Misc

Miscellaneous helpers that don’t fit anywhere else: byte-order conversion, base64, hex dumps, small math utilities.

Source code:

• helpers.h

• helpers.c

get_hostname()¶

Retrieves the hostname of the current system. On Linux, it reads from /etc/hostname, while on ESP32, it returns a default value.

const char *get_hostname(void);

Parameters

Returns

A pointer to a static string containing the hostname of the system.

Notes

The returned string is statically allocated and should not be modified or freed by the caller.

node_uuid()¶

The node_uuid() function retrieves a unique identifier for the current machine. On Linux, it reads or generates a UUID stored in /yuneta/store/agent/uuid/uuid.json. On ESP32, it derives the UUID from the device’s MAC address.

const char *node_uuid(void);

Parameters

Returns

Returns a pointer to a string containing the unique node UUID.

Notes

The returned UUID is generated once and stored persistently. On Linux, if the UUID file does not exist, a new one is created. On ESP32, the UUID is derived from the MAC address.

check_open_fds()¶

Returns the number of currently open file descriptors in the process. On Linux, reads from /proc/self/fd. On other systems, returns 0.

int check_open_fds(void);

Parameters

Returns

The number of open file descriptors in the calling process. Returns 0 on non-Linux platforms.

cpu_usage()¶

Returns the accumulated CPU time of the current process in jiffies (scheduler clock ticks). On Linux, reads from /proc/self/stat. On other systems, returns 0.

uint64_t cpu_usage(void);

Parameters

Returns

The sum of user time (utime) and system time (stime) in jiffies. Returns 0 on non-Linux platforms.

cpu_usage_percent()¶

Calculates the CPU usage percentage of the current process over an elapsed time interval. Must be called repeatedly to track CPU usage over time.

double cpu_usage_percent(
    uint64_t *last_cpu_ticks,
    uint64_t *last_ms
);

Parameters

Returns

CPU usage percentage as a double ranging from 0.0 to 100.0+. Returns 0.0 on the first call or if the time interval is zero.

create_random_uuid()¶

Generates a cryptographically secure random UUID (version 4) and formats it as a string.

int create_random_uuid(
    char *bf,
    int bfsize
);

Parameters

Returns

Returns 0 on success. Returns -1 if the buffer is too small or if random number generation fails.

free_ram_in_kb()¶

Returns the amount of free RAM available in the system in kilobytes. On Linux, reads from /proc/meminfo. On other systems, returns 0.

unsigned long free_ram_in_kb(void);

Parameters

Returns

The amount of free RAM in kilobytes.

get_name_from_nn_table()¶

Looks up a name string in a number-to-name lookup table by matching a numeric value.

const char *get_name_from_nn_table(
    const number_name_table_t *table,
    int number
);

Parameters

Returns

A pointer to the name string corresponding to the given number, or NULL if not found.

get_number_from_nn_table()¶

Looks up a numeric value in a number-to-name lookup table by matching a name string.

int get_number_from_nn_table(
    const number_name_table_t *table,
    const char *name
);

Parameters

Returns

The numeric value corresponding to the given name, or -1 if not found.

get_yunetas_base()¶

Resolves the Yunetas base directory path. The environment variable YUNETAS_BASE takes priority, followed by standard paths.

const char *get_yunetas_base(void);

Parameters

Returns

A pointer to a static string containing the Yunetas base directory path.

is_yuneta_user()¶

Checks whether a given username belongs to the “yuneta” group or is exactly the “yuneta” user.

int is_yuneta_user(
    const char *username
);

Parameters

Returns

Returns TRUE if the user is “yuneta” or belongs to the “yuneta” group. Returns FALSE otherwise.

print_open_fds()¶

Logs information about all currently open file descriptors in the process using a formatted prefix string.

int print_open_fds(
    const char *fmt,
    ...
);

Parameters

Returns

The number of open file descriptors found and logged.

source2base64_for_yunetas()¶

Converts a file to base64-encoded format, finding the file in either the current path or relative to the Yunetas base directory.

gbuffer_t *source2base64_for_yunetas(
    const char *source,
    char *comment,
    int commentlen
);

Parameters

Returns

A gbuffer_t pointer containing the base64-encoded file content, or NULL if the file is not found.

total_ram_in_kb()¶

Returns the total amount of RAM installed in the system in kilobytes. On Linux, reads from /proc/meminfo.

unsigned long total_ram_in_kb(void);

Parameters

Returns

The total RAM in kilobytes.

yuneta_getgrnam()¶

Portable wrapper around getgrnam() that looks up group information by name. Uses static implementations when CONFIG_FULLY_STATIC is defined.

struct group *yuneta_getgrnam(
    const char *name
);

Parameters

Returns

A pointer to a struct group, or NULL if the group is not found.

yuneta_getgrouplist()¶

Portable wrapper around getgrouplist() that retrieves all groups a user belongs to.

int yuneta_getgrouplist(
    const char *user,
    gid_t group,
    gid_t *groups,
    int *ngroups
);

Parameters

Returns

The number of groups on success. Returns -1 if the array is too small.

yuneta_getpwnam()¶

Portable wrapper around getpwnam() that looks up user information by username.

struct passwd *yuneta_getpwnam(
    const char *name
);

Parameters

Returns

A pointer to a struct passwd, or NULL if the username is not found.

yuneta_getpwuid()¶

Portable wrapper around getpwuid() that looks up user information by user ID.

struct passwd *yuneta_getpwuid(
    uid_t uid
);

Parameters

Returns

A pointer to a struct passwd, or NULL if the user ID is not found.