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g2cindex.c(3) Library Functions Manual g2cindex.c(3)

NAME

g2cindex.c - Write summary output to an index file, as is done by utility grb2index.

SYNOPSIS

#include 'grib2_int.h'
#include <libgen.h>
#include <stdarg.h>
#include <time.h>

Macros


#define G2C_INDEX_BASENAME_LEN 40
Length of the basename in header record 2. #define G2C_INDEX_BITMAP_BYTES 6
Length of bitmap section included in the index record. #define G2C_INDEX_DATE_STR_LEN 10
Length of date string in index record. #define G2C_INDEX_FIXED_LEN 44
Length of beginning of index record. #define G2C_INDEX_FIXED_LEN_2 48
Length of beginning of index record for large files. #define G2C_INDEX_HEADER_LEN 81
Length of the two header lines at the top of the index file. #define G2C_INDEX_STR1_LEN 7
Length of str1 string in index record. #define G2C_INDEX_TIME_STR_LEN 8
Length of time string in index record.

Functions


EXTERN_MUTEX (m)
Use externally-defined mutex for thread-safety. int g2c_get_prod_sections (G2C_MESSAGE_INFO_T *msg, int fieldnum, G2C_SECTION_INFO_T **sec3, G2C_SECTION_INFO_T **sec4, G2C_SECTION_INFO_T **sec5, G2C_SECTION_INFO_T **sec6, G2C_SECTION_INFO_T **sec7)
Given a pointer to a message, and a field number, return pointers to all relevent section structs for that product. int g2c_open_index (const char *data_file, const char *index_file, int mode, int *g2cid)
Open a GRIB2 file with the help of an index file. int g2c_open_index1 (const char *index_file)
Open a GRIB1 index file and read the contents. int g2c_start_index1_record (FILE *f, int rw_flag, unsigned int *b2_msg, unsigned int *b2_pds, unsigned int *b2_gds, unsigned int *b2_bms, unsigned int *b2_bds, unsigned int *msglen, unsigned char *version, unsigned char *pds_val, unsigned char *gds_val, unsigned char *bms_val, unsigned char *bds_val, unsigned char *pds_val2, unsigned char *pds_val3, unsigned char *gds_val2)
Read or write the start of a version 1 index record. int g2c_start_index_record (FILE *f, int rw_flag, int *reclen, int *msg, int *local, int *gds, int *pds, int *drs, int *bms, int *data, size_t *msglen, unsigned char *version, unsigned char *discipline, short *fieldnum)
Read or write the start of a version 2 index record. int g2c_start_index_record_lf (FILE *f, int rw_flag, int *reclen, size_t *msg, size_t *local, size_t *gds, size_t *pds, size_t *drs, size_t *bms, size_t *data, size_t *msglen, unsigned char *version, unsigned char *discipline, short *fieldnum)
Read or write the start of a version 2 index record. int g2c_write_index (int g2cid, int mode, const char *index_file)
Create an index file from a GRIB2 file, just like those created by the grb2index utility. static int read_hdr_rec1 (FILE *f, int *ip, int *jp, int *kp, char *date_str, char *time_str)
Read the header record apparently named after Steve Lord. static int read_hdr_rec2 (FILE *f, int *skipp, int *total_lenp, int *num_recp, char *basename, int *index_version)
Read the second header record of an index file.

Variables


G2C_FILE_INFO_T g2c_file [G2C_MAX_FILES+1]
Global file information.

Detailed Description

Write summary output to an index file, as is done by utility grb2index.

Author

Ed Hartnett

Date

10/12/22

Definition in file g2cindex.c.

Macro Definition Documentation

#define G2C_INDEX_BASENAME_LEN 40

Length of the basename in header record 2.

Definition at line 20 of file g2cindex.c.

#define G2C_INDEX_BITMAP_BYTES 6

Length of bitmap section included in the index record.

Definition at line 23 of file g2cindex.c.

#define G2C_INDEX_DATE_STR_LEN 10

Length of date string in index record.

Definition at line 32 of file g2cindex.c.

