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

       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(),          │ Thread safety │ MT-Safe │
       │ envz_strip()                                                                │               │         │
       └─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

       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.

       #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);
       }

       Standard C library (libc, -lc)

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

       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.

argz_add(3)

Linux man-pages 6.9.1                              2024-06-15                                        envz_add(3)

       GNU.

#include<envz.h>error_tenvz_add(char**restrictenvz,size_t*restrictenvz_len,constchar*restrictname,constchar*restrictvalue);char*envz_entry(constchar*restrictenvz,size_tenvz_len,constchar*restrictname);char*envz_get(constchar*restrictenvz,size_tenvz_len,constchar*restrictname);error_tenvz_merge(char**restrictenvz,size_t*restrictenvz_len,constchar*restrictenvz2,size_tenvz2_len,intoverride);voidenvz_remove(char**restrictenvz,size_t*restrictenvz_len,constchar*restrictname);voidenvz_strip(char**restrictenvz,size_t*restrictenvz_len);