dlopen: switch to new pathfinder class
Instead of find_exec, without changing behaviour use new pathfinder class with new allocator_interface around tmp_pathbuf and new vstrlist class. * pathfinder.h (pathfinder): New file. * vstrlist.h (allocator_interface, allocated_type, vstrlist): New file. * dlfcn.cc (dlopen): Avoid redundant GetModuleHandleExW with RTLD_NOLOAD and RTLD_NODELETE. Switch to new pathfinder class, using (tmp_pathbuf_allocator): New class. (get_full_path_of_dll): Drop.
This commit is contained in:
Michael Haubenwallner
committed by
Corinna Vinschen
Corinna Vinschen
parent
091a0ac120
commit
97974e3076
@@ -20,6 +20,74 @@ details. */
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#include "cygtls.h"
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#include "tls_pbuf.h"
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#include "ntdll.h"
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#include "pathfinder.h"
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/* Dumb allocator using memory from tmp_pathbuf.w_get ().
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Does not reuse free'd memory areas. Instead, memory
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is released when the tmp_pathbuf goes out of scope.
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ATTENTION: Requesting memory from an instance of tmp_pathbuf breaks
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when another instance on a newer stack frame has provided memory. */
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class tmp_pathbuf_allocator
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: public allocator_interface
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{
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tmp_pathbuf & tp_;
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union
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{
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PWCHAR wideptr;
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void * voidptr;
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char * byteptr;
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} freemem_;
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size_t freesize_;
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/* allocator_interface */
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virtual void * alloc (size_t need)
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{
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if (need == 0)
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need = 1; /* GNU-ish */
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size_t chunksize = NT_MAX_PATH * sizeof (WCHAR);
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if (need > chunksize)
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api_fatal ("temporary buffer too small for %d bytes", need);
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if (need > freesize_)
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{
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/* skip remaining, use next chunk */
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freemem_.wideptr = tp_.w_get ();
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freesize_ = chunksize;
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}
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void * ret = freemem_.voidptr;
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/* adjust remaining, aligned at 8 byte boundary */
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need = need + 7 - (need - 1) % 8;
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freemem_.byteptr += need;
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if (need > freesize_)
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freesize_ = 0;
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else
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freesize_ -= need;
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return ret;
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}
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/* allocator_interface */
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virtual void free (void *)
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{
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/* no-op: released by tmp_pathbuf at end of scope */
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}
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tmp_pathbuf_allocator ();
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tmp_pathbuf_allocator (tmp_pathbuf_allocator const &);
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tmp_pathbuf_allocator & operator = (tmp_pathbuf_allocator const &);
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public:
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/* use tmp_pathbuf of current stack frame */
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tmp_pathbuf_allocator (tmp_pathbuf & tp)
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: allocator_interface ()
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, tp_ (tp)
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, freemem_ ()
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, freesize_ (0)
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{}
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};
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static void
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set_dl_error (const char *str)
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@@ -28,84 +96,61 @@ set_dl_error (const char *str)
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_my_tls.locals.dl_error = 1;
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}
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/* Look for an executable file given the name and the environment
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variable to use for searching (eg., PATH); returns the full
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pathname (static buffer) if found or NULL if not. */
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inline const char *
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check_path_access (const char *mywinenv, const char *name, path_conv& buf)
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{
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return find_exec (name, buf, mywinenv, FE_NNF | FE_DLL);
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}
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/* Search LD_LIBRARY_PATH for dll, if it exists. Search /usr/bin and /usr/lib
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by default. Return valid full path in path_conv real_filename. */
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static inline bool
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gfpod_helper (const char *name, path_conv &real_filename)
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{
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if (strchr (name, '/'))
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real_filename.check (name, PC_SYM_FOLLOW | PC_NULLEMPTY);
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else if (!check_path_access ("LD_LIBRARY_PATH", name, real_filename))
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check_path_access ("/usr/bin:/usr/lib", name, real_filename);
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if (!real_filename.exists ())
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real_filename.error = ENOENT;
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return !real_filename.error;
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}
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/* Identify basename and baselen within name,
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return true if there is a dir in name. */
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static bool
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get_full_path_of_dll (const char* str, path_conv &real_filename)
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spot_basename (const char * &basename, int &baselen, const char * name)
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{
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int len = strlen (str);
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/* empty string? */
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if (len == 0)
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{
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set_errno (EINVAL);
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return false; /* Yes. Let caller deal with it. */
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}
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tmp_pathbuf tp;
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char *name = tp.c_get ();
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strcpy (name, str); /* Put it somewhere where we can manipulate it. */
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char *basename = strrchr (name, '/');
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basename = strrchr (name, '/');
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basename = basename ? basename + 1 : name;
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char *suffix = strrchr (name, '.');
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if (suffix && suffix < basename)
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suffix = NULL;
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baselen = name + strlen (name) - basename;
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return basename > name;
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}
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/* Is suffix ".so"? */
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if (suffix && !strcmp (suffix, ".so"))
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/* Setup basenames using basename and baselen,
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return true if basenames do have some suffix. */
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static void
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collect_basenames (pathfinder::basenamelist & basenames,
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const char * basename, int baselen)
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{
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/* like strrchr (basename, '.'), but limited to baselen */
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const char *suffix = basename + baselen;
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while (--suffix >= basename)
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if (*suffix == '.')
