[PATCH] cygcheck: follow symbolic links
Igor Peshansky
pechtcha@cs.nyu.edu
Mon Feb 13 18:44:00 GMT 2006
As promised in <http://cygwin.com/ml/cygwin/2006-02/msg00071.html>, the
attached patch teaches cygcheck to follow symlinks when looking for
executables, and also flags scripts. Sorry, had legal delays in sending
this (as you can see, I had this working since 02/03). Comments welcome.
Igor
2006-02-03 Igor Peshansky <pechtcha@cs.nyu.edu>
* cygcheck.cc (LINK_EXTENSION): New macro.
(check_existence): New static function.
(find_on_path): Check for symbolic links if asked.
(EXE_MAGIC,SHORTCUT_MAGIC,SYMLINK_COOKIE,SYMLINK_MAGIC): New
macros.
(is_exe,is_symlink,readlink): New static functions.
(track_down): Only call dll_info() for executables, display
an error for symlinks, and print magic number for others.
(find_app_on_path): New static function.
(cygcheck, dump_sysinfo): Call find_app_on_path() instead of
find_on_path().
--
http://cs.nyu.edu/~pechtcha/
|\ _,,,---,,_ pechtcha@cs.nyu.edu | igor@watson.ibm.com
ZZZzz /,`.-'`' -. ;-;;,_ Igor Peshansky, Ph.D. (name changed!)
|,4- ) )-,_. ,\ ( `'-' old name: Igor Pechtchanski
'---''(_/--' `-'\_) fL a.k.a JaguaR-R-R-r-r-r-.-.-. Meow!
"Las! je suis sot... -Mais non, tu ne l'es pas, puisque tu t'en rends compte."
"But no -- you are no fool; you call yourself a fool, there's proof enough in
that!" -- Rostand, "Cyrano de Bergerac"
-------------- next part --------------
Index: winsup/utils/cygcheck.cc
===================================================================
RCS file: /cvs/src/src/winsup/utils/cygcheck.cc,v
retrieving revision 1.88
diff -u -p -r1.88 cygcheck.cc
--- winsup/utils/cygcheck.cc 19 Jan 2006 21:16:38 -0000 1.88
+++ winsup/utils/cygcheck.cc 3 Feb 2006 17:40:34 -0000
@@ -249,9 +249,41 @@ init_paths ()
}
}
+#define LINK_EXTENSION ".lnk"
+
+static bool
+check_existence (char *file, int showall, int foundone, char *first)
+{
+ if (GetFileAttributes (file) != (DWORD) - 1)
+ {
+ char *lastdot = strrchr (file, '.');
+ bool is_link = lastdot && !strcmp (lastdot, LINK_EXTENSION);
+ // If file is a link, fix up the extension before printing
+ if (is_link)
+ *lastdot = '\0';
+ if (showall)
+ printf ("Found: %s\n", file);
+ if (foundone)
+ {
+ char *flastdot = strrchr (first, '.');
+ bool f_is_link = flastdot && !strcmp (flastdot, LINK_EXTENSION);
+ // if first is a link, fix up the extension before printing
+ if (f_is_link)
+ *flastdot = '\0';
+ printf ("Warning: %s hides %s\n", first, file);
+ if (f_is_link)
+ *flastdot = '.';
+ }
+ if (is_link)
+ *lastdot = '.';
+ return true;
+ }
+ return false;
+}
+
static char *
find_on_path (char *file, char *default_extension,
- int showall = 0, int search_sysdirs = 0)
+ int showall = 0, int search_sysdirs = 0, int checklinks = 0)
{
static char rv[4000];
char tmp[4000], *ptr = rv;
@@ -270,11 +302,21 @@ find_on_path (char *file, char *default_
if (strchr (file, ':') || strchr (file, '\\') || strchr (file, '/'))
{
+ // FIXME: this will find "foo" before "foo.exe" -- contrary to Windows
