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nuttx-apps/fsutils/passwd/passwd_delete.c

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/****************************************************************************
* apps/fsutils/passwd/passwd_delete.c
*
* Copyright (C) 2016 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <errno.h>
#include "passwd.h"
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: passwd_copyfile
*
* Description:
* Copy copysize from instream to outstream (or until an error or EOF is
* encountered)
*
* Input Parameters:
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is returned on
* failure.
*
****************************************************************************/
static int passwd_copyfile(FAR char *iobuffer, FILE *instream,
FILE *outstream, size_t copysize)
{
FAR char *buffer;
ssize_t nxfrd;
size_t nwritten;
size_t nread;
size_t nbytes;
size_t gulpsize;
size_t ncopied;
size_t remaining;
bool eof;
/* Copy 'offset' bytes from the instream to the outstream */
for (ncopied = 0, remaining = copysize, eof = false;
ncopied < copysize && !eof;
ncopied += nwritten)
{
/* How big of a gulp can we take on this pass through the loop */
gulpsize = remaining;
if (gulpsize > CONFIG_FSUTILS_PASSWD_IOBUFFER_SIZE)
{
gulpsize = CONFIG_FSUTILS_PASSWD_IOBUFFER_SIZE;
}
/* Read a buffer of data from the instream */
buffer = iobuffer;
nbytes = gulpsize;
nread = 0;
do
{
nxfrd = fread(buffer, 1, nbytes, instream);
if (nxfrd == 0)
{
/* Zero is returned on either a read error or end-of-file */
if (ferror(instream))
{
/* Read error */
int errcode = errno;
DEBUGASSERT(errcode > 0);
if (errcode != EINTR)
{
return -errcode;
}
}
else
{
/* End of file encountered.
*
* This occurs normally when copying to the end-of-the file.
* In that case, the caller just sticks a huge number in for
* copysize and lets the end-of-file indication terminate the
* copy.
*/
eof = true;
/* Was anything buffered on this pass? */
if (nread == 0)
{
/* No.. then we can just return success now */
return OK;
}
}
}
else
{
DEBUGASSERT(nxfrd > 0);
/* Update counters and pointers for successful read */
nread += nxfrd;
buffer += nxfrd;
nbytes -= nxfrd;
}
}
while (nread < gulpsize && !eof);
/* Write the buffer of data to outstream */
buffer = iobuffer;
nbytes = nread;
nwritten = 0;
do
{
nxfrd = fwrite(buffer, 1, nbytes, outstream);
if (nxfrd == 0)
{
/* Write error */
int errcode = errno;
DEBUGASSERT(errcode > 0);
if (errcode != EINTR)
{
return -errcode;
}
}
else
{
DEBUGASSERT(nxfrd > 0);
/* Update counters and pointers for successful write */
nwritten += nxfrd;
buffer += nxfrd;
nbytes -= nxfrd;
}
}
while (nwritten < nread);
remaining -= nwritten;
}
return OK;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: passwd_delete
*
* Description:
* Delete on record from the password file at offset.
*
* Input Parameters:
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is returned on
* failure.
*
****************************************************************************/
int passwd_delete(off_t offset)
{
FAR char *iobuffer;
FILE *instream;
FILE *outstream;
int ret;
/* Allocate an I/O buffer for the transfer */
iobuffer = (FAR char *)malloc(CONFIG_FSUTILS_PASSWD_IOBUFFER_SIZE);
if (iobuffer == NULL)
{
return -ENOMEM;
}
/* Rename the /set/password file */
ret = rename(CONFIG_FSUTILS_PASSWD_PATH,
CONFIG_FSUTILS_PASSWD_PATH ".tmp");
if (ret < 0)
{
ret = -errno;
DEBUGASSERT(ret < 0);
goto errout_with_iobuffer;
}
/* Open the renamed file for reading; re-create the /etc/passwd file for
* writing.
*/
instream = fopen(CONFIG_FSUTILS_PASSWD_PATH ".tmp", "r");
if (instream == NULL)
{
ret = -errno;
DEBUGASSERT(ret < 0);
goto errout_with_tmpfile;
}
outstream = fopen(CONFIG_FSUTILS_PASSWD_PATH, "w");
if (outstream == NULL)
{
ret = -errno;
DEBUGASSERT(ret < 0);
goto errout_with_instream;
}
/* Copy 'offset' bytes from the renamed file to the original file */
ret = passwd_copyfile(iobuffer, instream, outstream, offset);
if (ret < 0)
{
goto errout_with_outstream;
}
/* Now read from the instream and discard the current line */
for (; ; )
{
int ch = fgetc(instream);
if (ch == EOF)
{
if (feof(instream))
{
/* Could this really happen without encountering the
* newline terminator?
*/
break;
}
else
{
ret = -errno;
DEBUGASSERT(ret < 0);
goto errout_with_instream;
}
}
else if (ch == '\n')
{
break;
}
}
/* Copy the rest of the file */
ret = passwd_copyfile(iobuffer, instream, outstream, SIZE_MAX);
errout_with_outstream:
(void)fclose(outstream);
errout_with_instream:
(void)fclose(instream);
errout_with_tmpfile:
if (ret < 0)
{
/* Restore the previous /etc/passwd file */
(void)unlink(CONFIG_FSUTILS_PASSWD_PATH);
(void)rename(CONFIG_FSUTILS_PASSWD_PATH ".tmp",
CONFIG_FSUTILS_PASSWD_PATH);
}
else
{
/* Delete the previous /etc/passwd file */
(void)unlink(CONFIG_FSUTILS_PASSWD_PATH ".tmp");
}
errout_with_iobuffer:
free(iobuffer);
return ret;
}
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