#define G2C_INDEX_FIXED_LEN 44

Length of beginning of index record.

Definition at line 26 of file g2cindex.c.

#define G2C_INDEX_FIXED_LEN_2 48

Length of beginning of index record for large files.

Definition at line 29 of file g2cindex.c.

#define G2C_INDEX_HEADER_LEN 81

Length of the two header lines at the top of the index file.

Definition at line 17 of file g2cindex.c.

#define G2C_INDEX_STR1_LEN 7

Length of str1 string in index record.

Definition at line 38 of file g2cindex.c.

#define G2C_INDEX_TIME_STR_LEN 8

Length of time string in index record.

Definition at line 35 of file g2cindex.c.

Function Documentation

EXTERN_MUTEX (m)

Use externally-defined mutex for thread-safety.

int g2c_get_prod_sections (G2C_MESSAGE_INFO_T * msg, int fieldnum, G2C_SECTION_INFO_T ** sec3, G2C_SECTION_INFO_T ** sec4, G2C_SECTION_INFO_T ** sec5, G2C_SECTION_INFO_T ** sec6, G2C_SECTION_INFO_T ** sec7)

Given a pointer to a message, and a field number, return pointers to all relevent section structs for that product. Each product is defined in a section 4, and has an associated section 3, 5, 6, and 7.

Parameters

msg Pointer to a G2C_MESSAGE_INFO_T with information about the message.
fieldnum The field number (first field in message is 0).
sec3 Pointer that gets a pointer to the G2C_SECTION_INFO_T struct for the section 3 associated with this product.
sec4 Pointer that gets a pointer to the G2C_SECTION_INFO_T struct for the section 4 associated with this product.
sec5 Pointer that gets a pointer to the G2C_SECTION_INFO_T struct for the section 5 associated with this product.
sec6 Pointer that gets a pointer to the G2C_SECTION_INFO_T struct for the section 6 associated with this product. NULL is returned if there is no section 6.
sec7 Pointer that gets a pointer to the G2C_SECTION_INFO_T struct for the section 7 associated with this product.

Note

This is an internal function and should not be called by users.

Returns

  • G2C_NOERROR No error.
  • G2C_EINVAL Invalid input.
  • G2C_ENOSECTION Section not found.

Author

Ed Hartnett

Date

10/27/22

Definition at line 317 of file g2cindex.c.

References G2C_EINVAL, G2C_ENOSECTION, G2C_NOERROR, g2c_section_info::next, g2c_section_info::prev, g2c_message_info::sec, g2c_section_info::sec_info, and g2c_section_info::sec_num.

Referenced by g2c_write_index().

int g2c_open_index (const char * data_file, const char * index_file, int mode, int * g2cid)

Open a GRIB2 file with the help of an index file. The index file, generated by the grb2index utility, of the g2c_write_index() function, contains the byte offsets for the sections of each message in the GRIB2 file. When a GRIB2 file is opened with an index file, the library does not have to scan the file to locate all metadata.

Parameters

data_file The name of the data file to which the index applies.
index_file The name that will be given to the index file. An existing file will be overwritten.
mode Open mode flags.
g2cid Pointer that gets the g2cid for this file. Ignored if NULL.

Returns

•
G2C_NOERROR No error.

Author

Ed Hartnett

Date

10/12/22

Definition at line 902 of file g2cindex.c.

References add_msg(), add_section(), g2c_message_info::bytes_to_bms, g2c_message_info::bytes_to_data, g2c_message_info::bytes_to_local, g2c_message_info::bytes_to_msg, g2c_message_info::discipline, g2c_add_file(), G2C_EBADSECTION, G2C_EFILE, G2C_EINVAL, G2C_ENAMETOOLONG, g2c_file, g2c_file_io_ubyte(), g2c_file_io_uint(), G2C_FILE_READ, G2C_INDEX_BASENAME_LEN, G2C_INDEX_DATE_STR_LEN, G2C_INDEX_HEADER_LEN, G2C_INDEX_STR1_LEN, G2C_INDEX_TIME_STR_LEN, g2c_log_section1(), G2C_MAX_NAME, G2C_NOERROR, g2c_rw_section1_metadata(), g2c_start_index_record(), g2c_start_index_record_lf(), LOG, g2c_message_info::master_version, MUTEX_LOCK, and MUTEX_UNLOCK.

