gmt-makemap/modules/gmt/modgmt.cpp

#include "modgmt.h"

#if defined MODGMT_WORKAROUND_EXIT
// Exit handler.
static void gmtonexithandler(int ret, void* x)
{
 reinterpret_cast<struct gmtworkthreadpars*>(x)->ret=ret;
 close(reinterpret_cast<struct gmtworkthreadpars*>(x)->fd);
 pthread_exit(&(reinterpret_cast<struct gmtworkthreadpars*>(x)->ret));
}
#endif

// This function call GMT_Call_Module in separate thread. It just a hack to workaround absence of callbacks.
static void* gmtworkthread(void* x)
{
 struct gmtworkthreadpars* p=reinterpret_cast<struct gmtworkthreadpars*>(x);
#if defined MODGMT_WORKAROUND_EXIT
 on_exit(gmtonexithandler,x);
#endif
 GMT_Append_Option(p->api,GMT_Make_Option(p->api,'>',const_cast<char*>(("/dev/fd/"+std::to_string(p->fd)).c_str())),p->opts);
 p->ret=GMT_Call_Module(p->api,p->module,GMT_MODULE_OPT,p->opts);
#if defined MODGMT_WORKAROUND_EXIT
 exit(p->ret);
#endif
 close(p->fd);
 return &p->ret;
}

// Wrapper for GMT_Call_Module, res is output.
int callgmtmodule(void *api, const char *module, struct GMT_OPTION *opts, std::string& res)
{
 int pipefd[2];
 ssize_t br;
 char buffer[4096];
 pthread_t wthr;
 struct gmtworkthreadpars p;
 int *pret;

 pipe(pipefd);
 p.api=api;
 p.module=module;
 p.opts=opts;
 p.fd=pipefd[1];

 pthread_create(&wthr,0,&gmtworkthread,&p);

 res.erase();
 do
 {
  br=read(pipefd[0],buffer,4096);
  res.append(buffer,br);
 } while(0!=br);
 close(pipefd[0]);
 res.shrink_to_fit();
 pthread_join(wthr,reinterpret_cast<void**>(&pret));

 return *pret;
}


// Initialisation function
int gmt_module_init(void* p)
{
 // Fill header and footer
 struct GMT_OPTION* opts;
 void* gmtapi;
 int ret;
 const char* ch="--GMT_HISTORY=f -C -P -K";
 const char* cf="--GMT_HISTORY=f -C -P -O";
 char* h=strdup(ch);
 char* f=strdup(cf);

 gmtapi=GMT_Create_Session("gmt_makemap",2,3,0);
 if(0==gmtapi) return 1;
 opts=GMT_Create_Options(gmtapi,0,h);
 ret=callgmtmodule(gmtapi,"psclip",opts,header);
 GMT_Destroy_Options(gmtapi,&opts);
 opts=GMT_Create_Options(gmtapi,0,f);
 if(0==ret) ret=callgmtmodule(gmtapi,"psclip",opts,footer);
 GMT_Destroy_Options(gmtapi,&opts);
 GMT_Destroy_Session(gmtapi);
 free(h); free(f);
 if(0!=ret) return ret;

 return 0;
}