char *fn = cygpath (file, NULL);
if (access (fn, F_OK) == 0)
return fn;
strcpy (rv, fn);
strcat (rv, default_extension);
+ if (access (rv, F_OK) == 0)
+ return rv;
+ if (!checklinks)
+ return fn;
+ strcat (rv, LINK_EXTENSION);
+ if (access (rv, F_OK) == 0)
+ return rv;
+ strcpy (rv, fn);
+ strcat (rv, LINK_EXTENSION);
return access (rv, F_OK) == 0 ? rv : fn;
}
@@ -286,14 +328,25 @@ find_on_path (char *file, char *default_
if (i == 0 || !search_sysdirs || strcasecmp (paths[i], paths[0]))
{
sprintf (ptr, "%s\\%s%s", paths[i], file, default_extension);
- if (GetFileAttributes (ptr) != (DWORD) - 1)
- {
- if (showall)
- printf ("Found: %s\n", ptr);
- if (ptr == tmp && verbose)
- printf ("Warning: %s hides %s\n", rv, ptr);
- ptr = tmp;
- }
+ if (check_existence (ptr, showall, ptr == tmp && verbose, rv))
+ ptr = tmp;
+
+ if (!checklinks)
+ continue;
+
+ sprintf (ptr, "%s\\%s%s%s", paths[i], file, default_extension, LINK_EXTENSION);
+ if (check_existence (ptr, showall, ptr == tmp && verbose, rv))
+ ptr = tmp;
+
+ if (!*default_extension)
+ continue;
+
+ sprintf (ptr, "%s\\%s", paths[i], file);
+ if (check_existence (ptr, showall, ptr == tmp && verbose, rv))
+ ptr = tmp;
+ sprintf (ptr, "%s\\%s%s", paths[i], file, LINK_EXTENSION);
+ if (check_existence (ptr, showall, ptr == tmp && verbose, rv))
+ ptr = tmp;
}
}
@@ -610,6 +663,101 @@ dll_info (const char *path, HANDLE fh, i
cygwin_info (fh);
}
+/* TODO: should the three functions below go into path.cc? */
+
+#define EXE_MAGIC ((int)*(unsigned short *)"MZ")
+#define SHORTCUT_MAGIC ((int)*(unsigned short *)"L\0")
+#define SYMLINK_COOKIE "!<symlink>"
+#define SYMLINK_MAGIC ((int)*(unsigned short *)SYMLINK_COOKIE)
+
+static bool
+is_exe (HANDLE fh)
+{
+ int magic = get_word (fh, 0x0);
+ return magic == EXE_MAGIC;
+}
+
+static bool
+is_symlink (HANDLE fh)
+{
+ int magic = get_word (fh, 0x0);
+ return magic == SHORTCUT_MAGIC || magic == SYMLINK_MAGIC;
+}
+
+static bool
+readlink (HANDLE fh, char *path, int maxlen)
+{
+ int got;
+ int magic = get_word (fh, 0x0);
+
+ if (magic == SHORTCUT_MAGIC)
+ {
+ int offset = get_word (fh, 0x4c);
+ int slen = get_word (fh, 0x4c + offset + 2);
+ if (slen >= maxlen)
+ {
+ display_error ("readlink: Path too long");
+ return false;
+ }
+ if (SetFilePointer (fh, 0x4c + offset + 4, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER
+ && GetLastError () != NO_ERROR)
+ {
+ display_error ("readlink: SetFilePointer()");
+ return false;
+ }
+
+ if (!ReadFile (fh, path, slen, (DWORD *) &got, 0))
+ {
+ display_error ("readlink: ReadFile()");
+ return false;
+ }
+ else if (got < slen)
+ {
+ display_error ("readlink: ReadFile()");
+ return false;
+ }
+ else
+ path[got] = '\0';
+ }
+ else if (magic == SYMLINK_MAGIC)
+ {
+ char cookie_buf[sizeof (SYMLINK_COOKIE) - 1];
+
+ if (SetFilePointer (fh, 0, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER
+ && GetLastError () != NO_ERROR)
+ {
+ display_error ("readlink: SetFilePointer()");
+ return false;
+ }
+
+ if (!ReadFile (fh, cookie_buf, sizeof (cookie_buf), (DWORD *) &got, 0))
