Update libbacktrace to r227145

1 files changed, 937 insertions, 0 deletions

diff --git a/src/libbacktrace/pecoff.c b/src/libbacktrace/pecoff.c
new file mode 100644
index 00000000000..ba555b56582
--- /dev/null
+++ b/src/libbacktrace/pecoff.c
@@ -0,0 +1,937 @@
+/* pecoff.c -- Get debug data from a PE/COFFF file for backtraces.
+   Copyright (C) 2015 Free Software Foundation, Inc.
+   Adapted from elf.c by Tristan Gingold, AdaCore.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    (1) Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+    (2) Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in
+    the documentation and/or other materials provided with the
+    distribution.
+
+    (3) The name of the author may not be used to
+    endorse or promote products derived from this software without
+    specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.  */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+#include "backtrace.h"
+#include "internal.h"
+
+/* Coff file header.  */
+
+typedef struct {
+  uint16_t machine;
+  uint16_t number_of_sections;
+  uint32_t time_date_stamp;
+  uint32_t pointer_to_symbol_table;
+  uint32_t number_of_symbols;
+  uint16_t size_of_optional_header;
+  uint16_t characteristics;
+} b_coff_file_header;
+
+/* Coff optional header.  */
+
+typedef struct {
+  uint16_t magic;
+  uint8_t  major_linker_version;
+  uint8_t  minor_linker_version;
+  uint32_t size_of_code;
+  uint32_t size_of_initialized_data;
+  uint32_t size_of_uninitialized_data;
+  uint32_t address_of_entry_point;
+  uint32_t base_of_code;
+  union {
+    struct {
+      uint32_t base_of_data;
+      uint32_t image_base;
+    } pe;
+    struct {
+      uint64_t image_base;
+    } pep;
+  } u;
+} b_coff_optional_header;
+
+/* Values of magic in optional header.  */
+
+#define PE_MAGIC 0x10b		/* PE32 executable.  */
+#define PEP_MAGIC 0x20b		/* PE32+ executable (for 64bit targets).  */
+
+/* Coff section header.  */
+
+typedef struct {
+  char name[8];
+  uint32_t virtual_size;
+  uint32_t virtual_address;
+  uint32_t size_of_raw_data;
+  uint32_t pointer_to_raw_data;
+  uint32_t pointer_to_relocations;
+  uint32_t pointer_to_line_numbers;
+  uint16_t number_of_relocations;
+  uint16_t number_of_line_numbers;
+  uint32_t characteristics;
+} b_coff_section_header;
+
+/* Coff symbol name.  */
+
+typedef union {
+  char short_name[8];
+  struct {
+    unsigned char zeroes[4];
+    unsigned char off[4];
+  } long_name;
+} b_coff_name;
+
+/* Coff symbol (external representation which is unaligned).  */
+
+typedef struct {
+  b_coff_name name;
+  unsigned char value[4];
+  unsigned char section_number[2];
+  unsigned char type[2];
+  unsigned char storage_class;
+  unsigned char number_of_aux_symbols;
+} b_coff_external_symbol;
+
+/* Symbol types.  */
+
+#define N_TBSHFT 4			/* Shift for the derived type.  */
+#define IMAGE_SYM_DTYPE_FUNCTION 2	/* Function derived type.  */
+
+/* Size of a coff symbol.  */
+
+#define SYM_SZ 18
+
+/* Coff symbol, internal representation (aligned).  */
+
+typedef struct {
+  const char *name;
+  uint32_t value;
+  int16_t sec;
+  uint16_t type;
+  uint16_t sc;
+} b_coff_internal_symbol;
+
+/* An index of sections we care about.  */
+
+enum debug_section
+{
+  DEBUG_INFO,
+  DEBUG_LINE,
+  DEBUG_ABBREV,
+  DEBUG_RANGES,
+  DEBUG_STR,
+  DEBUG_MAX
+};
+
+/* Names of sections, indexed by enum debug_section.  */
+
+static const char * const debug_section_names[DEBUG_MAX] =
+{
+  ".debug_info",
+  ".debug_line",
