From 635db51c275e7acb49dfe005b988d9ea6b05ded1 Mon Sep 17 00:00:00 2001
From: Enno Boland <g@s01.de>
Date: Fri, 6 Nov 2015 23:44:10 +0100
Subject: [PATCH 1/5] lib/package_alternatives.c: always use relative symlinks
 in alternatives

This commit adds relative link support to lib/package_alternatives.c.
Instead of creating absolute links, xbps will create relative links
to the target. This allows to follow links on systems even if the
aren't mounted on /.
---
 lib/package_alternatives.c           | 46 ++++++++++++++++++++++++++
 tests/xbps/xbps-alternatives/main.sh | 48 ++++++++++++++--------------
 2 files changed, 70 insertions(+), 24 deletions(-)

diff --git a/lib/package_alternatives.c b/lib/package_alternatives.c
index ec991cb9..8d1512a4 100644
--- a/lib/package_alternatives.c
+++ b/lib/package_alternatives.c
@@ -59,6 +59,50 @@ right(const char *str)
 	return strchr(str, ':') + 1;
 }
 
+static const char *
+normpath(char *path) {
+	char *seg, *p;
+reinit:
+	for (p = path, seg = NULL; *p; p++) {
+		if (strncmp(p, "/../", 4) == 0 || strncmp(p, "/..", 4) == 0) {
+			memmove(seg ? seg : p, p+3, strlen(p+3) + 1);
+			goto reinit;
+		}
+		else if (strncmp(p, "/./", 3) == 0 || strncmp(p, "/.", 3) == 0) {
+			memmove(p, p+2, strlen(p+2) + 1);
+		}
+		else if (*p == '/')
+			seg = p;
+	}
+	return path;
+}
+
+
+static char *
+relpath(char *from, char *to) {
+	int up;
+	char *p = to, *rel;
+	assert(from[0] == '/');
+	assert(to[0] == '/');
+	normpath(from);
+	normpath(to);
+
+	for (; *from == *to && *to; from++, to++) {
+		if (*to == '/')
+			p = to;
+	}
+
+	for (up = -1, from--; from && *from; from = strchr(from + 1, '/'), up++);
+
+	rel = calloc(3 * up + strlen(p), sizeof(char));
+
+	while (up--)
+		strcat(rel, "../");
+	if (*p)
+		strcat(rel, p+1);
+	return rel;
+}
+
 static int
 remove_symlinks(struct xbps_handle *xhp, xbps_array_t a, const char *grname)
 {
@@ -135,6 +179,8 @@ create_symlinks(struct xbps_handle *xhp, xbps_array_t a, const char *grname)
 		xbps_set_cb_state(xhp, XBPS_STATE_ALTGROUP_LINK_ADDED, 0, NULL,
 		    "Creating '%s' alternatives group symlink: %s -> %s", grname, l, tgt);
 		unlink(lnk);
+		if (tgt[0] == '/')
+			tgt = relpath(lnk + strlen(xhp->rootdir), tgt);
 		if ((rv = symlink(tgt, lnk)) != 0) {
 			xbps_dbg_printf(xhp, "failed to create alt symlink '%s'"
 			    "for group '%s': %s\n", lnk, grname,
diff --git a/tests/xbps/xbps-alternatives/main.sh b/tests/xbps/xbps-alternatives/main.sh
index 2444c6cd..e6368941 100644
--- a/tests/xbps/xbps-alternatives/main.sh
+++ b/tests/xbps/xbps-alternatives/main.sh
@@ -19,8 +19,8 @@ register_one_body() {
 	atf_check_equal $? 0
 	rv=1
 	if [ -e root/usr/bin/fileA ]; then
-		lnk=$(readlink root/usr/bin/file)
-		if [ "$lnk" = "/usr/bin/fileA" ]; then
+		lnk=$(readlink -f root/usr/bin/file)
+		if [ "$lnk" = "$PWD/root/usr/bin/fileA" ]; then
 			rv=0
 		fi
 		echo "A lnk: $lnk"
@@ -46,8 +46,8 @@ register_one_dangling_body() {
 	atf_check_equal $? 0
 	rv=1
 	if [ -h root/usr/bin/file ]; then
-		lnk=$(readlink root/usr/bin/file)
-		if [ "$lnk" = "/usr/bin/fileA" ]; then
+		lnk=$(readlink -f root/usr/bin/file)
+		if [ "$lnk" = "$PWD/root/usr/bin/fileA" ]; then
 			rv=0
 		fi
 		echo "A lnk: $lnk"
@@ -137,8 +137,8 @@ register_multi_body() {
 	atf_check_equal $? 0
 	rv=1
 	if [ -e root/usr/bin/fileA ]; then
-		lnk=$(readlink root/usr/bin/file)
-		if [ "$lnk" = "/usr/bin/fileA" ]; then
+		lnk=$(readlink -f root/usr/bin/file)
+		if [ "$lnk" = "$PWD/root/usr/bin/fileA" ]; then
 			rv=0
 		fi
 		echo "A lnk: $lnk"
@@ -149,8 +149,8 @@ register_multi_body() {
 	atf_check_equal $? 0
 	rv=1
 	if [ -e root/usr/bin/fileA -a -e root/usr/bin/fileB ]; then
-		lnk=$(readlink root/usr/bin/file)
-		if [ "$lnk" = "/usr/bin/fileA" ]; then
+		lnk=$(readlink -f root/usr/bin/file)
+		if [ "$lnk" = "$PWD/root/usr/bin/fileA" ]; then
 			rv=0
 		fi
 		echo "B lnk: $lnk"
@@ -229,8 +229,8 @@ unregister_multi_body() {
 	atf_check_equal $? 0
 
