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use environ on posix systems to read environment variables before the C runtime is initialized (issue #241)

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This commit is contained in:
daan 2020-05-05 19:37:50 -07:00
parent cefc930f72
commit 45974efdb7
1 changed files with 48 additions and 9 deletions
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53
src/options.c
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@ -400,6 +400,14 @@ static void mi_strlcat(char* dest, const char* src, size_t dest_size) {
dest[dest_size - 1] = 0;
}
static inline int mi_strnicmp(const char* s, const char* t, size_t n) {
if (n==0) return 0;
for (; *s != 0 && *t != 0 && n > 0; s++, t++, n--) {
if (toupper(*s) != toupper(*t)) break;
}
return (n==0 ? 0 : *s - *t);
}
#if defined _WIN32
// On Windows use GetEnvironmentVariable instead of getenv to work
// reliably even when this is invoked before the C runtime is initialized.
@ -411,11 +419,45 @@ static bool mi_getenv(const char* name, char* result, size_t result_size) {
size_t len = GetEnvironmentVariableA(name, result, (DWORD)result_size);
return (len > 0 && len < result_size);
}
#elif !defined(MI_USE_ENVIRON) || (MI_USE_ENVIRON!=0)
// On Posix systemsr use `environ` to acces environment variables
// even before the C runtime is initialized.
#if defined(__APPLE__)
#include <crt_externs.h>
static char** mi_get_environ(void) {
return (*_NSGetEnviron());
}
#else
extern char** environ;
static char** mi_get_environ(void) {
return environ;
}
#endif
static bool mi_getenv(const char* name, char* result, size_t result_size) {
if (name==NULL) return false;
const size_t len = strlen(name);
if (len == 0) return false;
char** env = mi_get_environ();
if (env == NULL) return false;
// compare all entries
for (; *env != NULL; env++) {
const char* s = *env;
if (mi_strnicmp(name, s, len) == 0 && s[len] == '=') { // case insensitive
// found it
mi_strlcpy(result, s + len + 1, result_size);
return true;
}
}
return false;
}
#else
// fallback: use standard C `getenv` but this cannot be used while initializing the C runtime
static bool mi_getenv(const char* name, char* result, size_t result_size) {
// cannot call getenv() when still initializing the C runtime.
if (_mi_preloading()) return false;
const char* s = getenv(name);
if (s == NULL) {
// in unix environments we check the upper case name too.
// we check the upper case name too.
char buf[64+1];
size_t len = strlen(name);
if (len >= sizeof(buf)) len = sizeof(buf) - 1;
@ -434,11 +476,8 @@ static bool mi_getenv(const char* name, char* result, size_t result_size) {
}
}
#endif
static void mi_option_init(mi_option_desc_t* desc) {
#ifndef _WIN32
// cannot call getenv() when still initializing the C runtime.
if (_mi_preloading()) return;
#endif
// Read option value from the environment
char buf[64+1];
mi_strlcpy(buf, "mimalloc_", sizeof(buf));
@ -471,9 +510,9 @@ static void mi_option_init(mi_option_desc_t* desc) {
desc->init = DEFAULTED;
}
}
mi_assert_internal(desc->init != UNINIT);
}
else {
else if (!_mi_preloading()) {
desc->init = DEFAULTED;
}
mi_assert_internal(desc->init != UNINIT);
}