Re: scratch_buffer: Document the exported API

[Bruno Haible]

Paul Eggert wrote:
> The idea was that the gl_* symbols would not compete with the like-named 
> __libc_* symbols when Gnulib dynarray is built under glibc. I don't 
> recall the details about the competition, unfortunately.

Ah, it's to avoid conflicts with glibc. I thought it was pure convenience.

Indeed, glibc exports lots of __libc_* symbols:

$ nm --dynamic /lib/x86_64-linux-gnu/libc.so.6 | grep __libc_
0000000000114b30 T __libc_alloca_cutoff
00000000000368a0 T __libc_allocate_rtsig
00000000000368a0 T __libc_allocate_rtsig_private
0000000000084d80 T __libc_calloc
0000000000136280 T __libc_clntudp_bufcreate
0000000000036890 T __libc_current_sigrtmax
0000000000036890 T __libc_current_sigrtmax_private
0000000000036880 T __libc_current_sigrtmin
0000000000036880 T __libc_current_sigrtmin_private
0000000000143820 T __libc_dlclose
0000000000143e20 T __libc_dl_error_tsd
00000000001436d0 T __libc_dlopen_mode
0000000000143770 T __libc_dlsym
                 U __libc_enable_secure
0000000000077800 T __libc_fatal
00000000000cc3c0 T __libc_fork
0000000000084540 T __libc_free
0000000000174410 T __libc_freeres
0000000000106340 T __libc_ifunc_impl_list
00000000000205a0 T __libc_init_first
0000000000035270 T __libc_longjmp
0000000000086ef0 T __libc_mallinfo
0000000000084180 T __libc_malloc
00000000000852e0 T __libc_mallopt
0000000000084b10 T __libc_memalign
00000000000f5b20 T __libc_pread
0000000000115270 T __libc_pthread_init
0000000000086940 T __libc_pvalloc
00000000000f5b80 T __libc_pwrite
0000000000084710 T __libc_realloc
0000000000137e50 T __libc_rpc_getport
0000000000108b20 T __libc_sa_len
0000000000089710 T __libc_scratch_buffer_grow
0000000000089790 T __libc_scratch_buffer_grow_preserve
0000000000089840 T __libc_scratch_buffer_set_array_size
0000000000039f00 W __libc_secure_getenv
0000000000035270 T __libc_siglongjmp
0000000000020750 T __libc_start_main
00000000000453a0 T __libc_system
00000000001751e0 T __libc_thread_freeres
0000000000086690 T __libc_valloc
00000000000cc740 T __libc_vfork

Worth a comment.


2021-03-06  Bruno Haible  <bruno@clisp.org>

        scratch_buffer: Add comment.
        * lib/scratch_buffer.h: Add comment.

diff --git a/lib/scratch_buffer.h b/lib/scratch_buffer.h
index f4b5f9e..da4455d 100644
--- a/lib/scratch_buffer.h
+++ b/lib/scratch_buffer.h
@@ -112,10 +112,12 @@ extern void *scratch_buffer_dupfree (struct 
scratch_buffer *buffer,
 
 #include <libc-config.h>
 
+/* Avoid possible conflicts with symbols exported by the GNU libc.  */
 #define __libc_scratch_buffer_dupfree gl_scratch_buffer_dupfree
 #define __libc_scratch_buffer_grow gl_scratch_buffer_grow
 #define __libc_scratch_buffer_grow_preserve gl_scratch_buffer_grow_preserve
 #define __libc_scratch_buffer_set_array_size gl_scratch_buffer_set_array_size
+
 #include <malloc/scratch_buffer.h>
 
 #endif /* _GL_SCRATCH_BUFFER_H */