[hjl@valinux.com: Re: A PE patch.]
DJ Delorie
dj@delorie.com
Wed Jan 24 12:33:00 GMT 2001
Could people please look at this patch and try it? The original code
assumed things it shouldn't, and thus you couldn't run, say, objdump
on MS system DLLs. I like the idea about making bfd dynamic, but I
refuse to accept patches to this code without a "gut feeling" that it
will work *and* lots of testing, so the more people test it the
better.
------- Start of forwarded message -------
Date: Wed, 24 Jan 2001 11:15:05 -0800
From: "H . J . Lu" <hjl@valinux.com>
To: DJ Delorie <dj@redhat.com>
Subject: Re: A PE patch.
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In-Reply-To: <200101241909.OAA06907@greed.delorie.com>; from dj@redhat.com on Wed, Jan 24, 2001 at 02:09:12PM -0500
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Here is the updated version. There is a bug in my old patch.
--
H.J. Lu (hjl@valinux.com)
---
2001-01-23 H.J. Lu <hjl@gnu.org>
* include/coff/pe.h (struct external_PEI_DOS_hdr): New.
(struct external_PEI_IMAGE_hdr): New.
* bfd/peicode.h (coff_swap_filehdr_in): Remove the e_magic
checking.
(pe_bfd_object_p): Rewrite with external_PEI_DOS_hdr and
external_PEI_IMAGE_hdr.
Index: include/coff/pe.h
===================================================================
RCS file: /work/cvs/gnu/binutils/include/coff/pe.h,v
retrieving revision 1.1.1.7
diff -u -p -r1.1.1.7 pe.h
--- include/coff/pe.h 2000/09/05 17:49:11 1.1.1.7
+++ include/coff/pe.h 2001/01/24 18:46:34
@@ -125,6 +125,45 @@
#undef FILNMLEN
#define FILNMLEN 18 /* # characters in a file name. */
+struct external_PEI_DOS_hdr
+{
+ /* DOS header fields - always at offset zero in the EXE file. */
+ char e_magic[2]; /* Magic number, 0x5a4d. */
+ char e_cblp[2]; /* Bytes on last page of file, 0x90. */
+ char e_cp[2]; /* Pages in file, 0x3. */
+ char e_crlc[2]; /* Relocations, 0x0. */
+ char e_cparhdr[2]; /* Size of header in paragraphs, 0x4. */
+ char e_minalloc[2]; /* Minimum extra paragraphs needed, 0x0. */
+ char e_maxalloc[2]; /* Maximum extra paragraphs needed, 0xFFFF. */
+ char e_ss[2]; /* Initial (relative) SS value, 0x0. */
+ char e_sp[2]; /* Initial SP value, 0xb8. */
+ char e_csum[2]; /* Checksum, 0x0. */
+ char e_ip[2]; /* Initial IP value, 0x0. */
+ char e_cs[2]; /* Initial (relative) CS value, 0x0. */
+ char e_lfarlc[2]; /* File address of relocation table, 0x40. */
+ char e_ovno[2]; /* Overlay number, 0x0. */
+ char e_res[4][2]; /* Reserved words, all 0x0. */
+ char e_oemid[2]; /* OEM identifier (for e_oeminfo), 0x0. */
+ char e_oeminfo[2]; /* OEM information; e_oemid specific, 0x0. */
+ char e_res2[10][2]; /* Reserved words, all 0x0. */
+ char e_lfanew[4]; /* File address of new exe header, usually 0x80. */
+ char dos_message[16][4]; /* Other stuff, always follow DOS header. */
+};
+
+struct external_PEI_IMAGE_hdr
+{
+ char nt_signature[4]; /* required NT signature, 0x4550. */
+
+ /* From standard header. */
+ char f_magic[2]; /* Magic number. */
+ char f_nscns[2]; /* Number of sections. */
+ char f_timdat[4]; /* Time & date stamp. */
+ char f_symptr[4]; /* File pointer to symtab. */
+ char f_nsyms[4]; /* Number of symtab entries. */
+ char f_opthdr[2]; /* Sizeof(optional hdr). */
+ char f_flags[2]; /* Flags. */
+};
+
struct external_PEI_filehdr
{
/* DOS header fields - always at offset zero in the EXE file. */
Index: bfd/peicode.h
===================================================================
RCS file: /work/cvs/gnu/binutils/bfd/peicode.h,v
retrieving revision 1.9
diff -u -p -r1.9 peicode.h
--- bfd/peicode.h 2001/01/23 20:11:14 1.9
+++ bfd/peicode.h 2001/01/24 18:36:09
@@ -208,26 +208,6 @@ coff_swap_filehdr_in (abfd, src, dst)
filehdr_dst->f_flags = bfd_h_get_16(abfd, (bfd_byte *)filehdr_src-> f_flags);
filehdr_dst->f_symptr = bfd_h_get_32 (abfd, (bfd_byte *) filehdr_src->f_symptr);
-#ifdef COFF_IMAGE_WITH_PE
- /* There are really two magic numbers involved; the magic number
- that says this is a NT executable (PEI) and the magic number that
- determines the architecture. The former is DOSMAGIC, stored in
- the e_magic field. The latter is stored in the f_magic field.