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break;
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int suffixlen;
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if (suffix >= basename)
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suffixlen = basename + baselen - suffix;
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else
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{
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/* Does the file exist? */
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if (gfpod_helper (name, real_filename))
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return true;
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/* No, replace ".so" with ".dll". */
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strcpy (suffix, ".dll");
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suffixlen = 0;
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suffix = NULL;
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}
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/* Does the filename start with "lib"? */
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char const * ext = "";
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/* Without some suffix, reserve space for a trailing dot to override
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GetModuleHandleExA's automatic adding of the ".dll" suffix. */
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int extlen = suffix ? 0 : 1;
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/* If we have the ".so" suffix, ... */
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if (suffixlen == 3 && !strncmp (suffix, ".so", 3))
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{
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/* ... keep the basename with original suffix, before ... */
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basenames.appendv (basename, baselen, NULL);
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/* ... replacing the ".so" with the ".dll" suffix. */
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baselen -= 3;
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ext = ".dll";
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extlen = 4;
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}
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/* If the basename starts with "lib", ... */
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if (!strncmp (basename, "lib", 3))
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{
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/* Yes, replace "lib" with "cyg". */
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strncpy (basename, "cyg", 3);
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/* Does the file exist? */
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if (gfpod_helper (name, real_filename))
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return true;
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/* No, revert back to "lib". */
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strncpy (basename, "lib", 3);
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/* ... replace "lib" with "cyg", before ... */
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basenames.appendv ("cyg", 3, basename+3, baselen-3, ext, extlen, NULL);
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}
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if (gfpod_helper (name, real_filename))
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return true;
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/* If nothing worked, create a relative path from the original incoming
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filename and let LoadLibrary search for it using the system default
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DLL search path. */
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real_filename.check (str, PC_SYM_FOLLOW | PC_NOFULL | PC_NULLEMPTY);
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if (!real_filename.error)
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return true;
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set_errno (real_filename.error);
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return false;
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/* ... using original basename with new suffix. */
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basenames.appendv (basename, baselen, ext, extlen, NULL);
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}
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extern "C" void *
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@@ -113,64 +158,111 @@ dlopen (const char *name, int flags)
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{
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void *ret = NULL;
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if (name == NULL)
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do
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{
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ret = (void *) GetModuleHandle (NULL); /* handle for the current module */
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if (name == NULL || *name == '\0')
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{
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ret = (void *) GetModuleHandle (NULL); /* handle for the current module */
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if (!ret)
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__seterrno ();
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break;
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}
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DWORD gmheflags = (flags & RTLD_NODELETE)
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? GET_MODULE_HANDLE_EX_FLAG_PIN
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: 0;
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tmp_pathbuf tp; /* single one per stack frame */
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tmp_pathbuf_allocator allocator (tp);
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pathfinder::basenamelist basenames (allocator);
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const char *basename;
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int baselen;
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bool have_dir = spot_basename (basename, baselen, name);
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collect_basenames (basenames, basename, baselen);
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/* handle for the named library */
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path_conv real_filename;
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wchar_t *wpath = tp.w_get ();
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pathfinder finder (allocator, basenames); /* eats basenames */
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if (have_dir)
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{
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/* search the specified dir */
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finder.add_searchdir (name, basename - 1 - name);
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}
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else
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{
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/* NOTE: The Windows loader (for linked dlls) does
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not use the LD_LIBRARY_PATH environment variable. */
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finder.add_envsearchpath ("LD_LIBRARY_PATH");
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/* Finally we better have some fallback. */
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finder.add_searchdir ("/usr/bin", 8);
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finder.add_searchdir ("/usr/lib", 8);
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}
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/* now search the file system */
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if (!finder.find (pathfinder::
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exists_and_not_dir (real_filename,
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PC_SYM_FOLLOW | PC_POSIX)))
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{
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/* If nothing worked, create a relative path from the original
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incoming filename and let LoadLibrary search for it using the
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system default DLL search path. */
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real_filename.check (name, PC_SYM_FOLLOW | PC_NOFULL | PC_NULLEMPTY);
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if (real_filename.error)
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break;
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}
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real_filename.get_wide_win32_path (wpath);
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/* Check if the last path component contains a dot. If so,
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leave the filename alone. Otherwise add a trailing dot
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to override LoadLibrary's automatic adding of a ".dll" suffix. */
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wchar_t *last_bs = wcsrchr (wpath, L'\\') ?: wpath;
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if (last_bs && !wcschr (last_bs, L'.'))
