tmpname.c File Reference

Detailed Description

Provides functions to generate unique temporary filenames.

Copyright

• (c) 2002 The University of Chicago, as Operator of Argonne National Laboratory.
• (c) 2002 The Regents of the University of California, as Operator of Los Alamos National Laboratory.

License

This file is distributed under the terms of the Software License Agreement found in the file LICENSE included with this distribution.

Author

M. Borland, C Saunders, R. Soliday

Definition in file tmpname.c.

#include "mdb.h"
#include "mdb_thread.h"
#include <time.h>
#include <unistd.h>
#include <errno.h>

Go to the source code of this file.

Functions
char *	tmpname (char *s)
	Supplies a unique temporary filename.
char *	mktempOAG (char *template)
	Generates a unique temporary filename based on a template.

Function Documentation

mktempOAG()

char * mktempOAG

(

char *

template

)

Generates a unique temporary filename based on a template.

Replaces the last six characters ('XXXXXX') of the template with random characters from a predefined set to create a unique temporary filename. It ensures that the generated filename does not already exist by checking the filesystem.

Parameters

template

A string containing the template for the temporary filename. The last six characters should be 'XXXXXX'.

Returns

A pointer to the modified template with the unique temporary filename. If no unique name could be generated, the first character of the template is set to null.

Definition at line 91 of file tmpname.c.

                                {
  int len, pid;
  char *XXXXXX;
  static uint64_t value;
  uint64_t random_time_bits;
  unsigned int count;
  int save_errno = errno;
  struct_stat64 st;
  static const char letters[] =
    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 
#define ATTEMPTS_MIN (62 * 62 * 62)
 
#if ATTEMPTS_MIN < TMP_MAX
  unsigned int attempts = TMP_MAX;
#else
  unsigned int attempts = ATTEMPTS_MIN;
#endif
 
  len = strlen(template);
  if (len < 6 || memcmp(&template[len - 6], "XXXXXX", 6)) {
    template[0] = '\0';
    return (template);
  }
 
  /* This is where the Xs start.  */
  XXXXXX = &template[len - 6];
 
  /* Get some more or less random data.  */
  random_time_bits = time(NULL);
 
  pid = __getpid();
  mdb_thread_lock(&tmpname_lock);
  value += random_time_bits ^ (pid * pid);
  for (count = 0; count < attempts; value += 7777, ++count) {
    uint64_t v = value;
 
    /* Fill in the random bits.  */
    XXXXXX[0] = letters[v % 62];
    v /= 31;
    XXXXXX[1] = letters[v % 62];
    v /= 31;
    XXXXXX[2] = letters[v % 62];
    v /= 31;
    XXXXXX[3] = letters[v % 62];
    v /= 31;
    XXXXXX[4] = letters[v % 62];
    v /= 31;
    XXXXXX[5] = letters[v % 62];
 
#if defined(vxWorks)
    if (!fexists(template) < 0) {
      mdb_thread_unlock(&tmpname_lock);
      return (template);
    }
#else
    if (__lxstat64(_STAT_VER, template, &st) < 0) {
      if (errno == ENOENT) {
        __set_errno(save_errno);
        mdb_thread_unlock(&tmpname_lock);
        return (template);
      } else {
        /* Give up now. */
        template[0] = '\0';
        mdb_thread_unlock(&tmpname_lock);
        return (template);
      }
    }
#endif
  }
 
  /* We got out of the loop because we ran out of combinations to try.  */
  template[0] = '\0';
  mdb_thread_unlock(&tmpname_lock);
  return (template);
}

tmpname()

char * tmpname

(

char *

s

)

Supplies a unique temporary filename.

Generates a unique temporary filename by appending the process ID and an incrementing counter to a base name. Ensures that the filename does not already exist.

Parameters

s	Pointer to a buffer where the temporary filename will be stored. If NULL, the function allocates memory for the filename.

Returns

A pointer to the unique temporary filename string.

Definition at line 37 of file tmpname.c.

{
  static long i = 1;
  static long pid = -1;
  if (s == NULL)
    s = tmalloc((unsigned)(40 * sizeof(*s)));
  mdb_thread_lock(&tmpname_lock);
  if (pid < 0)
#if !defined(vxWorks)
    pid = getpid();
#endif
  do {
#if defined(vxWorks)
    sprintf(s, "tmp.%ld", i);
#else
      sprintf(s, "tmp%ld.%ld", pid, i);
#endif
    i += 1;
    if (!fexists(s)) {
      mdb_thread_unlock(&tmpname_lock);
      break;
    }
  } while (1);
  return (s);
}