 	if [ -e root/usr/bin/fileA ]; then
-		lnk=$(readlink root/usr/bin/file)
-		if [ "$lnk" = "/usr/bin/fileA" ]; then
+		lnk=$(readlink -f root/usr/bin/file)
+		if [ "$lnk" = "$PWD/root/usr/bin/fileA" ]; then
 			rv=0
 		fi
 		echo "A lnk: $lnk"
@@ -247,8 +247,8 @@ unregister_multi_body() {
 	atf_check_equal $? 0
 
 	if [ -e root/usr/bin/fileB ]; then
-		lnk=$(readlink root/usr/bin/file)
-		if [ "$lnk" = "/usr/bin/fileB" ]; then
+		lnk=$(readlink -f root/usr/bin/file)
+		if [ "$lnk" = "$PWD/root/usr/bin/fileB" ]; then
 			rv=0
 		fi
 		echo "A lnk: $lnk"
@@ -287,8 +287,8 @@ set_pkg_body() {
 
 	rv=1
 	if [ -e root/usr/bin/B1 ]; then
-		lnk=$(readlink root/usr/bin/1)
-		if [ "$lnk" = "/usr/bin/B1" ]; then
+		lnk=$(readlink -f root/usr/bin/1)
+		if [ "$lnk" = "$PWD/root/usr/bin/B1" ]; then
 			rv=0
 		fi
 		echo "A lnk: $lnk"
@@ -297,8 +297,8 @@ set_pkg_body() {
 
 	rv=1
 	if [ -e root/usr/bin/B2 ]; then
-		lnk=$(readlink root/usr/bin/2)
-		if [ "$lnk" = "/usr/bin/B2" ]; then
+		lnk=$(readlink -f root/usr/bin/2)
+		if [ "$lnk" = "$PWD/root/usr/bin/B2" ]; then
 			rv=0
 		fi
 		echo "A lnk: $lnk"
@@ -310,8 +310,8 @@ set_pkg_body() {
 
 	rv=1
 	if [ -e root/usr/bin/A1 ]; then
-		lnk=$(readlink root/usr/bin/1)
-		if [ "$lnk" = "/usr/bin/A1" ]; then
+		lnk=$(readlink -f root/usr/bin/1)
+		if [ "$lnk" = "$PWD/root/usr/bin/A1" ]; then
 			rv=0
 		fi
 		echo "A lnk: $lnk"
@@ -320,8 +320,8 @@ set_pkg_body() {
 
 	rv=1
 	if [ -e root/usr/bin/A2 ]; then
-		lnk=$(readlink root/usr/bin/2)
-		if [ "$lnk" = "/usr/bin/A2" ]; then
+		lnk=$(readlink -f root/usr/bin/2)
+		if [ "$lnk" = "$PWD/root/usr/bin/A2" ]; then
 			rv=0
 		fi
 		echo "A lnk: $lnk"
@@ -353,8 +353,8 @@ set_pkg_group_body() {
 
 	rv=1
 	if [ -e root/usr/bin/B1 ]; then
-		lnk=$(readlink root/usr/bin/1)
-		if [ "$lnk" = "/usr/bin/A1" ]; then
+		lnk=$(readlink -f root/usr/bin/1)
+		if [ "$lnk" = "$PWD/root/usr/bin/A1" ]; then
 			rv=0
 		fi
 		echo "A lnk: $lnk"
@@ -363,8 +363,8 @@ set_pkg_group_body() {
 
 	rv=1
 	if [ -e root/usr/bin/B2 ]; then
-		lnk=$(readlink root/usr/bin/2)
-		if [ "$lnk" = "/usr/bin/B2" ]; then
+		lnk=$(readlink -f root/usr/bin/2)
+		if [ "$lnk" = "$PWD/root/usr/bin/B2" ]; then
 			rv=0
 		fi
 		echo "A lnk: $lnk"

From 8bd2808108cb13c12fbccb97e4e0bf81e7e585ba Mon Sep 17 00:00:00 2001
From: Enno Boland <g@s01.de>
Date: Sun, 8 Nov 2015 10:37:26 +0100
Subject: [PATCH 2/5] lib/package_alternatives.c: fix wrong /. handling for
 normalizing paths.

