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netcdf-c/libdispatch/dinfermodel.c
Dennis Heimbigner f1506d552e Change (again), and hopefully simplify, the file model inference algorithm. 
* For URL paths, the new approach essentially centralizes all information
  in the URL into the "#mode=" fragment key and uses that value
  to determine the dispatcher for (most) URLs.

* The new approach has the following steps:

  1. canonicalize the path if it is a URL.
  2. use the mode= fragment key to determine the dispatcher
  3. if dispatcher still not determined, then use the mode flags
     argument to nc_open/nc_create to determine the dispatcher.
  4. if the path points to something readable, attempt to read the
     magic number at the front, and use that to determine the dispatcher.
     this case may override all previous cases.

* Misc changes.

  1. Update documentation
  2. Moved some unit tests from libdispatch to unit_test directory.
  3. Fixed use of wrong #ifdef macro in test_filter_reg.c
     [I think this may fix an previously reported esupport query].
2019-09-29 12:59:28 -06:00

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/**
* @file
*
* Infer as much as possible from the omode + path.
* Rewrite the path to a canonical form.
*
* 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
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include "ncdispatch.h"
#include "ncwinpath.h"
#include "netcdf_mem.h"
#include "fbits.h"
#include "ncbytes.h"
#include "nclist.h"
#include "nclog.h"
#ifdef ENABLE_BYTERANGE
#include "nchttp.h"
#endif
#undef DEBUG
/* If Defined, then use only stdio for all magic number io;
otherwise use stdio or mpio as required.
*/
#undef USE_STDIO
/**
Sort info for open/read/close of
file when searching for magic numbers
*/
struct MagicFile {
const char* path;
struct NCURI* uri;
int omode;
NCmodel* model;
fileoffset_t filelen;
int use_parallel;
void* parameters; /* !NULL if inmemory && !diskless */
FILE* fp;
#ifdef USE_PARALLEL
MPI_File fh;
#endif
#ifdef ENABLE_BYTERANGE
void* curl; /* avoid need to include curl.h */
char* curlurl; /* url to use with CURLOPT_SET_URL */
#endif
};
/** @internal Magic number for HDF5 files. To be consistent with
* H5Fis_hdf5, use the complete HDF5 magic number */
static char HDF5_SIGNATURE[MAGIC_NUMBER_LEN] = "\211HDF\r\n\032\n";
#define modelcomplete(model) ((model)->impl != 0)
#ifdef DEBUG
static void dbgflush(void)
{
fflush(stdout);
fflush(stderr);
}
static void
fail(int err)
{
return;
}
static int
check(int err)
{
if(err != NC_NOERR)
fail(err);
return err;
}
#else
#define check(err) (err)
#endif
/*
Define a table of "mode=" string values
from which the implementation can be inferred.
Note that only cases that can currently
take URLs are included.
*/
static struct FORMATMODES {
const char* tag;
const int impl; /* NC_FORMATX_XXX value */
} formatmodes[] = {
{"dap2",NC_FORMATX_DAP2},
{"dap4",NC_FORMATX_DAP4},
{"netcdf-3",NC_FORMATX_NC3},
{"classic",NC_FORMATX_NC3},
{"netcdf-4",NC_FORMATX_NC4},
{"enhanced",NC_FORMATX_NC4},
{"udf0",NC_FORMATX_UDF0},
{"udf1",NC_FORMATX_UDF1},
{"zarr",NC_FORMATX_ZARR},
{NULL,0},
};
/* Define the legal singleton mode tags;
thse should also appear in the above mode table. */
static const char* modesingles[] = {
"dap2", "dap4", "bytes", "zarr", NULL
};
/* Map FORMATX to readability to get magic number */
static struct Readable {
int impl;
int readable;
} readable[] = {
{NC_FORMATX_NC3,1},
{NC_FORMATX_NC_HDF5,1},
{NC_FORMATX_NC_HDF4,1},
{NC_FORMATX_PNETCDF,1},
{NC_FORMATX_DAP2,0},
{NC_FORMATX_DAP4,0},
{NC_FORMATX_UDF0,0},
{NC_FORMATX_UDF1,0},
{NC_FORMATX_ZARR,0},
{0,0},
};
/* Define the known URL protocols and their interpretation */
