New remove option : -u / --unneeded (FS#6505).

With --unneeded option 'pacman -R' doesn't stop in case of dependency error;
it removes the needed-dependency targets from the target-list instead.  See
also: http://archlinux.org/pipermail/pacman-dev/2007-October/009653.html .

The patch also adds a new causingpkg field to pmdepmissing_t which indicates
the to-be-removed package which would cause a dependency break. This is
needed, because miss->depend.name may be a provision. miss->causingpkg will
be useful in -R dependency error messages too.

[Xavier: renamed inducer to causingpkg, removed the _alpm_pkgname_pkg_cmp
helper function as requested by Aaron. This might be added by a further
commit.  Other small cleanups, updated manpage and bash completion.]

Signed-off-by: Chantry Xavier <shiningxc@gmail.com>

8 files changed, 78 insertions, 7 deletions

diff --git a/contrib/bash_completion b/contrib/bash_completion
index bb30ffd0..7f5d1b08 100644
--- a/contrib/bash_completion
+++ b/contrib/bash_completion
@@ -187,6 +187,7 @@ _pacman ()
           dbonly) mod="${mod}k" ;;
           nosave) mod="${mod}n" ;;
           recursive) mod="${mod}s" ;;
+          unneeded) mod="${mod}u" ;;
         esac ;;
       *) toparse="${a}" ;;
     esac
@@ -243,6 +244,7 @@ _pacman ()
           -k --dbonly \
           -n --nosave \
           -s --recursive \
+          -u --unneeded \
           --config \
           --logfile \
           --noconfirm \
diff --git a/doc/pacman.8.txt b/doc/pacman.8.txt
index c17700d7..8a3f675d 100644
--- a/doc/pacman.8.txt
+++ b/doc/pacman.8.txt
@@ -233,6 +233,11 @@ Remove Options[[RO]]
 	to a backwards '\--sync' operation, and helps keep a clean system without
 	orphans.
 
+*-u, \--unneeded*::
+	Removes the targets that are not required by any other packages.
+	This is mostly useful when removing a group without using the '-c' option,
+	to avoid breaking any dependencies.
+
 
 Sync Options[[SO]]
 ------------------
diff --git a/lib/libalpm/alpm.h b/lib/libalpm/alpm.h
index 027b1fee..bcc344d8 100644
--- a/lib/libalpm/alpm.h
+++ b/lib/libalpm/alpm.h
@@ -281,7 +281,8 @@ typedef enum _pmtransflag_t {
 	PM_TRANS_FLAG_NOCONFLICTS = 0x800,
 	PM_TRANS_FLAG_PRINTURIS = 0x1000,
 	PM_TRANS_FLAG_NEEDED = 0x2000,
-	PM_TRANS_FLAG_ALLEXPLICIT = 0x4000
+	PM_TRANS_FLAG_ALLEXPLICIT = 0x4000,
+	PM_TRANS_FLAG_UNNEEDED = 0x8000
 } pmtransflag_t;
 
 /* Transaction Events */
@@ -378,6 +379,7 @@ alpm_list_t *alpm_deptest(pmdb_t *db, alpm_list_t *targets);
 
 const char *alpm_miss_get_target(const pmdepmissing_t *miss);
 pmdepend_t *alpm_miss_get_dep(pmdepmissing_t *miss);
+const char *alpm_miss_get_causingpkg(const pmdepmissing_t *miss);
 
 alpm_list_t *alpm_checkdbconflicts(pmdb_t *db_local);
 
diff --git a/lib/libalpm/deps.c b/lib/libalpm/deps.c
index 5c63e9d6..c08c59e9 100644
--- a/lib/libalpm/deps.c
+++ b/lib/libalpm/deps.c
@@ -68,7 +68,8 @@ static void _alpm_graph_free(void *data)
 	free(graph);
 }
 
-pmdepmissing_t *_alpm_depmiss_new(const char *target, pmdepend_t *dep)
+pmdepmissing_t *_alpm_depmiss_new(const char *target, pmdepend_t *dep,
+		const char *causingpkg)
 {
 	pmdepmissing_t *miss;
 
@@ -78,6 +79,7 @@ pmdepmissing_t *_alpm_depmiss_new(const char *target, pmdepend_t *dep)
 
