svn_error.h

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/**
 * @copyright
 * ====================================================================
 * Copyright (c) 2000-2004 CollabNet.  All rights reserved.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution.  The terms
 * are also available at http://subversion.tigris.org/license-1.html.
 * If newer versions of this license are posted there, you may use a
 * newer version instead, at your option.
 *
 * This software consists of voluntary contributions made by many
 * individuals.  For exact contribution history, see the revision
 * history and logs, available at http://subversion.tigris.org/.
 * ====================================================================
 * @endcopyright
 *
 * @file svn_error.h
 * @brief Common exception handling for Subversion.
 */




#ifndef SVN_ERROR_H
#define SVN_ERROR_H

#include <apr.h>
#include <apr_errno.h>     /* APR's error system */
#include <apr_pools.h>

#ifndef DOXYGEN_SHOULD_SKIP_THIS
#define APR_WANT_STDIO
#endif
#include <apr_want.h>

#include "svn_types.h"

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/** the best kind of (@c svn_error_t *) ! */
#define SVN_NO_ERROR   0

/* The actual error codes are kept in a separate file; see comments
   there for the reasons why. */
#include "svn_error_codes.h"

/** Set the error location for debug mode. */
void svn_error__locate (const char *file, long line);


/** Put an English description of @a statcode into @a buf and return @a buf,
 * null-terminated, @a statcode is either an svn error or apr error.
 */
char *svn_strerror (apr_status_t statcode, char *buf, apr_size_t bufsize);



/** SVN error creation and destruction. 
 *
 * @defgroup svn_error_error_creation_destroy error creation and destruction
 * @{
 */

/** Create a nested exception structure.
 *
 * Input:  an APR or SVN custom error code,
 *         a "child" error to wrap,
 *         a specific message
 *
 * Returns:  a new error structure (containing the old one).
 *
 * Notes: Errors are always allocated in a subpool of the global pool,
 *        since an error's lifetime is generally not related to the
 *        lifetime of any convenient pool.  Errors must be freed
 *        with @c svn_error_clear().  The specific message should be NULL
 *        if there is nothing to add to the general message associated
 *        with the error code.
 *
 *        If creating the "bottommost" error in a chain, pass @c NULL for
 *        the child argument.
 */
svn_error_t *svn_error_create (apr_status_t apr_err,
                               svn_error_t *child,
                               const char *message);

/** Wrapper macro to collect file and line information */
#define svn_error_create \
  (svn_error__locate(__FILE__,__LINE__), (svn_error_create))

/** Create an error structure with the given @a apr_err and @a child,
 * with a printf-style error message produced by passing @a fmt, using
 * @c apr_psprintf.
 */
svn_error_t *svn_error_createf (apr_status_t apr_err,
                                svn_error_t *child,
                                const char *fmt, 
                                ...)
       __attribute__ ((format (printf, 3, 4)));

/** Wrapper macro to collect file and line information */
#define svn_error_createf \
  (svn_error__locate(__FILE__,__LINE__), (svn_error_createf))

/** Wrap a status from an APR function.  If @a fmt is NULL, this is
 * equivalent to @c svn_error_create(status, NULL, NULL).  Otherwise,
 * the error message is constructed by formatting @a fmt and the
 * following arguments according to @c apr_psprintf, and then
 * appending ": " and the error message corresponding to @a status.
 * (If UTF-8 translation of the APR error message fails, the ": " and
 * APR error are not appended to the error message.)
 */
svn_error_t *svn_error_wrap_apr (apr_status_t status, const char *fmt, ...);

/** Wrapper macro to collect file and line information */
#define svn_error_wrap_apr \
  (svn_error__locate(__FILE__,__LINE__), (svn_error_wrap_apr))

/** A quick n' easy way to create a wrappered exception with your own
 * message, before throwing it up the stack.  (It uses all of the
 * child's fields.)
 */
svn_error_t *svn_error_quick_wrap (svn_error_t *child, const char *new_msg);

/** Wrapper macro to collect file and line information */
#define svn_error_quick_wrap \
  (svn_error__locate(__FILE__,__LINE__), (svn_error_quick_wrap))

/** Add @a new_err to the end of @a chain's chain of errors.  The @a new_err 
 * chain will be copied into @a chain's pool and destroyed, so @a new_err 
 * itself becomes invalid after this function.
 */
void svn_error_compose (svn_error_t *chain, svn_error_t *new_err);


/** Free the memory used by @a error, as well as all ancestors and
 * descendants of @a error. 
 *
 * Unlike other Subversion objects, errors are managed explicitly; you 
 * MUST clear an error if you are ignoring it, or you are leaking memory. 
 * For convenience, @a error may be @c NULL, in which case this function does 
 * nothing; thus, @c svn_error_clear(svn_foo(...)) works as an idiom to 
 * ignore errors.
 */
void svn_error_clear (svn_error_t *error);


/** Very basic default error handler: print out error stack, and quit
 * iff the @a fatal flag is set.
 */
void svn_handle_error (svn_error_t *error,
                       FILE *stream,
                       svn_boolean_t fatal);

/** Basic, default warning handler.
 *
 * Just prints @a error to the stdio stream given in @a stream. Allocations
 * are performed in the error's pool.
 */
void svn_handle_warning (FILE *stream, svn_error_t *error);


/** A statement macro for checking error return values.
 *
 * Evaluate @a expr.  If it yields an error, return that error from the
 * current function.  Otherwise, continue.
 *
 * The <tt>do { ... } while (0)</tt> wrapper has no semantic effect, 
 * but it makes this macro syntactically equivalent to the expression
 * statement it resembles.  Without it, statements like
 *
 * <tt>
 *   if (a)
 *     SVN_ERR (some operation);
 *   else
 *     foo;
 * </tt>
 *
 * would not mean what they appear to.
 */
#define SVN_ERR(expr)                           \
  do {                                          \
    svn_error_t *svn_err__temp = (expr);        \
    if (svn_err__temp)                          \
      return svn_err__temp;                     \
  } while (0)


/** A statement macro, very similar to @c SVN_ERR.
 *
 * This macro will wrap the error with the specified text before 
 * returning the error.
 */
#define SVN_ERR_W(expr, wrap_msg)                           \
  do {                                                      \
    svn_error_t *svn_err__temp = (expr);                    \
    if (svn_err__temp)                                      \
      return svn_error_quick_wrap(svn_err__temp, wrap_msg); \
  } while (0)


/** A statement macro, similar to @c SVN_ERR, but returns an integer.
 *
 * Evaluate @a expr. If it yields an error, handle that error and
 * return @c EXIT_FAILURE.
 */
#define SVN_INT_ERR(expr)                                   \
  do {                                                      \
    svn_error_t *svn_err__temp = (expr);                    \
    if (svn_err__temp) {                                    \
      svn_handle_error (svn_err__temp, stderr, FALSE);      \
      svn_error_clear (svn_err__temp);                      \
      return EXIT_FAILURE; }                                \
  } while (0)

/** @} */

#ifdef __cplusplus
}
#endif /* __cplusplus */

#endif /* SVN_ERROR_H */