[Buildroot] [PATCH 1/2] ext2.mk: ensure file system block count is not zero (0)

[Buildroot] [PATCH 1/2] ext2.mk: ensure file system block count is not zero (0)

[J Evans]

Signed-off-by: J Evans <g4@novadsp.com>
---
 fs/ext2/ext2.mk | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/ext2/ext2.mk b/fs/ext2/ext2.mk
index 30f1d17..3a0c764 100644
--- a/fs/ext2/ext2.mk
+++ b/fs/ext2/ext2.mk
@@ -6,7 +6,9 @@
 
 EXT2_OPTS = -G $(BR2_TARGET_ROOTFS_EXT2_GEN) -R $(BR2_TARGET_ROOTFS_EXT2_REV)
 
-ifneq ($(strip $(BR2_TARGET_ROOTFS_EXT2_BLOCKS)),0)
+ifeq ($(strip $(BR2_TARGET_ROOTFS_EXT2_BLOCKS)),0)
+$(error BR2_TARGET_ROOTFS_EXT2_BLOCKS cannot be zero (0))
+else
 EXT2_OPTS += -b $(BR2_TARGET_ROOTFS_EXT2_BLOCKS)
 endif
 
-- 
2.7.4

[Buildroot] [PATCH 2/2] mke2img: add parameter sanity checks to prevent odd error messages from genext2.fs

[J Evans]

Signed-off-by: J Evans <g4@novadsp.com>
---
 package/mke2img/mke2img | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/package/mke2img/mke2img b/package/mke2img/mke2img
index b773aa9..c50dc66 100755
--- a/package/mke2img/mke2img
+++ b/package/mke2img/mke2img
@@ -44,6 +44,12 @@ main() {
     if [ -z "${image}" ]; then
         error "you must specify an output image file with '-o'\n"
     fi
+    if [ -z "${nb_blocks}" ]; then
+        error "Error: you must specify a file system block count with '-b'. This cannot be zero, e.g. 61440 == 60MB\n"
+    fi
+    if [ "${nb_blocks}" -eq 0 ]; then
+        error "Error: The file system block count size cannot be zero. e.g. 61440 == 60MB \n"
+    fi
     case "${gen}:${rev}" in
     2:0|2:1|3:1|4:1)
         ;;
-- 
2.7.4

[Buildroot] [PATCH 1/2] ext2.mk: ensure file system block count is not zero (0)

[Thomas Petazzoni]

Hello,

On Sat, 29 Apr 2017 17:01:21 +0100, J Evans wrote:

> -ifneq ($(strip $(BR2_TARGET_ROOTFS_EXT2_BLOCKS)),0)
> +ifeq ($(strip $(BR2_TARGET_ROOTFS_EXT2_BLOCKS)),0)
> +$(error BR2_TARGET_ROOTFS_EXT2_BLOCKS cannot be zero (0))
> +else
>  EXT2_OPTS += -b $(BR2_TARGET_ROOTFS_EXT2_BLOCKS)
>  endif

What is the motivation for checking that the size is not zero? Zero is
like any other size too small to contain the target directory contents,
so I don't see why we would add a specific check for it.

Your commit log unfortunately only explains *what* the commit is doing
(which is obvious by reading the code) but not *why* this change is
necessary.

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

[Buildroot] [PATCH 2/2] mke2img: add parameter sanity checks to prevent odd error messages from genext2.fs

[Thomas Petazzoni]

Hello,

On Sat, 29 Apr 2017 17:01:22 +0100, J Evans wrote:

> +    if [ -z "${nb_blocks}" ]; then
> +        error "Error: you must specify a file system block count with '-b'. This cannot be zero, e.g. 61440 == 60MB\n"
> +    fi

Check this is useless: there is already error checking done by getopt
itself, because the -b option *must* have an argument. Indeed, the
current mke2img behaves like this:

$ ./package/mke2img/mke2img -b
mke2img: option 'b' expects a mandatory argument

So it is already checked that ${nb_blocks} cannot be empty.

> +    if [ "${nb_blocks}" -eq 0 ]; then
> +        error "Error: The file system block count size cannot be zero. e.g. 61440 == 60MB \n"
> +    fi

See my reply to the previous commit: I don't see why 0 should be
checked specifically. Please explain in the commit log why it should be.