+  ".debug_abbrev",
+  ".debug_ranges",
+  ".debug_str"
+};
+
+/* Information we gather for the sections we care about.  */
+
+struct debug_section_info
+{
+  /* Section file offset.  */
+  off_t offset;
+  /* Section size.  */
+  size_t size;
+  /* Section contents, after read from file.  */
+  const unsigned char *data;
+};
+
+/* Information we keep for an coff symbol.  */
+
+struct coff_symbol
+{
+  /* The name of the symbol.  */
+  const char *name;
+  /* The address of the symbol.  */
+  uintptr_t address;
+};
+
+/* Information to pass to coff_syminfo.  */
+
+struct coff_syminfo_data
+{
+  /* Symbols for the next module.  */
+  struct coff_syminfo_data *next;
+  /* The COFF symbols, sorted by address.  */
+  struct coff_symbol *symbols;
+  /* The number of symbols.  */
+  size_t count;
+};
+
+/* A dummy callback function used when we can't find any debug info.  */
+
+static int
+coff_nodebug (struct backtrace_state *state ATTRIBUTE_UNUSED,
+	      uintptr_t pc ATTRIBUTE_UNUSED,
+	      backtrace_full_callback callback ATTRIBUTE_UNUSED,
+	      backtrace_error_callback error_callback, void *data)
+{
+  error_callback (data, "no debug info in PE/COFF executable", -1);
+  return 0;
+}
+
+/* A dummy callback function used when we can't find a symbol
+   table.  */
+
+static void
+coff_nosyms (struct backtrace_state *state ATTRIBUTE_UNUSED,
+	     uintptr_t addr ATTRIBUTE_UNUSED,
+	     backtrace_syminfo_callback callback ATTRIBUTE_UNUSED,
+	     backtrace_error_callback error_callback, void *data)
+{
+  error_callback (data, "no symbol table in PE/COFF executable", -1);
+}
+
+/* Read a potentially unaligned 4 byte word at P, using native endianness.  */
+
+static uint32_t
+coff_read4 (const unsigned char *p)
+{
+  uint32_t res;
+
+  memcpy (&res, p, 4);
+  return res;
+}
+
+/* Read a potentially unaligned 2 byte word at P, using native endianness.
+   All 2 byte word in symbols are always aligned, but for coherency all
+   fields are declared as char arrays.  */
+
+static uint16_t
+coff_read2 (const unsigned char *p)
+{
+  uint16_t res;
+
+  memcpy (&res, p, sizeof (res));
+  return res;
+}
+
+/* Return the length (without the trailing 0) of a COFF short name.  */
+
+static size_t
+coff_short_name_len (const char *name)
+{
+  int i;
+
+  for (i = 0; i < 8; i++)
+    if (name[i] == 0)
+      return i;
+  return 8;
+}
+
+/* Return true iff COFF short name CNAME is the same as NAME (a NUL-terminated
+   string).  */
+
+static int
+coff_short_name_eq (const char *name, const char *cname)
+{
+  int i;
+
+  for (i = 0; i < 8; i++)
+    {
+      if (name[i] != cname[i])
+	return 0;
+      if (name[i] == 0)
+	return 1;
+    }
+  return name[8] == 0;
+}
+
+/* Return true iff NAME is the same as string at offset OFF.  */
+
+static int
+coff_long_name_eq (const char *name, unsigned int off,
+		   struct backtrace_view *str_view)
+{
+  if (off >= str_view->len)
+    return 0;
+  return strcmp (name, (const char *)str_view->data + off) == 0;
+}
+
+/* Compare struct coff_symbol for qsort.  */
+
+static int
+coff_symbol_compare (const void *v1, const void *v2)
+{
+  const struct coff_symbol *e1 = (const struct coff_symbol *) v1;
+  const struct coff_symbol *e2 = (const struct coff_symbol *) v2;
+
+  if (e1->address < e2->address)
+    return -1;
+  else if (e1->address > e2->address)
+    return 1;
+  else
+    return 0;
+}
+
+/* Convert SYM to internal (and aligned) format ISYM, using string table
+   from STRTAB and STRTAB_SIZE, and number of sections SECTS_NUM.
