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authorRich Felker <dalias@aerifal.cx>2018-02-23 02:54:01 -0500
committerRich Felker <dalias@aerifal.cx>2018-02-23 02:57:52 -0500
commit82f176803ae07e34229906d5c7c62889e665dc97 (patch)
tree8ba87ec513170697964a04c7502a6abb6b8aacc4 /src/misc/getentropy.c
parente20658209177667e490c661dfd35b976749ef3f7 (diff)
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add getentropy function
based loosely on patch by Hauke Mehrtens; converted to wrap the public API of the underlying getrandom function rather than direct syscalls, so that if/when a fallback implementation of getrandom is added it will automatically get picked up by getentropy too.
Diffstat (limited to 'src/misc/getentropy.c')
-rw-r--r--src/misc/getentropy.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/src/misc/getentropy.c b/src/misc/getentropy.c
new file mode 100644
index 00000000..4c61ae26
--- /dev/null
+++ b/src/misc/getentropy.c
@@ -0,0 +1,31 @@
+#include <sys/random.h>
+#include <pthread.h>
+#include <errno.h>
+
+int getentropy(void *buffer, size_t len)
+{
+ int cs, ret;
+ char *pos = buffer;
+
+ if (len > 256) {
+ errno = EIO;
+ return -1;
+ }
+
+ pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
+
+ while (len) {
+ ret = getrandom(pos, len, 0);
+ if (ret < 0) {
+ if (errno == EINTR) continue;
+ else break;
+ }
+ pos += ret;
+ len -= ret;
+ ret = 0;
+ }
+
+ pthread_setcancelstate(cs, 0);
+
+ return ret;
+}