[PATCH] cygcheck: follow symbolic links
Igor Peshansky
pechtcha@cs.nyu.edu
Thu Sep 28 13:06:00 GMT 2006
On Mon, 24 Jul 2006, Corinna Vinschen wrote:
> On Jul 21 20:52, Igor Peshansky wrote:
> > In any case, here's the latest incarnation, with get_word and get_dword
> > folded into path.cc, and display_error returned to cygcheck.cc, where it
> > belongs. Tested reasonably well (with symlinks pointing to symlinks,
> > etc). I'll let you judge the neatness of the ChangeLog entry. If I'm
> > lucky, this might just get into 1.5.21[*].
> > Igor
> > [*] Corinna, I'm guessing this is sufficiently different that you can't
> > accept it without "the fax" -- I'll keep pinging the guy who's holding
> > this up, but this message is also supposed to confirm that there is a
> > working patch, and the delay is simply bureaucratic. Oh, the
> > frustration... If you judge the changes from the previous incarnation
> > to not be significant, just go ahead and apply this, given the previous
> > approval.
>
> The latest fax was about this change, so I think this should still be
> covered, shouldn't it? Ping the guy nevertheless. We should stay on
> the safe side in legal questions.
>
> I'd be happy to apply the patch, but it would be nice if you could tweak
> the formatting somewhat:
>
> > + if (GetLastError () != NO_ERROR) display_error ("get_dword");
>
> The display_error call should be on its own line, as usual. This
> happens multiple times in your patch.
>
> > + if (is_exe (fh))
> > + dll_info (path, fh, lvl, 1);
> > + else if (is_symlink (fh))
> > + display_error ("track_down: Huh? Got a symlink!");
>
> Is that really the supposed message here?
>
> > + printf (" - Not a DLL: magic number %x (%d) '%s'\n", magic, magic, (char *)&magic);
>
> Please split the printf so that it's not longer than 80 chars.
>
> > + /* TODO: check for invalid path contents (see ../cygwin/path.cc:3313 */
>
> Since source code lines are most volatile, I'd not refer to a line number
> in another source code. Just mention the function name. */
>
> > + if (got != sizeof (buf) || memcmp (buf, SYMLINK_COOKIE, sizeof (buf)) != 0)
>
> Split the line, please.
>
> > + if (SetFilePointer (fh, 0x4c + offset + 4, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER
>
> Same here.
>
> > + {
> > + return false;
> > + }
>
> I'd rather not have these one liners in curly brackets. It's a bit
> irritating since sometimes you put them in curly brackets, sometimes you
> don't.
>
> The code looks ok, otherwise.
Looks like I've been remiss in following up on this, though I regenerated
the patch that same day. Attached is the new version of the patch. I
believe "the fax" (the new one) has been sent, but I've received no
notification of that, presumably because Corinna is not around...
Igor
==============================================================================
ChangeLog:
2006-09-28 Igor Peshansky <pechtcha@cs.nyu.edu>
* cygcheck.cc (get_word, get_dword): Move to path.cc.
(LINK_EXTENSION): New macro.
(check_existence): New static function.
(find_on_path): Check for symbolic links if asked.
(dll_info): New error handling.
(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().
* path.cc (cmp_shortcut_header): New static function.
(get_word, get_dword): Moved from cygcheck.cc.
(EXE_MAGIC, SHORTCUT_MAGIC, SYMLINK_COOKIE, SYMLINK_MAGIC): New
macros.
(is_exe, is_symlink, readlink): New functions.
* path.h (is_exe, is_symlink, readlink): Declare.
(get_word, get_dword): Ditto.
