On 03/12/2015 23:26, Harald van Dijk wrote:
On 03/12/2015 22:17, Stephane Chazelas wrote:
2015-12-03 22:02:14 +0100, Harald van Dijk:
[....]
$ for shell in bash mksh posh zsh; do printf %s: "$shell"; $shell
-c 'IFS=,; echo a, | { read v; echo "<$v>"; }'; done
bash:<a>
mksh:<a>
posh:<a,>
zsh:<a,>
As far as I can tell, the posh/zsh behaviour is the correct
behaviour, but I'm not convinced yet my interpretation is correct.
[...]
zsh and pdksh (and other descendants of the Forsyth shell) treat it as
separator (and are not compliant), mksh (derived from pdksh)
changed it recently. posh (also based on pdksh) still hasn't changed it.
[...]
I do see your point. Thanks for the clear example, I think I agree with
you, the description of field splitting mentions that delimiters are
used as terminators:
"The shell shall treat each character of the IFS as a delimiter and
use the delimiters as field terminators to [...]"
It should not be much of a problem to extend the patch I posted to cover
the rules as you describe them, I will make an attempt at this later.
Here it is. Attached is an updated patch that ignores the complete
terminator if only a single field remains, otherwise ignores only
trailing IFS whitespace.
Cheers,
Harald van Dijk
diff --git a/src/expand.c b/src/expand.c
index b2d710d..c6e87d5 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -203,7 +203,7 @@ expandarg(union node *arg, struct arglist *arglist, int flag)
* TODO - EXP_REDIR
*/
if (flag & EXP_FULL) {
- ifsbreakup(p, &exparg);
+ ifsbreakup(p, 0, &exparg);
*exparg.lastp = NULL;
exparg.lastp = &exparg.list;
expandmeta(exparg.list, flag);
@@ -1016,9 +1016,11 @@ recordregion(int start, int end, int nulonly)
* Break the argument string into pieces based upon IFS and add the
* strings to the argument list. The regions of the string to be
* searched for IFS characters have been stored by recordregion.
+ * If maxargs is non-zero, at most maxargs arguments will be created, by
+ * joining together the last arguments.
*/
void
-ifsbreakup(char *string, struct arglist *arglist)
+ifsbreakup(char *string, int maxargs, struct arglist *arglist)
{
struct ifsregion *ifsp;
struct strlist *sp;
@@ -1054,12 +1056,58 @@ ifsbreakup(char *string, struct arglist *arglist)
start = p;
continue;
}
+ /* If only reading one more argument:
+ * If we have exactly one field, read that field without its terminator.
+ * If we have more than one field, read all fields including their terminators,
+ * except for trailing IFS whitespace.
+ *
+ * This means that if we have only IFS characters left, and at most one
+ * of them is non-whitespace, we stop reading here.
+ * Otherwise, we read all the remaining characters except for trailing
+ * IFS whitespace.
+ *
+ * To keep track of this, the variable s indicates what we've seen so far.
+ * 0: only IFS whitespace.
+ * 1: exactly one IFS non-whitespace character.
+ * 2: non-IFS characters, or multiple IFS non-whitespace characters.
+ *
+ * In any case, q indicates the start of the characters to remove, or NULL
+ * if no characters should be removed.
+ */
+ if (maxargs == 1) {
+ int s = !ifsspc;
+ q = p;
+ for (;;) {
+ p++;
+ if (p >= string + ifsp->endoff) {
+ if (q)
+ *q = '\0';
+ goto add;
+ }
+ if (*p == (char)CTLESC)
+ p++;
+ if (strchr(ifs, *p)) {
+ if (strchr(defifs, *p)) {
+ if (!q)
+ q = p;
+ continue;
+ }
+ if (s == 0) {
+ s = 1;
+ continue;
+ }
+ }
+ s = 2;
+ q = 0;
+ }
+ }
*q = '\0';
sp = (struct strlist *)stalloc(sizeof *sp);
sp->text = start;
*arglist->lastp = sp;
arglist->lastp = &sp->next;
p++;
+ if (maxargs) maxargs--;
if (!nulonly) {
for (;;) {
if (p >= string + ifsp->endoff) {
diff --git a/src/expand.h b/src/expand.h
index 6a90f67..26dc5b4 100644
--- a/src/expand.h
+++ b/src/expand.h
@@ -69,7 +69,7 @@ char *_rmescapes(char *, int);
int casematch(union node *, char *);
void recordregion(int, int, int);
void removerecordregions(int);
-void ifsbreakup(char *, struct arglist *);
+void ifsbreakup(char *, int, struct arglist *);
void ifsfree(void);
/* From arith.y */
diff --git a/src/miscbltin.c b/src/miscbltin.c
index b596fd2..39b9c47 100644
--- a/src/miscbltin.c
+++ b/src/miscbltin.c
@@ -67,28 +67,21 @@
* less fields than variables -> remaining variables unset.
*
* @param line complete line of input
+ * @param ac argument count
* @param ap argument (variable) list
* @param len length of line including trailing '\0'
*/
static void
-readcmd_handle_line(char *s, char **ap)
+readcmd_handle_line(char *s, int ac, char **ap)
{
struct arglist arglist;
struct strlist *sl;
- char *backup;
- char *line;
- /* ifsbreakup will fiddle with stack region... */
- line = stackblock();
s = grabstackstr(s);
- /* need a copy, so that delimiters aren't lost
- * in case there are more fields than variables */
- backup = sstrdup(line);
-
arglist.lastp = &arglist.list;
- ifsbreakup(s, &arglist);
+ ifsbreakup(s, ac, &arglist);
*arglist.lastp = NULL;
ifsfree();
@@ -104,21 +97,6 @@ readcmd_handle_line(char *s, char **ap)
return;
}
- /* remaining fields present, but no variables left. */
- if (!ap[1] && sl->next) {
- size_t offset;
- char *remainder;
-
- /* FIXME little bit hacky, assuming that ifsbreakup
- * will not modify the length of the string */
- offset = sl->text - s;
- remainder = backup + offset;
- rmescapes(remainder);
- setvar(*ap, remainder, 0);
-
- return;
- }
-
/* set variable to field */
rmescapes(sl->text);
setvar(*ap, sl->text, 0);
@@ -211,7 +189,7 @@ start:
out:
recordregion(startloc, p - (char *)stackblock(), 0);
STACKSTRNUL(p);
- readcmd_handle_line(p + 1, ap);
+ readcmd_handle_line(p + 1, argc - (ap - argv), ap);
return status;
}