static struct NCPROTOCOLLIST {
const char* protocol;
const char* substitute;
const char* mode;
} ncprotolist[] = {
{"http",NULL,NULL},
{"https",NULL,NULL},
{"file",NULL,NULL},
{"dods","http","dap2"},
{"dap4","http","dap4"},
{NULL,NULL,NULL} /* Terminate search */
};
/* Forward */
static int NC_omodeinfer(int useparallel, int omode, NCmodel*);
static int check_file_type(const char *path, int omode, int use_parallel, void *parameters, NCmodel* model, NCURI* uri);
static int parseurlmode(const char* modestr, NClist* list);
static int processuri(const char* path, NCURI** urip, char** newpathp, NClist* modeargs);
static char* list2string(NClist* modelist);
static char* envv2string(NClist* envv);
static int issingleton(const char* tag);;
static void set_default_mode(int* cmodep);
static int openmagic(struct MagicFile* file);
static int readmagic(struct MagicFile* file, long pos, char* magic);
static int closemagic(struct MagicFile* file);
static int NC_interpret_magic_number(char* magic, NCmodel* model);
#ifdef DEBUG
static void printmagic(const char* tag, char* magic,struct MagicFile*);
#endif
static int isreadable(NCmodel*);
/*
If the path looks like a URL, then parse it, reformat it,
and compute the mode= flags. Then return it and the the reformatted path.
*/
static int
processuri(const char* path, NCURI** urip, char** newpathp, NClist* modeargs)
{
int i,j,stat = NC_NOERR;
int found = 0;
const char** fragp = NULL;
NClist* fraglist = NULL;
struct NCPROTOCOLLIST* protolist;
NCURI* uri = NULL;
size_t pathlen = strlen(path);
char* str = NULL;
if(path == NULL || pathlen == 0) {stat = NC_EURL; goto done;}
/* Defaults */
if(newpathp) *newpathp = NULL;
if(urip) *urip = NULL;
if(ncuriparse(path,&uri)) goto done; /* not url */
/* Look up the protocol */
for(found=0,protolist=ncprotolist;protolist->protocol;protolist++) {
if(strcmp(uri->protocol,protolist->protocol) == 0) {
found = 1;
break;
}
}
if(!found)
{stat = NC_EINVAL; goto done;} /* unrecognized URL form */
/* process the corresponding mode arg */
if(protolist->mode != NULL)
nclistpush(modeargs,strdup(protolist->mode));
/* Substitute the protocol in any case */
if(protolist->substitute) ncurisetprotocol(uri,protolist->substitute);
/* Iterate over the url fragment parameters and collect,
but remove mode= proto= and protocol= */
fraglist = nclistnew();
for(fragp=ncurifragmentparams(uri);fragp && *fragp;fragp+=2) {
int elide = 0;
const char* name = fragp[0];
const char* value = fragp[1];
if(strcmp(name,"protocol")==0
|| strcmp(name,"proto")==0) { /* for back compatibility */
nclistpush(modeargs,strdup(value));
elide = 1;
} else if(strcmp(name,"mode")==0) {
/* Capture the list of mode arguments */
if((stat = parseurlmode(value,modeargs))) goto done;
elide = 1;
} else if(issingleton(name) && (value == NULL || strlen(value)==0)) {
nclistpush(modeargs,strdup(name));
elide = 1;
} /*else ignore*/
if(!elide) {
/* Copy over */
nclistpush(fraglist,strdup(name));
if(value == NULL) value = "";
nclistpush(fraglist,strdup(value));
}
}
/* At this point modeargs should contain all mode-like args from the URL */
/* Remove duplicates */
for(i=nclistlength(modeargs)-1;i>=0;i--) {
const char* mode = nclistget(modeargs,i);
for(j=0;j<i;j++) {
const char* other = nclistget(modeargs,i);
if(strcasecmp(mode,other)==0) {
nclistremove(modeargs,i); /* duplicate */
break;
}
}
}
/* Convert the modelist to a new mode= fragment */
if(nclistlength(modeargs) > 0) {
str = list2string(modeargs);
/* Re-insert mode into fraglist */
nclistinsert(fraglist,0,str);
nclistinsert(fraglist,0,strdup("mode"));
}
/* Convert frag list to a string */
str = envv2string(fraglist);
ncurisetfragments(uri,str);
