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Add mktemp() and mkstemp()

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This commit is contained in:
Gregory Nutt 2014-11-05 09:39:18 -06:00
parent 22811f0358
commit d13731711f
4 changed files with 385 additions and 1 deletions
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4
include/stdlib.h
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@ -1,7 +1,7 @@
/****************************************************************************
* include/stdlib.h
*
* Copyright (C) 2007-2013 Gregory Nutt. All rights reserved.
* Copyright (C) 2007-2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
@ -182,6 +182,8 @@ long int labs(long int j);
#ifdef CONFIG_HAVE_LONG_LONG
long long int llabs(long long int j);
#endif
int mktemp(FAR char *template);
int mkstemp(FAR char *template);
/* Sorting */

4
libc/stdlib/Make.defs
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@ -40,6 +40,10 @@ CSRCS += lib_llabs.c lib_rand.c lib_qsort.c
CSRCS += lib_strtol.c lib_strtoll.c lib_strtoul.c lib_strtoull.c
CSRCS += lib_strtod.c lib_checkbase.c
ifeq ($(CONFIG_FS_WRITABLE),y)
CSRCS += lib_mktemp.c lib_mkstemp.c
endif
# Add the stdlib directory to the build
DEPPATH += --dep-path stdlib

297
libc/stdlib/lib_mkstemp.c Normal file
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@ -0,0 +1,297 @@
/****************************************************************************
* libc/stdlib/lib_mkstemp.c
*
* Copyright (C) 2014 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 <nuttx/compiler.h>
#include <stdint.h>
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <semaphore.h>
#include <errno.h>
#ifdef CONFIG_FS_WRITABLE
/****************************************************************************
* Pre-processor definitions
****************************************************************************/
#ifndef CONFIG_LIBC_TMPDIR
# define CONFIG_LIBC_TMPDIR "/tmp"
#endif
#define MAX_XS 6
#define MIN_NUMERIC 0 /* 0-9: Numeric */
#define MAX_NUMERIC 9
#define MIN_UPPERCASE 10 /* 10-35: Upper case */
#define MAX_UPPERCASE 35
#define MIN_LOWERCASE 36 /* 36-61: Lower case */
#define MAX_LOWERCASE 61
#define MAX_BASE62 MAX_LOWERCASE
/* 62**1 = 62
* 62**2 = 3844
* 62**3 = 238328
* 62**4 = 14776336
* 62**5 = 916132832
* 62**6 = 56800235584 > UINT32_MAX
*/
#define BIG_XS 5
/****************************************************************************
* Private Data
****************************************************************************/
static uint8_t g_base62[MAX_XS];
static sem_t g_b62sem = SEM_INITIALIZER(1);
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: base62_to_char
*
* Description:
* Convert a base62 value to a printable character.
*
****************************************************************************/
static char base62_to_char(uint8_t base62)
{
if (base62 <= MAX_NUMERIC)
{
return '0' + base62;
}
else if (base62 <= MAX_UPPERCASE)
{
return 'A' + base62 - MIN_UPPERCASE;
}
else /* if (base62 <= MAX_LOWERCASE) */
{
DEBUGASSERT(base62 <= MAX_LOWERCASE);
return 'a' + base62 - MIN_LOWERCASE;
}
}
/****************************************************************************
* Name: incr_base62
*
* Description:
* increment the base62 value array.
*
****************************************************************************/
static void incr_base62(void)
{
int i;
for (i = 0; i < MAX_XS; i++)
{
if (g_base62[i] < MAX_LOWERCASE)
{
g_base62[i]++;
return;
}
else
{
g_base62[i] = 0;
}
}
}
/****************************************************************************
* Name: get_base62
*
* Description:
* Atomically copy and increment the base62 array.
*
****************************************************************************/
static void get_base62(FAR uint8_t *ptr)
{
int ret;
while ((ret = sem_wait(&g_b62sem)) < 0)
{
DEBUGASSERT(errno == EINTR);
}
memcpy(ptr, g_base62, MAX_XS);
incr_base62();
sem_post(&g_b62sem);
}
/****************************************************************************
* Name: copy_base62
*
* Description:
* Copy the base62 array into the template filename, converting each
* base62 value to a printable character.
*
****************************************************************************/
static void copy_base62(FAR char *dest, int len)
{
FAR const uint8_t *src;
src = g_base62;
if (len < MAX_XS)
{
src += MAX_XS - len;
}
for (; len > 0; len--)
{
*dest++ = base62_to_char(*src++);
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: mkstemp
*
* Description:
* The mkstemp() function replaces the contents of the string pointed to
* by template by a unique filename, and returns a file descriptor for the
* file open for reading and writing. The function thus prevents any
* possible race condition between testing whether the file exists and
* opening it for use. The string in template should look like a filename
* with six trailing 'X' s; mkstemp() replaces each 'X' with a character
* from the portable filename character set. The characters are chosen
* such that the resulting name does not duplicate the name of an existing
* file at the time of a call to mkstemp().
*
* Input Parameters:
* template - The base file name that will be modified to produce the
* unique file name. This must be a full path beginning with /tmp.
* This function will modify only the first XXXXXX characters within
* that full path.
*
* Returned Value:
*
* Upon successful completion, mkstemp() returns an open file descriptor.
* Otherwise, -1 is returned if no suitable file could be created.
*
****************************************************************************/
int mkstemp(FAR char *template)
{
uint8_t base62[MAX_XS];
uint32_t retries;
FAR char *xptr;
FAR char *ptr;
int xlen;
int fd;
int i;
/* Count the number of X's at the end of the template */
xptr = strchr(template, 'X');
if (!xptr)
{
/* No Xs? There should always really be 6 */
return open(template, O_RDWR | O_CREAT | O_EXCL, 0666);
}
/* There is at least one.. count all of them */
for (xlen = 0, ptr = xptr; xlen < MAX_XS && *ptr == 'X'; xlen++, ptr++);
/* Ignore any X's after the sixth */
if (xlen > MAX_XS)
{
xlen = MAX_XS;
}
/* If xlen is small, then we need to determine the maximum number of
* retries before the values will repeat.
*/
if (xlen >= BIG_XS)
{
retries = UINT32_MAX;
}
else
{
for (i = 1, retries = 62; i < xlen; i++, retries *= 62);
}
/* Then loop until we find a unique file name */
while (retries > 0)
{
/* Sample and increment the base62 counter */
get_base62(base62);
/* Form the candidate file name */
copy_base62(xptr, xlen);
/* Attempt to open the candidate file -- creating it exclusively
*
* REVISIT: This prohibits the use of this function to create unique
* directories
*/
fd = open(template, O_RDWR | O_CREAT | O_EXCL, 0666);
if (fd >= 0)
{
/* We have it... return the file descriptor */
return fd;
}
}
/* We could not find an unique filename */
return ERROR;
}
#endif /* CONFIG_FS_WRITABLE */

81
libc/stdlib/lib_mktemp.c Normal file
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@ -0,0 +1,81 @@
/****************************************************************************
* libc/stdlib/lib_mktemp.c
*
* Copyright (C) 2014 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 <nuttx/compiler.h>
#include <unistd.h>
#include <stdlib.h>
#ifdef CONFIG_FS_WRITABLE
/****************************************************************************
* Pre-processor definitions
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: mktemp
*
* Description:
* The use of mktemp is dangerous; use mkstemp instead.
*
****************************************************************************/
int mktemp(FAR char *template)
{
int fd = mkstemp(template);
if (fd < 0)
{
return ERROR;
}
close(fd);
return OK;
}
#endif /* CONFIG_FS_WRITABLE */