Syslinux - Jan 2014 - [PATCH 02/05] utils/mkdiskimage.in: With option -s: Avoid zeroizing the partition even if truncate() failed

Hi,

following is a series of patches derived from my proposed diff.
Based on syslinux-6.03-pre1, but should also apply down to 4.xx.

I hope to have imitated the changelog style sufficiently.
Mine are a bit longer than usual with patches in the archive, i fear.
Instructions for the future are welcome.

Each intermediate state is tested for its designated purpose only.
The final state after applying all patches is tested with various
options, suitable and unsuitable file types of various sizes.

----------------------------------------------------------------

I will think about another patch for an option which zeroizes
the whole device even if the partition size is given explicitely
and matches a cylinder end. (mkdiskimage_05.patch only zeroizes
a known incomplete cylinder after the partition end.)

Although mkdiskimage should be suitable now for USB sticks
on unix-like systems beyond Linux, i still have no clue about
USB sticks at NT/2K/XP/DOS systems.
There is hope that the sysseek() method of size determination
will work with a suitable file object. If only it has an address
for sysopen().


Have a nice day :)

Thomas

utils/mkdiskimage.in: Option -s caused freshly created image files to be too
small by a factor of 512.

--- utils/mkdiskimage_orig.in	2014-01-23 12:23:34.000000000 +0100
+++ utils/mkdiskimage.in	2014-01-30 20:35:13.000000000 +0100
@@ -218,7 +218,7 @@ $totalsize = $c*$h*$s;
 $tracks    = $c*$h;
 
 # If -s is given, try to simply use truncate...
-unless ($opt{'s'} && truncate(OUTPUT, $totalsize)) {
+unless ($opt{'s'} && truncate(OUTPUT, $totalsize * 512)) {
     $track = "\0" x (512*$s);
 
     # Print fractional track

utils/mkdiskimage.in: With option -s: Avoid zeroizing the partition even if
truncate() failed.

--- utils/mkdiskimage_patched_01.in	2014-01-30 20:43:02.000000000 +0100
+++ utils/mkdiskimage.in	2014-01-30 20:45:09.000000000 +0100
@@ -217,8 +217,11 @@ print OUTPUT "\x55\xaa";
 $totalsize = $c*$h*$s;
 $tracks    = $c*$h;
 
-# If -s is given, try to simply use truncate...
-unless ($opt{'s'} && truncate(OUTPUT, $totalsize * 512)) {
+# If -s is given, simply use truncate. Do not care for success. Failure is
+# normal with Linux block devices.
+if ($opt{'s'}) {
+    truncate(OUTPUT, $totalsize * 512);
+} else {
     $track = "\0" x (512*$s);
 
     # Print fractional track

Op 2014-01-30 om 21:54 schreef Thomas Schmitt:
> Hi,
> 
> following is a series of patches derived from my proposed diff.
> Based on syslinux-6.03-pre1, but should also apply down to 4.xx.
> 
> I hope to have imitated the changelog style sufficiently.
> Mine are a bit longer than usual with patches in the archive, i fear.
Yes, they are long.

> Instructions for the future are welcome.
A few weeks ago we did some hand-ons training
with a new series of patches.
 
That learning-by-doing was somehow pushed/helped/guided
by having these patch series in the e-mail backlog.

I'll repost the patches in a format that can be processed
with a tool like `git am` which does "apply patch"
and "add commit message". Please feel free to ask again
for feedback on provided patches. Don't worry about somebodies
else email-backlog, just show that you care.

> Each intermediate state is tested for its designated purpose only.
> The final state after applying all patches is tested with various
> options, suitable and unsuitable file types of various sizes.
> 
> ----------------------------------------------------------------
> 
> I will think about another patch for an option which zeroizes
> the whole device even if the partition size is given explicitely
> and matches a cylinder end. (mkdiskimage_05.patch only zeroizes
> a known incomplete cylinder after the partition end.)
> 
> Although mkdiskimage should be suitable now for USB sticks
> on unix-like systems beyond Linux, i still have no clue about
> USB sticks at NT/2K/XP/DOS systems.
> There is hope that the sysseek() method of size determination
> will work with a suitable file object. If only it has an address
> for sysopen().
> 
> 
> Have a nice day :)
> 
> Thomas
> 

Groeten
Geert Stappers
-- 
Leven en laten leven

---
 utils/mkdiskimage.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/utils/mkdiskimage.in b/utils/mkdiskimage.in
index 533193a..a95a077 100644
--- a/utils/mkdiskimage.in
+++ b/utils/mkdiskimage.in
@@ -218,7 +218,7 @@ $totalsize = $c*$h*$s;
 $tracks    = $c*$h;
 
 # If -s is given, try to simply use truncate...
-unless ($opt{'s'} && truncate(OUTPUT, $totalsize)) {
+unless ($opt{'s'} && truncate(OUTPUT, $totalsize * 512)) {
     $track = "\0" x (512*$s);
 
     # Print fractional track
-- 
2.0.0

On 07/10/2014 12:18 PM, Geert Stappers wrote:
>>
>> following is a series of patches derived from my proposed diff.
>> Based on syslinux-6.03-pre1, but should also apply down to 4.xx.
>>
>> I hope to have imitated the changelog style sufficiently.
>> Mine are a bit longer than usual with patches in the archive, i fear.
> 
> Yes, they are long.
> 
There seems to be no patch descriptions at all, which would really help
long-term maintainability.

	-hpa