Referenced by main().

int g2c_open_index1 (const char * index_file)

Open a GRIB1 index file and read the contents.

Parameters

index_file The name that will be given to the index file. An existing file will be overwritten.

Returns

•
G2C_NOERROR No error.

Author

Ed Hartnett

Date

10/12/22

Definition at line 800 of file g2cindex.c.

References G2C_EFILE, G2C_EINVAL, G2C_FILE_READ, G2C_INDEX1_BDS_VAL_LEN, G2C_INDEX1_BMS_VAL_LEN, G2C_INDEX1_GDS_VAL_LEN, G2C_INDEX1_PDS_VAL_LEN, G2C_INDEX_BASENAME_LEN, G2C_INDEX_DATE_STR_LEN, G2C_INDEX_HEADER_LEN, G2C_INDEX_TIME_STR_LEN, G2C_NOERROR, g2c_start_index1_record(), LOG, MUTEX_LOCK, MUTEX_UNLOCK, read_hdr_rec1(), and read_hdr_rec2().

int g2c_start_index1_record (FILE * f, int rw_flag, unsigned int * b2_msg, unsigned int * b2_pds, unsigned int * b2_gds, unsigned int * b2_bms, unsigned int * b2_bds, unsigned int * msglen, unsigned char * version, unsigned char * pds_val, unsigned char * gds_val, unsigned char * bms_val, unsigned char * bds_val, unsigned char * pds_val2, unsigned char * pds_val3, unsigned char * gds_val2)

Read or write the start of a version 1 index record. For more detail on version 1 of the index format, see the grbindex documentation in the NCEPLIBS-grib_util.

Parameters

f FILE * to open index file.
rw_flag True if function should write, false if it should read.
b2_msg Pointer that gets the bytes to skip in file before msg.
b2_pds Pointer that gets bytes to skip in message before pds.
b2_gds Pointer that gets bytes to skip in message before gds (0 if no gds).
b2_bms Pointer that gets bytes to skip in message before bms (0 if no bms).
b2_bds Pointer that gets bytes to skip in message before bds.
msglen Pointer that gets bytes total in the message.
version Pointer that gets grib version number (always 1 for this function).
pds_val Pointer that gets an arry of 27 bytes of the product definition section (pds).
gds_val Pointer that gets an arry of 41 bytes of the gds.
bms_val Pointer that gets an arry of 5 bytes of the bms.
bds_val Pointer that gets an arry of 10 bytes, bytes 41-100 of the bds.
pds_val2 Pointer that gets an arry of 59 bytes 41-100 of the pds. Ignored if null.
pds_val3 Pointer that gets an arry of 11 bytes 29-40 of the pds. Ignored if null.
gds_val2 Pointer that gets an arry of 135 bytes 43-178 of the gds. Ignored if null.

Returns

  • G2C_NOERROR No error.
  • G2C_EINVAL Invalid input.
  • G2C_EFILE File I/O error.

Author

Ed Hartnett 9/11/23

Definition at line 238 of file g2cindex.c.

References G2C_EFILE, G2C_EINVAL, g2c_file_io_ubyte(), g2c_file_io_uint(), G2C_INDEX1_BDS_VAL_LEN, G2C_INDEX1_BMS_VAL_LEN, G2C_INDEX1_GDS_VAL_LEN, G2C_INDEX1_PDS_VAL_LEN, and G2C_NOERROR.

Referenced by g2c_open_index1().

int g2c_start_index_record (FILE * f, int rw_flag, int * reclen, int * msg, int * local, int * gds, int * pds, int * drs, int * bms, int * data, size_t * msglen, unsigned char * version, unsigned char * discipline, short * fieldnum)

Read or write the start of a version 2 index record.

