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tools subcmd: support optarg as separate argument

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In addition to "-ovalue" and "--opt=value" syntax, allow also "-o value"
and "--opt value" for options with optional argument when the newly
added PARSE_OPT_OPTARG_ALLOW_NEXT flag is set.

This behavior is turned off by default since it does not make sense for
tools using non-option command line arguments. Consider the ambiguity
of "cmd -d x", where "-d x" can mean either "-d with argument of x" or
"-d without argument, followed by non-option argument x". This is not an
issue in the case that the tool takes no non-option arguments.

To implement this, a new local variable, force_defval, is created in
get_value(), along with a comment explaining the logic.

Link: https://lore.kernel.org/r/20260528103254.2990068-3-tglozar@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
This commit is contained in:
Tomas Glozar
2026-05-28 12:32:50 +02:00
parent 48209d763c
commit 534d9a93db
2 changed files with 46 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

53
tools/lib/subcmd/parse-options.c
View File

@@ -72,6 +72,7 @@ static int get_value(struct parse_opt_ctx_t *p,
const char *s, *arg = NULL;
const int unset = flags & OPT_UNSET;
int err;
bool force_defval = false;
if (unset && p->opt)
return opterror(opt, "takes no value", flags);
@@ -123,6 +124,42 @@ static int get_value(struct parse_opt_ctx_t *p,
}
}
if (opt->flags & PARSE_OPT_OPTARG && !p->opt) {
if (!(p->flags & PARSE_OPT_OPTARG_ALLOW_NEXT)) {
/*
* If the option has an optional argument, and the argument is not
* provided in the option itself, do not attempt to get it from
* the next argument, unless PARSE_OPT_OPTARG_ALLOW_NEXT is set.
*
* This prevents a non-option argument from being interpreted as an
* optional argument of a preceding option, for example:
*
* $ cmd --opt val
* -> is "val" argument of "--opt" or a separate non-option
* argument?
*
* With PARSE_OPT_OPTARG_ALLOW_NEXT, "val" is interpreted as
* the argument of "--opt", i.e. the same as "--opt=val".
* Without PARSE_OPT_OPTARG_ALLOW_NEXT, --opt is interpreted
* as having the default value, and "val" as a separate non-option
* argument.
*
* PARSE_OPT_OPTARG_ALLOW_NEXT is useful for commands that take no
* non-option arguments and want to allow more flexibility in
* optional argument passing.
*/
force_defval = true;
}
if (p->argc <= 1 || p->argv[1][0] == '-') {
/*
* If next argument is an option or does not exist,
* use the default value.
*/
force_defval = true;
}
}
if (opt->flags & PARSE_OPT_NOBUILD) {
char reason[128];
bool noarg = false;
@@ -148,7 +185,7 @@ static int get_value(struct parse_opt_ctx_t *p,
noarg = true;
if (opt->flags & PARSE_OPT_NOARG)
noarg = true;
if (opt->flags & PARSE_OPT_OPTARG && !p->opt)
if (force_defval)
noarg = true;
switch (opt->type) {
@@ -212,7 +249,7 @@ static int get_value(struct parse_opt_ctx_t *p,
err = 0;
if (unset)
*(const char **)opt->value = NULL;
else if (opt->flags & PARSE_OPT_OPTARG && !p->opt)
else if (force_defval)
*(const char **)opt->value = (const char *)opt->defval;
else
err = get_arg(p, opt, flags, (const char **)opt->value);
@@ -244,7 +281,7 @@ static int get_value(struct parse_opt_ctx_t *p,
return (*opt->callback)(opt, NULL, 1) ? (-1) : 0;
if (opt->flags & PARSE_OPT_NOARG)
return (*opt->callback)(opt, NULL, 0) ? (-1) : 0;
if (opt->flags & PARSE_OPT_OPTARG && !p->opt)
if (force_defval)
return (*opt->callback)(opt, NULL, 0) ? (-1) : 0;
if (get_arg(p, opt, flags, &arg))
return -1;
@@ -255,7 +292,7 @@ static int get_value(struct parse_opt_ctx_t *p,
*(int *)opt->value = 0;
return 0;
}
if (opt->flags & PARSE_OPT_OPTARG && !p->opt) {
if (force_defval) {
*(int *)opt->value = opt->defval;
return 0;
}
@@ -271,7 +308,7 @@ static int get_value(struct parse_opt_ctx_t *p,
*(unsigned int *)opt->value = 0;
return 0;
}
if (opt->flags & PARSE_OPT_OPTARG && !p->opt) {
if (force_defval) {
*(unsigned int *)opt->value = opt->defval;
return 0;
}
@@ -289,7 +326,7 @@ static int get_value(struct parse_opt_ctx_t *p,
*(long *)opt->value = 0;
return 0;
}
if (opt->flags & PARSE_OPT_OPTARG && !p->opt) {
if (force_defval) {
*(long *)opt->value = opt->defval;
return 0;
}
@@ -305,7 +342,7 @@ static int get_value(struct parse_opt_ctx_t *p,
*(unsigned long *)opt->value = 0;
return 0;
}
if (opt->flags & PARSE_OPT_OPTARG && !p->opt) {
if (force_defval) {
*(unsigned long *)opt->value = opt->defval;
return 0;
}
@@ -321,7 +358,7 @@ static int get_value(struct parse_opt_ctx_t *p,
*(u64 *)opt->value = 0;
return 0;
}
if (opt->flags & PARSE_OPT_OPTARG && !p->opt) {
if (force_defval) {
*(u64 *)opt->value = opt->defval;
return 0;
}

1
tools/lib/subcmd/parse-options.h
View File

@@ -33,6 +33,7 @@ enum parse_opt_flags {
PARSE_OPT_KEEP_ARGV0 = 4,
PARSE_OPT_KEEP_UNKNOWN = 8,
PARSE_OPT_NO_INTERNAL_HELP = 16,
PARSE_OPT_OPTARG_ALLOW_NEXT = 32,
};
enum parse_opt_option_flags {