FUNCTION FXPOSIT, XFILE, EXT_NO, readonly=readonly, COMPRESS=COMPRESS, $ SILENT = Silent, EXTNUM = extnum, ERRMSG= ERRMSG, LUNIT = lunit ;+ ; NAME: ; FXPOSIT ; PURPOSE: ; Return the unit number of a FITS file positioned at specified extension ; EXPLANATION: ; The FITS file will be ready to be read at the beginning of the ; specified extension. Exither an extension number or extension name ; can be specified. Called by headfits.pro, mrdfits.pro, readfits.pro ; ; CALLING SEQUENCE: ; unit=FXPOSIT(FILE, EXT_NO_OR_NAME, /READONLY, COMPRESS=program, ; ERRMSG= , EXTNUM= , UNIT=, /SILENT) ; ; INPUT PARAMETERS: ; FILE = FITS file name, scalar string ; EXT_NO_OR_NAME = Either the extension to be moved to (scalar ; nonnegative integer) or the name of the extension to read ; (scalar string) ; ; RETURNS: ; Unit number of file or -1 if an error is detected. ; ; OPTIONAL INPUT KEYWORD PARAMETER: ; /READONLY - If this keyword is set and non-zero, then OPENR rather ; than OPENU will be used to open the FITS file. ; COMPRESS - If this keyword is set and non-zero, then then treat ; the file as compressed. If 1 assume a gzipped file. ; and use IDLs internal decompression facility. For Unix ; compressed or bzip2 compressed files spawn off a process to ; decompress and use its output as the FITS stream. If the ; keyword is not 1, then use its value as a string giving the ; command needed for decompression. ; LUNIT - Integer giving the file unit number. Use this keyword if ; you want to override the default use of GET_LUN to obtain ; a unit number. ; /SILENT If set, then suppress any messages about invalid characters ; in the FITS file. ; ; OPTIONAL OUTPUT KEYWORDS: ; EXTNUM - Nonnegative integer give the extension number actually read ; Useful only if the extension was specified by name. ; ERRMSG = If this keyword is present, then any error messages will be ; returned to the user in this parameter rather than ; depending on the MESSAGE routine in IDL. If no errors are ; encountered, then a null string is returned. ; SIDE EFFECTS: ; Opens and returns a file unit. ; PROCEDURE: ; Open the appropriate file, or spawn a command and intercept ; the output. ; Call FXMOVE to get to the appropriate extension. ; PROCEDURE CALLS: ; FXMOVE() ; MODIFICATION HISTORY: ; Derived from William Thompson's FXFINDEND routine. ; Modified by T.McGlynn, 5-October-1994. ; Modified by T.McGlynn, 25-Feb-1995 to handle compressed ; files. Pipes cannot be accessed using FXHREAD so ; MRD_HREAD was written. ; W. Landsman 23-Apr-1997 Force the /bin/sh shell when uncompressing ; T. McGlynn 03-June-1999 Use /noshell option to get rid of processes left by spawn. ; Use findfile to retain ability to use wildcards ; W. Landsman 03-Aug-1999 Use EXPAND_TILDE under Unix to find file ; T. McGlynn 04-Apr-2000 Put reading code into FXMOVE, ; additional support for compression from