incubator-nuttx/include/nuttx/envpath.h

145 lines
5.3 KiB
C

/****************************************************************************
* include/nuttx/envpath.h
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
#ifndef __INCLUDE_NUTTX_ENVPATH_H
#define __INCLUDE_NUTTX_ENVPATH_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#ifdef CONFIG_LIB_ENVPATH
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Types
****************************************************************************/
/* ENVPATH_HANDLE is an opaque handle used to traverse the absolute paths
* assigned to the PATH environment variable.
*/
typedef FAR void *ENVPATH_HANDLE;
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
#ifdef __cplusplus
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif
/****************************************************************************
* Name: envpath_init
*
* Description:
* Initialize for the traversal of each value in the PATH variable. The
* usage is sequence is as follows:
*
* Input Parameters:
* name - The variable name of environment to searches path list.
*
* 1) Call envpath_init() to initialize for the traversal. envpath_init()
* will return an opaque handle that can then be provided to
* envpath_next() and envpath_release().
* 2) Call envpath_next() repeatedly to examine every file that lies
* in the directories of the PATH variable
* 3) Call envpath_release() to free resources set aside by envpath_init().
*
* Input Parameters:
* None
*
* Returned Value:
* On success, envpath_init() return a non-NULL, opaque handle that may
* subsequently be used in calls to envpath_next() and envpath_release().
* On error, a NULL handle value will be returned. The most likely cause
* of an error would be that there is no value associated with the PATH
* variable.
*
****************************************************************************/
ENVPATH_HANDLE envpath_init(FAR const char *name);
/****************************************************************************
* Name: envpath_next
*
* Description:
* Traverse all possible values in the PATH variable in attempt to find
* the full path to an executable file when only a relative path is
* provided.
*
* Input Parameters:
* handle - The handle value returned by envpath_init
* relpath - The relative path to the file to be found.
*
* Returned Value:
* On success, a non-NULL pointer to a null-terminated string is provided.
* This is the full path to a file that exists in the file system. This
* function will verify that the file exists (but will not verify that it
* is marked executable).
*
* NOTE: The string pointer return in the success case points to allocated
* memory. This memory must be freed by the called by calling kmm_free().
*
* NULL is returned if no path is found to any file with the provided
* 'relpath' from any absolute path in the PATH variable. In this case,
* there is no point in calling envpath_next() further; envpath_release()
* must be called to release resources set aside by expath_init().
*
****************************************************************************/
FAR char *envpath_next(ENVPATH_HANDLE handle, FAR const char *relpath);
/****************************************************************************
* Name: envpath_release
*
* Description:
* Release all resources set aside by envpath_init() when the handle value
* was created. The handle value is invalid on return from this function.
* Attempts to all envpath_next() or envpath_release() with such a 'stale'
* handle will result in undefined (i.e., not good) behavior.
*
* Input Parameters:
* handle - The handle value returned by envpath_init
*
* Returned Value:
* None
*
****************************************************************************/
void envpath_release(ENVPATH_HANDLE handle);
#undef EXTERN
#ifdef __cplusplus
}
#endif
#endif /* CONFIG_LIB_ENVPATH */
#endif /* INCLUDE_NUTTX_ENVPATH_H */