diff options
Diffstat (limited to 'libc')
| -rw-r--r-- | libc/misc/internals/tempname.c | 63 |
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; } |