/* Rebuild the path (including fragment)*/
if(newpathp)
*newpathp = ncuribuild(uri,NULL,NULL,NCURIALL);
if(urip) {
*urip = uri;
uri = NULL;
}
#ifdef DEBUG
fprintf(stderr,"newpath=|%s|\n",*newpathp); fflush(stderr);
#endif
done:
nclistfreeall(fraglist);
nullfree(str);
if(uri != NULL) ncurifree(uri);
return check(stat);
}
/* Parse a mode string at the commas */
static int
parseurlmode(const char* modestr, NClist* list)
{
int stat = NC_NOERR;
const char* p = NULL;
const char* endp = NULL;
if(modestr == NULL || *modestr == '\0') goto done;
/* Split modestr at the commas or EOL */
p = modestr;
for(;;) {
char* s;
ptrdiff_t slen;
endp = strchr(p,',');
if(endp == NULL) endp = p + strlen(p);
slen = (endp - p);
if((s = malloc(slen+1)) == NULL) {stat = NC_ENOMEM; goto done;}
memcpy(s,p,slen);
s[slen] = '\0';
nclistpush(list,s);
if(*endp == '\0') break;
p = endp+1;
}
done:
return check(stat);
}
/* Convert an envv into a comma'd string*/
static char*
envv2string(NClist* envv)
{
int i;
NCbytes* buf = NULL;
char* result = NULL;
if(envv == NULL || nclistlength(envv) == 0) return NULL;
buf = ncbytesnew();
for(i=0;i<nclistlength(envv);i+=2) {
const char* key = nclistget(envv,i);
const char* val = nclistget(envv,i+1);
if(key == NULL || strlen(key) == 0) continue;
if(val == NULL) val = "";
if(i > 0) ncbytescat(buf,"&");
ncbytescat(buf,key);
ncbytescat(buf,"=");
ncbytescat(buf,val);
}
result = ncbytesextract(buf);
ncbytesfree(buf);
return result;
}
/* Convert a list into a comma'd string */
static char*
list2string(NClist* modelist)
{
int i;
NCbytes* buf = NULL;
char* result = NULL;
if(modelist == NULL || nclistlength(modelist)==0) return NULL;
buf = ncbytesnew();
for(i=0;i<nclistlength(modelist);i++) {
const char* m = nclistget(modelist,i);
if(m == NULL || strlen(m) == 0) continue;
if(i > 0) ncbytescat(buf,",");
ncbytescat(buf,m);
}
result = ncbytesextract(buf);
ncbytesfree(buf);
return result;
}
/* Given a mode= argument, fill in the impl and possibly mode flags */
static int
processmodearg(const char* arg, NCmodel* model)
{
int stat = NC_NOERR;
struct FORMATMODES* format = formatmodes;
for(;format->tag;format++) {
if(strcmp(format->tag,arg)==0) {
model->impl = format->impl;
}
}
return check(stat);
}
/* Search singleton list */
static int
issingleton(const char* tag)
{
const char** p;
for(p=modesingles;*p;p++) {
if(strcmp(*p,tag)==0) return 1;
}
return 0;
}
/*
Infer from the mode + useparallel
only call if iscreate or file is not easily readable.
*/
static int
NC_omodeinfer(int useparallel, int cmode, NCmodel* model)
{
int stat = NC_NOERR;
/* If no format flags are set, then use default */
if(!fIsSet(cmode,NC_FORMAT_ALL))
set_default_mode(&cmode);
/* Process the cmode; may override some already set flags */
if(fIsSet(cmode,NC_64BIT_OFFSET)) {
model->impl = NC_FORMATX_NC3;
model->format = NC_FORMAT_64BIT_OFFSET;
goto done;
}
if(fIsSet(cmode,NC_64BIT_DATA)) {
model->impl = NC_FORMATX_NC3;
model->format = NC_FORMAT_64BIT_DATA;
goto done;
}
if(fIsSet(cmode,NC_NETCDF4)) {
model->impl = NC_FORMATX_NC4;
if(fIsSet(cmode,NC_CLASSIC_MODEL))
model->format = NC_FORMAT_NETCDF4_CLASSIC;
else
model->format = NC_FORMAT_NETCDF4;
goto done;
}
if(fIsSet(cmode,(NC_UDF0|NC_UDF1))) {
model->format = NC_FORMAT_NETCDF4;
if(fIsSet(cmode,NC_UDF0)) {
model->impl = NC_FORMATX_UDF0;
} else {
model->impl = NC_FORMATX_UDF1;
}
goto done;
}
/* Default to classic model */
model->format = NC_FORMAT_CLASSIC;
model->impl = NC_FORMATX_NC3;
done:
/* Apply parallel flag */
if(useparallel) {
if(model->impl == NC_FORMATX_NC3)
model->impl = NC_FORMATX_PNETCDF;
}
return check(stat);
}
/*
If the mode flags do not necessarily specify the
format, then default it by adding in appropriate flags.
