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authorLaurent Bercot <ska-skaware@skarnet.org>2014-09-18 18:55:44 +0000
committerLaurent Bercot <ska-skaware@skarnet.org>2014-09-18 18:55:44 +0000
commit3534b428629be185e096be99e3bd5fdfe32d5544 (patch)
tree210ef3198ed66bc7f7b7bf6a85e4579f455e5a36 /src/sysdeps/trydevrandom.c
downloadskalibs-3534b428629be185e096be99e3bd5fdfe32d5544.tar.xz
initial commit with rc for skalibs-2.0.0.0
Diffstat (limited to 'src/sysdeps/trydevrandom.c')
-rw-r--r--src/sysdeps/trydevrandom.c54
1 files changed, 54 insertions, 0 deletions
diff --git a/src/sysdeps/trydevrandom.c b/src/sysdeps/trydevrandom.c
new file mode 100644
index 0000000..395d008
--- /dev/null
+++ b/src/sysdeps/trydevrandom.c
@@ -0,0 +1,54 @@
+/* ISC license. */
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <errno.h>
+
+static int fd_read (int fd, char *buf, unsigned int len)
+{
+ register int r ;
+ do r = read(fd, buf, len) ;
+ while ((r == -1) && (errno == EINTR)) ;
+ return r ;
+}
+
+static unsigned int allread (int fd, register char *buf, register unsigned int len)
+{
+ register unsigned int written = 0 ;
+ while (len)
+ {
+ register int w = fd_read(fd, buf, len) ;
+ if (!w) errno = EPIPE ;
+ if (w <= 0) break ;
+ written += w ;
+ buf += w ;
+ len -= w ;
+ }
+ return written ;
+}
+
+static int byte_diff (char *s, unsigned int n, char *t)
+{
+ for (;;)
+ {
+ if (!n) return 0 ;
+ if (*s != *t) break ;
+ ++s ; ++t ; --n ;
+ }
+ return ((int)(unsigned int)(unsigned char) *s)
+ - ((int)(unsigned int)(unsigned char) *t);
+}
+
+int main ()
+{
+ char a[64] ;
+ char b[64] ;
+ int fd = open("/dev/random", O_RDONLY) ;
+ if ((fd == -1) || (allread(fd, a, 64) < 64) ) return 111 ;
+ close(fd) ;
+ fd = open("/dev/random", O_RDONLY) ;
+ if ((fd == -1) || (allread(fd, b, 64) < 64) ) return 111 ;
+ close(fd) ;
+ return !byte_diff(a, 64, b) ;
+}