// pecoff.c:
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>


#ifdef HAVE_WINDOWS_H
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif

#ifndef NOMINMAX
#define NOMINMAX
#endif

#include <windows.h>

#ifdef HAVE_TLHELP32_H
#include <tlhelp32.h>

#ifdef UNICODE
/* If UNICODE is defined, all the symbols are replaced by a macro to use the
   wide variant. But we need the ansi variant, so undef the macros. */
#undef MODULEENTRY32
#undef Module32First
#undef Module32Next
#endif
#endif

#if defined(_ARM_)
#define NTAPI
#else
#define NTAPI __stdcall
#endif

/* This is a simplified (but binary compatible) version of what Microsoft
   defines in their documentation. */
struct dll_notification_data
{
  ULONG reserved;
  /* The name as UNICODE_STRING struct. */
  PVOID full_dll_name;
  PVOID base_dll_name;
  PVOID dll_base;
  ULONG size_of_image;
};

#define LDR_DLL_NOTIFICATION_REASON_LOADED 1

typedef LONG NTSTATUS;
typedef VOID (CALLBACK *LDR_DLL_NOTIFICATION)(ULONG,
                          struct dll_notification_data*,
                          PVOID);
typedef NTSTATUS (NTAPI *LDR_REGISTER_FUNCTION)(ULONG,
                        LDR_DLL_NOTIFICATION, PVOID,
                        PVOID*);
#endif

/* 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;

/* Names of sections, indexed by enum dwarf_section in internal.h.  */

static const char * const debug_section_names[DEBUG_MAX] =
{
  ".debug_info",
  ".debug_line",
  ".debug_abbrev",
  ".debug_ranges",
  ".debug_str",
  ".debug_addr",
  ".debug_str_offsets",
  ".debug_line_str",
  ".debug_rnglists"
};

/* Information we gather for the sections we care about.  */

struct debug_section_info
{
  /* Section file offset.  */
  off_t offset;
  /* Section size.  */
  size_t size;
};

/* 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 (make sure to compile with -g)", -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,
             struct libbacktrace_base_address base_address,
             int is_64, 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;

      if (!is_64)
        {
          /* 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 =
        libbacktrace_add_base ((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,
      uintptr_t module_handle ATTRIBUTE_UNUSED)
{
  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;
  int is_64;
  struct libbacktrace_base_address image_base;
  struct libbacktrace_base_address base_address;
  struct dwarf_sections dwarf_sections;

  *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 unsigned char *vptr = fhdr_view.data;

    if (vptr[0] == 'M' && vptr[1] == 'Z')
      fhdr_off = coff_read4 (vptr + 0x3c);
    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, (const unsigned char *) 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, §s_view))
    goto fail;
  sects_view_valid = 1;
  opt_hdr = (const b_coff_optional_header *) sects_view.data;
  sects = (const b_coff_section_header *)
    ((const unsigned char *) sects_view.data + fhdr.size_of_optional_header);

  is_64 = 0;
  memset (&image_base, 0, sizeof image_base);
  if (fhdr.size_of_optional_header > sizeof (*opt_hdr))
    {
      if (opt_hdr->magic == PE_MAGIC)
    image_base.m = opt_hdr->u.pe.image_base;
      else if (opt_hdr->magic == PEP_MAGIC)
    {
      image_base.m = opt_hdr->u.pep.image_base;
      is_64 = 1;
    }
      else
    {
      error_callback (data, "bad magic in PE optional header", 0);
      goto fail;
    }
    }

  /* 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;

      str_size = coff_read4 ((const unsigned char *) syms_view.data
                 + syms_size);

      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, is_64,
                    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, §s_view, error_callback, data);
  sects_view_valid = 0;
  if (syms_view_valid)
    {
      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)
    {
      size_t size = sections[i].size;
      dwarf_sections.size[i] = size;
      if (size == 0)
    dwarf_sections.data[i] = NULL;
      else
    dwarf_sections.data[i] = ((const unsigned char *) debug_view.data
                  + (sections[i].offset - min_offset));
    }

  memset (&base_address, 0, sizeof base_address);
#ifdef HAVE_WINDOWS_H
  base_address.m = module_handle - image_base.m;
#endif

  if (!backtrace_dwarf_add (state, base_address, &dwarf_sections,
                0, /* FIXME: is_bigendian */
                NULL, /* altlink */
                error_callback, data, fileline_fn,
                NULL /* returned fileline_entry */))
    goto fail;

