1 files changed, 81 insertions, 0 deletions
diff --git a/safe_rw.c b/safe_rw.c
new file mode 100644
index 0000000..683d8b5
--- /dev/null
+++ b/safe_rw.c
@@ -0,0 +1,81 @@
+
+#include <stdlib.h>
+#include <sys/types.h>
+
+#include <assert.h>
+#include <errno.h>
+#include <limits.h>
+#include <poll.h>
+#include <unistd.h>
+
+#ifndef SSIZE_MAX
+#define SSIZE_MAX (SIZE_MAX / 2 - 1)
+#endif
+
+#include "safe_rw.h"
+
+ssize_t
+safe_write(const int fd, const void *const buf_, size_t count,
+           const int timeout)
+{
+    struct pollfd pfd;
+    const char *  buf = (const char *) buf_;
+    ssize_t       written;
+
+    pfd.fd     = fd;
+    pfd.events = POLLOUT;
+
+    assert(count <= SSIZE_MAX);
+    while (count > (size_t) 0) {
+        while ((written = write(fd, buf, count)) <= (ssize_t) 0) {
+            if (errno == EAGAIN) {
+                if (poll(&pfd, (nfds_t) 1, timeout) == 0) {
+                    errno = ETIMEDOUT;
+                    goto ret;
+                }
+            } else if (errno != EINTR) {
+                goto ret;
+            }
+        }
+        buf += written;
+        count -= (size_t) written;
+    }
+ret:
+    return (ssize_t)(buf - (const char *) buf_);
+}
+
+ssize_t
+safe_read(const int fd, void *const buf_, size_t count)
+{
+    unsigned char *buf = (unsigned char *) buf_;
+    ssize_t        readnb;
+
+    assert(count <= SSIZE_MAX);
+    do {
+        while ((readnb = read(fd, buf, count)) < (ssize_t) 0 && errno == EINTR)
+            ;
+        if (readnb < (ssize_t) 0) {
+            return readnb;
+        }
+        if (readnb == (ssize_t) 0) {
+            break;
+        }
+        count -= (size_t) readnb;
+        buf += readnb;
+    } while (count > (ssize_t) 0);
+
+    return (ssize_t)(buf - (unsigned char *) buf_);
+}
+
+ssize_t
+safe_read_partial(const int fd, void *const buf_, const size_t max_count)
+{
+    unsigned char *const buf = (unsigned char *) buf_;
+    ssize_t              readnb;
+
+    assert(max_count <= SSIZE_MAX);
+    while ((readnb = read(fd, buf, max_count)) < (ssize_t) 0 && errno == EINTR)
+        ;
+
+    return readnb;
+}