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[Qemu-devel] [PATCH v5 05/12] fdc: Throw an assertion on misconfigured f
From: |
John Snow |
Subject: |
[Qemu-devel] [PATCH v5 05/12] fdc: Throw an assertion on misconfigured fd_formats table |
Date: |
Fri, 22 Jan 2016 15:50:58 -0500 |
pick_geometry is a convoluted function that makes it difficult to tell
at a glance what QEMU's current behavior for choosing a floppy drive
type is when it can't quite identify the diskette.
The code iterates over all entries in the candidate geometry table
("fd_formats") and if our specific drive type matches a row in the table,
then either "match" is set to that entry (an exact match) and the loop
exits, or "first_match" will be non-negative (the first such entry that
shares the same drive type), and the loop continues. If our specific
drive type is NONE, then all drive types in the candidate geometry table
are considered. After iteration, if "match" was not set, we fall back to
"first match".
This means that either "match" was set, or we exited the loop without an
exact match, in which case:
- If drive type is NONE, the default is truly fd_formats[0], a 1.44MB
type, because "first_match" will always get set to the first item.
- If drive type is not NONE, pick_geometry's iteration was fussier and
only looked at rows that matched our drive type. However, since all
possible drive types are represented in the table, we still know that
"first match" was set.
- If drive type is not NONE and the fd_formats table lists no options for
our drive type, we choose fd_formats[1], an incomprehensibly bizarre
choice that can never happen anyway.
Correct this: If first_match is -1, it can ONLY mean we didn't edit our
fd_formats table correctly. Throw an assertion instead.
Reviewed-by: Eric Blake <address@hidden>
Signed-off-by: John Snow <address@hidden>
---
hw/block/fdc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index 18e363b..a8f0cf2 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -274,7 +274,9 @@ static void pick_geometry(FDrive *drv)
}
if (match == -1) {
if (first_match == -1) {
- match = 1;
+ error_setg(&error_abort, "No candidate geometries present in table
"
+ " for floppy drive type '%s'",
+ FloppyDriveType_lookup[drv->drive]);
} else {
match = first_match;
}
--
2.4.3
- [Qemu-devel] [PATCH v5 00/12] fdc: fix 2.88mb floppy diskette support, John Snow, 2016/01/22
- [Qemu-devel] [PATCH v5 02/12] fdc: reduce number of pick_geometry arguments, John Snow, 2016/01/22
- [Qemu-devel] [PATCH v5 01/12] fdc: move pick_geometry, John Snow, 2016/01/22
- [Qemu-devel] [PATCH v5 05/12] fdc: Throw an assertion on misconfigured fd_formats table,
John Snow <=
- [Qemu-devel] [PATCH v5 03/12] fdc: add drive type qapi enum, John Snow, 2016/01/22
- [Qemu-devel] [PATCH v5 07/12] fdc: Add fallback option, John Snow, 2016/01/22
- [Qemu-devel] [PATCH v5 08/12] fdc: add drive type option, John Snow, 2016/01/22
- [Qemu-devel] [PATCH v5 11/12] qtest/fdc: Support for 2.88MB drives, John Snow, 2016/01/22
- [Qemu-devel] [PATCH v5 04/12] fdc: add disk field, John Snow, 2016/01/22
- [Qemu-devel] [PATCH v5 06/12] fdc: add pick_drive, John Snow, 2016/01/22
- [Qemu-devel] [PATCH v5 10/12] fdc: rework pick_geometry, John Snow, 2016/01/22
- [Qemu-devel] [PATCH v5 09/12] fdc: add physical disk sizes, John Snow, 2016/01/22