ephemeris.c

/* 
   ephemeris via fastcgi 

   See http://swepar.blogspot.ch/2015/07/ein-exkurs-fast-cgi.html

*/

#include "ephemeris.h"

int main (int argc, char** argv) {

    query q = {};
    result r = {};
    
    char ephepath[MAXLEN_EPHE_PATH];
    initializations( ephepath );  

    swe_set_ephe_path( ephepath );

    while (FCGI_Accept() >= 0) {
      init_request(&q,&r);
      TRY {  
        const char *qs = getenv("QUERY_STRING");
        if (qs) {
          parse(qs, &q);
          compute(&q,&r);
          }
        output(&q,&r);
        }
      CATCH {
        do_header( );
        printf("error: %s \n",r.error);
        }  
     
    } /* while */

    return 0;

}

// The core part: Do the computations
void compute( query* q, result* r) {
  if (q->nplanets) compute_planets(q,r);
  if (q->house_system) compute_houses(q,r);
}

// Calls swe_calc_ut
void compute_planets(query* q, result* r) {
  if (q->nplanets == 0) return;
  if (!q->jd_given) THROW( r->error, "Specify Julian Date in UT (jd) for planet computation!" );
  r->ppos = malloc( q->nplanets*sizeof(double) );
  for (int i = 0; i < q->nplanets; i++) {
    double xx[6] = {};
    char serr[255] = "";
    int ipl = q->planets[i];
    int iret = swe_calc_ut( q->jd, ipl, q->iflag, xx, serr);
    if (iret < 0) {
      THROW( r->error, "Error from swe_calc: %s",serr);
    }
    strcpy(r->warning,serr);
    r->ppos[i] = xx[0];
  }
}

// Calls swe_houses
void compute_houses(query* q, result* r) {
  
  double cusps[13],armc[10];

  if (!q->lon_given) THROW( r->error, "Specify longitude (lon) for houses!" );
  if (!q->lat_given) THROW( r->error, "Specify latitude (lat) for houses!" );
  if (!q->jd_given)  THROW( r->error, "Specify Julian Date in UT (jd) for houses!" );
  
  int rc = swe_houses( q->jd, q->lat, q->lon, (int) q->house_system, cusps, armc ); 
 
  for (int i=0;i<12;i++) r->hpos[i] = cusps[i+1];    

  if (rc != 0) THROW( r->error,"Error code %d when computing house cusps", rc );

  }

// Write result to output
void output(query* q,result* r) {
      do_header( );
      if (q->nplanets) {
        printf("planets:");
        print_numbers( r->ppos, q->nplanets);
        printf("\r\n");
      }
      if (q->house_system) {
        printf("houses:");
        print_numbers( r->hpos, 12);
        printf("\r\n");
        }
      if (q->debug) {
        printf("pid: %d\r\n", getpid());
        }
      if (r->warning[0]) {
        for (char* x=r->warning;*x!='\0';x++) {
          if (*x=='\r') *x = ';';
          if (*x=='\n') *x = ' ';
          }
        printf("warning: %s",r->warning);
      }
  }

// Output a list of numbers
// Using sprintf on an auxiliary string
// There was a problem with printf("...%.lf...") in fastcgi
// See http://stackoverflow.com/questions/31525028/printf-swallowing-bytes-in-fcgi-mode
void print_numbers( double* numbers, int n) {
  if (n<=0) return;
  char s[15],t[n*15];
  *t = '\0';
  for (int i=0;i<n;i++) {
    sprintf(s,"%s%.4lf",i>0?",":"",numbers[i]);
    strcat(t,s);
    }
  printf(t);
}

// Generates the HTTP header part of the response
void do_header() {
  printf("Content-type: text/plain\r\n\r\n");
  }

// Parse the query string
void parse( const char *query_string, query *q) {
  char *from, *to, *end;
// Copy query string, to preserve the original
  int len = strlen(query_string);
  char qs[len+1];
  strcpy(qs,query_string);
  end = qs + len;
// Split up qs along '&', parse single parameters
  for( from = qs; from < end; from=to+1) {
    if ((to = strchr(from,'&'))) *to = '\0';
    if (strlen(from)==0) continue;
// Read the single parameter
    analyze_parameter(from,q);
    if (to==NULL) break;  
    }

}

// Parse a single parameter
void analyze_parameter( char *par, query *q ){

  char *name = par, *value;

// May be "name" or "name=value"
  value = strchr(par,'=');
  if (value) {
    *value = '\0';
    value++;
    }
  else value = "";
  if (*name == '\0') return;

