Good day,
I am writing about a recent experience just in case it helps someone
else in the future. I wrote an EPUB to TXT converter and announced
it on the DOS Ain't Dead forum. It is an AWK script and it is named
epub2txt.awk. It "shells out" to other utilities to do much of the
work, including another AWK script named xml2tsv.awk.
I found that when i used DJGPP gawk.exe to run epub2txt.awk, it almost
always produced terrible FAT corruption. Running the DIR command in
the work directory and would show a bunch of garbage file names and
subdirectory names.
During troubleshooting, i tried holding down the F5 key during boot
to make FreeDOS skip fdconfig.sys and fdauto.bat. That seemed to
help. Then i found that commenting out the BUFFERS= and JemmEx lines
in fdconfig.sys seemed to reduce the chances of FAT corruption. It
merely made the problem more intermittent. I could not find any
stable, working configuation.
I tried other versions of DJGPP gawk.exe. Every version i could find
produced the same FAT corruption.
I switched to nawk32.exe and that eliminated the FAT corruption. At
some point, i noticed data corruption within one of the output files.
Fortunately it was reproducible. I found that it was related to the
parent process (epub2txt.awk) having a file open when it ran a child
process (xml2tsv.awk).
I modified epub2txt.awk to make sure all files were closed prior to
running the child process. This change prevented the data
corruption with nawk32.exe. This change also fixed the issue with
DJGPP gawk.exe. If i am careful to close all files prior to running
a child process with gawk.exe, then it runs correctly without
corrupting the drive.
FAIL: print "hello" >"file1.txt"
FAIL: system("gawk.exe -f child.awk <file2.xml >file3.tsv")
FAIL: while ((getline <"file3.tsv") > 0) { ... }
FAIL: close("file3.tsv")
FAIL: print "world" >>"file1.txt"
FAIL: close("file1.txt")
PASS: print "hello" >"file1.txt"
PASS: # The next line is the fix, closing files prior to child process.
PASS: close("file1.txt")
PASS: system("gawk.exe -f child.awk <file2.xml >file3.tsv")
PASS: while ((getline <"file3.tsv") > 0) { ... }
PASS: close("file3.tsv")
PASS: print "world" >>"file1.txt"
PASS: close("file1.txt")
That's it for now.
-Ben
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