Parameters

f FILE * to open index file.
rw_flag True if function should write, false if it should read.
reclen Pointer to reclen.
msg Pointer to msg.
local Pointer to local.
gds Pointer to gds.
pds Pointer to pds.
drs Pointer to drs.
bms Pointer to bms.
data Pointer to data.
msglen Pointer to msglen.
version Pointer to version.
discipline Pointer to discipline.
fieldnum Pointer to fieldnum, 0- based. (It is 1-based in the index file.)

Returns

  • G2C_NOERROR No error.
  • G2C_EINVAL Invalid input.
  • G2C_EFILE File I/O error.

Author

Ed Hartnett 10/26/22

Definition at line 70 of file g2cindex.c.

References G2C_EINVAL, g2c_file_io_short(), g2c_file_io_ubyte(), g2c_file_io_uint(), g2c_file_io_ulonglong(), G2C_NOERROR, and LOG.

Referenced by g2c_open_index(), and g2c_write_index().

int g2c_start_index_record_lf (FILE * f, int rw_flag, int * reclen, size_t * msg, size_t * local, size_t * gds, size_t * pds, size_t * drs, size_t * bms, size_t * data, size_t * msglen, unsigned char * version, unsigned char * discipline, short * fieldnum)

Read or write the start of a version 2 index record.

Parameters

f FILE pointer to open index file.
rw_flag True if function should write, false if it should read.
reclen Pointer to reclen, the length of the index record in bytes.
msg Pointer to bytes to skip in file to reach msg.
local Pointer to bytes to skip in message to reach local.
gds Pointer to bytes to skip in message to reach gds.
pds Pointer to bytes to skip in message to reach pds.
drs Pointer to bytes to skip in message to reach drs.
bms Pointer to bytes to skip in message to reach bms.
data Pointer to bytes to skip in message to reach data.
msglen Pointer to msglen.
version Pointer to version.
discipline Pointer to discipline.
fieldnum Pointer to fieldnum, 0- based. (It is 1-based in the index file.)

Returns

  • G2C_NOERROR No error.
  • G2C_EINVAL Invalid input.
  • G2C_EFILE File I/O error.

Author

Ed Hartnett 10/26/22

Definition at line 151 of file g2cindex.c.

References G2C_EINVAL, g2c_file_io_short(), g2c_file_io_ubyte(), g2c_file_io_uint(), g2c_file_io_ulonglong(), G2C_NOERROR, and LOG.

Referenced by g2c_open_index(), and g2c_write_index().

int g2c_write_index (int g2cid, int mode, const char * index_file)

Create an index file from a GRIB2 file, just like those created by the grb2index utility. The index file starts with two header records:

1.
81-byte header with 'gb2ix1' in columns 42-47.
2.
81-byte header with number of bytes to skip before index records, total length in bytes of the index records, number of index records, and grib file basename written in format ('ix1form:',3i10,2x,a40).

Each following index record corresponds to a grib message and has the internal format:

  • byte 001 - 004 length of index record
  • byte 005 - 008 bytes to skip in data file before grib message
  • byte 009 - 012 bytes to skip in message before lus (local use) (0, if none).
  • byte 013 - 016 bytes to skip in message before gds
  • byte 017 - 020 bytes to skip in message before pds
  • byte 021 - 024 bytes to skip in message before drs
  • byte 025 - 028 bytes to skip in message before bms
  • byte 029 - 032 bytes to skip in message before data section
  • byte 033 - 040 bytes total in the message
  • byte 041 - 041 grib version number (currently 2)
  • byte 042 - 042 message discipline
  • byte 043 - 044 field number within grib2 message (1-based)
  • byte 045 - ii identification section (ids)
  • byte ii+1- jj grid definition section (gds)
  • byte jj+1- kk product definition section (pds)
  • byte kk+1- ll the data representation section (drs)
  • byte ll+1-ll+6 first 6 bytes of the bit map section (bms)

Parameters

g2cid File it for an open GRIB2 file, as returned by g2c_open().
mode Mode flags. Set G2C_NOCLOBBER to avoid overwriting and existing file.
index_file The name that will be given to the index file. An existing file will be overwritten.

