envz_add(3)

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

LIBRARY
Standard C library (libc, -lc)

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);

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.

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.

ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
Interface | Attribute | Value
 | Thread safety | MT-Safe

STANDARDS
GNU.

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

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

        for (size_t 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);
    }

SEE ALSO
argz_add(3)