+   Return -1 in case of error (invalid section number or string index).  */
+
+static int
+coff_expand_symbol (b_coff_internal_symbol *isym,
+		    const b_coff_external_symbol *sym,
+		    uint16_t sects_num,
+		    const unsigned char *strtab, size_t strtab_size)
+{
+  isym->type = coff_read2 (sym->type);
+  isym->sec = coff_read2 (sym->section_number);
+  isym->sc = sym->storage_class;
+
+  if (isym->sec > 0 && (uint16_t) isym->sec > sects_num)
+    return -1;
+  if (sym->name.short_name[0] != 0)
+    isym->name = sym->name.short_name;
+  else
+    {
+      uint32_t off = coff_read4 (sym->name.long_name.off);
+
+      if (off >= strtab_size)
+	return -1;
+      isym->name = (const char *) strtab + off;
+    }
+  return 0;
+}
+
+/* Return true iff SYM is a defined symbol for a function.  Data symbols
+   aren't considered because they aren't easily identified (same type as
+   section names, presence of symbols defined by the linker script).  */
+
+static int
+coff_is_function_symbol (const b_coff_internal_symbol *isym)
+{
+  return (isym->type >> N_TBSHFT) == IMAGE_SYM_DTYPE_FUNCTION
+    && isym->sec > 0;
+}
+
+/* Initialize the symbol table info for coff_syminfo.  */
+
+static int
+coff_initialize_syminfo (struct backtrace_state *state,
+			 uintptr_t base_address,
+			 const b_coff_section_header *sects, size_t sects_num,
+			 const b_coff_external_symbol *syms, size_t syms_size,
+			 const unsigned char *strtab, size_t strtab_size,
+			 backtrace_error_callback error_callback,
+			 void *data, struct coff_syminfo_data *sdata)
+{
+  size_t syms_count;
+  char *coff_symstr;
+  size_t coff_symstr_len;
+  size_t coff_symbol_count;
+  size_t coff_symbol_size;
+  struct coff_symbol *coff_symbols;
+  struct coff_symbol *coff_sym;
+  char *coff_str;
+  size_t i;
+
+  syms_count = syms_size / SYM_SZ;
+
+  /* We only care about function symbols.  Count them.  Also count size of
+     strings for in-symbol names.  */
+  coff_symbol_count = 0;
+  coff_symstr_len = 0;
+  for (i = 0; i < syms_count; ++i)
+    {
+      const b_coff_external_symbol *asym = &syms[i];
+      b_coff_internal_symbol isym;
+
+      if (coff_expand_symbol (&isym, asym, sects_num, strtab, strtab_size) < 0)
+	{
+	  error_callback (data, "invalid section or offset in coff symbol", 0);
+	  return 0;
+	}
+      if (coff_is_function_symbol (&isym))
+	{
+	  ++coff_symbol_count;
+	  if (asym->name.short_name[0] != 0)
+	    coff_symstr_len += coff_short_name_len (asym->name.short_name) + 1;
+	}
+
+      i += asym->number_of_aux_symbols;
+    }
+
+  coff_symbol_size = (coff_symbol_count + 1) * sizeof (struct coff_symbol);
+  coff_symbols = ((struct coff_symbol *)
+		  backtrace_alloc (state, coff_symbol_size, error_callback,
+				   data));
+  if (coff_symbols == NULL)
+    return 0;
+
+  /* Allocate memory for symbols strings.  */
+  if (coff_symstr_len > 0)
+    {
+      coff_symstr = ((char *)
+		     backtrace_alloc (state, coff_symstr_len, error_callback,
+				      data));
+      if (coff_symstr == NULL)
+	{
+	  backtrace_free (state, coff_symbols, coff_symbol_size,
+			  error_callback, data);
+	  return 0;
+	}
+    }
+  else
+    coff_symstr = NULL;
+
+  /* Copy symbols.  */
+  coff_sym = coff_symbols;
+  coff_str = coff_symstr;
+  for (i = 0; i < syms_count; ++i)
+    {
+      const b_coff_external_symbol *asym = &syms[i];
+      b_coff_internal_symbol isym;
+
+      if (coff_expand_symbol (&isym, asym, sects_num, strtab, strtab_size))
+	{
+	  /* Should not fail, as it was already tested in the previous
+	     loop.  */
+	  abort ();
+	}
+      if (coff_is_function_symbol (&isym))
+	{
+	  const char *name;
+	  int16_t secnum;
+
+	  if (asym->name.short_name[0] != 0)
+	    {
