I want to develop a small program that checks which polygons from a shapefile intersect a given rectangle. This program is to be used in a website (with PHP's exec()
command). The problem is, my webserver cannot install GDAL, for reasons unknown to me. So I can't link to the shared libraries. Instead, I must link to static libraries, but these aren't given.
I've downloaded the GDAL source code from here (2.3.2 Latest Stable Release - September 2018), and followed the build instructions from here. Since I already have GDAL working on my Debian, and don't want to mess with it, I followed the "Install in non-root directory" instructions, with some adjusts from the last item in the "Some caveats" section:
cd /home/rodrigo/Downloads/gdal232/gdal-2.3.2
mkdir build
./configure --prefix=/home/rodrigo/Downloads/gdal232/gdal-2.3.2/build/ --without-ld-shared --disable-shared --enable-static
make
make install
export PATH=/home/rodrigo/Downloads/gdal232/gdal-2.3.2/build/bin:$PATH
export LD_LIBRARY_PATH=/home/rodrigo/Downloads/gdal232/gdal-2.3.2/build/lib:$LD_LIBRARY_PATH
export GDAL_DATA=/home/rodrigo/Downloads/gdal232/gdal-2.3.2/build/share/gdal
/usr/bin/gdalinfo --version
build/bin/gdalinfo --version
The first /usr/bin/gdalinfo --version
gives 2.1.2 (the previous installed version). The second, build/bin/gdalinfo --version
, gives 2.3.2 (the version just built).
By now, my program only uses the ogrsf_frmts.h
header, which is in /usr/include/gdal/
or /home/rodrigo/Downloads/gdal232/gdal-2.3.2/build/include/
directory, depending on the build. There's no ogrsf_frmts.a
file, but only a libgdal.a
. Is this the file I should be linking against? If so, how? I've tried so far:
gcc geofragc.cpp -l:libgdal.a
gcc geofragc.cpp -Wl,-Bstatic -l:libgdal.a
gcc geofragc.cpp -Wl,-Bstatic -l:/home/rodrigo/Downloads/gdal232/gdal-2.3.2/build/lib/libgdal.a
gcc geofragc.cpp -Wl,-Bstatic -l/home/rodrigo/Downloads/gdal232/gdal-2.3.2/build/lib/libgdal.a
gcc geofragc.cpp /home/rodrigo/Downloads/gdal232/gdal-2.3.2/build/lib/libgdal.a
gcc geofragc.cpp -l/home/rodrigo/Downloads/gdal232/gdal-2.3.2/build/lib/libgdal.a
gcc geofragc.cpp -l:/home/rodrigo/Downloads/gdal232/gdal-2.3.2/build/lib/libgdal.a
but nothing works. What am I missing?
EDIT
The second trial (gcc geofragc.cpp -Wl,-Bstatic -l:libgdal.a
) is giving the following error:
/usr/bin/ld: cannot find -lgcc_s
/usr/lib/gcc/x86_64-linux-gnu/6/../../../../lib/libgdal.a(gdalclientserver.o): In function `GDALServerSpawnAsync()':
(.text+0x1f5e): warning: Using 'getaddrinfo' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: cannot find -lgcc_s
collect2: error: ld returned 1 exit status
BuildingOnUnix – GDAL GDAL has been successfully built on Linux, IRIX, Solaris, BSD, and MacOS X. On Unix platforms you might be able to build it as follows (assuming it is unpacked or checked out of subversion as gdal):
Control whether a found dependency can be used for the GDAL build. It is also possible to ask GDAL to disable the use of any external dependency (besides the required one, PROJ) by default by setting the following option to OFF. Individual libraries shall then be enabled explicitly with GDAL_USE_<Packagename_in_upper_case>:BOOL=ON. Defaults to ON.
GDAL, and it's utilities should now build on Cygwin and other platforms where shared libraries are not supported. However, to build your own applications against it, you will need to link against a more extensive set of libraries. The gdal-config --libs command can be used to determine the library set.
The path to the external GDAL module is set and the library is built using the NDK's build process. Finally, the Java portion that uses the JNI library. You can build and adapt the Java Swig bindings to expose whole GDAL API to the Java portion of an Android application.
You can use the gdal-config
program to get correct options for compilation and linking. This program is a part of the GDAL library and it has its own options:
hekto@ubuntu:~$ gdal-config --help
Usage: gdal-config [OPTIONS]
Options:
[--prefix[=DIR]]
[--libs]
[--dep-libs]
[--cflags]
[--datadir]
[--version]
[--ogr-enabled]
[--gnm-enabled]
[--formats]
You have to make sure this program is on your search path, or you can create an alias - for example:
alias gdal-config='/home/rodrigo/Downloads/gdal232/gdal-2.3.2/bin/gdal-config'
Now your compilation and linking command becomes the following one:
g++ `gdal-config --cflags` geofragc.cpp `gdal-config --libs` `gdal-config --dep-libs`
You have to use the g++
compiler to link with C++-built libraries.
Another option is to create a Makefile
with these lines:
CXXFLAGS += ${shell gdal-config --cflags}
LDLIBS += ${shell gdal-config --libs}
LDLIBS += ${shell gdal-config --dep-libs}
geofragc: geofragc.cpp
and just call make
with this Makefile
.
I hope, it'll help.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With