From 3ab75c62144738bdf545236e72e572090f90f028 Mon Sep 17 00:00:00 2001
From: Aaron Culliney <devnull@deadc0de.org>
Date: Sat, 17 Oct 2015 10:58:29 -0700
Subject: [PATCH] Refactor : improved error handling of track write

---
 src/disk.c | 54 +++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 39 insertions(+), 15 deletions(-)

diff --git a/src/disk.c b/src/disk.c
index 8bbe7b5e..36793583 100644
--- a/src/disk.c
+++ b/src/disk.c
@@ -473,26 +473,50 @@ static bool load_track_data(void) {
 static bool save_track_data(void) {
     SCOPE_TRACE_DISK("save_track_data");
 
+    size_t expected = 0;
+    uint8_t *buf = NULL;
     if (disk6.disk[disk6.drive].nibblized) {
         // .nib image
-        int track_pos = NIB_TRACK_SIZE * (disk6.disk[disk6.drive].phase >> 1);
-        fseek(disk6.disk[disk6.drive].fp, track_pos, SEEK_SET);
-        if (fwrite(disk6.disk[disk6.drive].track_image, 1, NIB_TRACK_SIZE, disk6.disk[disk6.drive].fp) != NIB_TRACK_SIZE) {
-            ERRLOG("could not write nib data ...");
-            return false;
-        }
+        expected = NIB_TRACK_SIZE;
+        buf = disk6.disk[disk6.drive].track_image;
     } else {
         // .dsk, .do, .po images
-        uint8_t buf[DSK_TRACK_SIZE];
-        denibblize_track(disk6.disk[disk6.drive].track_image, disk6.drive, buf);
-        int track_pos = DSK_TRACK_SIZE * (disk6.disk[disk6.drive].phase >> 1);
-        fseek(disk6.disk[disk6.drive].fp, track_pos, SEEK_SET);
-        if (fwrite(buf, 1, DSK_TRACK_SIZE, disk6.disk[disk6.drive].fp) != DSK_TRACK_SIZE) {
-            ERRLOG("could not write dsk data ...");
-            return false;
-        }
+        uint8_t _buf[DSK_TRACK_SIZE] = { 0 };
+        denibblize_track(disk6.disk[disk6.drive].track_image, disk6.drive, _buf);
+        expected = DSK_TRACK_SIZE;
+        buf = _buf; // !!!
     }
-    fflush(disk6.disk[disk6.drive].fp);
+
+    const long track_pos = expected * (disk6.disk[disk6.drive].phase >> 1);
+    TEMP_FAILURE_RETRY(fseek(disk6.disk[disk6.drive].fp, track_pos, SEEK_SET));
+
+    size_t idx = 0;
+    do {
+        size_t ct = fwrite(buf+idx, 1, expected-idx, disk6.disk[disk6.drive].fp);
+        if (UNLIKELY(ct == 0)) {
+            if (ferror(disk6.disk[disk6.drive].fp)) {
+                // hopefully a transient error ...
+                if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) {
+                    usleep(10);
+                    continue;
+                } else {
+                    ERRLOG("OOPS, fatal error reading disk image %s at phase %d", disk6.disk[disk6.drive].file_name,  disk6.disk[disk6.drive].phase);
+                    break;
+                }
+            } else {
+                ERRLOG("OOPS, EOF attemping to read disk image %s at phase %d", disk6.disk[disk6.drive].file_name,  disk6.disk[disk6.drive].phase);
+                break;
+            }
+        }
+        idx += ct;
+
+        if (LIKELY(idx == expected)) {
+            break;
+        }
+        assert(idx < expected && "the world is not sane");
+    } while (1);
+
+    TEMP_FAILURE_RETRY(fflush(disk6.disk[disk6.drive].fp));
 
     disk6.disk[disk6.drive].track_dirty = false;
     return true;