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libct/nsenter: add and use bailx

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We use bail to report fatal errors, and bail always append %m
(aka strerror(errno)). In case an error condition did not set
errno, the log message will end up with ": Success" or an error
from a stale errno value. Either case is confusing for users.

Introduce bailx which is the same as bail except it does not
append %m, and use it where appropriate.

The naming follows libc's err(3) and errx(3).

PS we still use bail in a few cases after read or write, even
if that read/write did not return an error, because the code
does not distinguish between short read/write and error (-1).
This will be addressed by the next commit.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This commit is contained in:
Kir Kolyshkin
2025-10-11 17:40:48 -07:00
parent 9c8f476cb6
commit 067b8335e7
2 changed files with 37 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files
libcontainer/nsenter/log.h
+13 -8
View File
@@ -26,15 +26,20 @@ bool log_enabled_for(int level);
void write_log(int level, const char *format, ...) __attribute__((format(printf, 2, 3)));
extern int logfd;
#define bail(fmt, ...) \
do { \
if (logfd < 0) \
fprintf(stderr, "FATAL: " fmt ": %m\n", \
##__VA_ARGS__); \
else \
write_log(FATAL, fmt ": %m", ##__VA_ARGS__); \
exit(1); \
/* bailx logs a message to logfd (or stderr, if logfd is not available)
* and terminates the program.
*/
#define bailx(fmt, ...) \
do { \
if (logfd < 0) \
fprintf(stderr, "FATAL: " fmt "\n", ##__VA_ARGS__); \
else \
write_log(FATAL, fmt, ##__VA_ARGS__); \
exit(1); \
} while(0)
/* bail is the same as bailx, except it also adds ": %m" (errno). */
#define bail(fmt, ...) bailx(fmt ": %m", ##__VA_ARGS__)
#endif /* NSENTER_LOG_H */
libcontainer/nsenter/nsexec.c
+24 -20
View File
@@ -208,7 +208,7 @@ static int try_mapping_tool(const char *app, int pid, char *map, size_t map_len)
* or programming issue.
*/
if (!app)
bail("mapping tool not present");
bailx("mapping tool not present");
child = fork();
if (child < 0)
@@ -274,7 +274,7 @@ static void update_uidmap(const char *path, int pid, char *map, size_t map_len)
bail("failed to update /proc/%d/uid_map", pid);
write_log(DEBUG, "update /proc/%d/uid_map got -EPERM (trying %s)", pid, path);
if (try_mapping_tool(path, pid, map, map_len))
bail("failed to use newuid map on %d", pid);
bailx("failed to use newuid map on %d", pid);
}
}
@@ -289,7 +289,7 @@ static void update_gidmap(const char *path, int pid, char *map, size_t map_len)
bail("failed to update /proc/%d/gid_map", pid);
write_log(DEBUG, "update /proc/%d/gid_map got -EPERM (trying %s)", pid, path);
if (try_mapping_tool(path, pid, map, map_len))
bail("failed to use newgid map on %d", pid);
bailx("failed to use newgid map on %d", pid);
}
}
@@ -340,14 +340,16 @@ static void nl_parse(int fd, struct nlconfig_t *config)
/* Retrieve the netlink header. */
len = read(fd, &hdr, NLMSG_HDRLEN);
if (len < 0)
bail("failed to read netlink header");
if (len != NLMSG_HDRLEN)
bail("invalid netlink header length %zu", len);
bailx("invalid netlink header length %zu", len);
if (hdr.nlmsg_type == NLMSG_ERROR)
bail("failed to read netlink message");
bailx("failed to read netlink message");
if (hdr.nlmsg_type != INIT_MSG)
bail("unexpected msg type %d", hdr.nlmsg_type);
bailx("unexpected msg type %d", hdr.nlmsg_type);
/* Retrieve data. */
size = NLMSG_PAYLOAD(&hdr, 0);
@@ -356,8 +358,10 @@ static void nl_parse(int fd, struct nlconfig_t *config)
bail("failed to allocate %zu bytes of memory for nl_payload", size);
len = read(fd, data, size);
if (len < 0)
bail("failed to read netlink payload");
if (len != size)
bail("failed to read netlink payload, %zu != %zu", len, size);