*/
static void
set_default_mode(int* modep)
{
int mode = *modep;
int dfaltformat;
dfaltformat = nc_get_default_format();
switch (dfaltformat) {
case NC_FORMAT_64BIT_OFFSET: mode |= NC_64BIT_OFFSET; break;
case NC_FORMAT_64BIT_DATA: mode |= NC_64BIT_DATA; break;
case NC_FORMAT_NETCDF4: mode |= NC_NETCDF4; break;
case NC_FORMAT_NETCDF4_CLASSIC: mode |= (NC_NETCDF4|NC_CLASSIC_MODEL); break;
case NC_FORMAT_CLASSIC: /* fall thru */
default: break; /* default to classic */
}
*modep = mode; /* final result */
}
/**************************************************/
/*
Infer model for this dataset using some
combination of cmode, path, and reading the dataset.
See the documentation in docs/internal.dox.
@param path
@param omode
@param iscreate
@param useparallel
@param params
@param model
@param newpathp
*/
int
NC_infermodel(const char* path, int* omodep, int iscreate, int useparallel, void* params, NCmodel* model, char** newpathp)
{
int i,stat = NC_NOERR;
char* newpath = NULL;
NCURI* uri = NULL;
int omode = *omodep;
NClist* modeargs = nclistnew();
/* Phase 1: Reformat the uri to canonical form; store canonical form
into newpath. Return the "mode=" list in modeargs */
if((stat = processuri(path, &uri, &newpath, modeargs))) goto done;
if(newpath == NULL) newpath = strdup(path); /* No change */
/* Phase 2: Process the modeargs list to see if we can tell the formatx */
/* Note that if the path was not a URL, then modeargs will be empty list*/
for(i=0;i<nclistlength(modeargs);i++) {
const char* arg = nclistget(modeargs,i);
if((stat=processmodearg(arg,model))) goto done;
}
/* Phase 2.5: Special case: if this is a URL, and there are no mode args
and model.impl is still not defined, default to DAP2 */
if(uri != NULL && nclistlength(modeargs) == 0 && !modelcomplete(model)) {
model->impl = NC_FORMATX_DAP2;
model->format = NC_FORMAT_NC3;
}
/* Phase 3: mode inference from mode flags */
/* The modeargs did not give us a model (probably not a URL).
So look at the combination of mode flags and the useparallel flag */
if(!modelcomplete(model)) {
if((stat = NC_omodeinfer(useparallel,omode,model))) goto done;
}
/* Phase 4: Infer from file content, if possible;
this has highest precedence, so it may override
previous decisions. Note that we do this last
because we need previously determined model info
to guess if this file is readable.