 	STRDUP(miss->target, target, RET_ERR(PM_ERR_MEMORY, NULL));
 	miss->depend = _alpm_dep_dup(dep);
+	STRDUP(miss->causingpkg, causingpkg, RET_ERR(PM_ERR_MEMORY, NULL));
 
 	return(miss);
 }
@@ -86,6 +88,7 @@ void _alpm_depmiss_free(pmdepmissing_t *miss)
 {
 	_alpm_dep_free(miss->depend);
 	FREE(miss->target);
+	FREE(miss->causingpkg);
 	FREE(miss);
 }
 
@@ -298,7 +301,7 @@ alpm_list_t SYMEXPORT *alpm_checkdeps(pmdb_t *db, int reversedeps,
 				_alpm_log(PM_LOG_DEBUG, "checkdeps: missing dependency '%s' for package '%s'\n",
 						missdepstring, alpm_pkg_get_name(tp));
 				free(missdepstring);
-				miss = _alpm_depmiss_new(alpm_pkg_get_name(tp), depend);
+				miss = _alpm_depmiss_new(alpm_pkg_get_name(tp), depend, "");
 				baddeps = alpm_list_add(baddeps, miss);
 			}
 		}
@@ -311,17 +314,18 @@ alpm_list_t SYMEXPORT *alpm_checkdeps(pmdb_t *db, int reversedeps,
 			pmpkg_t *lp = i->data;
 			for(j = alpm_pkg_get_depends(lp); j; j = j->next) {
 				pmdepend_t *depend = j->data;
+				pmpkg_t *causingpkg = alpm_list_find(modified, depend, satisfycmp);
 				/* we won't break this depend, if it is already broken, we ignore it */
 				/* 1. check upgrade list for satisfiers */
 				/* 2. check dblist for satisfiers */
-				if(alpm_list_find(modified, depend, satisfycmp) &&
+				if(causingpkg &&
 				   !alpm_list_find(upgrade, depend, satisfycmp) &&
 				   !alpm_list_find(dblist, depend, satisfycmp)) {
 					char *missdepstring = alpm_dep_get_string(depend);
 					_alpm_log(PM_LOG_DEBUG, "checkdeps: transaction would break '%s' dependency of '%s'\n",
 							missdepstring, alpm_pkg_get_name(lp));
 					free(missdepstring);
-					miss = _alpm_depmiss_new(lp->name, depend);
+					miss = _alpm_depmiss_new(lp->name, depend, alpm_pkg_get_name(causingpkg));
 					baddeps = alpm_list_add(baddeps, miss);
 				}
 			}
@@ -675,6 +679,16 @@ const char SYMEXPORT *alpm_miss_get_target(const pmdepmissing_t *miss)
 	return(miss->target);
 }
 
+const char SYMEXPORT *alpm_miss_get_causingpkg(const pmdepmissing_t *miss)
+{
+	ALPM_LOG_FUNC;
+
+	/* Sanity checks */
+	ASSERT(miss != NULL, return(NULL));
+
+	return miss->causingpkg;
+}
+
 pmdepend_t SYMEXPORT *alpm_miss_get_dep(pmdepmissing_t *miss)
 {
 	ALPM_LOG_FUNC;
diff --git a/lib/libalpm/deps.h b/lib/libalpm/deps.h
index fdbfebed..439a92a2 100644
--- a/lib/libalpm/deps.h
+++ b/lib/libalpm/deps.h
@@ -37,6 +37,7 @@ struct __pmdepend_t {
 struct __pmdepmissing_t {
 	char *target;
 	pmdepend_t *depend;
+	char *causingpkg; /* this is used in case of remove dependency error only */
 };
 