+ {
+ display_error ("readlink: Readfile()");
+ return false;
+ }
+ else if (got == sizeof (cookie_buf)
+ && memcmp (cookie_buf, SYMLINK_COOKIE, sizeof (cookie_buf)) == 0)
+ {
+ if (!ReadFile (fh, path, maxlen, (DWORD *) &got, 0))
+ {
+ display_error ("readlink: ReadFile()");
+ return false;
+ }
+ else if (got >= maxlen)
+ {
+ display_error ("readlink: Path too long");
+ path[0] = '\0';
+ return false;
+ }
+ else
+ path[got] = '\0';
+ }
+ }
+ else
+ return false;
+ return true;
+}
+
// Return true on success, false if error printed
static bool
track_down (char *file, char *suffix, int lvl)
@@ -682,7 +830,17 @@ track_down (char *file, char *suffix, in
d->state = DID_ACTIVE;
- dll_info (path, fh, lvl, 1);
+ if (is_exe (fh))
+ dll_info (path, fh, lvl, 1);
+ else if (is_symlink (fh))
+ display_error ("track_down: Huh? Got a symlink!");
+ else
+ {
+ int magic = get_word (fh, 0x0);
+ magic &= 0x00FFFFFF;
+ printf (" - Not a DLL: magic number %x (%d) '%s'\n", magic, magic, (char *)&magic);
+ }
+
d->state = DID_INACTIVE;
if (!CloseHandle (fh))
display_error ("track_down: CloseHandle()");
@@ -711,11 +869,55 @@ ls (char *f)
display_error ("ls: CloseHandle()");
}
+// Find a real application on the path (possibly following symlinks)
+static char *
+find_app_on_path (char *app, int showall = 0)
+{
+ char *papp = find_on_path (app, (char *) ".exe", showall, 0, 1);
+
+ HANDLE fh =
+ CreateFile (papp, GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE,
+ NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+ if (fh == INVALID_HANDLE_VALUE)
+ {
+ printf (" - Cannot open\n");
+ return NULL;
+ }
+
+ if (is_symlink (fh))
+ {
+ static char tmp[4000] = "";
+ char *ptr;
+ readlink(fh, tmp, 3999);
+ ptr = cygpath(tmp, NULL);
+ for (char *p = ptr; (p = strchr (p, '/')); p++)
+ *p = '\\';
+ printf (" -> %s\n", ptr);
+ if (!strchr (ptr, '\\'))
+ {
+ char *lastsep;
+ strncpy (tmp, cygpath (papp, NULL), 3999);
+ for (char *p = tmp; (p = strchr (p, '/')); p++)
+ *p = '\\';
+ lastsep = strrchr (tmp, '\\');
+ strncpy(lastsep+1, ptr, 3999-(lastsep-tmp));
+ ptr = tmp;
+ }
+ if (!CloseHandle (fh))
+ display_error ("find_app_on_path: CloseHandle()");
+ return find_app_on_path (ptr, showall);
+ }
+
+ if (!CloseHandle (fh))
+ display_error ("find_app_on_path: CloseHandle()");
+ return papp;
+}
+
// Return true on success, false if error printed
static bool
cygcheck (char *app)
{
- char *papp = find_on_path (app, (char *) ".exe", 1, 0);
+ char *papp = find_app_on_path (app, 1);
if (!papp)
{
printf ("Error: could not find %s\n", app);
@@ -1441,7 +1643,7 @@ dump_sysinfo ()
printf
("Looking to see where common programs can be found, if at all...\n");
for (i = 0; common_apps[i].name; i++)
- if (!find_on_path ((char *) common_apps[i].name, (char *) ".exe", 1, 0))
+ if (!find_app_on_path ((char *) common_apps[i].name, 1))
{
if (common_apps[i].missing_is_good)
printf ("Not Found: %s (good!)\n", common_apps[i].name);
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