Manpages - envz_add.3

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

  #include <envz.h>

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

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.

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.

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

These functions are a GNU extension.

  #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);
  }

*argz_add*(3)

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