Cleanups, tests and optimizations for #74.

1 files changed, 59 insertions, 0 deletions

diff --git a/tests/odirect_read.c b/tests/odirect_read.c
new file mode 100644
index 0000000..8fc746b
--- /dev/null
+++ b/tests/odirect_read.c
@@ -0,0 +1,59 @@
+#ifdef __linux__
+
+#include <stdio.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#ifndef O_DIRECT
+#define O_DIRECT 00040000 /* direct disk access hint */
+#endif
+
+int main(int argc, char** argv) {
+    if (argc != 2) {
+        fprintf(stderr, "Expected 1 argument: the file to read.\n");
+        return 1;
+    }
+
+    int fd = open(argv[1], O_RDONLY | O_DIRECT);
+    if (fd == -1) {
+        perror("failed to open file");
+        return 1;
+    }
+
+    const size_t buf_size = 4096;
+    unsigned char* buf = mmap(NULL, buf_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+    if (buf == MAP_FAILED) {
+        perror("mmap failed");
+        return 1;
+    }
+
+    while (1) {
+        ssize_t amt_read = read(fd, buf, buf_size);
+        if (amt_read == 0) {
+            break;
+        }
+        if (amt_read == -1) {
+            perror("failed to read file");
+            return 1;
+        }
+        fwrite(buf, 1, amt_read, stdout);
+        fflush(stdout);
+    }
+
+    return 0;
+}
+
+#else  // __linux__
+
+#include <stdio.h>
+
+int main() {
+    fprintf(stderr, "Not supported on this platform.\n");
+    return 1;
+}
+
+#endif  // __linux__