From a2b4fe1466c167cec93757cee4d80129f93ee963 Mon Sep 17 00:00:00 2001
From: Peter Evans <pevans@activecampaign.com>
Date: Sun, 31 Dec 2017 20:28:11 -0600
Subject: [PATCH] Write an fread function for segments; use in apple2.dd

---
 include/vm_segment.h |  1 +
 src/apple2.dd.c      |  9 +++++++--
 src/vm_segment.c     | 22 ++++++++++++++++++++++
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/include/vm_segment.h b/include/vm_segment.h
index 39ee838..c2655a0 100644
--- a/include/vm_segment.h
+++ b/include/vm_segment.h
@@ -54,6 +54,7 @@ struct vm_segment {
 };
 
 extern int vm_segment_copy(vm_segment *, vm_segment *, size_t, size_t, size_t);
+extern int vm_segment_fread(vm_segment *, FILE *, size_t);
 extern int vm_segment_read_map(vm_segment *, size_t, vm_segment_read_fn);
 extern int vm_segment_set(vm_segment *, size_t, vm_8bit);
 extern int vm_segment_write_map(vm_segment *, size_t, vm_segment_write_fn);
diff --git a/src/apple2.dd.c b/src/apple2.dd.c
index 52a5cee..bc51ce1 100644
--- a/src/apple2.dd.c
+++ b/src/apple2.dd.c
@@ -33,6 +33,7 @@ int
 apple2dd_insert(apple2dd *drive, FILE *stream)
 {
     struct stat finfo;
+    int err;
 
     if (stream == NULL) {
         log_critical("File stream is null");
@@ -57,8 +58,12 @@ apple2dd_insert(apple2dd *drive, FILE *stream)
     drive->track_pos = 0;
     drive->sector_pos = 0;
 
-    // FIXME: vm_segment code should be doing this
-    fread(drive->data->memory, sizeof(vm_8bit), finfo.st_size, stream);
+    // Read the data from the stream and write into the memory segment
+    err = vm_segment_fread(drive->data, stream, finfo.st_size);
+    if (err != OK) {
+        log_critical("Could not read data into disk drive");
+        return err;
+    }
 
     return OK;
 }
diff --git a/src/vm_segment.c b/src/vm_segment.c
index c02e03e..9f0c473 100644
--- a/src/vm_segment.c
+++ b/src/vm_segment.c
@@ -204,3 +204,25 @@ vm_segment_write_map(vm_segment *segment,
     segment->write_table[addr] = fn;
     return OK;
 }
+
+/*
+ * Read the given file stream and write the contents into the given
+ * segment, up to len bytes. If we could not read from the file stream
+ * for some reason, signal that and return an error.
+ */
+int
+vm_segment_fread(vm_segment *segment, FILE *stream, size_t len)
+{
+    fread(segment->memory, sizeof(vm_8bit), len, stream);
+
+    // fread() may return zero in the case of an error, but it may
+    // return a positive non-zero number short of len; we can't quite
+    // count on just that to tell us something went wrong (especially if
+    // len was not a valid length for the file to begin with).
+    if (ferror(stream)) {
+        log_critical("Could not read file stream: %s\n", strerror(errno));
+        return ERR_BADFILE;
+    }
+
+    return OK;
+}