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shared/install: rework alias check and add test

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This mostly reuses existing checkers used by pid1, so handling of aliases
should be consistent. Hopefully, with the test it'll be clearer what it
happening.

Support for .wants/.requires "aliases" is restored. Those are still used in the
wild quite a bit, so we need to support them.

See https://github.com/systemd/systemd/pull/13119 for a discussion of aliases
with an instance that point to a different template: this is allowed.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2020-01-10 14:27:04 +01:00
parent 9a4f9e69e1
commit 3f57bc2267
3 changed files with 203 additions and 38 deletions
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src/shared/install.c
+54 -37
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@@ -1708,36 +1708,67 @@ static int install_info_discover_and_check(
return install_info_may_process(ret ? *ret : NULL, paths, changes, n_changes);
}
int unit_file_verify_alias(const UnitFileInstallInfo *i, const char *dst) {
int unit_file_verify_alias(const UnitFileInstallInfo *i, const char *dst, char **ret_dst) {
_cleanup_free_ char *dst_updated = NULL;
int r;
if (unit_name_is_valid(i->name, UNIT_NAME_TEMPLATE) &&
!unit_name_is_valid(dst, UNIT_NAME_TEMPLATE) &&
!i->default_instance)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Aliases for templates without DefaultInstance must be templates.");
/* Verify that dst is a valid either a valid alias or a valid .wants/.requires symlink for the target
* unit *i. Return negative on error or if not compatible, zero on success.
*
* ret_dst is set in cases where "instance propagation" happens, i.e. when the instance part is
* inserted into dst. It is not normally set, even on success, so that the caller can easily
* distinguish the case where instance propagation occured.
*/
if (unit_name_is_valid(i->name, UNIT_NAME_INSTANCE | UNIT_NAME_TEMPLATE) &&
!unit_name_is_valid(dst, UNIT_NAME_TEMPLATE | UNIT_NAME_INSTANCE))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Aliases for template instances must be a templates or template instances containing the instance name.");
const char *path_alias = strrchr(dst, '/');
if (path_alias) {
/* This branch covers legacy Alias= function of creating .wants and .requires symlinks. */
_cleanup_free_ char *dir = NULL;
if (unit_name_is_valid(i->name, UNIT_NAME_INSTANCE | UNIT_NAME_TEMPLATE) &&
unit_name_is_valid(dst, UNIT_NAME_INSTANCE)) {
_cleanup_free_ char *src_inst = NULL, *dst_inst = NULL;
path_alias ++; /* skip over slash */
r = unit_name_to_instance(i->name, &src_inst);
dir = dirname_malloc(dst);
if (!dir)
return log_oom();
if (!endswith(dir, ".wants") && !endswith(dir, ".requires"))
return log_warning_errno(SYNTHETIC_ERRNO(EXDEV),
"Invalid path \"%s\" in alias.", dir);
/* That's the name we want to use for verification. */
r = unit_symlink_name_compatible(path_alias, i->name);
if (r < 0)
return log_error_errno(r, "Failed to verify alias validity: %m");
if (r == 0)
return log_warning_errno(SYNTHETIC_ERRNO(EXDEV),
"Invalid unit %s symlink %s.",
i->name, dst);
} else {
/* If the symlink target has an instance set and the symlink source doesn't, we "propagate
* the instance", i.e. instantiate the symlink source with the target instance. */
if (unit_name_is_valid(dst, UNIT_NAME_TEMPLATE)) {
_cleanup_free_ char *inst = NULL;
r = unit_name_to_instance(i->name, &inst);
if (r < 0)
return log_error_errno(r, "Failed to extract instance name from %s: %m", i->name);
if (r == UNIT_NAME_INSTANCE) {
r = unit_name_replace_instance(dst, inst, &dst_updated);
if (r < 0)
return log_error_errno(r, "Failed to build unit name from %s+%s: %m",
dst, inst);
}
}
r = unit_validate_alias_symlink_and_warn(dst_updated ?: dst, i->name);
if (r < 0)
return r;
r = unit_name_to_instance(dst, &dst_inst);
if (r < 0)
return r;
if (!strstr(dst_inst, src_inst?src_inst:i->default_instance))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Aliases for template instances must be a templates or template instances containing the instance name.");
}
*ret_dst = TAKE_PTR(dst_updated);
return 0;
}
@@ -1757,31 +1788,17 @@ static int install_info_symlink_alias(
assert(config_path);
STRV_FOREACH(s, i->aliases) {
_cleanup_free_ char *alias_path = NULL, *dst = NULL;
_cleanup_free_ char *alias_path = NULL, *dst = NULL, *dst_updated = NULL;
q = install_full_printf(i, *s, &dst);
if (q < 0)
return q;
q = unit_file_verify_alias(i, dst);
q = unit_file_verify_alias(i, dst, &dst_updated);
if (q < 0)
continue;
if (unit_name_is_valid(i->name, UNIT_NAME_INSTANCE) &&
unit_name_is_valid(dst, UNIT_NAME_TEMPLATE)) {
_cleanup_free_ char *s_copy = NULL, *instance = NULL;
q = unit_name_to_instance(i->name, &instance);
if (q < 0)
return q;
q = unit_name_replace_instance(dst, instance, &s_copy);
if (q < 0)
return q;
free_and_replace(dst, s_copy);
}
alias_path = path_make_absolute(dst, config_path);
alias_path = path_make_absolute(dst_updated ?: dst, config_path);
if (!alias_path)
return -ENOMEM;