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git/parse-options-cb.c
René Scharfe 169bed7421 parse-options: avoid arithmetic on pointer that's potentially NULL 
parse_options_dup() counts the number of elements in the given array
without the end marker, allocates enough memory to hold all of them plus
an end marker, then copies them and terminates the new array.  The
counting part is done by advancing a pointer through the array, and the
original pointer is reconstructed using pointer subtraction before the
copy operation.

The function is also prepared to handle a NULL pointer passed to it.
None of its callers do that currently, but this feature was used by
46e91b663b ("checkout: split part of it to new command 'restore'",
2019-04-25); it seems worth keeping.

It ends up doing arithmetic on that NULL pointer, though, which is
undefined in standard C, when it tries to calculate "NULL - 0".  Better
avoid doing that by remembering the originally given pointer value.

There is another issue, though.  memcpy(3) does not support NULL
pointers, even for empty arrays.  Use COPY_ARRAY instead, which does
support such empty arrays.  Its call is also shorter and safer by
inferring the element type automatically.

Coccinelle and contrib/coccinelle/array.cocci did not propose to use
COPY_ARRAY because of the pointer subtraction and because the source is
const -- the semantic patch cautiously only considers pointers and array
references of the same type.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-13 11:44:00 +09:00

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#include "git-compat-util.h"
#include "parse-options.h"
#include "cache.h"
#include "commit.h"
#include "color.h"
#include "string-list.h"
#include "argv-array.h"
#include "sha1-array.h"
/*----- some often used options -----*/
int parse_opt_abbrev_cb(const struct option *opt, const char *arg, int unset)
{
int v;
if (!arg) {
v = unset ? 0 : DEFAULT_ABBREV;
} else {
if (!*arg)
return error(_("option `%s' expects a numerical value"),
opt->long_name);
v = strtol(arg, (char **)&arg, 10);
if (*arg)
return error(_("option `%s' expects a numerical value"),
opt->long_name);
if (v && v < MINIMUM_ABBREV)
v = MINIMUM_ABBREV;
else if (v > the_hash_algo->hexsz)
v = the_hash_algo->hexsz;
}
*(int *)(opt->value) = v;
return 0;
}
int parse_opt_expiry_date_cb(const struct option *opt, const char *arg,
int unset)
{
if (unset)
arg = "never";
if (parse_expiry_date(arg, (timestamp_t *)opt->value))
die(_("malformed expiration date '%s'"), arg);
return 0;
}
int parse_opt_color_flag_cb(const struct option *opt, const char *arg,
int unset)
{
int value;
if (!arg)
arg = unset ? "never" : (const char *)opt->defval;
value = git_config_colorbool(NULL, arg);
if (value < 0)
return error(_("option `%s' expects \"always\", \"auto\", or \"never\""),
opt->long_name);
*(int *)opt->value = value;
return 0;
}
int parse_opt_verbosity_cb(const struct option *opt, const char *arg,
int unset)
{
int *target = opt->value;
BUG_ON_OPT_ARG(arg);
if (unset)
/* --no-quiet, --no-verbose */
*target = 0;
else if (opt->short_name == 'v') {
if (*target >= 0)
(*target)++;
else
*target = 1;
} else {
if (*target <= 0)
(*target)--;
else
*target = -1;
}
return 0;
}
int parse_opt_commits(const struct option *opt, const char *arg, int unset)
{
struct object_id oid;
struct commit *commit;
BUG_ON_OPT_NEG(unset);
if (!arg)
return -1;
if (get_oid(arg, &oid))
return error("malformed object name %s", arg);
commit = lookup_commit_reference(the_repository, &oid);
if (!commit)
return error("no such commit %s", arg);
commit_list_insert(commit, opt->value);
return 0;
}
int parse_opt_commit(const struct option *opt, const char *arg, int unset)
{
struct object_id oid;
struct commit *commit;
struct commit **target = opt->value;
if (!arg)
return -1;
if (get_oid(arg, &oid))
return error("malformed object name %s", arg);
commit = lookup_commit_reference(the_repository, &oid);
if (!commit)
return error("no such commit %s", arg);