- If the NT magic number isn't valid, the architecture magic number
- could be mimicked by some other field (specifically, the number
- of relocs in section 3). Since this routine can only be called
- correctly for a PEI file, check the e_magic number here, and, if
- it doesn't match, clobber the f_magic number so that we don't get
- a false match. */
-#if 0
- /* We can't assume that the PE header is at offset 0x80. When it
- isn't, the DOS header isn't read correctly, so we can't assume
- e_magic is set even for valid PE files. */
- if (bfd_h_get_16 (abfd, (bfd_byte *) filehdr_src->e_magic) != DOSMAGIC)
- filehdr_dst->f_magic = -1;
-#endif
-#endif
-
/* Other people's tools sometimes generate headers with an nsyms but
a zero symptr. */
if (filehdr_dst->f_nsyms != 0 && filehdr_dst->f_symptr == 0)
@@ -1255,16 +1235,10 @@ _("%s: Recognised but unhandled machine
static const bfd_target *
pe_bfd_object_p (bfd * abfd)
{
- /* We need to handle a PE image correctly. In PE images created by
- the GNU linker, the offset to the COFF header is always the size.
- However, this is not the case in images generated by other PE
- linkers. The PE format stores a four byte offset to the PE
- signature just before the COFF header at location 0x3c of the file.
- We pick up that offset, verify that the PE signature is there, and
- then set ourselves up to read in the COFF header. */
bfd_byte buffer[4];
+ struct external_PEI_DOS_hdr dos_hdr;
+ struct external_PEI_IMAGE_hdr image_hdr;
file_ptr offset;
- unsigned long signature;
/* Detect if this a Microsoft Import Library Format element. */
if (bfd_seek (abfd, 0x00, SEEK_SET) != 0
@@ -1275,44 +1249,56 @@ pe_bfd_object_p (bfd * abfd)
return NULL;
}
- signature = bfd_h_get_32 (abfd, buffer);
-
- if (signature == 0xffff0000)
+ if (bfd_h_get_32 (abfd, buffer) == 0xffff0000)
return pe_ILF_object_p (abfd);
- if (bfd_seek (abfd, 0x3c, SEEK_SET) != 0
- || bfd_read (buffer, 1, 4, abfd) != 4)
+ if (bfd_seek (abfd, 0x00, SEEK_SET) != 0
+ || bfd_read (&dos_hdr, 1, sizeof (dos_hdr), abfd)
+ != sizeof (dos_hdr))
{
if (bfd_get_error () != bfd_error_system_call)
bfd_set_error (bfd_error_wrong_format);
return NULL;
}
- offset = bfd_h_get_32 (abfd, buffer);
+ /* There are really two magic numbers involved; the magic number
+ that says this is a NT executable (PEI) and the magic number that
+ determines the architecture. The former is DOSMAGIC, stored in
+ the e_magic field. The latter is stored in the f_magic field.
+ If the NT magic number isn't valid, the architecture magic number
+ could be mimicked by some other field (specifically, the number
+ of relocs in section 3). Since this routine can only be called
+ correctly for a PEI file, check the e_magic number here, and, if
+ it doesn't match, clobber the f_magic number so that we don't get
+ a false match. */
+ if (bfd_h_get_16 (abfd, (bfd_byte *) dos_hdr.e_magic) != DOSMAGIC)
+ {
+ bfd_set_error (bfd_error_wrong_format);
+ return NULL;
+ }
- if (bfd_seek (abfd, offset, SEEK_SET) != 0
- || bfd_read (buffer, 1, 4, abfd) != 4)
+ offset = bfd_h_get_32 (abfd, (bfd_byte *) dos_hdr.e_lfanew);
+ if (bfd_seek (abfd, (file_ptr) offset, SEEK_SET) != 0
+ || bfd_read (&image_hdr, 1, sizeof (image_hdr), abfd)
+ != sizeof (image_hdr))
{
if (bfd_get_error () != bfd_error_system_call)
bfd_set_error (bfd_error_wrong_format);
return NULL;
}
-
- signature = bfd_h_get_32 (abfd, buffer);
- if (signature != 0x4550)
+ if (bfd_h_get_32 (abfd, (bfd_byte *) image_hdr.nt_signature)
+ != 0x4550)
{
bfd_set_error (bfd_error_wrong_format);
return NULL;
}
/* Here is the hack. coff_object_p wants to read filhsz bytes to
- pick up the COFF header. We adjust so that that will work. 20
- is the size of the i386 COFF filehdr. */
+ pick up the COFF header for PE, see "struct external_PEI_filehdr"
+ in include/coff/pe.h. We adjust so that that will work. */
if (bfd_seek (abfd,
- (bfd_tell (abfd)
- - bfd_coff_filhsz (abfd)
- + 20),
+ (file_ptr) (offset - sizeof (dos_hdr)),
SEEK_SET)
!= 0)
{
------- End of forwarded message -------
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