Initial Contribution

1 files changed, 131 insertions, 0 deletions

diff --git a/libdw/dwarf_nextcu.c b/libdw/dwarf_nextcu.c
new file mode 100644
index 00000000..e674a66e
--- /dev/null
+++ b/libdw/dwarf_nextcu.c
@@ -0,0 +1,131 @@
+/* Advance to next CU header.
+   Copyright (C) 2002, 2003, 2004 Red Hat, Inc.
+   Written by Ulrich Drepper <drepper@redhat.com>, 2002.
+
+   This program is Open Source software; you can redistribute it and/or
+   modify it under the terms of the Open Software License version 1.0 as
+   published by the Open Source Initiative.
+
+   You should have received a copy of the Open Software License along
+   with this program; if not, you may obtain a copy of the Open Software
+   License version 1.0 from http://www.opensource.org/licenses/osl.php or
+   by writing the Open Source Initiative c/o Lawrence Rosen, Esq.,
+   3001 King Ranch Road, Ukiah, CA 95482.   */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <libdwP.h>
+
+
+int
+dwarf_nextcu (dwarf, off, next_off, header_sizep, abbrev_offsetp,
+	      address_sizep, offset_sizep)
+     Dwarf *dwarf;
+     Dwarf_Off off;
+     Dwarf_Off *next_off;
+     size_t *header_sizep;
+     Dwarf_Off *abbrev_offsetp;
+     uint8_t *address_sizep;
+     uint8_t *offset_sizep;
+{
+  /* Maybe there has been an error before.  */
+  if (dwarf == NULL)
+    return -1;
+
+  /* If we reached the end before don't do anything.  */
+  if (off == (Dwarf_Off) -1l
+      /* Make sure there is enough space in the .debug_info section
+	 for at least the initial word.  We cannot test the rest since
+	 we don't know yet whether this is a 64-bit object or not.  */
+      || unlikely (off + 4 >= dwarf->sectiondata[IDX_debug_info]->d_size))
+    {
+      *next_off = (Dwarf_Off) -1l;
+      return 1;
+    }
+
+  /* This points into the .debug_info section to the beginning of the
+     CU entry.  */
+  char *bytes = (char *) dwarf->sectiondata[IDX_debug_info]->d_buf + off;
+
+  /* The format of the CU header is described in dwarf2p1 7.5.1:
+
+     1.  A 4-byte or 12-byte unsigned integer representing the length
+	 of the .debug_info contribution for that compilation unit, not
+	 including the length field itself. In the 32-bit DWARF format,
+	 this is a 4-byte unsigned integer (which must be less than
+	 0xffffff00); in the 64-bit DWARF format, this consists of the
+	 4-byte value 0xffffffff followed by an 8-byte unsigned integer
+	 that gives the actual length (see Section 7.4).
+
+      2. A 2-byte unsigned integer representing the version of the
+	 DWARF information for that compilation unit. For DWARF Version
+	 2.1, the value in this field is 2.
+
+      3. A 4-byte or 8-byte unsigned offset into the .debug_abbrev
+	 section. This offset associates the compilation unit with a
+	 particular set of debugging information entry abbreviations. In
+	 the 32-bit DWARF format, this is a 4-byte unsigned length; in
+	 the 64-bit DWARF format, this is an 8-byte unsigned length (see
+	 Section 7.4).
+
+      4. A 1-byte unsigned integer representing the size in bytes of
+	 an address on the target architecture. If the system uses
+	 segmented addressing, this value represents the size of the
+	 offset portion of an address.  */
+  uint64_t length = read_4ubyte_unaligned_inc (dwarf, bytes);
+  size_t offset_size = 4;
+  if (length == 0xffffffffu)
+    offset_size = 8;
+
+  /* Now we know how large the header is.  Note the trick in the
+     computation.  If the offset_size is 4 the '- 4' term undoes the
+     '2 *'.  If offset_size is 8 this term computes the size of the
+     escape value plus the 8 byte offset.  */
+  if (unlikely (off + 2 * offset_size - 4 + sizeof (uint16_t)
+		+ offset_size + sizeof (uint8_t)
+		>= dwarf->sectiondata[IDX_debug_info]->d_size))
+    {
+      *next_off = -1;
+      return 1;
+    }
+
+  if (length == 0xffffffffu)
+    /* This is a 64-bit DWARF format.  */
+    length = read_8ubyte_unaligned_inc (dwarf, bytes);
+
+  /* Read the version stamp.  Always a 16-bit value.
+     XXX Do we need the value?  */
+  read_2ubyte_unaligned_inc (dwarf, bytes);
+
+  /* Get offset in .debug_abbrev.  Note that the size of the entry
+     depends on whether this is a 32-bit or 64-bit DWARF definition.  */
+  uint64_t abbrev_offset;
+  if (offset_size == 4)
+    abbrev_offset = read_4ubyte_unaligned_inc (dwarf, bytes);
+  else
+    abbrev_offset = read_8ubyte_unaligned_inc (dwarf, bytes);
+  if (abbrev_offsetp != NULL)
+    *abbrev_offsetp = abbrev_offset;
+
+  /* The address size.  Always an 8-bit value.  */
+  uint8_t address_size = *bytes++;
+  if (address_sizep != NULL)
+    *address_sizep = address_size;
+
+  /* Store the offset size.  */
+  if (offset_sizep != NULL)
+    *offset_sizep = offset_size;
+
+  /* Store the header length.  */
+  if (header_sizep != NULL)
+    *header_sizep = (bytes
+		     - ((char *) dwarf->sectiondata[IDX_debug_info]->d_buf
+			+ off));
+
+  /* See above for an explanation of the trick in this formula.  */
+  *next_off = off + 2 * offset_size - 4 + length;
+
+  return 0;
+}