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   envz_add    ( 3 )

поддержка строки среды (environment string support)

   Дубль

(статьи: envz - поддержка строки среды )

Имя (Name)

envz_add, envz_entry, envz_get, envz_merge, envz_remove, envz_strip - environment string support


Синопсис (Synopsis)

#include <envz.h>

error_t envz_add(char **restrict envz, size_t *restrict envz_len, const char *restrict name, const char *restrict value);

char *envz_entry(const char *restrict envz, size_t envz_len, const char *restrict name);

char *envz_get(const char *restrict envz, size_t envz_len, const char *restrict name);

error_t envz_merge(char **restrict envz, size_t *restrict envz_len, const char *restrict envz2, size_t envz2_len, int override);

void envz_remove(char **restrict envz, size_t *restrict envz_len, const char *restrict name);

void envz_strip(char **restrict envz, size_t *restrict envz_len);


Описание (Description)

These functions are glibc-specific.

An argz vector is a pointer to a character buffer together with a length, see argz_add(3). An envz vector is a special argz vector, namely one where the strings have the form "name=value". Everything after the first '=' is considered to be the value. If there is no '=', the value is taken to be NULL. (While the value in case of a trailing '=' is the empty string "".)

These functions are for handling envz vectors.

envz_add() adds the string "name=value" (in case value is non- NULL) or "name" (in case value is NULL) to the envz vector (*envz, *envz_len) and updates *envz and *envz_len. If an entry with the same name existed, it is removed.

envz_entry() looks for name in the envz vector (envz, envz_len) and returns the entry if found, or NULL if not.

envz_get() looks for name in the envz vector (envz, envz_len) and returns the value if found, or NULL if not. (Note that the value can also be NULL, namely when there is an entry for name without '=' sign.)

envz_merge() adds each entry in envz2 to *envz, as if with envz_add(). If override is true, then values in envz2 will supersede those with the same name in *envz, otherwise not.

envz_remove() removes the entry for name from (*envz, *envz_len) if there was one.

envz_strip() removes all entries with value NULL.


Возвращаемое значение (Return value)

All envz functions that do memory allocation have a return type of error_t (an integer type), and return 0 for success, and ENOMEM if an allocation error occurs.


Атрибуты (Attributes)

For an explanation of the terms used in this section, see attributes(7).

┌──────────────────────────────────────┬───────────────┬─────────┐ │Interface Attribute Value │ ├──────────────────────────────────────┼───────────────┼─────────┤ │envz_add(), envz_entry(), envz_get(), │ Thread safety │ MT-Safe │ │envz_merge(), envz_remove(), │ │ │ │envz_strip() │ │ │ └──────────────────────────────────────┴───────────────┴─────────┘


Стандарты (Conforming to)

These functions are a GNU extension.


Примеры (Examples)

#include <stdio.h>
       #include <stdlib.h>
       #include <envz.h>

int main(int argc, char *argv[], char *envp[]) { int e_len = 0; char *str;

for (int i = 0; envp[i] != NULL; i++) e_len += strlen(envp[i]) + 1;

str = envz_entry(*envp, e_len, "HOME"); printf("%s\n", str); str = envz_get(*envp, e_len, "HOME"); printf("%s\n", str); exit(EXIT_SUCCESS); }


Смотри также (See also)

argz_add(3)