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* dwarf2read.c (read_initial_length): Handle older, non-standard,

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64-bit DWARF2 format.
This commit is contained in:
Kevin Buettner 2002-07-16 21:00:43 +00:00
parent 8dd72958e0
commit f7ef933922
2 changed files with 38 additions and 4 deletions
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5
gdb/ChangeLog
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@ -1,3 +1,8 @@
2002-07-16 Kevin Buettner <kevinb@redhat.com>
* dwarf2read.c (read_initial_length): Handle older, non-standard,
64-bit DWARF2 format.
2002-07-16 Joel Brobecker <brobecker@gnat.com>
* proc-api.c: use HAVE_SYS_PROC_H macro to avoid including

37
gdb/dwarf2read.c
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@ -3863,12 +3863,25 @@ read_address (bfd *abfd, char *buf, const struct comp_unit_head *cu_header,
return retval;
}
/* Reads the initial length from a section. The (draft) DWARF 2.1
/* Read the initial length from a section. The (draft) DWARF 3
specification allows the initial length to take up either 4 bytes
or 12 bytes. If the first 4 bytes are 0xffffffff, then the next 8
bytes describe the length and all offsets will be 8 bytes in length
instead of 4.
An older, non-standard 64-bit format is also handled by this
function. The older format in question stores the initial length
as an 8-byte quantity without an escape value. Lengths greater
than 2^32 aren't very common which means that the initial 4 bytes
is almost always zero. Since a length value of zero doesn't make
sense for the 32-bit format, this initial zero can be considered to
be an escape value which indicates the presence of the older 64-bit
format. As written, the code can't detect (old format) lengths
greater than 4GB. If it becomes necessary to handle lengths somewhat
larger than 4GB, we could allow other small values (such as the
non-sensical values of 1, 2, and 3) to also be used as escape values
indicating the presence of the old format.
The value returned via bytes_read should be used to increment
the relevant pointer after calling read_initial_length().
@ -3879,14 +3892,18 @@ read_address (bfd *abfd, char *buf, const struct comp_unit_head *cu_header,
[ Note: read_initial_length() and read_offset() are based on the
document entitled "DWARF Debugging Information Format", revision
2.1, draft 4, dated July 20, 2000. This document was obtained
3, draft 8, dated November 19, 2001. This document was obtained
from:
http://reality.sgi.com/dehnert_engr/dwarf/dwarf2p1-draft4-000720.pdf
http://reality.sgiweb.org/davea/dwarf3-draft8-011125.pdf
This document is only a draft and is subject to change. (So beware.)
- Kevin, Aug 4, 2000
Details regarding the older, non-standard 64-bit format were
determined empirically by examining 64-bit ELF files produced
by the SGI toolchain on an IRIX 6.5 machine.
- Kevin, July 16, 2002
] */
static LONGEST
@ -3907,6 +3924,18 @@ read_initial_length (bfd *abfd, char *buf, struct comp_unit_head *cu_header,
cu_header->offset_size = 8;
}
}
else if (retval == 0)
{
/* Handle (non-standard) 64-bit DWARF2 formats such as that used
by IRIX. */
retval = bfd_get_64 (abfd, (bfd_byte *) buf);
*bytes_read = 8;
if (cu_header != NULL)
{
cu_header->initial_length_size = 8;
cu_header->offset_size = 8;
}
}
else
{
*bytes_read = 4;