netcdf-c/libdispatch/durlmodel.c
Dennis Heimbigner 25d2e05444 Prepare for the path management code
Rename some files in prep for eventual implementation
of more comprehensive cross-platform file path management.
2020-10-13 19:12:15 -06:00

271 lines
6.8 KiB
C

/**
* @file
*
* URL Model Management.
*
* These functions support inferring the format X implementation for urls.
* It looks at various fragment (#...) pairs.
*
* Copyright 2018 University Corporation for Atmospheric
* Research/Unidata. See COPYRIGHT file for more info.
*/
#include "config.h"
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "ncdispatch.h"
#include "ncpathmgr.h"
#include "ncurlmodel.h"
/*
Define a table of legal mode string values.
Note that only cases that can currently
take URLs are included.
*/
static struct LEGALMODES {
const char* tag;
const int format; /* NC_FORMAT_XXX value */
const int implementation; /* NC_FORMATX_XXX value */
} legalmodes[] = {
/* Format X Implementation */
{"netcdf-3",NC_FORMAT_CLASSIC,NC_FORMATX_NC3},
{"classic",NC_FORMAT_CLASSIC,NC_FORMATX_NC3},
{"netcdf-4",NC_FORMAT_NETCDF4,NC_FORMATX_NC4},
{"enhanced",NC_FORMAT_NETCDF4,NC_FORMATX_NC4},
{"dap2",NC_FORMAT_CLASSIC,NC_FORMATX_DAP2},
{"dap4",NC_FORMAT_NETCDF4,NC_FORMATX_DAP4},
{"nczarr",NC_FORMAT_NETCDF4,NC_FORMATX_DAP4},
{NULL,0,0},
};
/* Define the known URL protocols and their interpretation */
static struct NCPROTOCOLLIST {
char* protocol;
char* substitute;
int implementation;
} ncprotolist[] = {
{"http",NULL,0},
{"https",NULL,0},
{"file",NULL,0},
{"dods","http",NC_FORMATX_DAP2},
{"dap4","http",NC_FORMATX_DAP4},
{NULL,NULL,0} /* Terminate search */
};
/* Parse a mode string at the commas nul terminate each tag */
static int
parseurlmode(const char* modestr0, char** listp)
{
int stat = NC_NOERR;
char* modestr = NULL;
char* p = NULL;
char* endp = NULL;
/* Make modifiable copy */
if((modestr=strdup(modestr0)) == NULL)
{stat=NC_ENOMEM; goto done;}
/* Split modestr at the commas or EOL */
p = modestr;
for(;;) {
endp = strchr(p,',');
if(endp == NULL) break;
/* Null terminate each comma-separated string */
*endp++ = '\0';
p = endp;
}
if(listp) *listp = modestr;
modestr = NULL;
done:
if(stat) {nullfree(modestr);}
return stat;
}
/* Parse url fragment for format etc. */
static int
url_getmodel(const char* modestr, NCmode* model)
{
int stat = NC_NOERR;
char* args = NULL;
char* p = NULL;
model->format = 0;
model->implementation = 0;
if((stat=parseurlmode(modestr,&args))) goto done;
p = args;
for(;*p;) {
struct LEGALMODES* legal = legalmodes;
while(legal->tag) {
if(strcmp(legal->tag,p)==0) {
if(model->format != 0 && legal->format != 0)
{stat = NC_EINVAL; goto done;}
if(model->implementation != 0 && legal->implementation != 0)
{stat = NC_EINVAL; goto done;}
if(legal->format != 0) model->format = legal->format;
if(legal->implementation != 0)
model->implementation = legal->implementation;
}
}
}
done:
nullfree(args);
return stat;
}
/**************************************************/
/**
* Provide a hidden interface to allow utilities
* to check if a given path name is really an ncdap3 url.
* If no, put null in basenamep, else put basename of the url
* minus any extension into basenamep; caller frees.
* Return 1 if it looks like a url, 0 otherwise.
