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authorEric Andersen <andersen@codepoet.org>2004-06-06 08:08:25 +0000
committerEric Andersen <andersen@codepoet.org>2004-06-06 08:08:25 +0000
commit4305cac76f1c70ae885da2d9680136442419cd56 (patch)
tree3650aa6a58c91f69222c37e8b416050db87e62a8 /libc
parentf495113ee77eaca68bd2e17bc3a085e904c7e630 (diff)
scrap the goofy time + getpid() based "randomness" and use
the real thing.
Diffstat (limited to 'libc')
-rw-r--r--libc/misc/internals/tempname.c63
1 files changed, 35 insertions, 28 deletions
diff --git a/libc/misc/internals/tempname.c b/libc/misc/internals/tempname.c
index 236a62e85..1ade1b2e6 100644
--- a/libc/misc/internals/tempname.c
+++ b/libc/misc/internals/tempname.c
@@ -21,6 +21,11 @@
* Modify code to remove dependency on libgcc long long arith support funcs.
*/
+/* June 6, 2004 Erik Andersen
+ *
+ * Don't use brain damaged getpid() based randomness.
+ */
+
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
@@ -49,7 +54,7 @@ static int direxists (const char *dir)
for use with mk[s]temp. Will fail (-1) if DIR is non-null and
doesn't exist, none of the searched dirs exists, or there's not
enough space in TMPL. */
-int __path_search (char *tmpl, size_t tmpl_len, const char *dir,
+int __path_search (char *tmpl, size_t tmpl_len, const char *dir,
const char *pfx, int try_tmpdir)
{
//const char *d;
@@ -67,6 +72,7 @@ int __path_search (char *tmpl, size_t tmpl_len, const char *dir,
plen = 5;
}
+ /* Disable support for $TMPDIR */
#if 0
if (try_tmpdir)
{
@@ -78,7 +84,7 @@ int __path_search (char *tmpl, size_t tmpl_len, const char *dir,
else
dir = NULL;
}
-#endif
+#endif
if (dir == NULL)
{
if (direxists (P_tmpdir))
@@ -111,10 +117,25 @@ int __path_search (char *tmpl, size_t tmpl_len, const char *dir,
static const char letters[] =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+static unsigned int fillrand(unsigned char *buf, unsigned int len)
+{
+ int fd;
+ unsigned int result = -1;
+ fd = open("/dev/urandom", O_RDONLY);
+ if (fd < 0) {
+ fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
+ }
+ if (fd >= 0) {
+ result = read(fd, buf, len);
+ close(fd);
+ }
+ return result;
+}
+
/* 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.
+ overwritten with the result.
KIND may be one of:
__GT_NOCREATE: simply verify that the name does not exist
@@ -124,17 +145,13 @@ static const char letters[] =
__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)
{
char *XXXXXX;
- struct timeval tv;
- uint32_t high, low, rh;
unsigned int k;
int len, i, count, fd, save_errno = errno;
- static uint64_t value; /* Do not initialize this,
- or lock it for multi-threaded
- apps -- the messier the better */
+ unsigned char randomness[6];
len = strlen (tmpl);
if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
@@ -146,28 +163,17 @@ int __gen_tempname (char *tmpl, int kind)
/* This is where the Xs start. */
XXXXXX = &tmpl[len - 6];
- /* Get some more or less random data. */
- gettimeofday (&tv, NULL);
- value += ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid ();
+ /* Get some random data. */
+ if (fillrand(randomness, sizeof(randomness)) != sizeof(randomness)) {
+ goto all_done;
+ }
+ for (i = 0 ; i < sizeof(randomness) ; i++) {
+ k = ((randomness[i]) % 62);
+ XXXXXX[i] = letters[k];
+ }
for (count = 0; count < TMP_MAX; value += 7777, ++count)
{
- low = value & UINT32_MAX;
- high = value >> 32;
-
- for (i = 0 ; i < 6 ; i++) {
- rh = high % 62;
- high /= 62;
-#define L ((UINT32_MAX % 62 + 1) % 62)
- k = (low % 62) + (L * rh);
-#undef L
-#define H ((UINT32_MAX / 62) + ((UINT32_MAX % 62 + 1) / 62))
- low = (low / 62) + (H * rh) + (k / 62);
-#undef H
- k %= 62;
- XXXXXX[i] = letters[k];
- }
-
switch(kind) {
case __GT_NOCREATE:
{
@@ -213,6 +219,7 @@ int __gen_tempname (char *tmpl, int kind)
}
/* We got out of the loop because we ran out of combinations to try. */
+all_done:
__set_errno (EEXIST);
return -1;
}