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resolved: put /etc/hosts hashmaps in a structure and pass that around 

This hides the details of juggling the two hashmaps from the callers a bit.
It also makes memory management a bit easier, because those two hashmaps share
some strings, so we can only free them together.

etc_hosts_parse() is made responsible to free the half-filled data structures
on error, which makes the caller a bit simpler.

No functional change. A refactoring to prepare for later changes.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2018-07-31 10:01:46 +02:00
parent 8d732e2f71
commit 37b7cc8d9a
2 changed files with 93 additions and 81 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

166
src/resolve/resolved-etc-hosts.c
View File

@ -25,35 +25,35 @@ typedef struct EtcHostsItemByName {
size_t n_addresses, n_allocated;
} EtcHostsItemByName;
static inline void etc_hosts_item_free(EtcHostsItem *item) {
strv_free(item->names);
free(item);
}
static inline void etc_hosts_item_by_name_free(EtcHostsItemByName *item) {
free(item->name);
free(item->addresses);
free(item);
}
static void etc_hosts_free(EtcHosts *hosts) {
hosts->by_address = hashmap_free_with_destructor(hosts->by_address, etc_hosts_item_free);
hosts->by_name = hashmap_free_with_destructor(hosts->by_name, etc_hosts_item_by_name_free);
}
void manager_etc_hosts_flush(Manager *m) {
EtcHostsItem *item;
EtcHostsItemByName *bn;
while ((item = hashmap_steal_first(m->etc_hosts_by_address))) {
strv_free(item->names);
free(item);
}
while ((bn = hashmap_steal_first(m->etc_hosts_by_name))) {
free(bn->name);
free(bn->addresses);
free(bn);
}
m->etc_hosts_by_address = hashmap_free(m->etc_hosts_by_address);
m->etc_hosts_by_name = hashmap_free(m->etc_hosts_by_name);
etc_hosts_free(&m->etc_hosts);
m->etc_hosts_mtime = USEC_INFINITY;
}
static int parse_line(Manager *m, unsigned nr, const char *line) {
static int parse_line(EtcHosts *hosts, unsigned nr, const char *line) {
_cleanup_free_ char *address_str = NULL;
struct in_addr_data address = {};
bool suppressed = false;
EtcHostsItem *item;
int r;
assert(m);
assert(hosts);
assert(line);
r = extract_first_word(&line, &address_str, NULL, EXTRACT_RELAX);
@ -78,9 +78,9 @@ static int parse_line(Manager *m, unsigned nr, const char *line) {
else {
/* If this is a normal address, then, simply add entry mapping it to the specified names */
item = hashmap_get(m->etc_hosts_by_address, &address);
item = hashmap_get(hosts->by_address, &address);
if (!item) {
r = hashmap_ensure_allocated(&m->etc_hosts_by_address, &in_addr_data_hash_ops);
r = hashmap_ensure_allocated(&hosts->by_address, &in_addr_data_hash_ops);
if (r < 0)
return log_oom();
@ -90,7 +90,7 @@ static int parse_line(Manager *m, unsigned nr, const char *line) {
item->address = address;
r = hashmap_put(m->etc_hosts_by_address, &item->address, item);
r = hashmap_put(hosts->by_address, &item->address, item);
if (r < 0) {
free(item);
return log_oom();
@ -124,9 +124,9 @@ static int parse_line(Manager *m, unsigned nr, const char *line) {
return log_oom();
}
bn = hashmap_get(m->etc_hosts_by_name, name);
bn = hashmap_get(hosts->by_name, name);
if (!bn) {
r = hashmap_ensure_allocated(&m->etc_hosts_by_name, &dns_name_hash_ops);
r = hashmap_ensure_allocated(&hosts->by_name, &dns_name_hash_ops);
if (r < 0)
return log_oom();
@ -134,7 +134,7 @@ static int parse_line(Manager *m, unsigned nr, const char *line) {
if (!bn)
return log_oom();
r = hashmap_put(m->etc_hosts_by_name, name, bn);
r = hashmap_put(hosts->by_name, name, bn);
if (r < 0) {
free(bn);
return log_oom();
@ -161,55 +161,12 @@ static int parse_line(Manager *m, unsigned nr, const char *line) {
return 0;
}
static int manager_etc_hosts_read(Manager *m) {
_cleanup_fclose_ FILE *f = NULL;
static int etc_hosts_parse(EtcHosts *hosts, FILE *f) {
_cleanup_(etc_hosts_free) EtcHosts t = {};
char line[LINE_MAX];
struct stat st;
usec_t ts;
unsigned nr = 0;
int r;
