/* Generate a temporary file name based on TMPL. TMPL must match the
rules for mk[s]temp (i.e. end in "XXXXXX"). The name constructed
does not exist at the time of the call to __gen_tempname. TMPL is
overwritten with the result.
KIND may be one of:
__GT_NOCREATE: simply verify that the name does not exist
at the time of the call.
__GT_FILE: create the file using open(O_CREAT|O_EXCL)
and return a read-write fd. The file is mode 0600.
__GT_BIGFILE: same as __GT_FILE but use open64().
__GT_DIR: create a directory, which will be mode 0700.
We use a clever algorithm to get hard-to-predict names. */
int
__gen_tempname (char *tmpl, int kind)
{
int len;
char *XXXXXX;
static uint64_t value;
uint64_t random_time_bits;
int count, fd = -1;
int save_errno = errno;
struct_stat64 st;
len = strlen (tmpl);
if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
{
__set_errno (EINVAL);
return -1;
}
/* This is where the Xs start. */
XXXXXX = &tmpl[len - 6];
/* Get some more or less random data. */
#ifdef RANDOM_BITS
RANDOM_BITS (random_time_bits);
#else
# if HAVE_GETTIMEOFDAY || _LIBC
{
struct timeval tv;
__gettimeofday (&tv, NULL);
random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
}
# else
random_time_bits = time (NULL);
# endif
#endif
value += random_time_bits ^ __getpid ();
for (count = 0; count < TMP_MAX; value += 7777, ++count)
{
uint64_t v = value;
/* Fill in the random bits. */
XXXXXX[0] = letters[v % 62];
v /= 62;
XXXXXX[1] = letters[v % 62];
v /= 62;
XXXXXX[2] = letters[v % 62];
v /= 62;
XXXXXX[3] = letters[v % 62];
v /= 62;
XXXXXX[4] = letters[v % 62];
v /= 62;
XXXXXX[5] = letters[v % 62];
switch (kind)
{
case __GT_FILE:
fd = __open (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
break;
case __GT_BIGFILE:
fd = __open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
break;
case __GT_DIR:
fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR);
break;
case __GT_NOCREATE:
/* This case is backward from the other three. __gen_tempname
succeeds if __xstat fails because the name does not exist.
Note the continue to bypass the common logic at the bottom
of the loop. */
if (__lxstat64 (_STAT_VER, tmpl, &st) < 0)
{
if (errno == ENOENT)
{
__set_errno (save_errno);
return 0;
}
else
/* Give up now. */
return -1;
}
continue;
default:
assert (! "invalid KIND in __gen_tempname");
}
if (fd >= 0)
{
__set_errno (save_errno);
return fd;
}
else if (errno != EEXIST)
return -1;
}
/* We got out of the loop because we ran out of combinations to try. */
__set_errno (EEXIST);
return -1;
}
/* Generate a temporary file name based on TMPL. TMPL must match the
rules for mk[s]temp (i.e. end in "XXXXXX"). The name constructed
does not exist at the time of the call to __gen_tempname. TMPL is
overwritten with the result.
KIND may be one of:
__GT_NOCREATE: simply verify that the name does not exist
at the time of the call.
__GT_FILE: create the file using open(O_CREAT|O_EXCL)
and return a read-write fd. The file is mode 0600.
