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Make I/O errors fatal instead of mere warnings (#63) 

An input/output error indicates a fatal condition, even if it
occurs when closing a file. Awk should not return success on I/O
error, but treat I/O errors as it already treats write errors.

Test case:

$ (trap '' PIPE; awk 'BEGIN { print "hi"; }'; echo "E $?" >&2) | :
awk: i/o error occurred while closing /dev/stdout
 source line number 1
E 2

The test case pipes a line into a dummy command that reads no
input, with SIGPIPE ignored so we rely on awk's own I/O checking.
No write error is detected, because the pipe is buffered; the
broken pipe is only detected as an I/O error on closing stdout.

Before this commit, "E 0" was printed (indicating status 0/success)
because an I/O error merely produced a warning. A shell script
was unable to detect the I/O error using the exit status.
This commit is contained in:
Martijn Dekker 2020-01-17 13:02:57 +01:00 committed by Arnold Robbins
parent 2976507cc1
commit fed1a562c3
3 changed files with 13 additions and 4 deletions
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4
FIXES
View File

@ -25,6 +25,10 @@ THIS SOFTWARE.
This file lists all bug fixes, changes, etc., made since the AWK book
was sent to the printers in August, 1987.
January 9, 2020:
Input/output errors on closing files are now fatal instead of
mere warnings. Thanks to Martijn Dekker <martijn@inlv.org>.
January 5, 2020:
Fix a bug in the concatentation of two string constants into
one done in the grammar. Fixes GitHub issue #61. Thanks

8
run.c
View File

@ -1769,13 +1769,13 @@ Cell *closefile(Node **a, int n)
for (i = 0; i < nfiles; i++) {
if (files[i].fname && strcmp(x->sval, files[i].fname) == 0) {
if (ferror(files[i].fp))
WARNING( "i/o error occurred on %s", files[i].fname );
FATAL( "i/o error occurred on %s", files[i].fname );
if (files[i].mode == '|' || files[i].mode == LE)
stat = pclose(files[i].fp);
else
stat = fclose(files[i].fp);
if (stat == EOF)
WARNING( "i/o error occurred closing %s", files[i].fname );
FATAL( "i/o error occurred closing %s", files[i].fname );
if (i > 2) /* don't do /dev/std... */
xfree(files[i].fname);
files[i].fname = NULL; /* watch out for ref thru this */
@ -1795,13 +1795,13 @@ void closeall(void)
for (i = 0; i < FOPEN_MAX; i++) {
if (files[i].fp) {
if (ferror(files[i].fp))
WARNING( "i/o error occurred on %s", files[i].fname );
FATAL( "i/o error occurred on %s", files[i].fname );
if (files[i].mode == '|' || files[i].mode == LE)
stat = pclose(files[i].fp);
else
stat = fclose(files[i].fp);
if (stat == EOF)
WARNING( "i/o error occurred while closing %s", files[i].fname );
FATAL( "i/o error occurred while closing %s", files[i].fname );
}
}
}

5
testdir/T.misc
View File

@ -466,3 +466,8 @@ echo '' >foo0
$awk 'END { print NF, $0 }' foo0 >foo1
awk '{ print NF, $0 }' foo0| tail -1 >foo2
cmp -s foo1 foo2 || echo 'BAD: T.misc END must preserve $0'
# Check for nonzero exit status on I/O error.
echo 'E 2' >foo1
(trap '' PIPE; "$awk" 'BEGIN { print "hi"; }' 2>/dev/null; echo "E $?" >foo2) | :
cmp -s foo1 foo2 || echo 'BAD: T.misc exit status on I/O error'