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/*
* Copyright 2020 Google LLC
*
* Use of this source code is governed by a BSD-style
* license that can be found in the LICENSE file or at
* https://developers.google.com/open-source/licenses/bsd
*/
#ifndef SYSTEM_H
#define SYSTEM_H
/* This header glues the reftable library to the rest of Git */
#define MINGW_DONT_HANDLE_IN_USE_ERROR
#include "compat/posix.h"
#include "compat/zlib-compat.h"
/*
* Return a random 32 bit integer. This function is expected to return
* pre-seeded data.
*/
uint32_t reftable_rand(void);
/*
* An implementation-specific temporary file. By making this specific to the
* implementation it becomes possible to tie temporary files into any kind of
* signal or atexit handlers for cleanup on abnormal situations.
*/
struct reftable_tmpfile {
const char *path;
int fd;
void *priv;
};
#define REFTABLE_TMPFILE_INIT ((struct reftable_tmpfile) { .fd = -1, })
/*
* Create a temporary file from a pattern similar to how mkstemp(3p) would.
* The `pattern` shall not be modified. On success, the structure at `out` has
* been initialized such that it is ready for use. Returns 0 on success, a
* reftable error code on error.
*/
int tmpfile_from_pattern(struct reftable_tmpfile *out, const char *pattern);
/*
* Close the temporary file's file descriptor without removing the file itself.
* This is a no-op in case the file has already been closed beforehand. Returns
* 0 on success, a reftable error code on error.
*/
int tmpfile_close(struct reftable_tmpfile *t);
/*
* Close the temporary file and delete it. This is a no-op in case the file has
* already been deleted or renamed beforehand. Returns 0 on success, a reftable
* error code on error.
*/
int tmpfile_delete(struct reftable_tmpfile *t);
/*
* Rename the temporary file to the provided path. The temporary file must be
* active. Return 0 on success, a reftable error code on error. Deactivates the
* temporary file.
*/
int tmpfile_rename(struct reftable_tmpfile *t, const char *path);
/*
* An implementation-specific file lock. Same as with `reftable_tmpfile`,
* making this specific to the implementation makes it possible to tie this
* into signal or atexit handlers such that we know to clean up stale locks on
* abnormal exits.
*/
struct reftable_flock {
const char *path;
int fd;
void *priv;
};
#define REFTABLE_FLOCK_INIT ((struct reftable_flock){ .fd = -1, })
/*
* Acquire the lock for the given target path by exclusively creating a file
* with ".lock" appended to it. If that lock exists, we wait up to `timeout_ms`
* to acquire the lock. If `timeout_ms` is 0 we don't wait, if it is negative
* we block indefinitely.
*
* Retrun 0 on success, a reftable error code on error.
*/
int flock_acquire(struct reftable_flock *l, const char *target_path,
long timeout_ms);
/*
* Close the lockfile's file descriptor without removing the lock itself. This
* is a no-op in case the lockfile has already been closed beforehand. Returns
* 0 on success, a reftable error code on error.
*/
int flock_close(struct reftable_flock *l);
/*
* Release the lock by unlinking the lockfile. This is a no-op in case the
* lockfile has already been released or committed beforehand. Returns 0 on
* success, a reftable error code on error.
*/
int flock_release(struct reftable_flock *l);
/*
* Commit the lock by renaming the lockfile into place. Returns 0 on success, a
* reftable error code on error.
*/
int flock_commit(struct reftable_flock *l);
#endif
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