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Diffstat (limited to 'REORG.TODO/stdlib/setenv.c')
| -rw-r--r-- | REORG.TODO/stdlib/setenv.c | 340 |
1 files changed, 340 insertions, 0 deletions
diff --git a/REORG.TODO/stdlib/setenv.c b/REORG.TODO/stdlib/setenv.c new file mode 100644 index 0000000000..f3c0220045 --- /dev/null +++ b/REORG.TODO/stdlib/setenv.c @@ -0,0 +1,340 @@ +/* Copyright (C) 1992-2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#if HAVE_CONFIG_H +# include <config.h> +#endif + +/* Pacify GCC; see the commentary about VALLEN below. This is needed + at least through GCC 4.9.2. Pacify GCC for the entire file, as + there seems to be no way to pacify GCC selectively, only for the + place where it's needed. Do not use DIAG_IGNORE_NEEDS_COMMENT + here, as it's not defined yet. */ +#pragma GCC diagnostic ignored "-Wmaybe-uninitialized" + +#include <errno.h> +#if !_LIBC +# if !defined errno && !defined HAVE_ERRNO_DECL +extern int errno; +# endif +# define __set_errno(ev) ((errno) = (ev)) +#endif + +#if _LIBC || HAVE_STDLIB_H +# include <stdlib.h> +#endif +#if _LIBC || HAVE_STRING_H +# include <string.h> +#endif +#if _LIBC || HAVE_UNISTD_H +# include <unistd.h> +#endif + +#if !_LIBC +# define __environ environ +# ifndef HAVE_ENVIRON_DECL +extern char **environ; +# endif +#endif + +#if _LIBC +/* This lock protects against simultaneous modifications of `environ'. */ +# include <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 unsetenv __unsetenv +# 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> + +/* 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) +{ + char **ep; + size_t size; + + /* Compute lengths before locking, so that the critical section is + less of a performance bottleneck. VALLEN is needed only if + COMBINED is null (unfortunately GCC is not smart enough to deduce + this; see the #pragma at the start of this file). Testing + COMBINED instead of VALUE causes setenv (..., NULL, ...) to dump + core now instead of corrupting memory later. */ + const size_t namelen = strlen (name); + size_t vallen; + if (combined == NULL) + vallen = strlen (value) + 1; + + 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 || __builtin_expect (*ep == NULL, 1)) + { + char **new_environ; + + /* We allocated this space; we can extend it. */ + new_environ = (char **) realloc (last_environ, + (size + 2) * sizeof (char *)); + if (new_environ == NULL) + { + UNLOCK; + return -1; + } + + if (__environ != last_environ) + memcpy ((char *) new_environ, (char *) __environ, + size * sizeof (char *)); + + new_environ[size] = NULL; + new_environ[size + 1] = NULL; + ep = new_environ + size; + + last_environ = __environ = new_environ; + } + if (*ep == NULL || replace) + { + char *np; + + /* Use the user string if given. */ + if (combined != NULL) + np = (char *) combined; + else + { + const size_t varlen = namelen + 1 + vallen; +#ifdef USE_TSEARCH + char *new_value; + int use_alloca = __libc_use_alloca (varlen); + if (__builtin_expect (use_alloca, 1)) + new_value = (char *) alloca (varlen); + else + { + new_value = malloc (varlen); + if (new_value == NULL) + { + UNLOCK; + return -1; + } + } +# ifdef _LIBC + __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1), + value, vallen); +# else + memcpy (new_value, name, namelen); + new_value[namelen] = '='; + memcpy (&new_value[namelen + 1], value, vallen); +# endif + + np = KNOWN_VALUE (new_value); + if (__glibc_likely (np == NULL)) +#endif + { +#ifdef USE_TSEARCH + if (__glibc_unlikely (! use_alloca)) + np = new_value; + else +#endif + { + np = malloc (varlen); + if (__glibc_unlikely (np == NULL)) + { + UNLOCK; + return -1; + } + +#ifdef USE_TSEARCH + memcpy (np, new_value, varlen); +#else + memcpy (np, name, namelen); + np[namelen] = '='; + memcpy (&np[namelen + 1], value, vallen); +#endif + } + /* And remember the value. */ + STORE_VALUE (np); + } +#ifdef USE_TSEARCH + else + { + if (__glibc_unlikely (! use_alloca)) + free (new_value); + } +#endif + } + + *ep = np; + } + + UNLOCK; + + return 0; +} + +int +setenv (const char *name, const char *value, int replace) +{ + if (name == NULL || *name == '\0' || strchr (name, '=') != NULL) + { + __set_errno (EINVAL); + return -1; + } + + return __add_to_environ (name, value, NULL, replace); +} + +int +unsetenv (const char *name) +{ + size_t len; + char **ep; + + if (name == NULL || *name == '\0' || strchr (name, '=') != NULL) + { + __set_errno (EINVAL); + return -1; + } + + len = strlen (name); + + LOCK; + + ep = __environ; + if (ep != NULL) + while (*ep != NULL) + { + if (!strncmp (*ep, name, len) && (*ep)[len] == '=') + { + /* Found it. Remove this pointer by moving later ones back. */ + char **dp = ep; + + do + dp[0] = dp[1]; + while (*dp++); + /* Continue the loop in case NAME appears again. */ + } + else + ++ep; + } + + UNLOCK; + + return 0; +} + +/* 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 +libc_freeres_fn (free_mem) +{ + /* Remove all traces. */ + clearenv (); + + /* Now remove the search tree. */ + __tdestroy (known_values, free); + known_values = NULL; +} + +# undef setenv +# undef unsetenv +# undef clearenv +weak_alias (__setenv, setenv) +weak_alias (__unsetenv, unsetenv) +weak_alias (__clearenv, clearenv) +#endif |