создать имя для временного файла (create a name for a temporary file)
Имя (Name)
tempnam - create a name for a temporary file
Синопсис (Synopsis)
#include <stdio.h>
char *tempnam(const char *dir, const char *pfx);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
tempnam():
Since glibc 2.19:
_DEFAULT_SOURCE
Glibc 2.19 and earlier:
_BSD_SOURCE || _SVID_SOURCE
Описание (Description)
Never use this function. Use mkstemp(3) or tmpfile(3) instead.
The tempnam() function returns a pointer to a string that is a
valid filename, and such that a file with this name did not exist
when tempnam() checked. The filename suffix of the pathname
generated will start with pfx in case pfx is a non-NULL string of
at most five bytes. The directory prefix part of the pathname
generated is required to be "appropriate" (often that at least
implies writable).
Attempts to find an appropriate directory go through the
following steps:
a) In case the environment variable TMPDIR exists and contains
the name of an appropriate directory, that is used.
b) Otherwise, if the dir argument is non-NULL and appropriate, it
is used.
c) Otherwise, P_tmpdir (as defined in <stdio.h>) is used when
appropriate.
d) Finally an implementation-defined directory may be used.
The string returned by tempnam() is allocated using malloc(3) and
hence should be freed by free(3).
Возвращаемое значение (Return value)
On success, the tempnam() function returns a pointer to a unique
temporary filename. It returns NULL if a unique name cannot be
generated, with errno set to indicate the error.
Ошибки (Error)
ENOMEM Allocation of storage failed.
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────┬───────────────┬─────────────┐
│Interface │ Attribute │ Value │
├──────────────────────────────────┼───────────────┼─────────────┤
│tempnam() │ Thread safety │ MT-Safe env │
└──────────────────────────────────┴───────────────┴─────────────┘
Стандарты (Conforming to)
SVr4, 4.3BSD, POSIX.1-2001. POSIX.1-2008 marks tempnam() as
obsolete.
Примечание (Note)
Although tempnam() generates names that are difficult to guess,
it is nevertheless possible that between the time that tempnam()
returns a pathname, and the time that the program opens it,
another program might create that pathname using open(2), or
create it as a symbolic link. This can lead to security holes.
To avoid such possibilities, use the open(2) O_EXCL flag to open
the pathname. Or better yet, use mkstemp(3) or tmpfile(3).
SUSv2 does not mention the use of TMPDIR; glibc will use it only
when the program is not set-user-ID. On SVr4, the directory used
under d) is /tmp (and this is what glibc does).
Because it dynamically allocates memory used to return the
pathname, tempnam() is reentrant, and thus thread safe, unlike
tmpnam(3).
The tempnam() function generates a different string each time it
is called, up to TMP_MAX (defined in <stdio.h>) times. If it is
called more than TMP_MAX times, the behavior is implementation
defined.
tempnam() uses at most the first five bytes from pfx.
The glibc implementation of tempnam() fails with the error EEXIST
upon failure to find a unique name.
Ошибки (баги) (Bugs)
The precise meaning of "appropriate" is undefined; it is
unspecified how accessibility of a directory is determined.
Смотри также (See also)
mkstemp(3), mktemp(3), tmpfile(3), tmpnam(3)
