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tinystdio: Resolve issue with tmpnam #8

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54 changes: 37 additions & 17 deletions newlib/libc/tinystdio/mktemp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -98,8 +98,12 @@ _gettemp (char *path,
int *doopen,
int flags)
{
char *start, *trv;
char *trv;
char *end;
static char inc = 0;
static char pos = 1;

__LIBC_LOCK();

end = path + strlen(path) - suffixlen;
trv = end;
Expand All @@ -112,13 +116,35 @@ _gettemp (char *path,
if (end - trv < 6)
{
errno = EINVAL;
__LIBC_UNLOCK();
return 0;
}

start = trv + 1;
trv += pos;

for (;;)
{
/* Increment the string of letters to generate another name */
for(;;)
{
if (trv == end)
{
__LIBC_UNLOCK();
return 0;
}

if ((*trv + inc - 1) == 'z') {
*trv++ = 'a';
pos++;
inc = 1;
}
else {
*trv += inc;
inc++;
break;
}
}

/*
* Use open to check if the file exists to avoid depending on
* stat or access. Don't rely on O_EXCL working, although if it
Expand All @@ -128,39 +154,33 @@ _gettemp (char *path,
if (fd < 0) {
if (errno != EACCES) {
if (errno != ENOENT)
{
__LIBC_UNLOCK();
return 0;
}
if (doopen)
{
fd = open (path, flags | O_CREAT | O_EXCL | O_RDWR,
0600);
if (fd >= 0) {
*doopen = fd;
__LIBC_UNLOCK();
return 1;
}
if (errno != EEXIST)
{
__LIBC_UNLOCK();
return 0;
}
} else {
__LIBC_UNLOCK();
return 1;
}
}
} else
close(fd);

/* Increment the string of letters to generate another name */
trv = start;
for(;;)
{
if (trv == end)
return 0;
if (*trv == 'z')
*trv++ = 'a';
else {
++ * trv;
break;
}
}
}
/*NOTREACHED*/
__LIBC_UNLOCK();
}

int
Expand Down