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wcscat (last_bs, L".");
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if (flags & RTLD_NOLOAD)
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{
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GetModuleHandleExW (gmheflags, wpath, (HMODULE *) &ret);
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if (ret)
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break;
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}
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#ifndef __x86_64__
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/* Workaround for broken DLLs built against Cygwin versions 1.7.0-49
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up to 1.7.0-57. They override the cxx_malloc pointer in their
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DLL initialization code even if loaded dynamically. This is a
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no-no since a later dlclose lets cxx_malloc point into nirvana.
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The below kludge "fixes" that by reverting the original cxx_malloc
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pointer after LoadLibrary. This implies that their overrides
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won't be applied; that's OK. All overrides should be present at
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final link time, as Windows doesn't allow undefined references;
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it would actually be wrong for a dlopen'd DLL to opportunistically
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override functions in a way that wasn't known then. We're not
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going to try and reproduce the full ELF dynamic loader here! */
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/* Store original cxx_malloc pointer. */
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struct per_process_cxx_malloc *tmp_malloc;
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tmp_malloc = __cygwin_user_data.cxx_malloc;
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#endif
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ret = (void *) LoadLibraryW (wpath);
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#ifndef __x86_64__
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/* Restore original cxx_malloc pointer. */
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__cygwin_user_data.cxx_malloc = tmp_malloc;
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#endif
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if (ret && gmheflags)
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GetModuleHandleExW (gmheflags, wpath, (HMODULE *) &ret);
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if (!ret)
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__seterrno ();
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}
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else
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{
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/* handle for the named library */
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path_conv pc;
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if (get_full_path_of_dll (name, pc))
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{
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tmp_pathbuf tp;
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wchar_t *path = tp.w_get ();
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pc.get_wide_win32_path (path);
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/* Check if the last path component contains a dot. If so,
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leave the filename alone. Otherwise add a trailing dot
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to override LoadLibrary's automatic adding of a ".dll" suffix. */
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wchar_t *last_bs = wcsrchr (path, L'\\') ?: path;
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if (last_bs && !wcschr (last_bs, L'.'))
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wcscat (last_bs, L".");
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#ifndef __x86_64__
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/* Workaround for broken DLLs built against Cygwin versions 1.7.0-49
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up to 1.7.0-57. They override the cxx_malloc pointer in their
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DLL initialization code even if loaded dynamically. This is a
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no-no since a later dlclose lets cxx_malloc point into nirvana.
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The below kludge "fixes" that by reverting the original cxx_malloc
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pointer after LoadLibrary. This implies that their overrides
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won't be applied; that's OK. All overrides should be present at
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final link time, as Windows doesn't allow undefined references;
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it would actually be wrong for a dlopen'd DLL to opportunistically
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override functions in a way that wasn't known then. We're not
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going to try and reproduce the full ELF dynamic loader here! */
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/* Store original cxx_malloc pointer. */
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struct per_process_cxx_malloc *tmp_malloc;
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tmp_malloc = __cygwin_user_data.cxx_malloc;
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#endif
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if (flags & RTLD_NOLOAD)
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GetModuleHandleExW (0, path, (HMODULE *) &ret);
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else
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ret = (void *) LoadLibraryW (path);
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if (ret && (flags & RTLD_NODELETE))
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GetModuleHandleExW (GET_MODULE_HANDLE_EX_FLAG_PIN, path,
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(HMODULE *) &ret);
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#ifndef __x86_64__
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/* Restore original cxx_malloc pointer. */
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__cygwin_user_data.cxx_malloc = tmp_malloc;
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#endif
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if (!ret)
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__seterrno ();
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}
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}
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while (0);
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if (!ret)
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set_dl_error ("dlopen");
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