Comtrol eCos - Manual (Page 360)

Chapter 13. C and math library overview
environ = (char **)&env;
str = getenv("PATH");
if (str==NULL) {
printf("The current PATH is unset\n");
} else {
printf("The current PATH is \"%s\"\n", str);
}
return 0;
}
Thread safety
The ISO C library has configuration options that control thread safety, i.e. working behavior if multiple threads call
the same function at the same time.
The following functionality has to be configured correctly, or used carefully in a multi-threaded environment:
• mblen()
• mbtowc()
• wctomb()
• printf() (and all standard I/O functions except for sprintf() and sscanf()
• strtok()
• rand() and srand()
• signal() and raise()
• asctime() , ctime() , gmtime() , and localtime()
• the errno variable
• the environ variable
• date and time settings
In some cases, to make eCos development easier, functions are provided (as specified by POSIX 1003.1) that
define re-entrant alternatives, i.e.
rand_r() , strtok_r() , asctime_r() , ctime_r() , gmtime_r() , and local-
time_r() . In other cases, configuration options are provided that control either locking of functions or their shared
data, such as with standard I/O streams, or by using per-thread data, such as with the errno variable.
In some other cases, like the setting of date and time, no re-entrant or thread-safe alternative or configuration is
provided as it is simply not a worthwhile addition (date and time should rarely need to be set.)
C library startup
The C library includes a function declared as:
void cyg_iso_c_start ( void )
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