+	      size_t len = coff_short_name_len (isym.name);
+	      name = coff_str;
+	      memcpy (coff_str, isym.name, len);
+	      coff_str[len] = 0;
+	      coff_str += len + 1;
+	    }
+	  else
+	    name = isym.name;
+
+	  /* Strip leading '_'.  */
+	  if (name[0] == '_')
+	    name++;
+
+	  /* Symbol value is section relative, so we need to read the address
+	     of its section.  */
+	  secnum = coff_read2 (asym->section_number);
+
+	  coff_sym->name = name;
+	  coff_sym->address = (coff_read4 (asym->value)
+			       + sects[secnum - 1].virtual_address
+			       + base_address);
+	  coff_sym++;
+	}
+
+      i += asym->number_of_aux_symbols;
+    }
+
+  /* End of symbols marker.  */
+  coff_sym->name = NULL;
+  coff_sym->address = -1;
+
+  backtrace_qsort (coff_symbols, coff_symbol_count,
+		   sizeof (struct coff_symbol), coff_symbol_compare);
+
+  sdata->next = NULL;
+  sdata->symbols = coff_symbols;
+  sdata->count = coff_symbol_count;
+
+  return 1;
+}
+
+/* Add EDATA to the list in STATE.  */
+
+static void
+coff_add_syminfo_data (struct backtrace_state *state,
+		       struct coff_syminfo_data *sdata)
+{
+  if (!state->threaded)
+    {
+      struct coff_syminfo_data **pp;
+
+      for (pp = (struct coff_syminfo_data **) (void *) &state->syminfo_data;
+	   *pp != NULL;
+	   pp = &(*pp)->next)
+	;
+      *pp = sdata;
+    }
+  else
+    {
+      while (1)
+	{
+	  struct coff_syminfo_data **pp;
+
+	  pp = (struct coff_syminfo_data **) (void *) &state->syminfo_data;
+
+	  while (1)
+	    {
+	      struct coff_syminfo_data *p;
+
+	      p = backtrace_atomic_load_pointer (pp);
+
+	      if (p == NULL)
+		break;
+
+	      pp = &p->next;
+	    }
+
+	  if (__sync_bool_compare_and_swap (pp, NULL, sdata))
+	    break;
+	}
+    }
+}
+
+/* Compare an ADDR against an elf_symbol for bsearch.  We allocate one
+   extra entry in the array so that this can look safely at the next
+   entry.  */
+
+static int
+coff_symbol_search (const void *vkey, const void *ventry)
+{
+  const uintptr_t *key = (const uintptr_t *) vkey;
+  const struct coff_symbol *entry = (const struct coff_symbol *) ventry;
+  uintptr_t addr;
+
+  addr = *key;
+  if (addr < entry->address)
+    return -1;
+  else if (addr >= entry[1].address)
+    return 1;
+  else
+    return 0;
+}
+
+/* Return the symbol name and value for an ADDR.  */
+
+static void
+coff_syminfo (struct backtrace_state *state, uintptr_t addr,
+	      backtrace_syminfo_callback callback,
+	      backtrace_error_callback error_callback ATTRIBUTE_UNUSED,
+	      void *data)
+{
+  struct coff_syminfo_data *sdata;
+  struct coff_symbol *sym = NULL;
+
+  if (!state->threaded)
+    {
+      for (sdata = (struct coff_syminfo_data *) state->syminfo_data;
+	   sdata != NULL;
+	   sdata = sdata->next)
+	{
+	  sym = ((struct coff_symbol *)
+		 bsearch (&addr, sdata->symbols, sdata->count,
+			  sizeof (struct coff_symbol), coff_symbol_search));
+	  if (sym != NULL)
+	    break;
+	}
+    }
+  else
+    {
+      struct coff_syminfo_data **pp;
+
+      pp = (struct coff_syminfo_data **) (void *) &state->syminfo_data;
+      while (1)
+	{
+	  sdata = backtrace_atomic_load_pointer (pp);
+	  if (sdata == NULL)
+	    break;
+
+	  sym = ((struct coff_symbol *)
+		 bsearch (&addr, sdata->symbols, sdata->count,
+			  sizeof (struct coff_symbol), coff_symbol_search));
+	  if (sym != NULL)
+	    break;
+
+	  pp = &sdata->next;
+	}
+    }
+
+  if (sym == NULL)
+    callback (data, addr, NULL, 0, 0);
+  else
+    callback (data, addr, sym->name, sym->address, 0);
+}
+
+/* Add the backtrace data for one PE/COFF file.  Returns 1 on success,
+   0 on failure (in both cases descriptor is closed).  */
+
+static int
+coff_add (struct backtrace_state *state, int descriptor,
