LibC: Rewrite environ handling
environ is only allocated on heap when you insert new variables. environment variables are only `free`'d if they are `malloc`'d by libc
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bdbde25784
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@ -4,6 +4,7 @@ set(LIBC_SOURCES
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ctype.cpp
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dirent.cpp
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dlfcn.cpp
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environ.cpp
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errno.cpp
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fcntl.cpp
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fenv.cpp
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@ -0,0 +1,216 @@
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#include <BAN/Assert.h>
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#include <errno.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/weak_alias.h>
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char** __environ;
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weak_alias(__environ, environ);
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static bool s_environ_malloced = false;
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static size_t s_environ_count = 0; // only valid when s_environ_malloced == true
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static uint8_t* s_environ_bitmap = nullptr; // if bit i is set, environ[i] has to be freed
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static int malloc_environ()
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{
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ASSERT(!s_environ_malloced);
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size_t environ_count = 0;
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while (environ[environ_count])
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environ_count++;
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const size_t bitmap_size = (environ_count + 7) / 8;
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auto* new_bitmap = static_cast<uint8_t*>(malloc(bitmap_size));
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if (new_bitmap == nullptr)
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return -1;
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memset(new_bitmap, 0, bitmap_size);
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char** new_environ = static_cast<char**>(malloc((environ_count + 1) * sizeof(char*)));
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if (new_environ == nullptr)
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{
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free(new_bitmap);
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return -1;
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}
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for (size_t i = 0; i < environ_count; i++)
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new_environ[i] = environ[i];
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new_environ[environ_count] = nullptr;
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environ = new_environ;
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s_environ_malloced = true;
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s_environ_count = environ_count;
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s_environ_bitmap = new_bitmap;
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return 0;
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}
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static int putenv_impl(char* string, bool malloced)
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{
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if (!s_environ_malloced && malloc_environ() == -1)
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return -1;
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const char* eq_addr = strchr(string, '=');
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if (eq_addr == nullptr)
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{
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errno = EINVAL;
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return -1;
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}
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const size_t namelen = eq_addr - string;
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for (int i = 0; environ[i]; i++)
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{
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if (strncmp(environ[i], string, namelen + 1) == 0)
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{
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const size_t byte = i / 8;
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const uint8_t mask = 1 << (i % 8);
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if (s_environ_bitmap[byte] & mask)
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free(environ[i]);
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if (malloced)
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s_environ_bitmap[i / 8] |= mask;
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else
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s_environ_bitmap[i / 8] &= ~mask;
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environ[i] = string;
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return 0;
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}
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}
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if ((s_environ_count + 1) % 8 == 0)
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{
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const size_t bytes = (s_environ_count + 1) / 8;
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void* new_bitmap = realloc(s_environ_bitmap, bytes);
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if (new_bitmap == nullptr)
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return -1;
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s_environ_bitmap = static_cast<uint8_t*>(new_bitmap);
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s_environ_bitmap[bytes - 1] = 0;
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}
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void* new_environ = realloc(environ, sizeof(char*) * (s_environ_count + 2));
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if (new_environ == nullptr)
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return -1;
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environ = static_cast<char**>(new_environ);
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environ[s_environ_count] = string;
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environ[s_environ_count + 1] = nullptr;
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s_environ_count++;
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if (malloced)
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{
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const size_t byte = s_environ_count / 8;
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const size_t mask = 1 << (s_environ_count % 8);
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s_environ_bitmap[byte] |= mask;
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}
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return 0;
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}
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char* getenv(const char* name)
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{
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if (environ == nullptr)
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return nullptr;
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const size_t namelen = strlen(name);
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for (int i = 0; environ[i]; i++)
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if (strncmp(name, environ[i], namelen) == 0)
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if (environ[i][namelen] == '=')
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return environ[i] + namelen + 1;
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return nullptr;
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}
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int setenv(const char* name, const char* val, int overwrite)
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{
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if (name == nullptr || !name[0] || strchr(name, '='))
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{
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errno = EINVAL;
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return -1;
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}
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if (!overwrite && getenv(name))
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return 0;
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const size_t namelen = strlen(name);
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const size_t vallen = strlen(val);
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char* string = (char*)malloc(namelen + vallen + 2);
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memcpy(string, name, namelen);
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string[namelen] = '=';
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memcpy(string + namelen + 1, val, vallen);
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string[namelen + vallen + 1] = '\0';
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return putenv_impl(string, true);
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}
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int unsetenv(const char* name)
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{
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if (name == nullptr || !name[0] || strchr(name, '='))
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{
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errno = EINVAL;
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return -1;
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}
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const size_t namelen = strlen(name);
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size_t i = 0;
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for (; environ[i]; i++)
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{
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if (strncmp(environ[i], name, namelen) || environ[i][namelen] != '=')
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continue;
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if (!s_environ_malloced)
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break;
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const size_t byte = i / 8;
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const size_t mask = 1 << (i % 8);
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if (s_environ_bitmap[byte] & mask)
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free(environ[i]);
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s_environ_count--;
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break;
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}
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for (; environ[i] && environ[i + 1]; i++)
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{
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environ[i] = environ[i + 1];
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if (!s_environ_malloced)
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continue;
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const size_t cbyte = i / 8;