assert_se(sd_event_now(m->event, clock_boottime_or_monotonic(), &ts) >= 0);
/* See if we checked /etc/hosts recently already */
if (m->etc_hosts_last != USEC_INFINITY && m->etc_hosts_last + ETC_HOSTS_RECHECK_USEC > ts)
return 0;
m->etc_hosts_last = ts;
if (m->etc_hosts_mtime != USEC_INFINITY) {
if (stat("/etc/hosts", &st) < 0) {
if (errno == ENOENT) {
r = 0;
goto clear;
}
return log_error_errno(errno, "Failed to stat /etc/hosts: %m");
}
/* Did the mtime change? If not, there's no point in re-reading the file. */
if (timespec_load(&st.st_mtim) == m->etc_hosts_mtime)
return 0;
}
f = fopen("/etc/hosts", "re");
if (!f) {
if (errno == ENOENT) {
r = 0;
goto clear;
}
return log_error_errno(errno, "Failed to open /etc/hosts: %m");
}
/* Take the timestamp at the beginning of processing, so that any changes made later are read on the next
* invocation */
r = fstat(fileno(f), &st);
if (r < 0)
return log_error_errno(errno, "Failed to fstat() /etc/hosts: %m");
manager_etc_hosts_flush(m);
FOREACH_LINE(line, f, return log_error_errno(errno, "Failed to read /etc/hosts: %m")) {
char *l;
@ -221,19 +178,70 @@ static int manager_etc_hosts_read(Manager *m) {
if (l[0] == '#')
continue;
r = parse_line(m, nr, l);
if (r == -ENOMEM) /* On OOM we abandon the half-built-up structure. All other errors we ignore and proceed */
goto clear;
r = parse_line(&t, nr, l);
if (r < 0)
return r;
}
*hosts = t;
t = (EtcHosts) {}; /* prevent cleanup */
return 0;
}
static int manager_etc_hosts_read(Manager *m) {
_cleanup_fclose_ FILE *f = NULL;
struct stat st;
usec_t ts;
int r;
assert_se(sd_event_now(m->event, clock_boottime_or_monotonic(), &ts) >= 0);
/* See if we checked /etc/hosts recently already */
if (m->etc_hosts_last != USEC_INFINITY && m->etc_hosts_last + ETC_HOSTS_RECHECK_USEC > ts)
return 0;
m->etc_hosts_last = ts;
if (m->etc_hosts_mtime != USEC_INFINITY) {
if (stat("/etc/hosts", &st) < 0) {
if (errno != ENOENT)
return log_error_errno(errno, "Failed to stat /etc/hosts: %m");
manager_etc_hosts_flush(m);
return 0;
}
/* Did the mtime change? If not, there's no point in re-reading the file. */
if (timespec_load(&st.st_mtim) == m->etc_hosts_mtime)
return 0;
}
f = fopen("/etc/hosts", "re");
if (!f) {
if (errno != ENOENT)
return log_error_errno(errno, "Failed to open /etc/hosts: %m");
manager_etc_hosts_flush(m);
return 0;
}
/* Take the timestamp at the beginning of processing, so that any changes made later are read on the next
* invocation */
r = fstat(fileno(f), &st);
if (r < 0)
return log_error_errno(errno, "Failed to fstat() /etc/hosts: %m");
manager_etc_hosts_flush(m);
r = etc_hosts_parse(&m->etc_hosts, f);
if (r == -ENOMEM)
/* On OOM we bail. All other errors we ignore and proceed. */
return r;
m->etc_hosts_mtime = timespec_load(&st.st_mtim);
m->etc_hosts_last = ts;
return 1;
clear:
manager_etc_hosts_flush(m);
return r;
}
int manager_etc_hosts_lookup(Manager *m, DnsQuestion* q, DnsAnswer **answer) {
@ -265,7 +273,7 @@ int manager_etc_hosts_lookup(Manager *m, DnsQuestion* q, DnsAnswer **answer) {
EtcHostsItem *item;
DnsResourceKey *found_ptr = NULL;
item = hashmap_get(m->etc_hosts_by_address, &k);
item = hashmap_get(m->etc_hosts.by_address, &k);
if (!item)
return 0;
@ -314,7 +322,7 @@ int manager_etc_hosts_lookup(Manager *m, DnsQuestion* q, DnsAnswer **answer) {
return 1;
}
bn = hashmap_get(m->etc_hosts_by_name, name);
bn = hashmap_get(m->etc_hosts.by_name, name);
if (!bn)
return 0;

8
src/resolve/resolved-manager.h
View File

@ -23,6 +23,11 @@ typedef struct Manager Manager;
#define MANAGER_SEARCH_DOMAINS_MAX 32
#define MANAGER_DNS_SERVERS_MAX 32
typedef struct EtcHosts {
Hashmap *by_address;
Hashmap *by_name;
} EtcHosts;
struct Manager {
sd_event *event;
@ -114,8 +119,7 @@ struct Manager {
unsigned n_dnssec_verdict[_DNSSEC_VERDICT_MAX];
/* Data from /etc/hosts */
Hashmap* etc_hosts_by_address;
Hashmap* etc_hosts_by_name;
EtcHosts etc_hosts;
usec_t etc_hosts_last, etc_hosts_mtime;
bool read_etc_hosts;