*/
if(!iscreate && isreadable(model)) {
/* Ok, we need to try to read the file */
if((stat = check_file_type(path, omode, useparallel, params, model, uri))) goto done;
}
/* Need a decision */
if(!modelcomplete(model))
{stat = NC_ENOTNC; goto done;}
/* Force flag consistency */
switch (model->impl) {
case NC_FORMATX_NC4:
case NC_FORMATX_NC_HDF4:
case NC_FORMATX_DAP4:
case NC_FORMATX_UDF0:
case NC_FORMATX_UDF1:
omode |= NC_NETCDF4;
if(model->format == NC_FORMAT_NETCDF4_CLASSIC)
omode |= NC_CLASSIC_MODEL;
break;
case NC_FORMATX_NC3:
omode &= ~NC_NETCDF4; /* must be netcdf-3 (CDF-1, CDF-2, CDF-5) */
if(model->format == NC_FORMAT_64BIT_OFFSET) omode |= NC_64BIT_OFFSET;
else if(model->format == NC_FORMAT_64BIT_DATA) omode |= NC_64BIT_DATA;
break;
case NC_FORMATX_PNETCDF:
omode &= ~NC_NETCDF4; /* must be netcdf-3 (CDF-1, CDF-2, CDF-5) */
if(model->format == NC_FORMAT_64BIT_OFFSET) omode |= NC_64BIT_OFFSET;
else if(model->format == NC_FORMAT_64BIT_DATA) omode |= NC_64BIT_DATA;
break;
case NC_FORMATX_DAP2:
omode &= ~(NC_NETCDF4|NC_64BIT_OFFSET|NC_64BIT_DATA|NC_CLASSIC_MODEL);
break;
default:
{stat = NC_ENOTNC; goto done;}
}
done:
if(uri) ncurifree(uri);
nclistfreeall(modeargs);
if(stat == NC_NOERR && newpathp) {*newpathp = newpath; newpath = NULL;}
nullfree(newpath);
*omodep = omode; /* in/out */
return check(stat);
}
static int
isreadable(NCmodel* model)
{
struct Readable* r;
/* Look up the protocol */
for(r=readable;r->impl;r++) {
if(model->impl == r->impl) return r->readable;
}
return 0;
}
/**************************************************/
#if 0
/* 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;
}
#endif
/**************************************************/
/**
* Provide a hidden interface to allow utilities
* to check if a given path name is really a url.
* If not, 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)) {
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;
}
/**************************************************/
/**
* @internal Given an existing file, figure out its format and return
* that format value (NC_FORMATX_XXX) in model arg. Assume any path
* conversion was already performed at a higher level.
*
* @param path File name.
* @param flags
* @param use_parallel
* @param parameters
* @param model Pointer that gets the model to use for the dispatch table.
* @param version Pointer that gets version of the file.
*
* @return ::NC_NOERR No error.
* @author Dennis Heimbigner
*/
static int
check_file_type(const char *path, int omode, int use_parallel,
void *parameters, NCmodel* model, NCURI* uri)
{
char magic[NC_MAX_MAGIC_NUMBER_LEN];
int status = NC_NOERR;
struct MagicFile magicinfo;
memset((void*)&magicinfo,0,sizeof(magicinfo));
magicinfo.path = path; /* do not free */
magicinfo.uri = uri; /* do not free */
magicinfo.omode = omode;
magicinfo.model = model; /* do not free */
magicinfo.parameters = parameters; /* do not free */
#ifdef USE_STDIO
magicinfo.use_parallel = 0;
#else
magicinfo.use_parallel = use_parallel;
#endif
if((status = openmagic(&magicinfo))) goto done;
/* Verify we have a large enough file */
if(magicinfo.filelen < MAGIC_NUMBER_LEN)
{status = NC_ENOTNC; goto done;}
if((status = readmagic(&magicinfo,0L,magic)) != NC_NOERR) {
status = NC_ENOTNC;
goto done;
}
/* Look at the magic number */
if(NC_interpret_magic_number(magic,model) == NC_NOERR
&& model->format != 0) {
if (model->format == NC_FORMAT_NC3 && use_parallel)
/* this is called from nc_open_par() and file is classic */
model->impl = NC_FORMATX_PNETCDF;
goto done; /* found something */
}
/* Remaining case when implementation is an HDF5 file;
search forward at starting at 512
and doubling to see if we have HDF5 magic number */
{
long pos = 512L;
for(;;) {
if((pos+MAGIC_NUMBER_LEN) > magicinfo.filelen)