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

[Buildroot] [PATCH 1/2] ext2.mk: ensure file system block count is not zero (0)

[Yann E. MORIN]

J, Thomas, All,

On 2017-04-29 21:03 +0200, Thomas Petazzoni spake thusly:
> On Sat, 29 Apr 2017 17:01:21 +0100, J Evans wrote:
> 
> > -ifneq ($(strip $(BR2_TARGET_ROOTFS_EXT2_BLOCKS)),0)
> > +ifeq ($(strip $(BR2_TARGET_ROOTFS_EXT2_BLOCKS)),0)
> > +$(error BR2_TARGET_ROOTFS_EXT2_BLOCKS cannot be zero (0))
> > +else
> >  EXT2_OPTS += -b $(BR2_TARGET_ROOTFS_EXT2_BLOCKS)
> >  endif
> 
> What is the motivation for checking that the size is not zero? Zero is
> like any other size too small to contain the target directory contents,
> so I don't see why we would add a specific check for it.

I agree, and that's exactly what I said in my review to the previous
iteration of the patch.

Just remove the check and keep the line:

    EXT2_OPTS += -b $(BR2_TARGET_ROOTFS_EXT2_BLOCKS)

Regards,
Yann E. MORIN.

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'

[Buildroot] [PATCH 2/2] mke2img: add parameter sanity checks to prevent odd error messages from genext2.fs

[Yann E. MORIN]

Thomas, All,

On 2017-04-29 21:06 +0200, Thomas Petazzoni spake thusly:
> Hello,
> 
> On Sat, 29 Apr 2017 17:01:22 +0100, J Evans wrote:
> 
> > +    if [ -z "${nb_blocks}" ]; then
> > +        error "Error: you must specify a file system block count with '-b'. This cannot be zero, e.g. 61440 == 60MB\n"

Really, just state that it must be specified, this the value is
explained in the help text.

    error "Error: you must specify a file system block count with '-b'.\n"

However, please also update the help text at the end of the script,m to
remove a hint about auto calculation:

    https://git.buildroot.org/buildroot/tree/package/mke2img/mke2img#n152

    -b BLOCKS
        Create a filesystem of BLOCKS 1024-byte blocs. The default is to
        compute the required number of blocks.

> > +    fi
> 
> Check this is useless: there is already error checking done by getopt
> itself, because the -b option *must* have an argument. Indeed, the
> current mke2img behaves like this:
> 
> $ ./package/mke2img/mke2img -b
> mke2img: option 'b' expects a mandatory argument
> 
> So it is already checked that ${nb_blocks} cannot be empty.

But if you don't pass the -b option, then nb_blocks *is* unset.

Adding the check is correct in my opinion.

> > +    if [ "${nb_blocks}" -eq 0 ]; then
> > +        error "Error: The file system block count size cannot be zero. e.g. 61440 == 60MB \n"
> > +    fi
> 
> See my reply to the previous commit: I don't see why 0 should be
> checked specifically. Please explain in the commit log why it should be.

Agreed, a zero size is like specifying any size that is too small to fit
the content of target/. There is no way we can check that the given size
is correct.

zero if of course special, because we *know* it is incorrect. But since
this is not the default value, the user would have explicitly set it to
zero. Which is justa little tad stupid to begin with.

As I previously said: I really don't see the point of checking that the
size is not zero.

Just keep the text tht nb_blocks is set, though, because it is required.

Regards,
Yann E. MORIN.

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'

[Buildroot] [PATCH 2/2] mke2img: add parameter sanity checks to prevent odd error messages from genext2.fs

[Thomas Petazzoni]

Hello,

On Sun, 30 Apr 2017 11:25:33 +0200, Yann E. MORIN wrote:

> > $ ./package/mke2img/mke2img -b
> > mke2img: option 'b' expects a mandatory argument
> > 
> > So it is already checked that ${nb_blocks} cannot be empty.  
> 
> But if you don't pass the -b option, then nb_blocks *is* unset.
> 
> Adding the check is correct in my opinion.

Ah, yes agreed.

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

[Buildroot] [PATCH 1/2] ext2.mk: ensure file system block count is not zero (0)

[jerry at chordia.co.uk]

Yann, all

> 
> Just remove the check and keep the line:
> 
>     EXT2_OPTS += -b $(BR2_TARGET_ROOTFS_EXT2_BLOCKS)

Yes, ideal. That will satisfy us both and (most importantly) make sure the
user cannot get this otherwise hard to debug error:

"genext2fs: Too many arguments. Try --help or else see the man page." 

BTW many thanks for patience etc. with this shower of patches.

BR,

Jerry.