+	  backtrace_error_callback error_callback, void *data,
+	  fileline *fileline_fn, int *found_sym, int *found_dwarf)
+{
+  struct backtrace_view fhdr_view;
+  off_t fhdr_off;
+  int magic_ok;
+  b_coff_file_header fhdr;
+  off_t opt_sects_off;
+  size_t opt_sects_size;
+  unsigned int sects_num;
+  struct backtrace_view sects_view;
+  int sects_view_valid;
+  const b_coff_optional_header *opt_hdr;
+  const b_coff_section_header *sects;
+  struct backtrace_view str_view;
+  int str_view_valid;
+  size_t str_size;
+  off_t str_off;
+  struct backtrace_view syms_view;
+  off_t syms_off;
+  size_t syms_size;
+  int syms_view_valid;
+  unsigned int syms_num;
+  unsigned int i;
+  struct debug_section_info sections[DEBUG_MAX];
+  off_t min_offset;
+  off_t max_offset;
+  struct backtrace_view debug_view;
+  int debug_view_valid;
+  uintptr_t image_base;
+
+  *found_sym = 0;
+  *found_dwarf = 0;
+
+  sects_view_valid = 0;
+  syms_view_valid = 0;
+  str_view_valid = 0;
+  debug_view_valid = 0;
+
+  /* Map the MS-DOS stub (if any) and extract file header offset.  */
+  if (!backtrace_get_view (state, descriptor, 0, 0x40, error_callback,
+			   data, &fhdr_view))
+    goto fail;
+
+  {
+    const char *vptr = (const char *)fhdr_view.data;
+
+    if (vptr[0] == 'M' && vptr[1] == 'Z')
+      memcpy (&fhdr_off, vptr + 0x3c, 4);
+    else
+      fhdr_off = 0;
+  }
+
+  backtrace_release_view (state, &fhdr_view, error_callback, data);
+
+  /* Map the coff file header.  */
+  if (!backtrace_get_view (state, descriptor, fhdr_off,
+			   sizeof (b_coff_file_header) + 4,
+			   error_callback, data, &fhdr_view))
+    goto fail;
+
+  if (fhdr_off != 0)
+    {
+      const char *magic = (const char *) fhdr_view.data;
+      magic_ok = memcmp (magic, "PE\0", 4) == 0;
+      fhdr_off += 4;
+
+      memcpy (&fhdr, fhdr_view.data + 4, sizeof fhdr);
+    }
+  else
+    {
+      memcpy (&fhdr, fhdr_view.data, sizeof fhdr);
+      /* TODO: test fhdr.machine for coff but non-PE platforms.  */
+      magic_ok = 0;
+    }
+  backtrace_release_view (state, &fhdr_view, error_callback, data);
+
+  if (!magic_ok)
+    {
+      error_callback (data, "executable file is not COFF", 0);
+      goto fail;
+    }
+
+  sects_num = fhdr.number_of_sections;
+  syms_num = fhdr.number_of_symbols;
+
+  opt_sects_off = fhdr_off + sizeof (fhdr);
+  opt_sects_size = (fhdr.size_of_optional_header
+		    + sects_num * sizeof (b_coff_section_header));
+
+  /* To translate PC to file/line when using DWARF, we need to find
+     the .debug_info and .debug_line sections.  */
+
+  /* Read the optional header and the section headers.  */
+
+  if (!backtrace_get_view (state, descriptor, opt_sects_off, opt_sects_size,
+			   error_callback, data, &sects_view))
+    goto fail;
+  sects_view_valid = 1;
+  opt_hdr = (const b_coff_optional_header *) sects_view.data;
+  sects = (const b_coff_section_header *)
+    (sects_view.data + fhdr.size_of_optional_header);
+
+  if (fhdr.size_of_optional_header > sizeof (*opt_hdr))
+    {
+      if (opt_hdr->magic == PE_MAGIC)
+	image_base = opt_hdr->u.pe.image_base;
+      else if (opt_hdr->magic == PEP_MAGIC)
+	image_base = opt_hdr->u.pep.image_base;
+      else
+	{
+	  error_callback (data, "bad magic in PE optional header", 0);
+	  goto fail;
+	}
+    }
+  else
+    image_base = 0;
+
+  /* Read the symbol table and the string table.  */
+
+  if (fhdr.pointer_to_symbol_table == 0)
+    {
+      /* No symbol table, no string table.  */
+      str_off = 0;
+      str_size = 0;
+      syms_num = 0;
+      syms_size = 0;
+    }
+  else
+    {
+      /* Symbol table is followed by the string table.  The string table
+	 starts with its length (on 4 bytes).
