please devendor json-c

[alexmyczko]

can you add cmake option to use system json-c? most people do not want code duplication

ERROR: Subproject json-c is buildable: NO

affected version: 26.03.0

i found no option for cmake to use system json-c (checked with ccmake . # in build dir)

[vonericsen]

We can look into how to do this through an option.

[shriya-deshmukh]

Hi @alexmyczko,

I have added an option to the meson.build file to use a system-installed json-c library if available.

Please check the **feature/Issue-299** branch.
How it works:
The build system now supports the -Duse_system_json=true option (requires -Djson_outputformat=true). When enabled, it uses the following strategy:

1. First Attempts to find json-c via pkg-config
2. If pkg-config is unavailable, uses find_library() to locate the library and has_header() to verify headers are present
3. If neither method succeeds, it builds json-c from the bundled subproject.

Please try this branch and let us know if it resolves your issue or improves your build experience. Any feedback would be greatly appreciated!

[alexmyczko]

so i'm calling meson right:

make[1]: Entering directory '/home/tar/debian/openseachest/openseaches
t-26.03.0+ds'                                                         
dh_auto_configure -- \                                                
-Duse_system_json=true \                                              
-Djson_outputformat=true \                                            
                                                                      
        cd obj-aarch64-linux-gnu && DEB_PYTHON_INSTALL_LAYOUT=deb LC_A
LL=C.UTF-8 meson setup .. --wrap-mode=nodownload --buildtype=plain --p
refix=/usr --sysconfdir=/etc --localstatedir=/var --libdir=lib/aarch64
-linux-gnu -Dpython.bytecompile=-1 -Duse_system_json=true -Djson_outpu
tformat=true                                                          
The Meson build system             

but still get

ERROR: Subproject json-c is buildable: NO                             
                                                                      
../subprojects/opensea-jsonformat/meson.build:326:8: ERROR: Neither a 
subproject directory nor a json-c.wrap file was found.   

i took meson.build and meson_options.txt from your branch.

have libjsoncpp-dev:arm64 1.9.6-5

and libjson-c-dev:arm64 0.18+ds-3

[shriya-deshmukh]

From error it looks like it is falling back to building from the subproject module.

With current approach it could be due to,

1. pkg-config can't find system json-c package
2. json-c headers are missing but the library is present
3. Or if json-c isn't installed

Could you help us checking if json-c is available on your system?
Please run:

pkg-config --list-all | grep json
ls -la /usr/include/json-c/
find /usr/lib /usr/local/lib -name "libjson-c.so*"

If the above doesn't clarify the issue, please share your meson.log file from the build directory

Also, please let us know your input on the design:

whether -Duse_system_json=true should:

Option A (Current): Try system detection, but silently fall back to subproject if not found
Option B (Proposed): Fail with clear instructions if system json-c isn't available

Which approach would be more helpful for your use case?

[alexmyczko]

tar@orange:~/debian/colmap/colmap-4.0.2$ pkg-config --list-all | grep json

libcjson_utils                 libcjson_utils - An implementation of JSON Pointer, Patch and Merge Patch based on cJSON.
json-glib-1.0                  JSON-GLib - JSON Parser for GLib.
jsoncpp                        jsoncpp - A C++ library for interacting with JSON
json-c                         json-c - A JSON implementation in C
libcjson                       libcjson - Ultralightweight JSON parser in ANSI C
libcjson_utils                 libcjson_utils - An implementation of JSON Pointer, Patch and Merge Patch based on cJSON.
json-glib-1.0                  JSON-GLib - JSON Parser for GLib.
jsoncpp                        jsoncpp - A C++ library for interacting with JSON
json-c                         json-c - A JSON implementation in C
libcjson                       libcjson - Ultralightweight JSON parser in ANSI C
nlohmann_json                  nlohmann_json - JSON for Modern C++
tar@orange:~/debian/colmap/colmap-4.0.2$ ls -la /usr/include/json-c/
total 184
drwxr-xr-x   2 root root  4096 Mar  6 16:49 .
drwxr-xr-x 397 root root 36864 Mar 18 15:22 ..
-rw-r--r--   1 root root  2592 Sep 15  2024 arraylist.h
-rw-r--r--   1 root root  2703 Sep 15  2024 debug.h
-rw-r--r--   1 root root   834 Feb 12 12:12 json.h
-rw-r--r--   1 root root  1368 Sep 15  2024 json_c_version.h
-rw-r--r--   1 root root   183 Feb 12 12:12 json_config.h
-rw-r--r--   1 root root   675 Sep 15  2024 json_inttypes.h
-rw-r--r--   1 root root 44635 Sep 15  2024 json_object.h
-rw-r--r--   1 root root  8394 Sep 15  2024 json_object_iterator.h
-rw-r--r--   1 root root  2455 Sep 15  2024 json_patch.h
-rw-r--r--   1 root root  4532 Sep 15  2024 json_pointer.h
-rw-r--r--   1 root root 10613 Sep 15  2024 json_tokener.h
-rw-r--r--   1 root root  1666 Sep 15  2024 json_types.h
-rw-r--r--   1 root root  3920 Sep 15  2024 json_util.h
-rw-r--r--   1 root root  3175 Sep 15  2024 json_visit.h
-rw-r--r--   1 root root 12380 Sep 15  2024 linkhash.h
-rw-r--r--   1 root root  4353 Sep 15  2024 printbuf.h
tar@orange:~/debian/colmap/colmap-4.0.2$ find /usr/lib /usr/local/lib -name "libjson-c.so*"

/usr/lib/aarch64-linux-gnu/libjson-c.so.5.4.0
/usr/lib/aarch64-linux-gnu/libjson-c.so
/usr/lib/aarch64-linux-gnu/libjson-c.so.5

[alexmyczko]

to answer your question, excerpt from debian/copyright:

Files-Excluded:                                                                
 subprojects/json-c                                                            
Comments:                                                                      
 devendor                

which means the orig.tar.gz distributed by debian, and being +ds (=debian source), i package a tarball without the vendored stuff

i don't care much if it is A or B, but would prefer B, as A will lead nowhere for the reason given above.

[shriya-deshmukh]

I have implemented option B - Fail with clear instructions if system json-c isn't available

Please check the updated meson.build files here:

• Add option to build using system json-c library #309
• Add option to build using system json-c library  opensea-jsonformat#2

Could you please test the latest code with -Duse_system_json=true.
Make sure you are using updated meson files for both openseachest and opensea-jsonformat subproject.