0;
+}
+
+static int
+control_show(const char *const *argv)
+{
+  struct dpkg_error err;
+  struct pkginfo *pkg;
+  const char *pkgname;
+  const char *filename;
+  const char *control_file;
+
+  pkgname = *argv++;
+  if (!pkgname || !*argv)
+    badusage(_("--%s needs at two arguments"),
+             cipaction->olong);
+
+  control_file = *argv++;
+  if (!control_file || *argv)
+    badusage(_("--%s takes at most two arguments"), cipaction->olong);
+
+  pkg_infodb_check_filetype(control_file);
+
+  modstatdb_open(msdbrw_readonly);
+
+  pkg = pkg_spec_parse_pkg(pkgname, &err);
+  if (pkg == NULL)
+    badusage(_("--%s needs a valid package name but '%.250s' is not: %s"),
+             cipaction->olong, pkgname, err.str);
+
+  if (pkg->status == stat_notinstalled)
+    ohshit(_("package '%s' is not installed"), pkg_name(pkg, pnaw_nonambig));
+
+  if (pkg_infodb_has_file(pkg, &pkg->installed, control_file))
+    filename = pkg_infodb_get_file(pkg, &pkg->installed, control_file);
+  else
+    ohshit(_("control file '%s' does not exist"), control_file);
+
+  modstatdb_shutdown();
+
+  file_show(filename);
+
+  return 0;
+}
+
 static void DPKG_ATTR_NORET
 printversion(const struct cmdinfo *ci, const char *value)
 {
@@ -731,6 +811,8 @@ static const struct cmdinfo cmdinfos[]= {
   ACTION( "search",                         'S', act_searchfiles,   searchfiles     ),
   ACTION( "show",                           'W', act_listpackages,  showpackages    ),
   ACTION( "control-path",                   'c', act_controlpath,   control_path    ),
+  ACTION( "control-list",                    0,  act_controllist,   control_list    ),
+  ACTION( "control-show",                    0,  act_controlshow,   control_show    ),
 
   { "admindir",   0,   1, NULL, &admindir,   NULL          },
   { "load-avail", 0,   0, &opt_loadavail, NULL, NULL, 1    },