c - lcc tmpnam crash -

when use lcc compiler , call tmpnam(buf) program crashes.

reason: l_tmpnam indicates buf must 14 bytes long, while string returned  "d:\documents , settings\paul\temporary\tmp9.tmp" longer 14.   

what wrong, how can behavior explained.

verbatim man tmpnam:

never use function. use mkstemp(3) or tmpfile(3) instead.

---

anyway, asked it:

the name generated tmpnam() consists of file name of maximum l_tmpnam lenght prefixed directory of name p_tmpdir.

so buffer passed tmpnam() best declared (if c99):

char pathname[strlen(p_tmpdir) + 1 + l_tmpnam + 1] = ""; /* +1 dir delimiting `/` , +1 zero-termination */ 

if non c99 might go this:

size_t sizetmpname = strlen(p_tmpdir) + 1 + l_tmpnam + 1; char * pathname = calloc(sizetmpname, sizeof (*pathname)); if (null == pathname)   perror("calloc() 'pathname'"); 

then call tmpnam() this:

if (null == tmpnam(pathname))   fprintf(stderr, "tmpnam(): unique name cannot generated.\n"); else   printf("unique name: %s\n", pathname);  ... /* soemthing */  /* if on non c99 , calloc(() called: */ free(pathname);