mkdtemp.c File Reference

#include "c.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

Include dependency graph for mkdtemp.c:

Go to the source code of this file.

Macros
#define	_DIAGASSERT(x)   do {} while (0)

Functions
static int	GETTEMP (char *path, int *doopen, int domkdir)
char *	mkdtemp (char *path)

Macro Definition Documentation

_DIAGASSERT

#define _DIAGASSERT

(

x

)

do {} while (0)

Definition at line 21 of file mkdtemp.c.

Function Documentation

GETTEMP()

static int GETTEMP ( char *  path, int *  doopen, int  domkdir  )

static

Definition at line 94 of file mkdtemp.c.

{
    char       *start,
               *trv;
    struct stat sbuf;
    u_int       pid;
 
    /*
     * To guarantee multiple calls generate unique names even if the file is
     * not created. 676 different possibilities with 7 or more X's, 26 with 6
     * or less.
     */
    static char xtra[2] = "aa";
    int         xcnt = 0;
 
    _DIAGASSERT(path != NULL);
    /* doopen may be NULL */
 
    pid = getpid();
 
    /* Move to end of path and count trailing X's. */
    for (trv = path; *trv; ++trv)
        if (*trv == 'X')
            xcnt++;
        else
            xcnt = 0;
 
    /* Use at least one from xtra.  Use 2 if more than 6 X's. */
    if (xcnt > 0)
    {
        *--trv = xtra[0];
        xcnt--;
    }
    if (xcnt > 5)
    {
        *--trv = xtra[1];
        xcnt--;
    }
 
    /* Set remaining X's to pid digits with 0's to the left. */
    for (; xcnt > 0; xcnt--)
    {
        *--trv = (pid % 10) + '0';
        pid /= 10;
    }
 
    /* update xtra for next call. */
    if (xtra[0] != 'z')
        xtra[0]++;
    else
    {
        xtra[0] = 'a';
        if (xtra[1] != 'z')
            xtra[1]++;
        else
            xtra[1] = 'a';
    }
 
    /*
     * check the target directory; if you have six X's and it doesn't exist
     * this runs for a *very* long time.
     */
    for (start = trv + 1;; --trv)
    {
        if (trv <= path)
            break;
        if (*trv == '/')
        {
            int         e;
 
            *trv = '\0';
            e = stat(path, &sbuf);
            *trv = '/';
            if (e == -1)
                return doopen == NULL && !domkdir;
            if (!S_ISDIR(sbuf.st_mode))
            {
                errno = ENOTDIR;
                return doopen == NULL && !domkdir;
            }
            break;
        }
    }
 
    for (;;)
    {
        if (doopen)
        {
            if ((*doopen =
                 open(path, O_CREAT | O_EXCL | O_RDWR, 0600)) >= 0)
                return 1;
            if (errno != EEXIST)
                return 0;
        }
        else if (domkdir)
        {
            if (mkdir(path, 0700) >= 0)
                return 1;
            if (errno != EEXIST)
                return 0;
        }
        else if (lstat(path, &sbuf))
            return errno == ENOENT ? 1 : 0;
 
        /* tricky little algorithm for backward compatibility */
        for (trv = start;;)
        {
            if (!*trv)
                return 0;
            if (*trv == 'z')
                *trv++ = 'a';
            else
            {
                if (isdigit((unsigned char) *trv))
                    *trv = 'a';
                else
                    ++*trv;
                break;
            }
        }
    }
    /* NOTREACHED */
}

References _DIAGASSERT, lstat, mkdir, S_ISDIR, stat::st_mode, and stat.

Referenced by mkdtemp().

mkdtemp()

char* mkdtemp

(

char *

path

)

Definition at line 286 of file mkdtemp.c.

{
    _DIAGASSERT(path != NULL);
 
    return GETTEMP(path, NULL, 1) ? path : NULL;
}

References _DIAGASSERT, and GETTEMP().