{status = NC_ENOTNC; goto done;}
if((status = readmagic(&magicinfo,pos,magic)) != NC_NOERR)
{status = NC_ENOTNC; goto done; }
NC_interpret_magic_number(magic,model);
if(model->impl == NC_FORMATX_NC4) break;
/* double and try again */
pos = 2*pos;
}
}
done:
closemagic(&magicinfo);
return check(status);
}
/**
\internal
\ingroup datasets
Provide open, read and close for use when searching for magic numbers
*/
static int
openmagic(struct MagicFile* file)
{
int status = NC_NOERR;
if(fIsSet(file->omode,NC_INMEMORY)) {
/* Get its length */
NC_memio* meminfo = (NC_memio*)file->parameters;
assert(meminfo != NULL);
file->filelen = (long long)meminfo->size;
#ifdef ENABLE_BYTERANGE
} else if(file->uri != NULL) {
/* Construct a URL minus any fragment */
file->curlurl = ncuribuild(file->uri,NULL,NULL,NCURISVC);
/* Open the curl handle */
if((status=nc_http_open(file->curlurl,&file->curl,&file->filelen))) goto done;
#endif
} else {
#ifdef USE_PARALLEL
if (file->use_parallel) {
int retval;
MPI_Offset size;
assert(file->parameters != NULL);
if((retval = MPI_File_open(((NC_MPI_INFO*)file->parameters)->comm,
(char*)file->path,MPI_MODE_RDONLY,
((NC_MPI_INFO*)file->parameters)->info,
&file->fh)) != MPI_SUCCESS) {
#ifdef MPI_ERR_NO_SUCH_FILE
int errorclass;
MPI_Error_class(retval, &errorclass);
if (errorclass == MPI_ERR_NO_SUCH_FILE)
#ifdef NC_ENOENT
status = NC_ENOENT;
#else
status = errno;
#endif
else
#endif
status = NC_EPARINIT;
goto done;
}
/* Get its length */
if((retval=MPI_File_get_size(file->fh, &size)) != MPI_SUCCESS)
{status = NC_EPARINIT; goto done;}
file->filelen = (long long)size;
} else
#endif /* USE_PARALLEL */
{
if(file->path == NULL || strlen(file->path)==0)
{status = NC_EINVAL; goto done;}
#ifdef _WIN32
file->fp = NCfopen(file->path, "rb");
#else
file->fp = NCfopen(file->path, "r");
#endif
if(file->fp == NULL)
{status = errno; goto done;}
/* Get its length */
{
int fd = fileno(file->fp);
#ifdef _WIN32
__int64 len64 = _filelengthi64(fd);
if(len64 < 0)
{status = errno; goto done;}
file->filelen = (long long)len64;
#else
off_t size;
size = lseek(fd, 0, SEEK_END);
if(size == -1)
{status = errno; goto done;}
file->filelen = (long long)size;
#endif
}
rewind(file->fp);
}
}
done:
return check(status);
}
static int
readmagic(struct MagicFile* file, long pos, char* magic)
{
int status = NC_NOERR;
memset(magic,0,MAGIC_NUMBER_LEN);
if(fIsSet(file->omode,NC_INMEMORY)) {
char* mempos;
NC_memio* meminfo = (NC_memio*)file->parameters;
if((pos + MAGIC_NUMBER_LEN) > meminfo->size)
{status = NC_EINMEMORY; goto done;}
mempos = ((char*)meminfo->memory) + pos;
memcpy((void*)magic,mempos,MAGIC_NUMBER_LEN);
#ifdef DEBUG
printmagic("XXX: readmagic",magic,file);
#endif
#ifdef ENABLE_BYTERANGE
} else if(file->uri != NULL) {
NCbytes* buf = ncbytesnew();
fileoffset_t start = (size_t)pos;
fileoffset_t count = MAGIC_NUMBER_LEN;
status = nc_http_read(file->curl,file->curlurl,start,count,buf);
if(status == NC_NOERR) {
if(ncbyteslength(buf) != count)
status = NC_EINVAL;
else
memcpy(magic,ncbytescontents(buf),count);
}
ncbytesfree(buf);
#endif
} else {
#ifdef USE_PARALLEL
if (file->use_parallel) {
MPI_Status mstatus;
int retval;
if((retval = MPI_File_read_at_all(file->fh, pos, magic,
MAGIC_NUMBER_LEN, MPI_CHAR, &mstatus)) != MPI_SUCCESS)
{status = NC_EPARINIT; goto done;}
} else
#endif /* USE_PARALLEL */
{
int count;
int i = fseek(file->fp,pos,SEEK_SET);
if(i < 0)
{status = errno; goto done;}
for(i=0;i<MAGIC_NUMBER_LEN;) {/* make sure to read proper # of bytes */
count=fread(&magic[i],1,(size_t)(MAGIC_NUMBER_LEN-i),file->fp);
if(count == 0 || ferror(file->fp))
{status = errno; goto done;}
i += count;
}
}
}
done:
if(file && file->fp) clearerr(file->fp);
return check(status);
}
/**
* Close the file opened to check for magic number.