__GT_BIGFILE: same as __GT_FILE but use open64().
__GT_DIR: create a directory, which will be mode 0700.
We use a clever algorithm to get hard-to-predict names. */
int
__gen_tempname (char *tmpl, int kind)
{
int len;
char *XXXXXX;
static uint64_t value;
uint64_t random_time_bits;
unsigned int count;
int fd = -1;
int save_errno = errno;
struct_stat64 st;
/* A lower bound on the number of temporary files to attempt to
generate. The maximum total number of temporary file names that
can exist for a given template is 62**6. It should never be
necessary to try all these combinations. Instead if a reasonable
number of names is tried (we define reasonable as 62**3) fail to
give the system administrator the chance to remove the problems. */
unsigned int attempts_min = 62 * 62 * 62;
/* The number of times to attempt to generate a temporary file. To
conform to POSIX, this must be no smaller than TMP_MAX. */
unsigned int attempts = attempts_min < TMP_MAX ? TMP_MAX : attempts_min;
len = strlen (tmpl);
if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
{
__set_errno (EINVAL);
return -1;
}
/* This is where the Xs start. */
XXXXXX = &tmpl[len - 6];
/* Get some more or less random data. */
#ifdef RANDOM_BITS
RANDOM_BITS (random_time_bits);
#else
# if HAVE_GETTIMEOFDAY || _LIBC
{
struct timeval tv;
__gettimeofday (&tv, NULL);
random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
}
# else
random_time_bits = time (NULL);
# endif
#endif
value += random_time_bits ^ __getpid ();
for (count = 0; count < attempts; value += 7777, ++count)
{
uint64_t v = value;
/* Fill in the random bits. */
XXXXXX[0] = letters[v % 62];
v /= 62;
XXXXXX[1] = letters[v % 62];
v /= 62;
XXXXXX[2] = letters[v % 62];
v /= 62;
XXXXXX[3] = letters[v % 62];
v /= 62;
XXXXXX[4] = letters[v % 62];
v /= 62;
XXXXXX[5] = letters[v % 62];
switch (kind)
{
case __GT_FILE:
fd = __open (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
break;
case __GT_BIGFILE:
fd = __open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
break;
case __GT_DIR:
fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR);
break;
case __GT_NOCREATE:
/* This case is backward from the other three. __gen_tempname
succeeds if __xstat fails because the name does not exist.
Note the continue to bypass the common logic at the bottom
of the loop. */
if (__lxstat64 (_STAT_VER, tmpl, &st) < 0)
{
if (errno == ENOENT)
{
__set_errno (save_errno);
return 0;
}
else
/* Give up now. */
return -1;
}
continue;
default:
assert (! "invalid KIND in __gen_tempname");
}
if (fd >= 0)
{
__set_errno (save_errno);
return fd;
}
else if (errno != EEXIST)
return -1;
}
/* We got out of the loop because we ran out of combinations to try. */
__set_errno (EEXIST);
return -1;
}
int
__try_tempname (char *tmpl, int suffixlen, void *args,
int (*tryfunc) (char *, void *))
{
int len;
char *XXXXXX;
static uint64_t value;
uint64_t random_time_bits;
unsigned int count;
int fd = -1;
int save_errno = errno;
/* A lower bound on the number of temporary files to attempt to
generate. The maximum total number of temporary file names that
can exist for a given template is 62**6. It should never be
necessary to try all of these combinations. Instead if a reasonable
number of names is tried (we define reasonable as 62**3) fail to
give the system administrator the chance to remove the problems. */
#define ATTEMPTS_MIN (62 * 62 * 62)
/* The number of times to attempt to generate a temporary file. To
conform to POSIX, this must be no smaller than TMP_MAX. */
#if ATTEMPTS_MIN < TMP_MAX
unsigned int attempts = TMP_MAX;
#else
unsigned int attempts = ATTEMPTS_MIN;
#endif
len = strlen (tmpl);
if (len < 6 + suffixlen || memcmp (&tmpl[len - 6 - suffixlen], "XXXXXX", 6))
{
__set_errno (EINVAL);
return -1;
}
/* This is where the Xs start. */
XXXXXX = &tmpl[len - 6 - suffixlen];
/* Get some more or less random data. */
#ifdef RANDOM_BITS
RANDOM_BITS (random_time_bits);
#else
{
struct timeval tv;
__gettimeofday (&tv, NULL);
random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
}
#endif
value += random_time_bits ^ __getpid ();
for (count = 0; count < attempts; value += 7777, ++count)
{
uint64_t v = value;
/* Fill in the random bits. */
XXXXXX[0] = letters[v % 62];
v /= 62;
XXXXXX[1] = letters[v % 62];
v /= 62;
XXXXXX[2] = letters[v % 62];
v /= 62;
XXXXXX[3] = letters[v % 62];
v /= 62;
XXXXXX[4] = letters[v % 62];
v /= 62;
XXXXXX[5] = letters[v % 62];
fd = tryfunc (tmpl, args);
if (fd >= 0)
{
__set_errno (save_errno);
return fd;
}
else if (errno != EEXIST)
return -1;
}
/* We got out of the loop because we ran out of combinations to try. */
__set_errno (EEXIST);
return -1;
}
