Attachment 121762 Details for Bug 94136 – standalone C program to print struct layouts

standalone C program to print struct layouts

sizes.c (text/plain), 5.82 KB, created by Simon McVittie on 2016-02-15 12:44:41 UTC

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Creator: Simon McVittie

Created: 2016-02-15 12:44:41 UTC

Size: 5.82 KB

patch

obsolete

>#include <inttypes.h>
>#include <stdint.h>
>#include <stdio.h>
>
>typedef struct DBusMessage DBusMessage;
>typedef struct DBusMessageIter DBusMessageIter;
>typedef struct DBusString DBusString;
>typedef struct DBusMessageRealIter DBusMessageRealIter;
>typedef struct DBusTypeReaderClass DBusTypeReaderClass;
>typedef struct DBusTypeReader DBusTypeReader;
>typedef struct DBusTypeWriter DBusTypeWriter;
>typedef uint32_t dbus_uint32_t;
>#define CHANGED_STAMP_BITS 21
>
>/**
> * DBusMessageIter struct; contains no public fields. 
> */
>struct DBusMessageIter
>{ 
>  void *dummy1;         /**< Don't use this */
>  void *dummy2;         /**< Don't use this */
>  dbus_uint32_t dummy3; /**< Don't use this */
>  int dummy4;           /**< Don't use this */
>  int dummy5;           /**< Don't use this */
>  int dummy6;           /**< Don't use this */
>  int dummy7;           /**< Don't use this */
>  int dummy8;           /**< Don't use this */
>  int dummy9;           /**< Don't use this */
>  int dummy10;          /**< Don't use this */
>  int dummy11;          /**< Don't use this */
>  int pad1;             /**< Don't use this */
>  int pad2;             /**< Don't use this */
>  void *pad3;           /**< Don't use this */
>};
>
>struct DBusTypeReader
>{
>  union {
>      struct {
>        dbus_uint32_t byte_order : 8; /**< byte order of the block */
>
>        dbus_uint32_t finished : 1;   /**< marks we're at end iterator for cases
>                                 * where we don't have another way to tell
>                                 */
>        dbus_uint32_t array_len_offset : 3; /**< bytes back from start_pos that len ends */
>      } bitfields;
>      dbus_uint32_t space;
>  } bitfields;
>  const DBusString *type_str;   /**< string containing signature of block */
>  int type_pos;                 /**< current position in signature */
>  const DBusString *value_str;  /**< string containing values of block */
>  int value_pos;                /**< current position in values */
>
>  const DBusTypeReaderClass *klass; /**< the vtable for the reader */
>  union
>  {
>    struct {
>      int start_pos;                /**< for array readers, the start of the array values */
>    } array;
>  } u; /**< class-specific data */
>};
>
>/**
> * The type writer is an iterator for writing to a block of values.
> */
>struct DBusTypeWriter
>{
>  union {
>    struct {
>      dbus_uint32_t byte_order : 8;            /**< byte order to write values with */
>
>      dbus_uint32_t container_type : 8;        /**< what are we inside? (e.g. struct, variant, array) */
>
>      dbus_uint32_t type_pos_is_expectation : 1; /**< type_pos can be either an insertion point for or an expected next type */
>
>      dbus_uint32_t enabled : 1; /**< whether to write values */
>    } bitfields;
>    dbus_uint32_t space;
>  } bitfields;
>
>  DBusString *type_str; /**< where to write typecodes (or read type expectations) */
>  int type_pos;         /**< current pos in type_str */
>  DBusString *value_str; /**< where to write values */
>  int value_pos;         /**< next position to write */
>
>  union
>  {
>    struct {
>      int start_pos; /**< position of first element in the array */
>      int len_pos;   /**< position of length of the array */
>      int element_type_pos; /**< position of array element type in type_str */
>    } array;
>  } u; /**< class-specific data */
>};
>
>struct DBusMessageRealIter
>{
>  DBusMessage *message; /**< Message used */
>  union {
>      struct {
>        dbus_uint32_t changed_stamp : CHANGED_STAMP_BITS; /**< stamp to detect invalid iters */
>        dbus_uint32_t iter_type : 3;      /**< whether this is a reader or writer iter */
>        dbus_uint32_t sig_refcount : 8;   /**< depth of open_signature() */
>      } bitfields;
>      dbus_uint32_t space;
>  } bitfields;
>  union
>  {
>    DBusTypeWriter writer; /**< writer */
>    DBusTypeReader reader; /**< reader */
>  } u; /**< the type writer or reader that does all the work */
>};
>
>#define stringify(member)
>#define MEMBER(structure, member) \
>  printf ("%zu-%zu %s\n", __builtin_offsetof (structure, member), \
>      __builtin_offsetof (structure, member) + sizeof (((structure *) NULL)->member) - 1,\
>      #member)
>
>int
>main (void)
>{
>  printf ("placeholder:\n");
>  MEMBER (DBusMessageIter, dummy1);
>  MEMBER (DBusMessageIter, dummy2);
>  MEMBER (DBusMessageIter, dummy3);
>  MEMBER (DBusMessageIter, dummy4);
>  MEMBER (DBusMessageIter, dummy5);
>  MEMBER (DBusMessageIter, dummy6);
>  MEMBER (DBusMessageIter, dummy7);
>  MEMBER (DBusMessageIter, dummy8);
>  MEMBER (DBusMessageIter, dummy9);
>  MEMBER (DBusMessageIter, dummy10);
>  MEMBER (DBusMessageIter, dummy11);
>  MEMBER (DBusMessageIter, pad1);
>  MEMBER (DBusMessageIter, pad2);
>  MEMBER (DBusMessageIter, pad3);
>  printf ("size: %zu\n", sizeof (DBusMessageIter));
>  printf ("\n");
>
>  printf ("reader:\n");
>  MEMBER (DBusMessageRealIter, message);
>  MEMBER (DBusMessageRealIter, bitfields.space);
>  MEMBER (DBusMessageRealIter, u.reader.bitfields.space);
>  MEMBER (DBusMessageRealIter, u.reader.type_str);
>  MEMBER (DBusMessageRealIter, u.reader.type_pos);
>  MEMBER (DBusMessageRealIter, u.reader.value_str);
>  MEMBER (DBusMessageRealIter, u.reader.value_pos);
>  MEMBER (DBusMessageRealIter, u.reader.klass);
>  MEMBER (DBusMessageRealIter, u.reader.u.array.start_pos);
>  printf ("size: %zu\n", sizeof (DBusMessageRealIter));
>  printf ("\n");
>
>  printf ("writer:\n");
>  MEMBER (DBusMessageRealIter, message);
>  MEMBER (DBusMessageRealIter, bitfields.space);
>  MEMBER (DBusMessageRealIter, u.writer.bitfields.space);
>  MEMBER (DBusMessageRealIter, u.writer.type_str);
>  MEMBER (DBusMessageRealIter, u.writer.type_pos);
>  MEMBER (DBusMessageRealIter, u.writer.value_str);
>  MEMBER (DBusMessageRealIter, u.writer.value_pos);
>  MEMBER (DBusMessageRealIter, u.writer.u.array.start_pos);
>  MEMBER (DBusMessageRealIter, u.writer.u.array.len_pos);
>  MEMBER (DBusMessageRealIter, u.writer.u.array.element_type_pos);
>  printf ("size: %zu\n", sizeof (DBusMessageRealIter));
>  printf ("\n");
>
>  return 0;
>}

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Attachments on bug 94136: 121762 | 121768 | 121769 | 121770 | 121771

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