Returns

•
G2C_NOERROR No error.

Author

Ed Hartnett

Date

10/12/22

Definition at line 431 of file g2cindex.c.

References g2c_message_info::bytes_in_msg, g2c_message_info::bytes_to_local, g2c_message_info::bytes_to_msg, g2c_section_info::bytes_to_sec, g2c_message_info::discipline, g2c_file_info::f, g2c_message_info::file, G2C_EBADID, G2C_EFILE, G2C_EINVAL, g2c_file, g2c_file_io_ubyte(), g2c_file_io_uint(), G2C_FILE_WRITE, g2c_get_prod_sections(), G2C_INDEX_BASENAME_LEN, G2C_INDEX_BITMAP_BYTES, G2C_INDEX_FIXED_LEN, G2C_INDEX_FIXED_LEN_2, G2C_INDEX_HEADER_LEN, G2C_LARGE_FILE_INDEX, G2C_MAX_FILES, G2C_NOCLOBBER, G2C_NOERROR, g2c_rw_section1_metadata(), g2c_rw_section3_metadata(), g2c_rw_section4_metadata(), g2c_rw_section5_metadata(), g2c_start_index_record(), g2c_start_index_record_lf(), LOG, g2c_message_info::master_version, MUTEX_LOCK, MUTEX_UNLOCK, g2c_message_info::next, g2c_message_info::num_fields, ONE_BYTE, g2c_message_info::sec1_len, and g2c_section_info::sec_len.

Referenced by main().

static int read_hdr_rec1 (FILE * f, int * ip, int * jp, int * kp, char * date_str, char * time_str) [static]

Read the header record apparently named after Steve Lord. This function reads the first of two 81-byte header records of an index file.

Parameters

f Pointer to open FILE.
ip Pointer that gets i value. Ignored if NULL.
jp Pointer that gets j value. Ignored if NULL.
kp Pointer that gets k value. Ignored if NULL.
date_str Pointer to char array of size G2C_INDEX_DATE_STR_LEN + 1 which will get the date string from the header. Ignored if NULL.
time_str Pointer to char array of size G2C_INDEX_TIME_STR_LEN + 1 which will get the time string from the header. Ignored if NULL.

Returns

0 for success, error code otherwise.

Author

Edward Hartnett

Date

9/10/23

Definition at line 684 of file g2cindex.c.

References G2C_EFILE, G2C_INDEX_DATE_STR_LEN, G2C_INDEX_HEADER_LEN, G2C_INDEX_STR1_LEN, G2C_INDEX_TIME_STR_LEN, G2C_NOERROR, and LOG.

Referenced by g2c_open_index1().

static int read_hdr_rec2 (FILE * f, int * skipp, int * total_lenp, int * num_recp, char * basename, int * index_version) [static]

Read the second header record of an index file. This function reads the second of two 81-byte header records of an index file.

Parameters

f Pointer to open FILE.
skipp Pointer that gets number of bytes to skip before index records. Ignored if NULL.
total_lenp Pointer that gets number of bytes in each index record. Ignored if NULL.
num_recp Pointer that gets number of index records in the file. Ignored if NULL.
basename Pointer to char array of size G2C_INDEX_BASENAME_LEN + 1 which will get the basename string from the second header record. Ignored if NULL.
index_version The version of the index, 1 for legacy, 2 to allow for > 2 GB GRIB2 files.

Returns

0 for success, error code otherwise.

Author

Edward Hartnett

Date

9/10/23

Definition at line 753 of file g2cindex.c.

References G2C_EFILE, G2C_INDEX_BASENAME_LEN, G2C_INDEX_HEADER_LEN, and G2C_NOERROR.

Referenced by g2c_open_index1().

Variable Documentation

G2C_FILE_INFO_T g2c_file[G2C_MAX_FILES+1] [extern]

Global file information.

Definition at line 10 of file g2cfile.c.

Referenced by g2c_open_index(), and g2c_write_index().

Author

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