zdir_patch(3)
=============

NAME
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zdir_patch - work with directory patches

SYNOPSIS
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//  This is a stable class, and may not change except for emergencies. It
//  is provided in stable builds.
// 
typedef enum {
    ZDIR_PATCH_CREATE = 1,                                  //  
    ZDIR_PATCH_DELETE = 2                                   //  
} zdir_patch_op_t;

//  Create new patch
CZMQ_EXPORT zdir_patch_t *
    zdir_patch_new (const char *path, zfile_t *file, zdir_patch_op_t op, const char *alias);

//  Destroy a patch
CZMQ_EXPORT void
    zdir_patch_destroy (zdir_patch_t **self_p);

//  Create copy of a patch. If the patch is null, or memory was exhausted,
//  returns null.                                                         
//  Caller owns return value and must destroy it when done.
CZMQ_EXPORT zdir_patch_t *
    zdir_patch_dup (zdir_patch_t *self);

//  Return patch file directory path
CZMQ_EXPORT const char *
    zdir_patch_path (zdir_patch_t *self);

//  Return patch file item
CZMQ_EXPORT zfile_t *
    zdir_patch_file (zdir_patch_t *self);

//  Return operation
CZMQ_EXPORT zdir_patch_op_t
    zdir_patch_op (zdir_patch_t *self);

//  Return patch virtual file path
CZMQ_EXPORT const char *
    zdir_patch_vpath (zdir_patch_t *self);

//  Calculate hash digest for file (create only)
CZMQ_EXPORT void
    zdir_patch_digest_set (zdir_patch_t *self);

//  Return hash digest for patch file
CZMQ_EXPORT const char *
    zdir_patch_digest (zdir_patch_t *self);

//  Self test of this class.
CZMQ_EXPORT void
    zdir_patch_test (bool verbose);

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DESCRIPTION
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The zdir_patch class works with one patch, which says "create this
file" or "delete this file" (referring to a zfile item each time).

Please add @discuss section in ../src/zdir_patch.c.

EXAMPLE
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.From zdir_patch_test method
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zfile_t *file = zfile_new (".", "bilbo");
assert (file);
zdir_patch_t *patch = zdir_patch_new (".", file, patch_create, "/");
assert (patch);
zfile_destroy (&file);

file = zdir_patch_file (patch);
assert (file);
assert (streq (zfile_filename (file, "."), "bilbo"));
assert (streq (zdir_patch_vpath (patch), "/bilbo"));
zdir_patch_destroy (&patch);
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