Edit
kc3-lang/gnulib/lib/setenv.c
Bruno Haible
- lib/setenv.c
-
/* Copyright (C) 1992,1995-1999,2000-2003,2005-2008 Free Software Foundation, Inc. This file is part of the GNU C Library. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #if !_LIBC # include <config.h> #endif #include <alloca.h> /* Specification. */ #include <stdlib.h> #include <errno.h> #ifndef __set_errno # define __set_errno(ev) ((errno) = (ev)) #endif #include <string.h> #if _LIBC || HAVE_UNISTD_H # include <unistd.h> #endif #if _LIBC || !HAVE_SETENV #if !_LIBC # include "malloca.h" #endif #if !_LIBC # define __environ environ #endif #if _LIBC /* This lock protects against simultaneous modifications of `environ'. */ # include <bits/libc-lock.h> __libc_lock_define_initialized (static, envlock) # define LOCK __libc_lock_lock (envlock) # define UNLOCK __libc_lock_unlock (envlock) #else # define LOCK # define UNLOCK #endif /* In the GNU C library we must keep the namespace clean. */ #ifdef _LIBC # define setenv __setenv # define clearenv __clearenv # define tfind __tfind # define tsearch __tsearch #endif /* In the GNU C library implementation we try to be more clever and allow arbitrarily many changes of the environment given that the used values are from a small set. Outside glibc this will eat up all memory after a while. */ #if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \ && defined __GNUC__) # define USE_TSEARCH 1 # include <search.h> typedef int (*compar_fn_t) (const void *, const void *); /* This is a pointer to the root of the search tree with the known values. */ static void *known_values; # define KNOWN_VALUE(Str) \ ({ \ void *value = tfind (Str, &known_values, (compar_fn_t) strcmp); \ value != NULL ? *(char **) value : NULL; \ }) # define STORE_VALUE(Str) \ tsearch (Str, &known_values, (compar_fn_t) strcmp) #else # undef USE_TSEARCH # define KNOWN_VALUE(Str) NULL # define STORE_VALUE(Str) do { } while (0) #endif /* If this variable is not a null pointer we allocated the current environment. */ static char **last_environ; /* This function is used by `setenv' and `putenv'. The difference between the two functions is that for the former must create a new string which is then placed in the environment, while the argument of `putenv' must be used directly. This is all complicated by the fact that we try to reuse values once generated for a `setenv' call since we can never free the strings. */ int __add_to_environ (const char *name, const char *value, const char *combined, int replace) { register char **ep; register size_t size; const size_t namelen = strlen (name); const size_t vallen = value != NULL ? strlen (value) + 1 : 0; LOCK; /* We have to get the pointer now that we have the lock and not earlier since another thread might have created a new environment. */ ep = __environ; size = 0; if (ep != NULL) { for (; *ep != NULL; ++ep) if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=') break; else ++size; } if (ep == NULL || *ep == NULL) { char **new_environ; #ifdef USE_TSEARCH char *new_value; #endif /* We allocated this space; we can extend it. */ new_environ = (char **) (last_environ == NULL ? malloc ((size + 2) * sizeof (char *)) : realloc (last_environ, (size + 2) * sizeof (char *))); if (new_environ == NULL) { UNLOCK; return -1; } /* If the whole entry is given add it. */ if (combined != NULL) /* We must not add the string to the search tree since it belongs to the user. */ new_environ[size] = (char *) combined; else { /* See whether the value is already known. */ #ifdef USE_TSEARCH # ifdef _LIBC new_value = (char *) alloca (namelen + 1 + vallen); __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1), value, vallen); # else new_value = (char *) malloca (namelen + 1 + vallen); if (new_value == NULL) { __set_errno (ENOMEM); UNLOCK; return -1; } memcpy (new_value, name, namelen); new_value[namelen] = '='; memcpy (&new_value[namelen + 1], value, vallen); # endif new_environ[size] = KNOWN_VALUE (new_value); if (new_environ[size] == NULL) #endif { new_environ[size] = (char *) malloc (namelen + 1 + vallen); if (new_environ[size] == NULL) { #if defined USE_TSEARCH && !defined _LIBC freea (new_value); #endif __set_errno (ENOMEM); UNLOCK; return -1; } #ifdef USE_TSEARCH memcpy (new_environ[size], new_value, namelen + 1 + vallen); #else memcpy (new_environ[size], name, namelen); new_environ[size][namelen] = '='; memcpy (&new_environ[size][namelen + 1], value, vallen); #endif /* And save the value now. We cannot do this when we remove the string since then we cannot decide whether it is a user string or not. */ STORE_VALUE (new_environ[size]); } #if defined USE_TSEARCH && !defined _LIBC freea (new_value); #endif } if (__environ != last_environ) memcpy ((char *) new_environ, (char *) __environ, size * sizeof (char *)); new_environ[size + 1] = NULL; last_environ = __environ = new_environ; } else if (replace) { char *np; /* Use the user string if given. */ if (combined != NULL) np = (char *) combined; else { #ifdef USE_TSEARCH char *new_value; # ifdef _LIBC new_value = alloca (namelen + 1 + vallen); __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1), value, vallen); # else new_value = malloca (namelen + 1 + vallen); if (new_value == NULL) { __set_errno (ENOMEM); UNLOCK; return -1; } memcpy (new_value, name, namelen); new_value[namelen] = '='; memcpy (&new_value[namelen + 1], value, vallen); # endif np = KNOWN_VALUE (new_value); if (np == NULL) #endif { np = malloc (namelen + 1 + vallen); if (np == NULL) { #if defined USE_TSEARCH && !defined _LIBC freea (new_value); #endif __set_errno (ENOMEM); UNLOCK; return -1; } #ifdef USE_TSEARCH memcpy (np, new_value, namelen + 1 + vallen); #else memcpy (np, name, namelen); np[namelen] = '='; memcpy (&np[namelen + 1], value, vallen); #endif /* And remember the value. */ STORE_VALUE (np); } #if defined USE_TSEARCH && !defined _LIBC freea (new_value); #endif } *ep = np; } UNLOCK; return 0; } int setenv (const char *name, const char *value, int replace) { return __add_to_environ (name, value, NULL, replace); } /* The `clearenv' was planned to be added to POSIX.1 but probably never made it. Nevertheless the POSIX.9 standard (POSIX bindings for Fortran 77) requires this function. */ int clearenv (void) { LOCK; if (__environ == last_environ && __environ != NULL) { /* We allocated this environment so we can free it. */ free (__environ); last_environ = NULL; } /* Clear the environment pointer removes the whole environment. */ __environ = NULL; UNLOCK; return 0; } #ifdef _LIBC static void free_mem (void) { /* Remove all traces. */ clearenv (); /* Now remove the search tree. */ __tdestroy (known_values, free); known_values = NULL; } text_set_element (__libc_subfreeres, free_mem); # undef setenv # undef clearenv weak_alias (__setenv, setenv) weak_alias (__clearenv, clearenv) #endif #endif /* _LIBC || !HAVE_SETENV */