---
 lib/package_alternatives.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/package_alternatives.c b/lib/package_alternatives.c
index 8d1512a4..d69db12b 100644
--- a/lib/package_alternatives.c
+++ b/lib/package_alternatives.c
@@ -71,7 +71,7 @@ reinit:
 		else if (strncmp(p, "/./", 3) == 0 || strncmp(p, "/.", 3) == 0) {
 			memmove(p, p+2, strlen(p+2) + 1);
 		}
-		else if (*p == '/')
+		if (*p == '/')
 			seg = p;
 	}
 	return path;

From 19a65158d9c325a3b3ee4deb59d81e2c0b73a74c Mon Sep 17 00:00:00 2001
From: Enno Boland <g@s01.de>
Date: Sun, 8 Nov 2015 10:38:31 +0100
Subject: [PATCH 3/5] lib/package_alternatives.c: get rid of goto in normpath.

---
 lib/package_alternatives.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/package_alternatives.c b/lib/package_alternatives.c
index d69db12b..390cf29c 100644
--- a/lib/package_alternatives.c
+++ b/lib/package_alternatives.c
@@ -62,11 +62,10 @@ right(const char *str)
 static const char *
 normpath(char *path) {
 	char *seg, *p;
-reinit:
 	for (p = path, seg = NULL; *p; p++) {
 		if (strncmp(p, "/../", 4) == 0 || strncmp(p, "/..", 4) == 0) {
 			memmove(seg ? seg : p, p+3, strlen(p+3) + 1);
-			goto reinit;
+			return normpath(path);
 		}
 		else if (strncmp(p, "/./", 3) == 0 || strncmp(p, "/.", 3) == 0) {
 			memmove(p, p+2, strlen(p+2) + 1);

From 78e3bde2692e57c31917df517980e88bc120e958 Mon Sep 17 00:00:00 2001
From: Enno Boland <g@s01.de>
Date: Sun, 8 Nov 2015 10:47:25 +0100
Subject: [PATCH 4/5] lib/package_alternatives.c: Handle // cases.

---
 lib/package_alternatives.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/package_alternatives.c b/lib/package_alternatives.c
index 390cf29c..36228e5c 100644
--- a/lib/package_alternatives.c
+++ b/lib/package_alternatives.c
@@ -66,9 +66,10 @@ normpath(char *path) {
 		if (strncmp(p, "/../", 4) == 0 || strncmp(p, "/..", 4) == 0) {
 			memmove(seg ? seg : p, p+3, strlen(p+3) + 1);
 			return normpath(path);
-		}
-		else if (strncmp(p, "/./", 3) == 0 || strncmp(p, "/.", 3) == 0) {
+		} else if (strncmp(p, "/./", 3) == 0 || strncmp(p, "/.", 3) == 0) {
 			memmove(p, p+2, strlen(p+2) + 1);
+		} else if (strncmp(p, "//", 2) == 0 || strncmp(p, "/", 2) == 0) {
+			memmove(p, p+1, strlen(p+1) + 1);
 		}
 		if (*p == '/')
 			seg = p;

From 2927e58df21d1a4fd016f41ff548b05cff57aef4 Mon Sep 17 00:00:00 2001
From: Enno Boland <g@s01.de>
Date: Mon, 9 Nov 2015 08:52:49 +0100
Subject: [PATCH 5/5] lib/package_alternatives.c: fix style

---
 lib/package_alternatives.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/lib/package_alternatives.c b/lib/package_alternatives.c
index 36228e5c..6a3539f0 100644
--- a/lib/package_alternatives.c
+++ b/lib/package_alternatives.c
@@ -60,8 +60,10 @@ right(const char *str)
 }
 
 static const char *
-normpath(char *path) {
+normpath(char *path)
+{
 	char *seg, *p;
+
 	for (p = path, seg = NULL; *p; p++) {
 		if (strncmp(p, "/../", 4) == 0 || strncmp(p, "/..", 4) == 0) {
 			memmove(seg ? seg : p, p+3, strlen(p+3) + 1);
@@ -79,9 +81,11 @@ normpath(char *path) {
 
 
 static char *
-relpath(char *from, char *to) {
+relpath(char *from, char *to)
+{
 	int up;
 	char *p = to, *rel;
+
 	assert(from[0] == '/');
 	assert(to[0] == '/');
 	normpath(from);