*
* @param file pointer to the MagicFile struct for this open file.
* @returns NC_NOERR for success
* @returns NC_EPARINIT if there was a problem closing file with MPI
* (parallel builds only).
* @author Dennis Heimbigner
*/
static int
closemagic(struct MagicFile* file)
{
int status = NC_NOERR;
if(fIsSet(file->omode,NC_INMEMORY)) {
/* noop */
#ifdef ENABLE_BYTERANGE
} else if(file->uri != NULL) {
status = nc_http_close(file->curl);
nullfree(file->curlurl);
#endif
} else {
#ifdef USE_PARALLEL
if (file->use_parallel) {
int retval;
if((retval = MPI_File_close(&file->fh)) != MPI_SUCCESS)
{status = NC_EPARINIT; return status;}
} else
#endif
{
if(file->fp) fclose(file->fp);
}
}
return status;
}
/*!
Interpret the magic number found in the header of a netCDF file.
This function interprets the magic number/string contained in the header of a netCDF file and sets the appropriate NC_FORMATX flags.
@param[in] magic Pointer to a character array with the magic number block.
@param[out] model Pointer to an integer to hold the corresponding netCDF type.
@param[out] version Pointer to an integer to hold the corresponding netCDF version.
@returns NC_NOERR if a legitimate file type found
@returns NC_ENOTNC otherwise
\internal
\ingroup datasets
*/
static int
NC_interpret_magic_number(char* magic, NCmodel* model)
{
int status = NC_NOERR;
/* Look at the magic number */
#ifdef USE_NETCDF4
if (strlen(UDF0_magic_number) && !strncmp(UDF0_magic_number, magic,
strlen(UDF0_magic_number)))
{
model->impl = NC_FORMATX_UDF0;
model->format = NC_FORMAT_NETCDF4;
goto done;
}
if (strlen(UDF1_magic_number) && !strncmp(UDF1_magic_number, magic,
strlen(UDF1_magic_number)))
{
model->impl = NC_FORMATX_UDF1;
model->format = NC_FORMAT_NETCDF4;
goto done;
}
#endif /* USE_NETCDF4 */
/* Use the complete magic number string for HDF5 */
if(memcmp(magic,HDF5_SIGNATURE,sizeof(HDF5_SIGNATURE))==0) {
model->impl = NC_FORMATX_NC4;
model->format = NC_FORMAT_NETCDF4;
goto done;
}
if(magic[0] == '\016' && magic[1] == '\003'
&& magic[2] == '\023' && magic[3] == '\001') {
model->impl = NC_FORMATX_NC_HDF4;
model->format = NC_FORMAT_NETCDF4;
goto done;
}
if(magic[0] == 'C' && magic[1] == 'D' && magic[2] == 'F') {
if(magic[3] == '\001') {
model->impl = NC_FORMATX_NC3;
model->format = NC_FORMAT_CLASSIC;
goto done;
}
if(magic[3] == '\002') {
model->impl = NC_FORMATX_NC3;
model->format = NC_FORMAT_64BIT_OFFSET;
goto done;
}
if(magic[3] == '\005') {
model->impl = NC_FORMATX_NC3;
model->format = NC_FORMAT_64BIT_DATA;
goto done;
}
}
/* No match */
status = NC_ENOTNC;
goto done;
done:
return check(status);
}
#ifdef DEBUG
static void
printmagic(const char* tag, char* magic, struct MagicFile* f)
{
int i;
fprintf(stderr,"%s: ispar=%d magic=",tag,f->use_parallel);
for(i=0;i<MAGIC_NUMBER_LEN;i++) {
unsigned int c = (unsigned int)magic[i];
c = c & 0x000000FF;
if(c == '\n')
fprintf(stderr," 0x%0x/'\\n'",c);
else if(c == '\r')
fprintf(stderr," 0x%0x/'\\r'",c);
else if(c < ' ')
fprintf(stderr," 0x%0x/'?'",c);
else
fprintf(stderr," 0x%0x/'%c'",c,c);
}
fprintf(stderr,"\n");
fflush(stderr);
}
#endif
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