[Mac OS] error: implicitly declaring library function 'strdup'

[bogdan0083]

Hi! 👋

I'm having issue building the sph2pipe on Mac OS Sonoma and Xcode 15. Here are the errors:

cc -o sph2pipe -s -w -g -O2  file_headers.c shorten_x.c sph2pipe.c -lm
file_headers.c:100:17: error: call to undeclared library function 'strdup' with type 'char *(const char *)'; ISO C99 and later do not support i
mplicit function declarations [-Wimplicit-function-declaration]
            inporder = strdup( fldsval );
                       ^
file_headers.c:100:17: note: include the header <string.h> or explicitly provide a declaration for 'strdup'
1 error generated.
sph2pipe.c:213:16: error: call to undeclared library function 'strdup' with type 'char *(const char *)'; ISO C99 and later do not support impli
cit function declarations [-Wimplicit-function-declaration]
            hdrfile = strdup( optarg );
                      ^

Here's similar issue in other project. They fixed it by defining _DARWIN_C_SOURCE. Like this:

file_headers.c:

#define _XOPEN_SOURCE 500  /* See feature_test_macros(7) */
#define _DARWIN_C_SOURCE
#include <math.h>
#include <string.h>
#include <unistd.h>

/* code goes on ... */

sph2pipe.c:

#define _SPH_CONVERT_MAIN_
#define _XOPEN_SOURCE 500  /* See feature_test_macros(7) */
#define _DARWIN_C_SOURCE
#include <string.h>
#include <unistd.h>

/* code goes on ... */

I might send PR if you are interested in fixing it. I'm not very proficient in C code and don't know if those changes could break anything, but I can confirm that the changes are working. After adding those headers code builds just fine.

Thanks!