core: fix "sector size" confusionsyslinux-4.00-pre45

Fix the case where the "sector size" used by the pm filesystem driver
isn't the same thing as the SECTOR_SIZE/SECTOR_SHIFT macros used in
the assembly code.  This is a per-device property, and in the
particular case of isolinux hybrid, they are not even currently the
same (for all others, they are the same for now, but not necessarily
in the future.)

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 34 insertions, 1 deletions

diff --git a/core/fs/fs.c b/core/fs/fs.c
index 792da02f..3ae12ec9 100644
--- a/core/fs/fs.c
+++ b/core/fs/fs.c
@@ -117,6 +117,35 @@ void getfssec(com32sys_t *regs)
     regs->ecx.l = bytes_read;
 }
 
+void getfsbytes(com32sys_t *regs)
+{
+    int sectors;
+    bool have_more;
+    uint32_t bytes_read;
+    char *buf;
+    struct file *file;
+    uint16_t handle;
+
+    handle = regs->esi.w[0];
+    file = handle_to_file(handle);
+
+    sectors = regs->ecx.w[0] >> SECTOR_SHIFT(file->fs);
+
+    buf = MK_PTR(regs->es, regs->ebx.w[0]);
+    bytes_read = file->fs->fs_ops->getfssec(file, buf, sectors, &have_more);
+
+    /*
+     * If we reach EOF, the filesystem driver will have already closed
+     * the underlying file... this really should be cleaner.
+     */
+    if (!have_more) {
+	_close_file(file);
+        regs->esi.w[0] = 0;
+    }
+
+    regs->ecx.l = bytes_read;
+}
+
 size_t pmapi_read_file(uint16_t *handle, void *buf, size_t sectors)
 {
     bool have_more;
@@ -353,8 +382,9 @@ void pm_close_file(com32sys_t *regs)
  *    invoke the fs-specific init function;
  *    initialize the cache if we need one;
  *    finally, get the current inode for relative path looking.
- *
  */
+__bss16 uint16_t SectorSize, SectorShift;
+
 void fs_init(com32sys_t *regs)
 {
     static struct fs_info fs;	/* The actual filesystem buffer */
@@ -411,4 +441,7 @@ void fs_init(com32sys_t *regs)
 	fs.root = fs.fs_ops->iget_root(&fs);
 	fs.cwd = get_inode(fs.root);
     }
+
+    SectorShift = fs.sector_shift;
+    SectorSize  = fs.sector_size;
 }