curl: add command line option to prohibit overwriting files

[cvengler]

About

This adds the parameter '--override' and '--no-override'.
If '--no-override' is set, file eutputs will fail if the file
already exists.
'--override' will change nothing.

Testing (Unix)

This happens in the root git directory.
Please adjust it to your system/config.

touch test
src/curl --no-override -o test https://www.emilengler.com

This will result in

curl: option -o: file exists and override is blocked
curl: try 'curl --help' or 'curl --manual' for more information

P.S: This is my first PR to this project so please correct me if I did some mistakes :)

[bagder]

Thanks!

To complete the work and have it "mergable", you also need to add documentation (see docs/cmdline-opts) and at least one test case that verifies it.

[bagder]

The CI failure is test 1139 which fails because the lack of docs for the flag.

[dfandrich]

On Sat, Sep 28, 2019 at 10:08:12PM -0700, Emil Engler wrote: This adds the parameter '--override' and '--no-override'.

IMHO --overwrite and --no-overwrite are more descriptive.

[cvengler]

@bagder What do you mean by lack of docs?
I have a docs/cmdline-opts/override.d

[bagder]

I have a docs/cmdline-opts/override.d

Oops, my mistake!

[cvengler]

@dfandrich 'override' is much more common.

grep -ro 'override' | wc -l
726
grep -ro 'overwrite' | wc -l
53

[cvengler]

@bagder Looks like it was malformed because I forgot an empty line at the end. Fixed it with 4850e30

[dfandrich]

The cases where "override" is used, the sense of the meaning is "override". In the cases where "overwrite" is used, the sense of the meaning is "overwrite". They are not synonyms. When overwriting a file, "overwrite" is the more correct term.

[jzakrzewski]

I'm with @dfandrich.
Basically one overrides an option but overwrites file/data.

[bagder]

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

[bagder]

The scan-build also warns:

tool_getparam.c:505:8: warning: Null pointer passed as an argument to a 'nonnull' parameter
    if(access(fname, F_OK) != -1)
       ^~~~~~~~~~~~~~~~~~~

[bagder]

Can I suggest a clearer wording that focuses on the use and the effects? Maybe something like this:

"This option allows curl to overwrite already existing files with the output options. If --no-overwrite is used, curl will instead return an error (which?) rather than overwriting an existing file. The default is to allow overwrites."

[cvengler]

@jzakrzewski Ok, I will change this to overwrite.
@bagder, could you rename the PR title to
"[param]: Add param to prohibit overwriting files"

[bagder]

@emilengler you can change the title yourself, right?

[bagder]

Windows build failures:

3>.\tool_getparam.c(520) : error C2220: warning treated as error - no 'object' file generated
3>.\tool_getparam.c(520) : warning C4100: 'overwrite_file_prohibit' : unreferenced formal parameter
3>.\tool_getparam.c(520) : warning C4100: 'fname' : unreferenced formal parameter

[cvengler]

@bagder No, only people with write access can change the title of a PR.
I will take a look at the windows errors soon

[jay]

Generally I'm not a fan of the way this was implemented, and does it serve a purpose to do prohibit overwriting a header filename or trace filename etc?

[jay]

we can't do printfs from these functions, it would need a warnf global I think. but a better idea is use stat or something else when access is not available

[cvengler]

stat still needs unistd.h I think

[cvengler]

Push

[jay]

I still don't like this idea, I think it is unnecessary to make it part of curl. It is easy enough in script to see if a file exists. In batch there's if not exist "filename" and in shell there's if [ ! -e "filename" ]

[cvengler]

Will close this because of inactivity.
Leaving this with up for grabs if someone is interested in taking it over