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1994-05-05
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Title: RECIO DESIGN AND DEVELOPMENT NOTES
Copyright: (C) 1994 William Pierpoint
Version: 2.02
Date: May 5, 1994
1.0 DATA STRUCTURES
1.1 REC structure for each record stream
* defined in recio.h.
* one static REC for recin (included in ROPEN_MAX count).
* allocate dynamic array of RECs dimensioned to ROPEN_MAX-NREC in ropen().
* Each REC has two associated buffers:
1) record string buffer containing current record;
allocate when first record read;
reallocate if record becomes larger.
2) field string buffer containing current field;
allocate when first field read;
reallocate if field becomes larger.
* deallocate dynamic RECs and associated buffers in rclose() and
rcloseall() if all record streams closed; deallocate associated
buffers for recin with an exit function registered with atexit().
1.2 REC r_flags assignments
Bit Description
----- -------------------------------------------------------------
0 If clear, colno start at 0; if set, colno start at 1
1 if clear, read mode; if set, write/append mode
2-6 Reserved
7 If clear, EOF not reached; if set, EOF reached
8-11 If clear, no error; else, rerror number
12-15 if clear, no warning; else, rwarning number
1.3 Accessing REC Members and Associated Buffers
How do I
* access the name of the record stream? rnames()
* access the current context number? rcxtno()
* access the current record number? rrecno()
* access the current field number? rfldno()
* access the current column number? rcolno()
* access the record string buffer? rrecs()
* access the field string buffer? rflds()
* determine if column numbers start at 0 or 1 rbegcolno()
* determine if there are more records left? reof()
* determine if there is an error on the stream? rerror()
* determine if there is a warning on the stream? rwarning()
* access the error message for the stream? rerrstr()
* force an error on a record stream? rseterr()
* clear an error on a record stream? rclearerr()
* increase the size of the record string buffer? rsetrecsiz()
* increase the size of the field string buffer? rsetfldsiz()
* replace the data in the field string buffer? rsetfldstr()
* set the field delimiter character? rsetfldch()
* set the text delimiter character? rsettxtch()
* set the context number? rsetcxtno()
* set column numbering to start at 0 or 1? rsetbegcolno()
2.0 CODE STRUCTURES
2.1 Structure Chart
╔═════════╗
║ recio.c ║
╚═╤══╤══╤═╝
│ │ │
╔════════╗ input │ │ │ output ╔════════╗
║ rget.c ╟───────────┘ │ └──────────╢ rput.c ║
char ╚═╤════╤═╝ column │ char ╚═╤════╤═╝ column
delimited │ │ delimited │ delimited │ │ delimited
╔═════════╗ │ │ ╔══════════╗ │ ╔═════════╗ │ │ ╔══════════╗
║ rgets.c ╟─┤ ├─╢ rcgets.c ║ │ ║ rputs.c ╟─┤ ├─╢ rcputs.c ║
╚═════════╝ │ │ ╚══════════╝ │ ╚═════════╝ │ │ ╚══════════╝
│ │ │ │ │
╔═════════╗ │ │ ╔══════════╗ │ ╔═════════╗ │ │ ╔══════════╗
║ rgetf.c ╟─┤ ├─╢ rcgetf.c ║ │ ║ rputf.c ╟─┤ ├─╢ rcputf.c ║
╚═════════╝ │ │ ╚══════════╝ │ ╚═════════╝ │ │ ╚══════════╝
│ │ │ │ │
╔═════════╗ │ │ ╔══════════╗ │ ╔═════════╗ │ │ ╔══════════╗
║ rbget.c ╟─┘ └─╢ rcbget.c ║ │ ║ rbput.c ╟─┘ └─╢ rcbput.c ║
╚═════════╝ ╚══════════╝ │ ╚═════════╝ ╚══════════╝
│
╔══════════╗ │ ╔═════════╗ ╔══════════╗
║ rwarn.c ╟───┴───╢ rerr.c ╟────────╢ rfix.c ║
╚══════════╝ ╚═════════╝ ╚══════════╝
2.2 Callback Error Function Skeleton
if valid record pointer [risvalid(rp)]
if past end of file [reof(rp)] (if reof test removed, past EOF will
else [error number set] become R_EMISDAT or R_WEMPSTR)
switch error number [rerror(rp)]
case read data errors [R_ERANGE || R_EINVDAT || R_EMISDAT]
case write data errors [R_ENOPUT]
switch context number [rcxtno(rp)]
case RECIN
switch field number [rfldno(rp)]
case 1 (first field read)
case 2 (second field read)
...
endcase
...
default [missing or unknown context number]
endcase
case out of memory [R_ENOMEM]
case fatal errors [R_EINVAL || R_EINVMOD]
default [possibly set by application with rseterr()]
endcase
endif
else [invalid record pointer]
switch error number [errno]
case out of memory [ENOMEM]
case out of record or file pointers [EMFILE]
case permission denied [EACCES]
case fatal errors [EINVAL]
default [possibly set by application with rseterr()]
endcase
endif
2.3 Callback Warning Function Skeleton
if valid record pointer [risvalid(rp)]
switch warning number [rwarning(rp)]
case read data warnings [R_WEMPSTR]
case write data warnings [R_WWIDTH]
case code runtime warnings [R_WNOREG]
default [possibly set by application with rsetwarn()]
endcase
endif
3.0 DEVELOPMENT NOTES
3.1 fgets (Microsoft C 5.1)
Previous notes of mine indicate that Microsoft's fgets function does not
work correctly when it reads a line of text that consists of only a newline.
However this can be worked around by first setting the string buffer to an
empty string. If you plan on retaining the newline, you will need to test
this further. The fgets function is used twice in the rgetrec function.
If porting to Microsoft C, you may need to implement this fix in rget.c:
*rrecs(rp) = '\0'; /* just prior to the first fgets (added v1.20) */
*str = '\0'; /* just prior to the second fgets */
3.2 fopen (Borland C 3.1)
fopen() calls __openfp() calls open(). Borland's "Library Reference"
documents error numbers for open(), but not for fopen(). These error
numbers are ENOENT, EMFILE, EACCES, and EINVACC. Because ropen() screens
the access code, the EINVACC error should not occur from the recio library.
3.3 strtol & strtoul (Borland C 3.1)
These functions stop consuming input once they overflow, setting ERANGE.
Hence endptr can point into the middle of a sequence of valid characters
having the expected form as given in ANSI X3.159-1989, Sections 4.10.1.5
and 4.10.1.6. IMHO this characteristic is not in conformance with the
ANSI standard as endptr should only point to the first unrecognized
character or to the terminating null character. Borland's strtod does
not have this problem.
Note that ANSI X3.159-1989 Section 4.10.1.6 allows strtoul (unsigned
long) to have an optional negative sign. A negative unsigned long?
Borland 3.1 strtoul converts a negative long to an unsigned number
without error. But I prefer to trap any negative numbers input to
unsigned fields. So str2ul is a wrapper function for strtoul that
first tests for a negative number and if one is found, flags the data
as invalid and returns zero.
The test suite includes -0 as a data value. The strtol function traps
this as an ERANGE error and returns the overflow limit. The rfixi and
rfixl functions substitute zero.
3