*/
int
nc__testurl(const char* path, char** basenamep)
{
NCURI* uri;
int ok = 0;
if(ncuriparse(path,&uri) == NCU_OK) {
char* slash = (uri->path == NULL ? NULL : strrchr(uri->path, '/'));
char* dot;
if(slash == NULL) slash = (char*)path; else slash++;
slash = nulldup(slash);
if(slash == NULL)
dot = NULL;
else
dot = strrchr(slash, '.');
if(dot != NULL && dot != slash) *dot = '\0';
if(basenamep)
*basenamep=slash;
else if(slash)
free(slash);
ncurifree(uri);
ok = 1;
}
return ok;
}
/*
Fill in the model fields to degree possible.
Assumes that the path is known to be a url
*/
int
NC_urlmodel(const char* path, int cmode, char** newurl, NCmode* model)
{
int stat = NC_NOERR;
int found = 0;
struct NCPROTOCOLLIST* protolist;
NCURI* url = NULL;
const char** fragp = NULL;
if(path == NULL) return 0;
/* Parse the url */
if(ncuriparse(path,&url) != NCU_OK)
return NC_EINVAL; /* Not parseable as url */
/* Look up the protocol */
for(found=0,protolist=ncprotolist;protolist->protocol;protolist++) {
if(strcmp(url->protocol,protolist->protocol) == 0) {
found = 1;
break;
}
}
if(found) {
model->implementation = protolist->implementation;
/* Substitute the protocol in any case */
if(protolist->substitute) ncurisetprotocol(url,protolist->substitute);
} else
{stat = NC_EINVAL; goto done;} /* Again, does not look like a url */
/* Iterate over the url fragment parameters */
for(fragp=ncurifragmentparams(url);fragp && *fragp;fragp+=2) {
const char* name = fragp[0];
const char* value = fragp[1];
if(strcmp(name,"protocol")==0)
name = value;
if(strcasecmp(name,"dap2") == 0) {
model->format = NC_FORMAT_NC3;
model->implementation = NC_FORMATX_DAP2;
/* No need to set iosp field */
} else if(strcasecmp(name,"dap4") == 0) {
model->format = NC_FORMAT_NETCDF4;
model->implementation = NC_FORMATX_DAP4;
/* No need to set iosp field */
} else if(strcmp(name,"mode")==0) {
if((stat = url_getmodel(value,model))) goto done;
}
}
if(model->implementation == 0) {/* Last resort: use the cmode */
/* If mode specifies netcdf-4, then this is assumed to be dap4 */
if(cmode & NC_NETCDF4) {
model->implementation = NC_FORMATX_DAP4;
} else {/* Default is DAP2 */
model->implementation = NC_FORMATX_DAP2;
}
}
if(model->implementation == 0) goto done; /* could not interpret */
switch (model->implementation) {
case NC_FORMATX_NC3:
model->format = NC_FORMAT_NC3;
break;
case NC_FORMATX_NC4:
model->format = NC_FORMAT_NETCDF4;
break;
case NC_FORMATX_DAP2:
model->format = NC_FORMAT_NC3;
break;
case NC_FORMATX_DAP4:
model->format = NC_FORMAT_NETCDF4;
break;
case NC_FORMATX_NCZARR:
model->format = NC_FORMAT_NETCDF4;
break;
default:
stat = NC_EINVAL;
goto done;
}
done:
if(newurl)
*newurl = ncuribuild(url,NULL,NULL,NCURIALL);
if(url) ncurifree(url);
return stat;
}
/* return 1 if path looks like a url; 0 otherwise */
int
NC_testurl(const char* path)
{
int isurl = 0;
NCURI* tmpurl = NULL;
if(path == NULL) return 0;
/* Ok, try to parse as a url */
if(ncuriparse(path,&tmpurl)==NCU_OK) {
/* Do some extra testing to make sure this really is a url */
/* Look for a known/accepted protocol */
struct NCPROTOCOLLIST* protolist;
for(protolist=ncprotolist;protolist->protocol;protolist++) {
if(strcmp(tmpurl->protocol,protolist->protocol) == 0) {
isurl=1;
break;
}
}
ncurifree(tmpurl);
return isurl;
}
return 0;
}