[OE-core] [PATCH] busybox: Make readlink compatible with coreutils

[Ricardo Ribalda Delgado]

Busybox readlink behaves diferently that coreutils readlink:

root at qt5122:~# touch /tmp/this_file_exist
root at qt5122:~# busybox readlink -f /tmp/this_file_exist
/tmp/this_file_exist
root at qt5122:~# readlink -f /tmp/this_file_exist
/tmp/this_file_exist

root at qt5122:~# readlink -f /tmp/this_file_does_not_exist
/tmp/this_file_does_not_exist
root at qt5122:~# busybox readlink -f /tmp/this_file_does_not_exist
root at qt5122:~#
This leads to apt-key miss-behaving and also secure apt-get

root at qt5122:~# apt-key exportall
touch: : No such file or directory

W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://release.qtec.com:5022/qtec/europa/deb/qt5122 ./ Release: At least one invalid signature was encountered.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda at gmail.com>
---
 .../busybox/busybox/fix-readlink-f.patch      | 96 +++++++++++++++++++
 meta/recipes-core/busybox/busybox_1.27.2.bb   |  1 +
 2 files changed, 97 insertions(+)
 create mode 100644 meta/recipes-core/busybox/busybox/fix-readlink-f.patch

diff --git a/meta/recipes-core/busybox/busybox/fix-readlink-f.patch b/meta/recipes-core/busybox/busybox/fix-readlink-f.patch
new file mode 100644
index 0000000000..505fdd032f
--- /dev/null
+++ b/meta/recipes-core/busybox/busybox/fix-readlink-f.patch
@@ -0,0 +1,96 @@
+From 747162109fb1c891baf6aafa1ca0410bd08d04a4 Mon Sep 17 00:00:00 2001
+From: Denys Vlasenko <vda.linux at googlemail.com>
+Date: Thu, 24 May 2018 17:29:14 +0200
+Subject: realpath,readlink -f: coreutils compat, closes 11021
+
+function                                             old     new   delta
+xmalloc_realpath_coreutils                             -     121    +121
+
+Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
+Upstream-Status: Backport https://bugs.busybox.net/show_bug.cgi?id=11021
+---
+ coreutils/readlink.c |  2 +-
+ coreutils/realpath.c |  2 +-
+ include/libbb.h      |  1 +
+ libbb/xreadlink.c    | 30 ++++++++++++++++++++++++++++++
+ 4 files changed, 33 insertions(+), 2 deletions(-)
+
+diff --git a/coreutils/readlink.c b/coreutils/readlink.c
+index b8e327d..49361ce 100644
+--- a/coreutils/readlink.c
++++ b/coreutils/readlink.c
+@@ -86,7 +86,7 @@ int readlink_main(int argc UNUSED_PARAM, char **argv)
+ 		logmode = LOGMODE_NONE;
+ 
+ 	if (opt & 1) { /* -f */
+-		buf = xmalloc_realpath(fname);
++		buf = xmalloc_realpath_coreutils(fname);
+ 	} else {
+ 		buf = xmalloc_readlink_or_warn(fname);
+ 	}
+diff --git a/coreutils/realpath.c b/coreutils/realpath.c
+index 0c2d544..d2b4bf2 100644
+--- a/coreutils/realpath.c
++++ b/coreutils/realpath.c
+@@ -36,7 +36,7 @@ int realpath_main(int argc UNUSED_PARAM, char **argv)
+ 	}
+ 
+ 	do {
+-		char *resolved_path = xmalloc_realpath(*argv);
++		char *resolved_path = xmalloc_realpath_coreutils(*argv);
+ 		if (resolved_path != NULL) {
+ 			puts(resolved_path);
+ 			free(resolved_path);
+diff --git a/include/libbb.h b/include/libbb.h
+index 8eccd81..64531c0 100644
+--- a/include/libbb.h
++++ b/include/libbb.h
+@@ -475,6 +475,7 @@ DIR *xopendir(const char *path) FAST_FUNC;
+ DIR *warn_opendir(const char *path) FAST_FUNC;
+ 
+ char *xmalloc_realpath(const char *path) FAST_FUNC RETURNS_MALLOC;
++char *xmalloc_realpath_coreutils(const char *path) FAST_FUNC RETURNS_MALLOC;
+ char *xmalloc_readlink(const char *path) FAST_FUNC RETURNS_MALLOC;
+ char *xmalloc_readlink_or_warn(const char *path) FAST_FUNC RETURNS_MALLOC;
+ /* !RETURNS_MALLOC: it's a realloc-like function */
+diff --git a/libbb/xreadlink.c b/libbb/xreadlink.c
+index 7d4cb60..cae322a 100644
+--- a/libbb/xreadlink.c
++++ b/libbb/xreadlink.c
+@@ -123,3 +123,33 @@ char* FAST_FUNC xmalloc_realpath(const char *path)
+ 	return xstrdup(realpath(path, buf));
+ #endif
+ }
++
++char* FAST_FUNC xmalloc_realpath_coreutils(const char *path)
++{
++	char *buf;
++
++	errno = 0;
++	buf = xmalloc_realpath(path);
++	/*
++	 * There is one case when "readlink -f" and
++	 * "realpath" from coreutils succeed,
++	 * even though file does not exist, such as:
++	 *     /tmp/file_does_not_exist
++	 * (the directory must exist).
++	 */
++	if (!buf && errno == ENOENT) {
++		char *last_slash = strrchr(path, '/');
++		if (last_slash) {
++			*last_slash++ = '\0';
++			buf = xmalloc_realpath(path);
++			if (buf) {
++				unsigned len = strlen(buf);
++                                buf = xrealloc(buf, len + strlen(last_slash) + 2);
++				buf[len++] = '/';
++				strcpy(buf + len, last_slash);
++			}
++		}
++	}
++
++	return buf;
++}
+-- 
+cgit v0.12
+
diff --git a/meta/recipes-core/busybox/busybox_1.27.2.bb b/meta/recipes-core/busybox/busybox_1.27.2.bb
index 36a6342aaf..cb1ae4c169 100644
--- a/meta/recipes-core/busybox/busybox_1.27.2.bb
+++ b/meta/recipes-core/busybox/busybox_1.27.2.bb
@@ -45,6 +45,7 @@ SRC_URI = "http://www.busybox.net/downloads/busybox-${PV}.tar.bz2;name=tarball \
            file://CVE-2011-5325.patch \
            file://CVE-2017-15873.patch \
            file://busybox-CVE-2017-16544.patch \
+           file://fix-readlink-f.patch \
 "
 SRC_URI_append_libc-musl = " file://musl.cfg "
 
-- 
2.17.0