D.Palmer. ; W. Landsman/D.Zarro 04-Jul-2000 Added test for !VERSION.OS EQ 'Win32' (WinNT) ; W. Landsman 12-Dec-2000 Added /SILENT keyword ; W. Landsman April 2002 Use FILE_SEARCH for V5.5 or later ; W. Landsman Feb 2004 Assume since V5.3 (OPENR,/COMPRESS available) ; W. Landsman,W. Thompson, 2-Mar-2004, Add support for BZIP2 ; W. Landsman Don't leave open file if an error occurs ; W. Landsman Sep 2004 Treat FTZ extension as gzip compressed ; W. Landsman Feb 2006 Removed leading spaces (prior to V5.5) ; W. Landsman Nov 2006 Allow specification of extension name ; Added EXTNUM, ERRMSG keywords ; W. Landsman/N.Piskunov Dec 2007 Added LUNIT keyword ;- ; ON_ERROR,2 compile_opt idl2 ; ; Check the number of parameters. ; IF N_PARAMS() LT 2 THEN BEGIN PRINT,'SYNTAX: UNIT = FXPOSIT(FILE, EXT_NO, /Readonly,' + $ 'ERRMSG= , /SILENT, compress=prog, LUNIT = lunit)' RETURN,-1 ENDIF PRINTERR = NOT ARG_PRESENT(ERRMSG) ERRMSG = '' FILE = FILE_SEARCH(XFILE, COUNT=COUNT) IF COUNT EQ 0 THEN BEGIN ERRMSG = 'Specified FITS File not found ' IF PRINTERR THEN MESSAGE,ERRMSG,/CON RETURN, -1 ; Don't print anything out, just report an error ENDIF FILE = FILE[0] ; ; Check if logical unit number is specified explicitly. ; IF KEYWORD_SET(LUNIT) THEN BEGIN UNIT=LUNIT GLUN = 0 ENDIF ELSE BEGIN UNIT = -1 GLUN = 1 ENDELSE ; ; Check if this is a compressed file. ; UCMPRS = ' ' IF KEYWORD_SET(compress) THEN BEGIN IF strcompress(string(compress),/remo) eq '1' THEN BEGIN compress = 'gunzip' ENDIF UCMPRS = compress; ENDIF ELSE BEGIN LEN = STRLEN(FILE) IF LEN GT 3 THEN $ TAIL = STRLOWCASE(STRMID(FILE, LEN-3, 3)) $ ELSE TAIL = ' ' IF STRMID(TAIL,1,2) EQ '.z' THEN $ UCMPRS = 'uncompress' $ ELSE IF TAIL EQ '.gz' or tail EQ 'ftz' THEN $ UCMPRS = 'gunzip' $ ELSE IF TAIL EQ 'bz2' THEN $ UCMPRS = 'bunzip2' ENDELSE ; Handle compressed files. IF UCMPRS EQ 'gunzip' THEN BEGIN IF KEYWORD_SET(READONLY) THEN BEGIN OPENR, UNIT, FILE, /COMPRESS, GET_LUN=glun, ERROR = ERROR ENDIF ELSE BEGIN OPENU, UNIT, FILE, /COMPRESS, GET_LUN=glun, ERROR = ERROR ENDELSE ENDIF ELSE IF UCMPRS NE ' ' THEN BEGIN IF (!VERSION.OS_FAMILY EQ 'unix') THEN BEGIN SPAWN, [UCMPRS,'-c',FILE], UNIT=UNIT, /NOSHELL ENDIF ELSE BEGIN PRINT, 'MRDFITS: Only Unix IDL supports piped spawns' PRINT, ' File must be uncompressed manually' RETURN, -1 ENDELSE ENDIF ELSE BEGIN ; ; Go to the start of the file. ; IF KEYWORD_SET(READONLY) THEN BEGIN OPENR, UNIT, FILE, GET_LUN=glun, ERROR = ERROR ENDIF ELSE BEGIN OPENU, UNIT, FILE, GET_LUN=glun, ERROR = ERROR ENDELSE IF ERROR NE 0 THEN BEGIN IF PRINTERR THEN PRINT,!ERROR_STATE.MSG ELSE $ ERRMSG = !ERROR_STATE.MSG RETURN,-1 ENDIF ENDELSE IF SIZE(EXT_NO,/TNAME) NE 'STRING' THEN $ IF EXT_NO LE 0 THEN RETURN, UNIT STAT = FXMOVE(UNIT, EXT_NO, SILENT = Silent, EXT_NO = extnum, $ ERRMSG=ERRMSG) IF STAT LT 0 THEN BEGIN IF(NOT KEYWORD_SET(LUNIT)) THEN FREE_LUN, UNIT RETURN, STAT ENDIF ELSE RETURN, UNIT END