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ext2.mk: ensure file system block count is not zero (0)

PATCH New J Evans 4 participants 8 messages Apr 29, 2017 – Apr 30, 2017 ext2 file system

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J Evans

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#0 lore raw

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

---
 fs/ext2/ext2.mk | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
fs/ext2/ext2.mk +3 -1
index 30f1d17..3a0c764 100644
@@ -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
 
Signature · 1 line
2.7.4
author
#1 lore raw

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

---
 package/mke2img/mke2img | 6 ++++++
 1 file changed, 6 insertions(+)
package/mke2img/mke2img +6 -0
index b773aa9..c50dc66 100755
@@ -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)
         ;;
Signature · 1 line
2.7.4
#2 lore raw

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

Hello,

package/mke2img/mke2img main() { · line 49

Quoted 3 lines · J Evans
package/mke2img/mke2img +3 -0
+    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.

package/mke2img/mke2img main() { · line 52

Quoted 3 lines
package/mke2img/mke2img +3 -0
+    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

Signature · 3 lines
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
#3 lore raw

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

Thomas, All,

On 2017-04-29 21:06 +0200, Thomas Petazzoni spake thusly:

Quoted 6 lines

Hello,

Quoted 2 lines · J Evans
package/mke2img/mke2img +2 -0
+    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.

Quoted 10 lines
Quoted 1 line

+ 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.

Quoted 6 lines

package/mke2img/mke2img main() { · line 52

Quoted 3 lines
package/mke2img/mke2img +3 -0
+    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.

Signature · 6 lines
.-----------------.--------------------.------------------.--------------------.
|  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.  |
'------------------------------^-------^------------------^--------------------'
#4 lore raw

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

Hello,

Quoted 8 lines · Yann E. MORIN
Quoted 4 lines
$ ./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

Signature · 3 lines
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
#5 lore raw

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

In reply to J Evans

Hello,

fs/ext2/ext2.mk line 13

Quoted 6 lines · J Evans
fs/ext2/ext2.mk +3 -1
-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

Signature · 3 lines
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
#6 lore raw

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

J, Thomas, All,

On 2017-04-29 21:03 +0200, Thomas Petazzoni spake thusly:

Quoted 12 lines · J Evans

fs/ext2/ext2.mk line 13

Quoted 7 lines
fs/ext2/ext2.mk +3 -1
-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.

Signature · 6 lines
.-----------------.--------------------.------------------.--------------------.
|  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.  |
'------------------------------^-------^------------------^--------------------'
#7 lore raw

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

Yann, all

Quoted 4 lines

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.