 /* Graphs */
@@ -51,7 +52,8 @@ struct __pmgraph_t {
 
 void _alpm_dep_free(pmdepend_t *dep);
 pmdepend_t *_alpm_dep_dup(const pmdepend_t *dep);
-pmdepmissing_t *_alpm_depmiss_new(const char *target, pmdepend_t *dep);
+pmdepmissing_t *_alpm_depmiss_new(const char *target, pmdepend_t *dep,
+		const char *causinpkg);
 void _alpm_depmiss_free(pmdepmissing_t *miss);
 alpm_list_t *_alpm_sortbydeps(alpm_list_t *targets, pmtranstype_t mode);
 void _alpm_recursedeps(pmdb_t *db, alpm_list_t *targs, int include_explicit);
diff --git a/lib/libalpm/remove.c b/lib/libalpm/remove.c
index 10a055bb..a0c308fb 100644
--- a/lib/libalpm/remove.c
+++ b/lib/libalpm/remove.c
@@ -124,11 +124,35 @@ int _alpm_remove_prepare(pmtrans_t *trans, pmdb_t *db, alpm_list_t **data)
 					alpm_list_free(lp);
 					lp = alpm_checkdeps(db, 1, trans->packages, NULL);
 				}
+			} else if (trans->flags & PM_TRANS_FLAG_UNNEEDED) {
+				/* Remove needed packages (which break dependencies) from the target list */
+				while(lp != NULL) {
+					alpm_list_t *i;
+					for(i = lp; i; i = i->next) {
+						pmdepmissing_t *miss = (pmdepmissing_t *)i->data;
+						void *vpkg;
+						pmpkg_t *pkg;
+						pmpkg_t *dummy = _alpm_pkg_new(miss->causingpkg, NULL);
+						trans->packages = alpm_list_remove(trans->packages, dummy,
+								_alpm_pkg_cmp, &vpkg);
+						_alpm_pkg_free(dummy);
+						pkg = vpkg;
+						if(pkg) {
+							_alpm_log(PM_LOG_WARNING, "removing %s from the target-list\n",
+									alpm_pkg_get_name(pkg));
+							_alpm_pkg_free(pkg);
+						}
+					}
+					alpm_list_free_inner(lp, (alpm_list_fn_free)_alpm_depmiss_free);
+					alpm_list_free(lp);
+					lp = alpm_checkdeps(db, 1, trans->packages, NULL);
+				}
 			} else {
 				if(data) {
 					*data = lp;
 				} else {
-					FREELIST(lp);
+					alpm_list_free_inner(lp, (alpm_list_fn_free)_alpm_depmiss_free);
+					alpm_list_free(lp);
 				}
 				RET_ERR(PM_ERR_UNSATISFIED_DEPS, -1);
 			}
diff --git a/pactest/tests/remove049.py b/pactest/tests/remove049.py
new file mode 100644
index 00000000..724f8da2
--- /dev/null
+++ b/pactest/tests/remove049.py
@@ -0,0 +1,19 @@
+self.description = "-Ru test"
+
+lp1 = pmpkg("pkg1")
+lp1.requiredby = [ "pkg3" ]
+self.addpkg2db("local", lp1)
+
+lp2 = pmpkg("pkg2")
+self.addpkg2db("local", lp2)
+
+lp3 = pmpkg("pkg3")
+lp3.depends = [ "pkg1" ]
+self.addpkg2db("local", lp3)
+
+self.args = "-Ru pkg1 pkg2"
+
+self.addrule("PACMAN_RETCODE=0")
+self.addrule("PKG_EXIST=pkg1")
+self.addrule("!PKG_EXIST=pkg2")
+self.addrule("PKG_EXIST=pkg3")
\ No newline at end of file
diff --git a/src/pacman/pacman.c b/src/pacman/pacman.c
index 61e0042a..7d584955 100644
--- a/src/pacman/pacman.c
+++ b/src/pacman/pacman.c
@@ -90,6 +90,7 @@ static void usage(int op, const char * const myname)
 			printf(_("  -k, --dbonly         only remove database entry, do not remove files\n"));
 			printf(_("  -n, --nosave         remove configuration files as well\n"));
 			printf(_("  -s, --recursive      remove dependencies also (that won't break packages)\n"));
+			printf(_("  -u, --unneeded       remove unneeded packages (that won't break packages)\n"));
 		} else if(op == PM_OP_UPGRADE) {
 			printf("%s:  %s {-U --upgrade} [%s] <%s>\n", str_usg, myname, str_opt, str_file);
 			printf("%s:\n", str_opt);
@@ -330,6 +331,7 @@ static int parseargs(int argc, char *argv[])
 		{"unrequired", no_argument,       0, 't'},
 		{"upgrades",   no_argument,       0, 'u'},
 		{"sysupgrade", no_argument,       0, 'u'},
+		{"unneeded",   no_argument,       0, 'u'},
 		{"verbose",    no_argument,       0, 'v'},
 		{"downloadonly", no_argument,     0, 'w'},
 		{"refresh",    no_argument,       0, 'y'},
@@ -472,6 +474,7 @@ static int parseargs(int argc, char *argv[])
 			case 'u':
 				config->op_s_upgrade = 1;
 				config->op_q_upgrade = 1;
+				config->flags |= PM_TRANS_FLAG_UNNEEDED;
 				break;
 			case 'v': (config->verbose)++; break;
 			case 'w':