--
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 1.90
diff -u -p -r1.90 cygcheck.cc
--- winsup/utils/cygcheck.cc 8 Feb 2006 14:19:40 -0000 1.90
+++ winsup/utils/cygcheck.cc 24 Jul 2006 17:52:15 -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 ? strdup (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;
}
}
@@ -330,38 +383,6 @@ already_did (char *file)
return d;
}
-static int
-get_word (HANDLE fh, int offset)
-{
- short rv;
- unsigned r;
-
- if (SetFilePointer (fh, offset, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER
- && GetLastError () != NO_ERROR)
- display_error ("get_word: SetFilePointer()");
-
- if (!ReadFile (fh, &rv, 2, (DWORD *) &r, 0))
- display_error ("get_word: Readfile()");
-
- return rv;
-}
-
-static int
-get_dword (HANDLE fh, int offset)
-{
- int rv;
- unsigned r;
-
- if (SetFilePointer (fh, offset, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER
- && GetLastError () != NO_ERROR)
- display_error ("get_dword: SetFilePointer()");
-
- if (!ReadFile (fh, &rv, 4, (DWORD *) &r, 0))
- display_error ("get_dword: Readfile()");
-
- return rv;
-}
-
struct Section
{
char name[8];
@@ -505,6 +526,8 @@ dll_info (const char *path, HANDLE fh, i
DWORD junk;
int i;
int pe_header_offset = get_dword (fh, 0x3c);
+ if (GetLastError () != NO_ERROR)
+ display_error ("get_dword");
int opthdr_ofs = pe_header_offset + 4 + 20;
unsigned short v[6];
@@ -528,12 +551,24 @@ dll_info (const char *path, HANDLE fh, i
printf ("\n");
int num_entries = get_dword (fh, opthdr_ofs + 92);
+ if (GetLastError () != NO_ERROR)
+ display_error ("get_dword");
int export_rva = get_dword (fh, opthdr_ofs + 96);
+ if (GetLastError () != NO_ERROR)
+ display_error ("get_dword");
int export_size = get_dword (fh, opthdr_ofs + 100);
+ if (GetLastError () != NO_ERROR)
+ display_error ("get_dword");
int import_rva = get_dword (fh, opthdr_ofs + 104);
+ if (GetLastError () != NO_ERROR)
+ display_error ("get_dword");
int import_size = get_dword (fh, opthdr_ofs + 108);
+ if (GetLastError () != NO_ERROR)
+ display_error ("get_dword");
int nsections = get_word (fh, pe_header_offset + 4 + 2);
+ if (nsections == -1)
+ display_error ("get_word");
char *sections = (char *) malloc (nsections * 40);
if (SetFilePointer (fh, pe_header_offset + 4 + 20 +
@@ -682,7 +717,20 @@ 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))
+ printf (" - Found a symlink instead of a DLL\n");
+ else
+ {
+ int magic = get_word (fh, 0x0);
+ if (magic == -1)
+ display_error ("get_word");
+ 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 +759,56 @@ 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;
+ if (!readlink (fh, tmp, 3999))
+ display_error("readlink failed");
+ 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 +1534,7 @@ 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);
Index: winsup/utils/path.cc
===================================================================
RCS file: /cvs/src/src/winsup/utils/path.cc,v
retrieving revision 1.9
diff -u -p -r1.9 path.cc
--- winsup/utils/path.cc 29 Apr 2005 16:39:34 -0000 1.9
+++ winsup/utils/path.cc 24 Jul 2006 17:52:15 -0000
@@ -9,14 +9,16 @@ Cygwin license. Please consult the file
details. */
/* The purpose of this file is to hide all the details about accessing
- Cygwin's mount table. If the format or location of the mount table
- changes, this is the file to change to match it. */
+ Cygwin's mount table, shortcuts, etc. If the format or location of
+ the mount table, or the shortcut format changes, this is the file to
+ change to match it. */
#define str(a) #a
#define scat(a,b) str(a##b)
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
+#include "path.h"
#include "cygwin/include/cygwin/version.h"
#include "cygwin/include/sys/mount.h"
#include "cygwin/include/mntent.h"
@@ -29,6 +31,202 @@ details. */
})
+static const GUID GUID_shortcut
+ = { 0x00021401L, 0, 0, 0xc0, 0, 0, 0, 0, 0, 0, 0x46 };
+
+enum {
+ WSH_FLAG_IDLIST = 0x01, /* Contains an ITEMIDLIST. */
+ WSH_FLAG_FILE = 0x02, /* Contains a file locator element. */
+ WSH_FLAG_DESC = 0x04, /* Contains a description. */
+ WSH_FLAG_RELPATH = 0x08, /* Contains a relative path. */
+ WSH_FLAG_WD = 0x10, /* Contains a working dir. */
+ WSH_FLAG_CMDLINE = 0x20, /* Contains command line args. */
+ WSH_FLAG_ICON = 0x40 /* Contains a custom icon. */
+};
+
+struct win_shortcut_hdr
+ {
+ DWORD size; /* Header size in bytes. Must contain 0x4c. */
+ GUID magic; /* GUID of shortcut files. */
+ DWORD flags; /* Content flags. See above. */
+
+ /* The next fields from attr to icon_no are always set to 0 in Cygwin
+ and U/Win shortcuts. */
+ DWORD attr; /* Target file attributes. */
+ FILETIME ctime; /* These filetime items are never touched by the */
+ FILETIME mtime; /* system, apparently. Values don't matter. */
+ FILETIME atime;
+ DWORD filesize; /* Target filesize. */
+ DWORD icon_no; /* Icon number. */
+
+ DWORD run; /* Values defined in winuser.h. Use SW_NORMAL. */
+ DWORD hotkey; /* Hotkey value. Set to 0. */
+ DWORD dummy[2]; /* Future extension probably. Always 0. */
+ };
+
+static bool
+cmp_shortcut_header (win_shortcut_hdr *file_header)
+{
+ /* A Cygwin or U/Win shortcut only contains a description and a relpath.
