nuttx/libs/libc/unistd/lib_getcwd.c

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/****************************************************************************
* libs/libc/unistd/lib_getcwd.c
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include "libc.h"
#ifndef CONFIG_DISABLE_ENVIRON
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: getwcd
*
* Description:
* getcwd() function places the absolute pathname of the current working
* directory in the array pointed to by 'buf', and returns 'buf.' The
* pathname copied to the array shall contain no components that are
* symbolic links. The 'size' argument is the size in bytes of the
* character array pointed to by the 'buf' argument.
*
* As an extension to the POSIX.1-2001 standard, getcwd() allocates
* the buffer dynamically using lib_malloc if buf is NULL. In this case,
* the allocated buffer has the length size unless size is zero, when buf
* is allocated as big as necessary. The caller should free the
* returned buffer.
*
* Input Parameters:
* buf - a pointer to the location in which the current working directory
* pathname is returned.
* size - The size in bytes available at 'buf'
*
* Returned Value:
* Upon successful completion, getcwd() returns the 'buf' argument.
* Otherwise, getcwd() returns a null pointer and sets errno to indicate
* the error:
*
* EINVAL
* The 'size' argument is 0 and the 'buf' argument is not NULL.
* ERANGE
* The size argument is greater than 0, but is smaller than the length
* of the current working directory pathname +1.
* EACCES
* Read or search permission was denied for a component of the pathname.
* ENOMEM
* Insufficient storage space is available.
*
****************************************************************************/
FAR char *getcwd(FAR char *buf, size_t size)
{
char *pwd;
/* Verify input parameters */
if (buf && size == 0)
{
set_errno(EINVAL);
return NULL;
}
if (size == 0)
{
size = PATH_MAX + 1;
}
/* If no working directory is defined, then default to the home directory */
pwd = getenv("PWD");
if (pwd == NULL)
{
pwd = CONFIG_LIB_HOMEDIR;
}
/* Verify that the cwd will fit into the user-provided buffer */
if (strlen(pwd) + 1 > size)
{
set_errno(ERANGE);
return NULL;
}
if (buf == NULL)
{
buf = lib_malloc(size);
if (!buf)
{
set_errno(ENOMEM);
return NULL;
}
}
/* Copy the cwd to the user buffer */
strcpy(buf, pwd);
return buf;
}
#endif /* !CONFIG_DISABLE_ENVIRON */