Changeset 8e3498b in mainline for uspace/lib/c/generic/vfs

Timestamp:

2017-12-04T18:44:24Z (8 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

bde5c04

Parents:

40feeac

Message:

vfs_read/write() should return error code separately from number of bytes transferred.

File:

• uspace/lib/c/generic/vfs/vfs.c (modified) (6 diffs)

uspace/lib/c/generic/vfs/vfs.c

@@ -86 +86 @@
  * and consume system resources.
  *
- * Functions that return int return a negative error code on error and do not
+ * Functions that return int return an error code on error and do not
  * set errno. Depending on function, success is signalled by returning either
  * EOK or a non-negative file handle.
@@ -104 +104 @@
  *      aoff64_t pos = 42;
  *      char buf[512];
- *      ssize_t size = vfs_read(file, &pos, buf, sizeof(buf));
- *      if (size < 0) {
+ *      size_t nread;
+ *      rc = vfs_read(file, &pos, buf, sizeof(buf), &nread);
+ *      if (rc != EOK) {
  *              vfs_put(file);
- *              return size;
+ *              return rc;
  *      }
  *
- *      // buf is now filled with data from file
+ *      // buf is now filled with nread bytes from file
  *
  *      vfs_put(file);
@@ -808 +809 @@
  * @param buf           Buffer, @a nbytes bytes long
  * @param nbytes        Number of bytes to read
- *
- * @return              On success, non-negative number of bytes read
- * @return              On failure, a negative error code
- */
-ssize_t vfs_read(int file, aoff64_t *pos, void *buf, size_t nbyte)
+ * @param nread         Place to store number of bytes actually read
+ *
+ * @return              On success, EOK and @a *nread is filled with number
+ *                      of bytes actually read.
+ * @return              On failure, an error code
+ */
+int vfs_read(int file, aoff64_t *pos, void *buf, size_t nbyte, size_t *nread)
 {
         ssize_t cnt = 0;
-        size_t nread = 0;
+        size_t nr = 0;
         uint8_t *bp = (uint8_t *) buf;
         int rc;
@@ -821 +824 @@
         do {
                 bp += cnt;
-                nread += cnt;
+                nr += cnt;
                 *pos += cnt;
-                rc = vfs_read_short(file, *pos, bp, nbyte - nread, &cnt);
-        } while (rc == EOK && cnt > 0 && (nbyte - nread - cnt) > 0);
-        
-        if (rc != EOK)
+                rc = vfs_read_short(file, *pos, bp, nbyte - nr, &cnt);
+        } while (rc == EOK && cnt > 0 && (nbyte - nr - cnt) > 0);
+        
+        if (rc != EOK) {
+                *nread = nr;
                 return rc;
-        
+        }
+        
+        nr += cnt;
         *pos += cnt;
-        return nread + cnt;
+        *nread = nr;
+        return EOK;
 }
 
@@ -1247 +1254 @@
  * @param buf           Data, @a nbytes bytes long
  * @param nbytes        Number of bytes to write
- *
- * @return              On success, non-negative number of bytes written
- * @return              On failure, a negative error code
- */
-ssize_t vfs_write(int file, aoff64_t *pos, const void *buf, size_t nbyte)
+ * @param nwritten      Place to store number of bytes written
+ *
+ * @return              On success, EOK, @a *nwr is filled with number
+ *                      of bytes written
+ * @return              On failure, an error code
+ */
+int vfs_write(int file, aoff64_t *pos, const void *buf, size_t nbyte,
+    size_t *nwritten)
 {
         ssize_t cnt = 0;
-        ssize_t nwritten = 0;
+        ssize_t nwr = 0;
         const uint8_t *bp = (uint8_t *) buf;
         int rc;
@@ -1260 +1270 @@
         do {
                 bp += cnt;
-                nwritten += cnt;
+                nwr += cnt;
                 *pos += cnt;
-                rc = vfs_write_short(file, *pos, bp, nbyte - nwritten, &cnt);
-        } while (rc == EOK && ((ssize_t )nbyte - nwritten - cnt) > 0);
-
-        if (rc != EOK)
+                rc = vfs_write_short(file, *pos, bp, nbyte - nwr, &cnt);
+        } while (rc == EOK && ((ssize_t )nbyte - nwr - cnt) > 0);
+
+        if (rc != EOK) {
+                *nwritten = nwr;
                 return rc;
-
+        }
+
+        nwr += cnt;
         *pos += cnt;
-        return nbyte;
+        *nwritten = nwr;
+        return EOK;
 }