  *found_dwarf = 1;

  return 1;

 fail:
  if (sects_view_valid)
    backtrace_release_view (state, §s_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;
}

#ifdef HAVE_WINDOWS_H
struct dll_notification_context
{
  struct backtrace_state *state;
  backtrace_error_callback error_callback;
  void *data;
};

static VOID CALLBACK
dll_notification (ULONG reason,
          struct dll_notification_data *notification_data,
          PVOID context)
{
  char module_name[MAX_PATH];
  int descriptor;
  struct dll_notification_context* dll_context =
    (struct dll_notification_context*) context;
  struct backtrace_state *state = dll_context->state;
  void *data = dll_context->data;
  backtrace_error_callback error_callback = dll_context->data;
  fileline fileline;
  int found_sym;
  int found_dwarf;
  HMODULE module_handle;

  if (reason != LDR_DLL_NOTIFICATION_REASON_LOADED)
    return;

  if (!GetModuleHandleExW ((GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS
                | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT),
               (wchar_t*) notification_data->dll_base,
               &module_handle))
    return;

  if (!GetModuleFileNameA ((HMODULE) module_handle, module_name, MAX_PATH - 1))
    return;

  descriptor = backtrace_open (module_name, error_callback, data, NULL);

  if (descriptor < 0)
    return;

  coff_add (state, descriptor, error_callback, data, &fileline, &found_sym,
        &found_dwarf, (uintptr_t) module_handle);
}
#endif /* defined(HAVE_WINDOWS_H) */

/* 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,
              const char *filename ATTRIBUTE_UNUSED, int descriptor,
              backtrace_error_callback error_callback,
              void *data, fileline *fileline_fn)
{
  int ret;
  int found_sym;
  int found_dwarf;
  fileline coff_fileline_fn;
  uintptr_t module_handle = 0;
#ifdef HAVE_TLHELP32_H
  fileline module_fileline_fn;
  int module_found_sym;
  HANDLE snapshot;
#endif

#ifdef HAVE_WINDOWS_H
  HMODULE nt_dll_handle;

  module_handle = (uintptr_t) GetModuleHandle (NULL);
#endif

  ret = coff_add (state, descriptor, error_callback, data,
          &coff_fileline_fn, &found_sym, &found_dwarf, module_handle);
  if (!ret)
    return 0;

#ifdef HAVE_TLHELP32_H
  do
    {
      snapshot = CreateToolhelp32Snapshot (TH32CS_SNAPMODULE, 0);
    }
  while (snapshot == INVALID_HANDLE_VALUE
     && GetLastError () == ERROR_BAD_LENGTH);

  if (snapshot != INVALID_HANDLE_VALUE)
    {
      MODULEENTRY32 entry;
      BOOL ok;
      entry.dwSize = sizeof (MODULEENTRY32);

      for (ok = Module32First (snapshot, &entry); ok; ok = Module32Next (snapshot, &entry))
    {
      if (strcmp (filename, entry.szExePath) == 0)
        continue;

      module_handle = (uintptr_t) entry.hModule;
      if (module_handle == 0)
        continue;

      descriptor = backtrace_open (entry.szExePath, error_callback, data,
                       NULL);
      if (descriptor < 0)
        continue;

      coff_add (state, descriptor, error_callback, data,
            &module_fileline_fn, &module_found_sym, &found_dwarf,
            module_handle);
      if (module_found_sym)
        found_sym = 1;
    }

      CloseHandle (snapshot);
    }
#endif

#ifdef HAVE_WINDOWS_H
  nt_dll_handle = GetModuleHandleW (L"ntdll.dll");
  if (nt_dll_handle)
    {
      LDR_REGISTER_FUNCTION register_func;
      const char register_name[] = "LdrRegisterDllNotification";
      register_func = (void*) GetProcAddress (nt_dll_handle,
                          register_name);

      if (register_func)
    {
      PVOID cookie;
      struct dll_notification_context *context
        = backtrace_alloc (state,
                   sizeof (struct dll_notification_context),
                   error_callback, data);

      if (context)
        {
          context->state = state;
          context->data = data;
          context->error_callback = error_callback;

          register_func (0, &dll_notification, context, &cookie);
        }
    }
    }
#endif /* defined(HAVE_WINDOWS_H) */

  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
    (void) __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;
}
// read.c:
#include <errno.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>