+	 Map the symbol table and the length of the string table.  */
+      syms_off = fhdr.pointer_to_symbol_table;
+      syms_size = syms_num * SYM_SZ;
+
+      if (!backtrace_get_view (state, descriptor, syms_off, syms_size + 4,
+			       error_callback, data, &syms_view))
+	goto fail;
+      syms_view_valid = 1;
+
+      memcpy (&str_size, syms_view.data + syms_size, 4);
+
+      str_off = syms_off + syms_size;
+
+      if (str_size > 4)
+	{
+	  /* Map string table (including the length word).  */
+
+	  if (!backtrace_get_view (state, descriptor, str_off, str_size,
+				   error_callback, data, &str_view))
+	    goto fail;
+	  str_view_valid = 1;
+	}
+    }
+
+  memset (sections, 0, sizeof sections);
+
+  /* Look for the symbol table.  */
+  for (i = 0; i < sects_num; ++i)
+    {
+      const b_coff_section_header *s = sects + i;
+      unsigned int str_off;
+      int j;
+
+      if (s->name[0] == '/')
+	{
+	  /* Extended section name.  */
+	  str_off = atoi (s->name + 1);
+	}
+      else
+	str_off = 0;
+
+      for (j = 0; j < (int) DEBUG_MAX; ++j)
+	{
+	  const char *dbg_name = debug_section_names[j];
+	  int match;
+
+	  if (str_off != 0)
+	    match = coff_long_name_eq (dbg_name, str_off, &str_view);
+	  else
+	    match = coff_short_name_eq (dbg_name, s->name);
+	  if (match)
+	    {
+	      sections[j].offset = s->pointer_to_raw_data;
+	      sections[j].size = s->virtual_size <= s->size_of_raw_data ?
