In ksh88, the test/[ built-in supported both the '<' and '>'
lexical sorting comparison operators, same as in [[. However, in
every version of ksh93, '<' does not work though '>' still does!
Still, the code for both is present in test_binop():
src/cmd/ksh93/bltins/test.c
548: case TEST_SGT:
549: return(strcoll(left, right)>0);
550: case TEST_SLT:
551: return(strcoll(left, right)<0);
Analysis: The binary operators are looked up in shtab_testops[] in
data/testops.c using a macro called sh_lookup, which expands to a
sh_locate() call. If we examine that function in sh/string.c, it's
easy to see that on systems using ASCII (i.e. all except IBM
mainframes), it assumes the table is sorted in ASCII order.
src/cmd/ksh93/sh/string.c
64: while((c= *tp->sh_name) && (CC_NATIVE!=CC_ASCII || c <= first))
The problem was that the '<' operator was not correctly sorted in
shtab_testops[]; it was sorted immediately before '>', but after
'='. The ASCII order is: < (60), = (61), > (62). This caused '<' to
never be found in the table.
The test_binop() function is also used by [[, yet '<' always worked
in that. This is because the parser has code that directly checks
for '<' and '>' within [[ (in sh/parse.c, lines 1949-1952).
This commit also adds '=~' to 'test', which took three lines of
code and allowed eliminating error handling in test_binop() as
test/[ and [[ now support the same binary ops. (re: fc2d5a60)
src/cmd/ksh93/*/*.[ch]:
- Rename a couple of very misleadingly named macros in test.h:
. For == and !=, the TEST_PATTERN bit is off for pattern compares
and on for literal string compares! Rename to TEST_STRCMP.
. The TEST_BINOP bit does not denote all binary operators, but
only the logical -a/-o ops in test/[. Rename to TEST_ANDOR.
src/cmd/ksh93/bltins/test.c: test_binop():
- Add support for =~. This is only used by test/[. The method is
implemented in two lines that convert the ERE to a shell pattern
by prefixing it with ~(E), then call test_strmatch with that
temporary string to match the ERE and update ${.sh.match}.
- Since all binary ops from shtab_testops[] are now accounted for,
remove unknown op error handling from this function.
src/cmd/ksh93/data/testops.c:
- shtab_testops[]:
. Correctly sort the '<' (TEST_SLT) entry.
. Remove ']]' (TEST_END). It's not an op and doesn't belong here.
- Update sh_opttest[] documentation with =~, \<, \>.
- Remove now-unused e_unsupported_op[] error message.
src/cmd/ksh93/sh/lex.c: sh_lex():
- Check for ']]' directly instead of relying on the removed
TEST_END entry from shtab_testops[].
src/cmd/ksh93/tests/bracket.sh:
- Add relevant tests.
src/cmd/ksh93/tests/builtins.sh:
- Fix an old test that globally deleted the 'test' builtin. Delete
it within the command substitution subshell only.
- Remove the test for non-support of =~ in test/[.
- Update the test for invalid test/[ op to use test directly.
c81473061a