/* This file implements file views when mmap is not available.  */

/* Create a view of SIZE bytes from DESCRIPTOR at OFFSET.  */

int
backtrace_get_view (struct backtrace_state *state, int descriptor,
            off_t offset, uint64_t size,
            backtrace_error_callback error_callback,
            void *data, struct backtrace_view *view)
{
  uint64_t got;
  ssize_t r;

  if ((uint64_t) (size_t) size != size)
    {
      error_callback (data, "file size too large", 0);
      return 0;
    }

  if (lseek (descriptor, offset, SEEK_SET) < 0)
    {
      error_callback (data, "lseek", errno);
      return 0;
    }

  view->base = backtrace_alloc (state, size, error_callback, data);
  if (view->base == NULL)
    return 0;
  view->data = view->base;
  view->len = size;

  got = 0;
  while (got < size)
    {
      r = read (descriptor, view->base, size - got);
      if (r < 0)
    {
      error_callback (data, "read", errno);
      free (view->base);
      return 0;
    }
      if (r == 0)
    break;
      got += (uint64_t) r;
    }

  if (got < size)
    {
      error_callback (data, "file too short", 0);
      free (view->base);
      return 0;
    }

  return 1;
}

/* Release a view read by backtrace_get_view.  */

void
backtrace_release_view (struct backtrace_state *state,
            struct backtrace_view *view,
            backtrace_error_callback error_callback,
            void *data)
{
  backtrace_free (state, view->base, view->len, error_callback, data);
  view->data = NULL;
  view->base = NULL;
}
// alloc.c:
#include <errno.h>
#include <stdlib.h>
#include <sys/types.h>


/* Allocation routines to use on systems that do not support anonymous
   mmap.  This implementation just uses malloc, which means that the
   backtrace functions may not be safely invoked from a signal
   handler.  */

/* Allocate memory like malloc.  If ERROR_CALLBACK is NULL, don't
   report an error.  */

void *
backtrace_alloc (struct backtrace_state *state ATTRIBUTE_UNUSED,
         size_t size, backtrace_error_callback error_callback,
         void *data)
{
  void *ret;

  ret = malloc (size);
  if (ret == NULL)
    {
      if (error_callback)
    error_callback (data, "malloc", errno);
    }
  return ret;
}

/* Free memory.  */

void
backtrace_free (struct backtrace_state *state ATTRIBUTE_UNUSED,
        void *p, size_t size ATTRIBUTE_UNUSED,
        backtrace_error_callback error_callback ATTRIBUTE_UNUSED,
        void *data ATTRIBUTE_UNUSED)
{
  free (p);
}

/* Grow VEC by SIZE bytes.  */

void *
backtrace_vector_grow (struct backtrace_state *state ATTRIBUTE_UNUSED,
               size_t size, backtrace_error_callback error_callback,
               void *data, struct backtrace_vector *vec)
{
  void *ret;

  if (size > vec->alc)
    {
      size_t alc;
      void *base;

      if (vec->size == 0)
    alc = 32 * size;
      else if (vec->size >= 4096)
    alc = vec->size + 4096;
      else
    alc = 2 * vec->size;

      if (alc < vec->size + size)
    alc = vec->size + size;

      base = realloc (vec->base, alc);
      if (base == NULL)
    {
      error_callback (data, "realloc", errno);
      return NULL;
    }

      vec->base = base;
      vec->alc = alc - vec->size;
    }

  ret = (char *) vec->base + vec->size;
  vec->size += size;
  vec->alc -= size;
  return ret;
}

/* Finish the current allocation on VEC.  */

void *
backtrace_vector_finish (struct backtrace_state *state,
             struct backtrace_vector *vec,
             backtrace_error_callback error_callback,
             void *data)
{
  void *ret;

  /* With this allocator we call realloc in backtrace_vector_grow,
     which means we can't easily reuse the memory here.  So just
     release it.  */
  if (!backtrace_vector_release (state, vec, error_callback, data))
    return NULL;
  ret = vec->base;
  vec->base = NULL;
  vec->size = 0;
  vec->alc = 0;
  return ret;
}

/* Release any extra space allocated for VEC.  */

int
backtrace_vector_release (struct backtrace_state *state ATTRIBUTE_UNUSED,
              struct backtrace_vector *vec,
              backtrace_error_callback error_callback,
              void *data)
{
  vec->alc = 0;

  if (vec->size == 0)
    {
      /* As of C17, realloc with size 0 is marked as an obsolescent feature, use
     free instead.  */
      free (vec->base);
      vec->base = NULL;
      return 1;
    }

  vec->base = realloc (vec->base, vec->size);
  if (vec->base == NULL)
    {
      error_callback (data, "realloc", errno);
      return 0;
    }

  return 1;
}