+		s->virtual_size : s->size_of_raw_data;
+	      break;
+	    }
+	}
+    }
+
+  if (syms_num != 0)
+    {
+      struct coff_syminfo_data *sdata;
+
+      sdata = ((struct coff_syminfo_data *)
+	       backtrace_alloc (state, sizeof *sdata, error_callback, data));
+      if (sdata == NULL)
+	goto fail;
+
+      if (!coff_initialize_syminfo (state, image_base,
+				    sects, sects_num,
+				    syms_view.data, syms_size,
+				    str_view.data, str_size,
+				    error_callback, data, sdata))
+	{
+	  backtrace_free (state, sdata, sizeof *sdata, error_callback, data);
+	  goto fail;
+	}
+
+      *found_sym = 1;
+
+      coff_add_syminfo_data (state, sdata);
+    }
+
+  backtrace_release_view (state, &sects_view, error_callback, data);
+  sects_view_valid = 0;
+  backtrace_release_view (state, &syms_view, error_callback, data);
+  syms_view_valid = 0;
+
+  /* Read all the debug sections in a single view, since they are
+     probably adjacent in the file.  We never release this view.  */
+
+  min_offset = 0;
+  max_offset = 0;
+  for (i = 0; i < (int) DEBUG_MAX; ++i)
+    {
+      off_t end;
+
+      if (sections[i].size == 0)
+	continue;
+      if (min_offset == 0 || sections[i].offset < min_offset)
+	min_offset = sections[i].offset;
+      end = sections[i].offset + sections[i].size;
+      if (end > max_offset)
+	max_offset = end;
+    }
+  if (min_offset == 0 || max_offset == 0)
+    {
+      if (!backtrace_close (descriptor, error_callback, data))
+	goto fail;
+      *fileline_fn = coff_nodebug;
+      return 1;
+    }
+
+  if (!backtrace_get_view (state, descriptor, min_offset,
+			   max_offset - min_offset,
+			   error_callback, data, &debug_view))
+    goto fail;
+  debug_view_valid = 1;
+
+  /* We've read all we need from the executable.  */
+  if (!backtrace_close (descriptor, error_callback, data))
+    goto fail;
+  descriptor = -1;
+
+  for (i = 0; i < (int) DEBUG_MAX; ++i)
+    {
+      if (sections[i].size == 0)
+	sections[i].data = NULL;
+      else
+	sections[i].data = ((const unsigned char *) debug_view.data
+			    + (sections[i].offset - min_offset));
+    }
+
+  if (!backtrace_dwarf_add (state, /* base_address */ 0,
+			    sections[DEBUG_INFO].data,
+			    sections[DEBUG_INFO].size,
+			    sections[DEBUG_LINE].data,
+			    sections[DEBUG_LINE].size,
+			    sections[DEBUG_ABBREV].data,
+			    sections[DEBUG_ABBREV].size,
+			    sections[DEBUG_RANGES].data,
+			    sections[DEBUG_RANGES].size,
+			    sections[DEBUG_STR].data,
+			    sections[DEBUG_STR].size,
+			    0, /* FIXME */
+			    error_callback, data, fileline_fn))
+    goto fail;
+
+  *found_dwarf = 1;
+
+  return 1;
+
+ fail:
+  if (sects_view_valid)
+    backtrace_release_view (state, &sects_view, error_callback, data);
+  if (str_view_valid)
+    backtrace_release_view (state, &str_view, error_callback, data);
+  if (syms_view_valid)
+    backtrace_release_view (state, &syms_view, error_callback, data);
+  if (debug_view_valid)
+    backtrace_release_view (state, &debug_view, error_callback, data);
+  if (descriptor != -1)
+    backtrace_close (descriptor, error_callback, data);
+  return 0;
+}
+
+/* Initialize the backtrace data we need from an ELF executable.  At
+   the ELF level, all we need to do is find the debug info
+   sections.  */
+
+int
+backtrace_initialize (struct backtrace_state *state, int descriptor,
+		      backtrace_error_callback error_callback,
+		      void *data, fileline *fileline_fn)
+{
+  int ret;
+  int found_sym;
+  int found_dwarf;
+  fileline coff_fileline_fn;
+
+  ret = coff_add (state, descriptor, error_callback, data,
+		  &coff_fileline_fn, &found_sym, &found_dwarf);
+  if (!ret)
+    return 0;
+
+  if (!state->threaded)
+    {
+      if (found_sym)
+	state->syminfo_fn = coff_syminfo;
+      else if (state->syminfo_fn == NULL)
+	state->syminfo_fn = coff_nosyms;
+    }
+  else
+    {
+      if (found_sym)
+	backtrace_atomic_store_pointer (&state->syminfo_fn, coff_syminfo);
+      else
+	__sync_bool_compare_and_swap (&state->syminfo_fn, NULL, coff_nosyms);
+    }
+
+  if (!state->threaded)
+    {
+      if (state->fileline_fn == NULL || state->fileline_fn == coff_nodebug)
+	*fileline_fn = coff_fileline_fn;
+    }
+  else
+    {
+      fileline current_fn;
+
+      current_fn = backtrace_atomic_load_pointer (&state->fileline_fn);
+      if (current_fn == NULL || current_fn == coff_nodebug)
+	*fileline_fn = coff_fileline_fn;
+    }
+
+  return 1;
+}