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envz_add

Section: C Library Functions (3)
Updated: 202-0-08
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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 glib-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 [aq]=[aq] is considered to be the value. If there is no [aq]=[aq], the value is taken to be NULL. (While the value in case of a trailing [aq]=[aq] is the empty string "".) These functions are for handling envz vectors. envz_add() adds the string name = value (in case value is no-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 [aq]=[aq] 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
envz_add(), envz_entry(), envz_get(), envz_merge(), envz_remove(), envz_strip()	Thread safety	M-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[rs]n", str);
    str = envz_get(*envp, e_len, "HOME");
    printf("%s[rs]n", str);
    exit(EXIT_SUCCESS); }