bailx("failed to read netlink payload, %zu != %zu", len, size);
/* Parse the netlink payload. */
config->data = data;
@@ -456,7 +460,7 @@ static int nstype(char *name)
* without corresponding handling could result in broken behaviour) and
* the rest of runc doesn't allow unknown namespace types anyway.
*/
bail("unknown namespace type %s", name);
bailx("unknown namespace type %s", name);
}
static nsset_t __open_namespaces(char *nsspec, struct namespace_t **ns_list, size_t *ns_len)
@@ -469,7 +473,7 @@ static nsset_t __open_namespaces(char *nsspec, struct namespace_t **ns_list, siz
namespace = strtok_r(nsspec, ",", &saveptr);
if (!namespace || !strlen(namespace) || !strlen(nsspec))
bail("ns paths are empty");
bailx("ns paths are empty");
do {
int fd;
@@ -485,7 +489,7 @@ static nsset_t __open_namespaces(char *nsspec, struct namespace_t **ns_list, siz
/* Split 'ns:path'. */
path = strstr(namespace, ":");
if (!path)
bail("failed to parse %s", namespace);
bailx("failed to parse %s", namespace);
*path++ = '\0';
fd = open(path, O_RDONLY);
@@ -530,7 +534,7 @@ static nsset_t __join_namespaces(nsset_t allow, struct namespace_t *ns_list, siz
/* Skip permission errors. */
if (saved_errno == EPERM)
continue;
bail("failed to setns into %s namespace", ns->type);
bailx("failed to setns into %s namespace: %s", ns->type, strerror(saved_errno));
}
joined |= type;
@@ -597,7 +601,7 @@ static void __close_namespaces(nsset_t to_join, nsset_t joined, struct namespace
/* Make sure we joined the namespaces we planned to. */
if (failed_to_join)
bail("failed to join {%s} namespaces: %s", nsset_to_str(failed_to_join), strerror(EPERM));
bailx("failed to join {%s} namespaces: %s", nsset_to_str(failed_to_join), strerror(EPERM));
free(ns_list);
}
@@ -936,7 +940,7 @@ void nsexec(void)
stage1_complete = true;
break;
default:
bail("unexpected sync value: %u", s);
bailx("unexpected sync value: %u", s);
}
}
write_log(DEBUG, "<- stage-1 synchronisation loop");
@@ -967,7 +971,7 @@ void nsexec(void)
stage2_complete = true;
break;
default:
bail("unexpected sync value: %u", s);
bailx("unexpected sync value: %u", s);
}
}
write_log(DEBUG, "<- stage-2 synchronisation loop");
@@ -1058,7 +1062,7 @@ void nsexec(void)
if (read(syncfd, &s, sizeof(s)) != sizeof(s))
bail("failed to sync with parent: read(SYNC_USERMAP_ACK)");
if (s != SYNC_USERMAP_ACK)
bail("failed to sync with parent: SYNC_USERMAP_ACK: got %u", s);
bailx("failed to sync with parent: SYNC_USERMAP_ACK: got %u", s);
/* Revert temporary re-dumpable setting. */
if (config.namespaces) {
@@ -1094,7 +1098,7 @@ void nsexec(void)
if (read(syncfd, &s, sizeof(s)) != sizeof(s))
bail("failed to sync with parent: read(SYNC_TIMEOFFSETS_ACK)");
if (s != SYNC_TIMEOFFSETS_ACK)
bail("failed to sync with parent: SYNC_TIMEOFFSETS_ACK: got %u", s);
bailx("failed to sync with parent: SYNC_TIMEOFFSETS_ACK: got %u", s);
}
/*
@@ -1130,7 +1134,7 @@ void nsexec(void)
}
if (s != SYNC_RECVPID_ACK) {
sane_kill(stage2_pid, SIGKILL);
bail("failed to sync with parent: SYNC_RECVPID_ACK: got %u", s);
bailx("failed to sync with parent: SYNC_RECVPID_ACK: got %u", s);
}
write_log(DEBUG, "signal completion to stage-0");
@@ -1177,7 +1181,7 @@ void nsexec(void)
if (read(syncfd, &s, sizeof(s)) != sizeof(s))
bail("failed to sync with parent: read(SYNC_GRANDCHILD)");
if (s != SYNC_GRANDCHILD)
bail("failed to sync with parent: SYNC_GRANDCHILD: got %u", s);
bailx("failed to sync with parent: SYNC_GRANDCHILD: got %u", s);
if (setsid() < 0)
bail("setsid failed");
@@ -1212,9 +1216,9 @@ void nsexec(void)
}
break;
default:
bail("unexpected jump value");
bailx("unexpected jump value");
}
/* Should never be reached. */
bail("should never be reached");
bailx("should never be reached");
}