diff options
Diffstat (limited to 'gdb/dwarf2read.c')
| -rw-r--r-- | gdb/dwarf2read.c | 37 |
1 files changed, 33 insertions, 4 deletions
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index 786dffc..0cf1cb6 100644 --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -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; |