[PATCH 3/4] dlopen: on x/lib search x/bin if exe is in x/bin
Michael Haubenwallner
michael.haubenwallner@ssi-schaefer.com
Wed Aug 31 18:08:00 GMT 2016
citing https://cygwin.com/ml/cygwin-developers/2016-08/msg00020.html
> Consider the file /usr/bin/cygz.dll:
> - dlopen (libz.so) success
> - dlopen (/usr/bin/libz.so) success
> - dlopen (/usr/lib/libz.so) fails
* dlfcn.c (dlopen): For dlopen("x/lib/N"), when the application
executable is in "x/bin/", search for "x/bin/N" before "x/lib/N".
---
winsup/cygwin/dlfcn.cc | 36 +++++++++++++++++++++++++++++++++++-
1 file changed, 35 insertions(+), 1 deletion(-)
diff --git a/winsup/cygwin/dlfcn.cc b/winsup/cygwin/dlfcn.cc
index e592512..f8b8743 100644
--- a/winsup/cygwin/dlfcn.cc
+++ b/winsup/cygwin/dlfcn.cc
@@ -153,6 +153,25 @@ collect_basenames (pathfinder::basenamelist & basenames,
basenames.appendv (basename, baselen, ext, extlen, NULL);
}
+/* Identify dir of current executable into exedirbuf using wpathbuf buffer.
+ Return length of exedirbuf on success, or zero on error. */
+static int
+get_exedir (char * exedirbuf, wchar_t * wpathbuf)
+{
+ /* Unless we have a special cygwin loader, there is no such thing like
+ DT_RUNPATH on Windows we can use to search for dlls, except for the
+ directory of the main executable. */
+ GetModuleFileNameW (NULL, wpathbuf, NT_MAX_PATH);
+ wchar_t * lastwsep = wcsrchr (wpathbuf, L'\\');
+ if (!lastwsep)
+ return 0;
+ *lastwsep = L'\0';
+ *exedirbuf = '\0';
+ if (cygwin_conv_path (CCP_WIN_W_TO_POSIX, wpathbuf, exedirbuf, NT_MAX_PATH))
+ return 0;
+ return strlen (exedirbuf);
+}
+
extern "C" void *
dlopen (const char *name, int flags)
{
@@ -184,13 +203,28 @@ dlopen (const char *name, int flags)
/* handle for the named library */
path_conv real_filename;
wchar_t *wpath = tp.w_get ();
+ char *cpath = tp.c_get ();
pathfinder finder (allocator, basenames); /* eats basenames */
if (have_dir)
{
+ int dirlen = basename - 1 - name;
+
+ /* if the specified dir is x/lib, and the current executable
+ dir is x/bin, do the /lib -> /bin mapping, which is the
+ same actually as adding the executable dir */
+ if (dirlen >= 4 && !strncmp (name + dirlen - 4, "/lib", 4))
+ {
+ int exedirlen = get_exedir (cpath, wpath);
+ if (exedirlen == dirlen &&
+ !strncmp (cpath, name, dirlen - 4) &&
+ !strcmp (cpath + dirlen - 4, "/bin"))
+ finder.add_searchdir (cpath, exedirlen);
+ }
+
/* search the specified dir */
- finder.add_searchdir (name, basename - 1 - name);
+ finder.add_searchdir (name, dirlen);
}
else
{
--
2.7.3
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