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shared/specifier: treat NULL the same as ""

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We would busily allocate an empty string to concatenate all of it's
zero characters to the output. Let's make things a bit simpler by letting
the specifier functions return NULL to mean "nothing to append".
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2022-01-20 22:34:08 +01:00
parent 601dc59be2
commit 01c6946081
2 changed files with 25 additions and 40 deletions
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src/shared/specifier.c
+20 -36
View File
@@ -35,7 +35,6 @@
int specifier_printf(const char *text, size_t max_length, const Specifier table[], const char *root, const void *userdata, char **ret) {
_cleanup_free_ char *result = NULL;
bool percent = false;
const char *f;
size_t l;
char *t;
int r;
@@ -48,8 +47,10 @@ int specifier_printf(const char *text, size_t max_length, const Specifier table[
return -ENOMEM;
t = result;
for (f = text; *f != '\0'; f++, l--) {
for (const char *f = text; *f != '\0'; f++, l--) {
if (percent) {
percent = false;
if (*f == '%')
*(t++) = '%';
else {
@@ -66,6 +67,8 @@ int specifier_printf(const char *text, size_t max_length, const Specifier table[
r = i->lookup(i->specifier, i->data, root, userdata, &w);
if (r < 0)
return r;
if (isempty(w))
continue;
j = t - result;
k = strlen(w);
@@ -82,8 +85,6 @@ int specifier_printf(const char *text, size_t max_length, const Specifier table[
*(t++) = *f;
}
}
percent = false;
} else if (*f == '%')
percent = true;
else
@@ -108,11 +109,13 @@ int specifier_printf(const char *text, size_t max_length, const Specifier table[
/* Generic handler for simple string replacements */
int specifier_string(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
char *n;
char *n = NULL;
n = strdup(strempty(data));
if (!n)
return -ENOMEM;
if (!isempty(data)) {
n = strdup(data);
if (!n)
return -ENOMEM;
}
*ret = n;
return 0;
@@ -186,10 +189,8 @@ int specifier_short_host_name(char specifier, const void *data, const char *root
int specifier_kernel_release(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
struct utsname uts;
char *n;
int r;
r = uname(&uts);
if (r < 0)
if (uname(&uts) < 0)
return -errno;
n = strdup(uts.release);
@@ -211,47 +212,31 @@ int specifier_architecture(char specifier, const void *data, const char *root, c
return 0;
}
static int specifier_os_release_common(const char *field, const char *root, char **ret) {
char *t = NULL;
int r;
r = parse_os_release(root, field, &t);
if (r < 0)
return r;
if (!t) {
/* fields in /etc/os-release might quite possibly be missing, even if everything is entirely
* valid otherwise. Let's hence return "" in that case. */
t = strdup("");
if (!t)
return -ENOMEM;
}
*ret = t;
return 0;
}
/* Note: fields in /etc/os-release might quite possibly be missing, even if everything is entirely valid
* otherwise. We'll return an empty value or NULL in that case from the functions below. */
int specifier_os_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
return specifier_os_release_common("ID", root, ret);
return parse_os_release(root, "ID", ret);
}
int specifier_os_version_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
return specifier_os_release_common("VERSION_ID", root, ret);
return parse_os_release(root, "VERSION_ID", ret);
}
int specifier_os_build_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
return specifier_os_release_common("BUILD_ID", root, ret);
return parse_os_release(root, "BUILD_ID", ret);
}
int specifier_os_variant_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
return specifier_os_release_common("VARIANT_ID", root, ret);
return parse_os_release(root, "VARIANT_ID", ret);
}
int specifier_os_image_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
return specifier_os_release_common("IMAGE_ID", root, ret);
return parse_os_release(root, "IMAGE_ID", ret);
}
int specifier_os_image_version(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
return specifier_os_release_common("IMAGE_VERSION", root, ret);
return parse_os_release(root, "IMAGE_VERSION", ret);
}
int specifier_group_name(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
@@ -291,7 +276,6 @@ int specifier_user_name(char specifier, const void *data, const char *root, cons
}
int specifier_user_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
if (asprintf(ret, UID_FMT, getuid()) < 0)
return -ENOMEM;
src/test/test-specifier.c
+5 -4
View File
@@ -56,6 +56,7 @@ TEST(specifier_printf) {
static const Specifier table[] = {
{ 'X', specifier_string, (char*) "AAAA" },
{ 'Y', specifier_string, (char*) "BBBB" },
{ 'e', specifier_string, NULL },
COMMON_SYSTEM_SPECIFIERS,
{}
};
@@ -63,21 +64,21 @@ TEST(specifier_printf) {
_cleanup_free_ char *w = NULL;
int r;
r = specifier_printf("xxx a=%X b=%Y yyy", SIZE_MAX, table, NULL, NULL, &w);
r = specifier_printf("xxx a=%X b=%Y e=%e yyy", SIZE_MAX, table, NULL, NULL, &w);
assert_se(r >= 0);
assert_se(w);
puts(w);
assert_se(streq(w, "xxx a=AAAA b=BBBB yyy"));
assert_se(streq(w, "xxx a=AAAA b=BBBB e= yyy"));
free(w);
r = specifier_printf("machine=%m, boot=%b, host=%H, version=%v, arch=%a", SIZE_MAX, table, NULL, NULL, &w);
r = specifier_printf("machine=%m, boot=%b, host=%H, version=%v, arch=%a, empty=%e", SIZE_MAX, table, NULL, NULL, &w);
assert_se(r >= 0);
assert_se(w);
puts(w);
w = mfree(w);
specifier_printf("os=%o, os-version=%w, build=%B, variant=%W", SIZE_MAX, table, NULL, NULL, &w);
specifier_printf("os=%o, os-version=%w, build=%B, variant=%W, empty=%e%e%e", SIZE_MAX, table, NULL, NULL, &w);
if (w)
puts(w);
}