The xtrace (set -x) output in dash is a bit of a pain, because arguments
containing whitespace aren't quoted. This can it impossible to tell
which bit belongs to which argument:
$ dash -c 'set -x; printf "%s\n" one "two three" four'
+ printf %s\n one two three four
one
two three
four
Another disadvantage is you cannot simply copy and paste the commands
from this xtrace output to repeat them for debugging purposes.
I wrote the attached patch which fixes this. I've been testing it for
about a week and had no issues.
The patch changes the following:
- Since we don't want every command name and argument quoted but only
those containing non-shell-safe characters, single_quote() has acquired
an extra argument indicating whether quoting should be conditional upon
the string containing non-shell-safe characters (1) or unconditional
(0). Shell-safe characters are defined as this set:
0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz%+,./:=@_^!-
- Quoting of variable assignments preceding commands needs to be handled
specially; in order for the output to be suitable for re-entry into the
shell, only the part after the "=" must be quoted. For this purpose, I
changed eprintlist() into two functions, eprintvarlist() to print the
variable assignments and eprintarglist() to print the rest.
Hope this is useful,
- Martijn
diff -ur dash-0.5.9.1.orig/src/alias.c dash-0.5.9.1/src/alias.c
--- dash-0.5.9.1.orig/src/alias.c 2014-09-28 10:19:32.000000000 +0200
+++ dash-0.5.9.1/src/alias.c 2017-02-23 03:01:57.000000000 +0100
@@ -197,7 +197,7 @@
void
printalias(const struct alias *ap) {
- out1fmt("%s=%s\n", ap->name, single_quote(ap->val));
+ out1fmt("%s=%s\n", ap->name, single_quote(ap->val, 0));
}
STATIC struct alias **
diff -ur dash-0.5.9.1.orig/src/eval.c dash-0.5.9.1/src/eval.c
--- dash-0.5.9.1.orig/src/eval.c 2016-09-02 16:12:23.000000000 +0200
+++ dash-0.5.9.1/src/eval.c 2017-02-23 03:14:56.000000000 +0100
@@ -95,7 +95,8 @@
STATIC int evalbltin(const struct builtincmd *, int, char **, int);
STATIC int evalfun(struct funcnode *, int, char **, int);
STATIC void prehash(union node *);
-STATIC int eprintlist(struct output *, struct strlist *, int);
+STATIC int eprintvarlist(struct output *, struct strlist *, int);
+STATIC void eprintarglist(struct output *, struct strlist *, int);
STATIC int bltincmd(int, char **);
@@ -786,8 +787,8 @@
out = &preverrout;
outstr(expandstr(ps4val()), out);
sep = 0;
- sep = eprintlist(out, varlist.list, sep);
- eprintlist(out, arglist.list, sep);
+ sep = eprintvarlist(out, varlist.list, sep);
+ eprintarglist(out, arglist.list, sep);
outcslow('\n', out);
#ifdef FLUSHERR
flushout(out);
@@ -1107,16 +1108,35 @@
STATIC int
-eprintlist(struct output *out, struct strlist *sp, int sep)
+eprintvarlist(struct output *out, struct strlist *sp, int sep)
{
while (sp) {
const char *p;
+ int i;
- p = " %s" + (1 - sep);
+ if (sep)
+ outfmt(out, " ");
sep |= 1;
- outfmt(out, p, sp->text);
+ i = 0;
+ while (sp->text[i] != '=' && sp->text[i] != '\0')
+ outfmt(out, "%c", sp->text[i++]);
+ if (sp->text[i] == '=')
+ outfmt(out, "=%s", single_quote(sp->text+i+1, 1));
sp = sp->next;
}
return sep;
}
+
+STATIC void
+eprintarglist(struct output *out, struct strlist *sp, int sep)
+{
+ while (sp) {
+ const char *p;
+
+ p = " %s" + (1 - sep);
+ sep |= 1;
+ outfmt(out, p, single_quote(sp->text, 1));
+ sp = sp->next;
+ }
+}
diff -ur dash-0.5.9.1.orig/src/mystring.c dash-0.5.9.1/src/mystring.c
--- dash-0.5.9.1.orig/src/mystring.c 2014-09-28 10:19:32.000000000 +0200
+++ dash-0.5.9.1/src/mystring.c 2017-02-23 03:10:48.000000000 +0100
@@ -184,13 +184,19 @@
/*
* Produce a possibly single quoted string suitable as input to the shell.
- * The return string is allocated on the stack.
+ * If 'conditional' is nonzero, quoting is only done if the string contains
+ * non-shellsafe characters; if it is zero, quoting is always done.
+ * If quoting was done, the return string is allocated on the stack,
+ * otherwise a pointer to the original string is returned.
*/
char *
-single_quote(const char *s) {
+single_quote(const char *s, int conditional) {
char *p;
+ if (conditional && s[strspn(s, SHELLSAFECHARS)] == '\0')
+ return (char *)s;
+
STARTSTACKSTR(p);
do {
diff -ur dash-0.5.9.1.orig/src/mystring.h dash-0.5.9.1/src/mystring.h
--- dash-0.5.9.1.orig/src/mystring.h 2014-09-28 10:19:32.000000000 +0200
+++ dash-0.5.9.1/src/mystring.h 2017-02-23 03:01:57.000000000 +0100
@@ -54,10 +54,13 @@
intmax_t atomax10(const char *);
int number(const char *);
int is_number(const char *);
-char *single_quote(const char *);
+char *single_quote(const char *, int);
char *sstrdup(const char *);
int pstrcmp(const void *, const void *);
const char *const *findstring(const char *, const char *const *, size_t);
#define equal(s1, s2) (strcmp(s1, s2) == 0)
#define scopy(s1, s2) ((void)strcpy(s2, s1))
+
+/* Characters that don't need quoting before re-entry into the shell */
+#define SHELLSAFECHARS "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz%+,./:=@_^!-"
diff -ur dash-0.5.9.1.orig/src/trap.c dash-0.5.9.1/src/trap.c
--- dash-0.5.9.1.orig/src/trap.c 2016-09-02 16:12:23.000000000 +0200
+++ dash-0.5.9.1/src/trap.c 2017-02-23 03:01:57.000000000 +0100
@@ -107,7 +107,7 @@
if (trap[signo] != NULL) {
out1fmt(
"trap -- %s %s\n",
- single_quote(trap[signo]),
+ single_quote(trap[signo], 0),
signal_names[signo]
);
}
diff -ur dash-0.5.9.1.orig/src/var.c dash-0.5.9.1/src/var.c
--- dash-0.5.9.1.orig/src/var.c 2014-10-07 16:30:35.000000000 +0200
+++ dash-0.5.9.1/src/var.c 2017-02-23 03:01:57.000000000 +0100
@@ -417,7 +417,7 @@
p = strchrnul(*ep, '=');
q = nullstr;
if (*p)
- q = single_quote(++p);
+ q = single_quote(++p, 0);
out1fmt("%s%s%.*s%s\n", prefix, sep, (int)(p - *ep), *ep, q);
}