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const size_t cmask = 1 << (i % 8);
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const size_t nbyte = (i + 1) / 8;
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const size_t nmask = 1 << ((i + 1) % 8);
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if (s_environ_bitmap[nbyte] & nmask)
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s_environ_bitmap[cbyte] |= cmask;
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else
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s_environ_bitmap[cbyte] &= ~cmask;
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}
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if (environ[i])
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{
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environ[i] = nullptr;
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if (s_environ_malloced)
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{
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const size_t byte = i / 8;
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const size_t mask = 1 << (i % 8);
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s_environ_bitmap[byte] &= ~mask;
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}
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}
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return 0;
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}
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int putenv(char* string)
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{
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if (string == nullptr || !string[0])
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{
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errno = EINVAL;
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return -1;
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}
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return putenv_impl(string, false);
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}
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@ -14,15 +14,10 @@
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#include <strings.h>
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#include <sys/stat.h>
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#include <sys/syscall.h>
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#include <sys/weak_alias.h>
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#include <unistd.h>
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#include <icxxabi.h>
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char** __environ;
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weak_alias(__environ, environ);
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static bool s_environ_malloced = false;
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void abort(void)
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{
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sigset_t set;
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@ -365,18 +360,6 @@ unsigned long long strtoull(const char* __restrict str, char** __restrict endp,
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return strtoT<unsigned long long>(str, endp, base, errno);
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}
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char* getenv(const char* name)
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{
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if (environ == nullptr)
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return nullptr;
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size_t len = strlen(name);
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for (int i = 0; environ[i]; i++)
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if (strncmp(name, environ[i], len) == 0)
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if (environ[i][len] == '=')
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return environ[i] + len + 1;
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return nullptr;
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}
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char* realpath(const char* __restrict file_name, char* __restrict resolved_name)
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{
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char buffer[PATH_MAX] {};
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@ -450,120 +433,6 @@ int system(const char* command)
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return stat_val;
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}
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int setenv(const char* name, const char* val, int overwrite)
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{
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if (name == nullptr || !name[0] || strchr(name, '='))
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{
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errno = EINVAL;
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return -1;
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}
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if (!overwrite && getenv(name))
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return 0;
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size_t namelen = strlen(name);
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size_t vallen = strlen(val);
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char* string = (char*)malloc(namelen + vallen + 2);
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memcpy(string, name, namelen);
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string[namelen] = '=';
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memcpy(string + namelen + 1, val, vallen);
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string[namelen + vallen + 1] = '\0';
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return putenv(string);
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}
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int unsetenv(const char* name)
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{
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if (name == nullptr || !name[0] || strchr(name, '='))
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{
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errno = EINVAL;
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return -1;
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}
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size_t len = strlen(name);
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bool found = false;
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for (int i = 0; environ[i]; i++)
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{
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if (!found && strncmp(environ[i], name, len) == 0 && environ[i][len] == '=')
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{
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free(environ[i]);
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found = true;
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}
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if (found)
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environ[i] = environ[i + 1];
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}
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return 0;
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}
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int putenv(char* string)
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{
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if (string == nullptr || !string[0])
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{
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errno = EINVAL;
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return -1;
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}
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if (!s_environ_malloced)
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{
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size_t env_count = 0;
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while (environ[env_count])
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env_count++;
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char** new_environ = static_cast<char**>(malloc((env_count + 1) * sizeof(char*)));
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if (new_environ == nullptr)
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return -1;
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for (size_t i = 0; i < env_count; i++)
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{
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const size_t bytes = strlen(environ[i]) + 1;
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new_environ[i] = (char*)malloc(bytes);
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memcpy(new_environ[i], environ[i], bytes);
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}
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new_environ[env_count] = nullptr;
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environ = new_environ;
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s_environ_malloced = true;
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}
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const char* eq_addr = strchr(string, '=');
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if (eq_addr == nullptr)
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{
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errno = EINVAL;
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return -1;
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}
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size_t namelen = eq_addr - string;
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for (int i = 0; environ[i]; i++)
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{
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if (strncmp(environ[i], string, namelen + 1) == 0)
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{
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free(environ[i]);
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environ[i] = string;
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return 0;
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}
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}
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size_t env_count = 0;
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while (environ[env_count])
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env_count++;
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char** new_envp = static_cast<char**>(malloc(sizeof(char*) * (env_count + 2)));
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if (new_envp == nullptr)
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return -1;
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for (size_t i = 0; i < env_count; i++)
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new_envp[i] = environ[i];
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new_envp[env_count] = string;
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new_envp[env_count + 1] = nullptr;
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free(environ);
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environ = new_envp;
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return 0;
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}
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static size_t temp_template_count_x(const char* _template)
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{
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const size_t len = strlen(_template);
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