*target = commit;
return 0;
}
int parse_opt_object_name(const struct option *opt, const char *arg, int unset)
{
struct object_id oid;
if (unset) {
oid_array_clear(opt->value);
return 0;
}
if (!arg)
return -1;
if (get_oid(arg, &oid))
return error(_("malformed object name '%s'"), arg);
oid_array_append(opt->value, &oid);
return 0;
}
int parse_opt_object_id(const struct option *opt, const char *arg, int unset)
{
struct object_id oid;
struct object_id *target = opt->value;
if (unset) {
*target = null_oid;
return 0;
}
if (!arg)
return -1;
if (get_oid(arg, &oid))
return error(_("malformed object name '%s'"), arg);
*target = oid;
return 0;
}
int parse_opt_tertiary(const struct option *opt, const char *arg, int unset)
{
int *target = opt->value;
BUG_ON_OPT_ARG(arg);
*target = unset ? 2 : 1;
return 0;
}
struct option *parse_options_dup(const struct option *o)
{
const struct option *orig = o;
struct option *opts;
int nr = 0;
while (o && o->type != OPTION_END) {
nr++;
o++;
}
ALLOC_ARRAY(opts, nr + 1);
COPY_ARRAY(opts, orig, nr);
memset(opts + nr, 0, sizeof(*opts));
opts[nr].type = OPTION_END;
return opts;
}
struct option *parse_options_concat(struct option *a, struct option *b)
{
struct option *ret;
size_t i, a_len = 0, b_len = 0;
for (i = 0; a[i].type != OPTION_END; i++)
a_len++;
for (i = 0; b[i].type != OPTION_END; i++)
b_len++;
ALLOC_ARRAY(ret, st_add3(a_len, b_len, 1));
for (i = 0; i < a_len; i++)
ret[i] = a[i];
for (i = 0; i < b_len; i++)
ret[a_len + i] = b[i];
ret[a_len + b_len] = b[b_len]; /* final OPTION_END */
return ret;
}
int parse_opt_string_list(const struct option *opt, const char *arg, int unset)
{
struct string_list *v = opt->value;
if (unset) {
string_list_clear(v, 0);
return 0;
}
if (!arg)
return -1;
string_list_append(v, arg);
return 0;
}
int parse_opt_noop_cb(const struct option *opt, const char *arg, int unset)
{
return 0;
}
/**
* Report that the option is unknown, so that other code can handle
* it. This can be used as a callback together with
* OPTION_LOWLEVEL_CALLBACK to allow an option to be documented in the
* "-h" output even if it's not being handled directly by
* parse_options().
*/
enum parse_opt_result parse_opt_unknown_cb(struct parse_opt_ctx_t *ctx,
const struct option *opt,
const char *arg, int unset)
{
BUG_ON_OPT_ARG(arg);
return PARSE_OPT_UNKNOWN;
}
/**
* Recreates the command-line option in the strbuf.
*/
static int recreate_opt(struct strbuf *sb, const struct option *opt,
const char *arg, int unset)
{
strbuf_reset(sb);
if (opt->long_name) {
strbuf_addstr(sb, unset ? "--no-" : "--");
strbuf_addstr(sb, opt->long_name);
if (arg) {
strbuf_addch(sb, '=');
strbuf_addstr(sb, arg);
}
} else if (opt->short_name && !unset) {
strbuf_addch(sb, '-');
strbuf_addch(sb, opt->short_name);
if (arg)
strbuf_addstr(sb, arg);
} else
return -1;
return 0;
}
/**
* For an option opt, recreates the command-line option in opt->value which
* must be an char* initialized to NULL. This is useful when we need to pass
* the command-line option to another command. Since any previous value will be
* overwritten, this callback should only be used for options where the last
* one wins.
*/
int parse_opt_passthru(const struct option *opt, const char *arg, int unset)
{
static struct strbuf sb = STRBUF_INIT;
char **opt_value = opt->value;
if (recreate_opt(&sb, opt, arg, unset) < 0)
return -1;
free(*opt_value);
*opt_value = strbuf_detach(&sb, NULL);
return 0;
}
/**
* For an option opt, recreate the command-line option, appending it to
* opt->value which must be a argv_array. This is useful when we need to pass
* the command-line option, which can be specified multiple times, to another
* command.
*/
int parse_opt_passthru_argv(const struct option *opt, const char *arg, int unset)
{
static struct strbuf sb = STRBUF_INIT;
struct argv_array *opt_value = opt->value;
if (recreate_opt(&sb, opt, arg, unset) < 0)
return -1;
argv_array_push(opt_value, sb.buf);
return 0;
}
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