+ Cygwin shortcuts also might contain an ITEMIDLIST. The run type is
+ always set to SW_NORMAL. */
+ return file_header->size == sizeof (win_shortcut_hdr)
+ && !memcmp (&file_header->magic, &GUID_shortcut, sizeof GUID_shortcut)
+ && (file_header->flags & ~WSH_FLAG_IDLIST)
+ == (WSH_FLAG_DESC | WSH_FLAG_RELPATH)
+ && file_header->run == SW_NORMAL;
+}
+
+int
+get_word (HANDLE fh, int offset)
+{
+ unsigned short rv;
+ unsigned r;
+
+ SetLastError(NO_ERROR);
+ if (SetFilePointer (fh, offset, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER
+ && GetLastError () != NO_ERROR)
+ return -1;
+
+ if (!ReadFile (fh, &rv, 2, (DWORD *) &r, 0))
+ return -1;
+
+ return rv;
+}
+
+/*
+ * Check the value of GetLastError() to find out whether there was an error.
+ */
+int
+get_dword (HANDLE fh, int offset)
+{
+ int rv;
+ unsigned r;
+
+ SetLastError(NO_ERROR);
+ if (SetFilePointer (fh, offset, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER
+ && GetLastError () != NO_ERROR)
+ return -1;
+
+ if (!ReadFile (fh, &rv, 4, (DWORD *) &r, 0))
+ return -1;
+
+ return rv;
+}
+
+#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)
+
+bool
+is_exe (HANDLE fh)
+{
+ int magic = get_word (fh, 0x0);
+ return magic == EXE_MAGIC;
+}
+
+bool
+is_symlink (HANDLE fh)
+{
+ int magic = get_word (fh, 0x0);
+ if (magic != SHORTCUT_MAGIC && magic != SYMLINK_MAGIC)
+ return false;
+ DWORD got;
+ BY_HANDLE_FILE_INFORMATION local;
+ if (!GetFileInformationByHandle (fh, &local))
+ return false;
+ if (magic == SHORTCUT_MAGIC)
+ {
+ DWORD size;
+ if (!local.dwFileAttributes & FILE_ATTRIBUTE_READONLY)
+ return false; /* Not a Cygwin symlink. */
+ if ((size = GetFileSize (fh, NULL)) > 8192)
+ return false; /* Not a Cygwin symlink. */
+ char buf[size];
+ SetFilePointer (fh, 0, 0, FILE_BEGIN);
+ if (!ReadFile (fh, buf, size, &got, 0))
+ return false;
+ if (got != size || !cmp_shortcut_header ((win_shortcut_hdr *) buf))
+ return false; /* Not a Cygwin symlink. */
+ /* TODO: check for invalid path contents
+ (see symlink_info::check() in ../cygwin/path.cc) */
+ }
+ else /* magic == SYMLINK_MAGIC */
+ {
+ if (!local.dwFileAttributes & FILE_ATTRIBUTE_SYSTEM)
+ return false; /* Not a Cygwin symlink. */
+ char buf[sizeof (SYMLINK_COOKIE) - 1];
+ SetFilePointer (fh, 0, 0, FILE_BEGIN);
+ if (!ReadFile (fh, buf, sizeof (buf), &got, 0))
+ return false;
+ if (got != sizeof (buf) ||
+ memcmp (buf, SYMLINK_COOKIE, sizeof (buf)) != 0)
+ return false; /* Not a Cygwin symlink. */
+ }
+ return true;
+}
+
+/* Assumes is_symlink(fh) is true */
+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)
+ {
+ SetLastError (ERROR_FILENAME_EXCED_RANGE);
+ return false;
+ }
+ if (SetFilePointer (fh, 0x4c + offset + 4, 0, FILE_BEGIN) ==
+ INVALID_SET_FILE_POINTER && GetLastError () != NO_ERROR)
+ return false;
+
+ if (!ReadFile (fh, path, slen, (DWORD *) &got, 0))
+ return false;
+ else if (got < slen)
+ {
+ SetLastError (ERROR_READ_FAULT);
+ 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)
+ return false;
+
+ if (!ReadFile (fh, cookie_buf, sizeof (cookie_buf), (DWORD *) &got, 0))
+ 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))
+ return false;
+ else if (got >= maxlen)
+ {
+ SetLastError (ERROR_FILENAME_EXCED_RANGE);
+ path[0] = '\0';
+ return false;
+ }
+ else
+ path[got] = '\0';
+ }
+ }
+ else
+ return false;
+ return true;
+}
+
static struct mnt
{
const char *native;
Index: winsup/utils/path.h
===================================================================
RCS file: /cvs/src/src/winsup/utils/path.h,v
retrieving revision 1.2
diff -u -p -r1.2 path.h
--- winsup/utils/path.h 4 Mar 2003 05:30:50 -0000 1.2
+++ winsup/utils/path.h 24 Jul 2006 17:52:15 -0000
@@ -9,3 +9,9 @@ Cygwin license. Please consult the file
details. */
char *cygpath (const char *s, ...);
+bool is_exe (HANDLE);
+bool is_symlink (HANDLE);
+bool readlink (HANDLE, char *, int);
+int get_word (HANDLE, int);
+int get_dword (HANDLE, int);
+
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