// Specific parsing for specific parameters:
  if (strcmp(name,"jd")==0) {
    if (sscanf(value,"%lf",&q->jd)==0) {
      THROW( q->error, "Invalid Julian Date value '%s' (must be a number)", value);
      }
    if (q->jd < SWIEPH_START || q->jd > SWIEPH_END) {
      THROW( q->error,
       "Julian Date %lf out of bounds" 
       "(must be between %lf and %lf )",
       q->jd,SWIEPH_START,SWIEPH_END);
      }
    q->jd_given = true;
    }    
  else if (strcmp(name,"lon")==0) {
    if (sscanf(value,"%lf",&q->lon)==0) {
      THROW( q->error,
       "Invalid longitude '%s' (must be a decimal number)", value);
      }    
    q->lon_given = true;       
    }
  else if (strcmp(name,"lat")==0) {
    if (sscanf(value,"%lf",&q->lat)==0) {
      THROW( q->error,
        "Invalid latitude '%s' (must be a decimal number)", value);
      } 
    q->lat_given = true;       
    }
  else if (strcmp(name,"iflag")==0) {
    if (strlen(value) == 0) q->iflag = 0;
    else if (sscanf(value,"%d",&q->iflag)==0) {
      THROW( q->error,
        "Could not read iflag '%s' - must be a number", value);
      }    
    }
  else if (strcmp(name,"planets")==0) {
    parse_planets(value, q );
    }
  else if (strcmp(name,"houses")==0) {
    parse_house_system( value, q);
    }
  else if (strcmp(name,"debug")==0) {
    q->debug = true;
    }
      

}


// "planets" = list of Swiss Ephemeris object numbers
void parse_planets(char* input, query* q) {

  if (strlen(input)==0) {
// Default set of Planets: Sun, Moon, Mercury .. Pluto
    q->nplanets = 10;
    q->planets  = malloc( 10*sizeof(int));
    memcpy( q->planets, (int[]) { 0,1,2,3,4,5,6,7,8,9}, 10*sizeof(int) );
    }
  else {
// planet numbers from the parameter
    q->nplanets = parse_csv_integers(input,& q->planets, q->error );
  }


}

// "houses" = a letter, specifying the system to be used
void parse_house_system(char* input, query* q) {

  switch (strlen(input)) {
    case 0:
      q->house_system = 'P';  // Placidus is default
      return;
    case 1:
      if (strchr("KORCAEVWXHTBMUGY",*input)==NULL) {
        THROW( q->error,
           "Illegal house system identifier '%c'" 
           " - see programmer's manual for values",*input);
        }
      q->house_system = *input;
      return;
    default:
      THROW( q->error,
             "Specify exactly one house system (one letter)," 
             " or none to use default");
    }

}

// Read a list of integers, comma-separated
int parse_csv_integers(char* input, int** numbers, char* error) {
  int total;
  char *s = input,*t;
// Precompute total, for getting effective malloc size  
  for (total = 1; *s; total += (*s == ','), s++);
// Temporarily allocate the array on stack  
  int n[total];
  for (s=input,total=0;(t=strtok(s,","));s=NULL) {
    if (sscanf(t,"%d",n+total++)==0) {
      THROW( error, "Can't read number '%s'", t);
      }
    }
  *numbers = malloc( total*sizeof(int));
  memcpy( *numbers, n, total*sizeof(int) );
  return total;
  }

// Clear out all results from last computation
void init_request(query *q, result *r) {
  if (q->planets) { free(q->planets); }
  if (r->ppos) { free(r->ppos); }
  *q = EMPTY_QUERY;
  *r = EMPTY_RESULT;
  q->error = &(r->error[0]); 
  r->error[0] = r->warning[0] = '\0';
  }

// Read config file ".ephemeris" for initial settings
// Thus, 'ephepath' can be set at run time
void initializations( char* ephepath ) {
  strcpy(ephepath,EPHE_PATH);  // Default
  FILE *config = fopen(".ephemeris","r"); 
  if (config) {
    const int LINE_SIZE = 255;
    char line[LINE_SIZE+1],*name,*value,*p;
    while (fgets(line, LINE_SIZE,config) != NULL) {
      int i = strlen(line);
      if (i==0) continue;
      while (line[--i]=='\n') line[i] = '\0';
      for (name  = line;*name !='\0' && isspace(*name);name++);
      value = strchr(line,'=');
      if (value) {
        *value ='\0';
        p = value;
        for (p=value-1;isspace(*p);p--) *p ='\0';       
        for (value++;isspace(*value);value++);
        if (strcmp(name,"ephepath")==0) {
          strcpy(ephepath,value);
          }   
        }            
      }
    fclose(config);
    }
  }