General code issues

[ahkok]

Some basic default compiler warnings are thrown. You will want to fix these (fairly trivial)

gcc -DHAVE_CONFIG_H -I. -fPIC -O2 -g -Wall -W -Wformat-security -D_FORTIFY_SOURCE=2 -fno-common -std=gnu99 -g -O3 -feliminate-unused-debug-types -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=32 -Wformat -Wformat-security -m64 -fasynchronous-unwind-tables -Wp,-D_REENTRANT -ftree-loop-distribute-patterns -Wl,-z -Wl,now -Wl,-z -Wl,relro -fno-semantic-interposition -ffat-lto-objects -fno-signed-zeros -fno-trapping-math -fassociative-math -Wl,-sort-common -Wl,--enable-new-dtags -mtune=skylake -MT libwhich.lo -MD -MP -MF .deps/libwhich.Tpo -c libwhich.c  -fPIC -DPIC -o .libs/libwhich.o
libwhich.c:197:22: warning: ‘struct dl_phdr_info’ declared inside parameter list will not be visible outside of this definition or declaration
  197 | int get_names(struct dl_phdr_info *info, size_t size, void *data)
      |                      ^~~~~~~~~~~~
libwhich.c: In function ‘get_names’:
libwhich.c:200:13: error: dereferencing pointer to incomplete type ‘struct dl_phdr_info’
  200 |     if (info->dlpi_name[0]) {
      |             ^~
libwhich.c:197:49: warning: unused parameter ‘size’ [-Wunused-parameter]
  197 | int get_names(struct dl_phdr_info *info, size_t size, void *data)
      |                                          ~~~~~~~^~~~
libwhich.c: In function ‘dllist’:
libwhich.c:210:5: warning: implicit declaration of function ‘dl_iterate_phdr’ [-Wimplicit-function-declaration]
  210 |     dl_iterate_phdr(get_names, (void*)&dynamic_libraries);
      |     ^~~~~~~~~~~~~~~
libwhich.c: In function ‘dlpath’:
libwhich.c:217:5: warning: implicit declaration of function ‘dlinfo’ [-Wimplicit-function-declaration]
  217 |     dlinfo(handle, RTLD_DI_LINKMAP, &map);
      |     ^~~~~~
libwhich.c:217:20: error: ‘RTLD_DI_LINKMAP’ undeclared (first use in this function)
  217 |     dlinfo(handle, RTLD_DI_LINKMAP, &map);
      |                    ^~~~~~~~~~~~~~~
libwhich.c:217:20: note: each undeclared identifier is reported only once for each function it appears in
libwhich.c:214:50: warning: unused parameter ‘name’ [-Wunused-parameter]
  214 | const char *dlpath(void *handle, struct vector_t name)
      |                                  ~~~~~~~~~~~~~~~~^~~~

[ahkok]

#define _GNU_SOURCE
#include <link.h>
#include <dlfcn.h>

are needed for dlinfo()

[vtjnash]

It seems like you aren't using the provided makefile, as these are already part of it.

[ahkok]

Can you please consider doing the sensible thing and autoscan the project and not have hand coded build scripts? Set an SOVER, use autotools to properly install, add a pkg-config file, etc...?

[vtjnash]

There's no shared libraries, just a single binary file