/* Copyright (C) 1996 DJ Delorie, see COPYING.DJ for details */ /* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */ #include #include #include #include #include /* This routine assumes that the environ array and all strings it points to were malloc'd. Nobody else should modify the environment except crt1.c */ extern char **environ; static char **prev_environ = NULL; /* to know when it's safe to call `free' */ static int ecount = -1; static int emax = -1; static int putenv_bss_count = -1; /* This gets incremented every time some variable in the environment is added, deleted, or changes its value. It is meant to be used by functions that depend on values of environment variables, but don't want to call `getenv' unnecessarily (example: `__use_lfn'). Users should compare this variable with their static variable whose value is initialized to zero; thus this variable begins with 1 so first time users look they will call `getenv'. */ unsigned __environ_changed = 1; int putenv(const char *val) { int vlen = strlen(val); char *epos = strchr(val, '='); /* Feature: VAL without a `=' means delete the entry. GNU `putenv' works that way, and `env' from GNU Sh-utils counts on this behavior. */ int nlen = epos ? epos - val + 1 : vlen; int eindex; /* Force recomputation of the static counters. The second condition of the next if clause covers the case that somebody pointed environ to another array, which invalidates `ecount' and `emax'. This can be used to change the environment to something entirely different, or to effectively discard it altogether. GNU `env' from Sh-utils does just that. */ if (putenv_bss_count != __bss_count || environ != prev_environ) { for (ecount=0; environ[ecount]; ecount++); emax = ecount; /* Bump the count to a value no function has yet seen, even if they were dumped with us. */ __environ_changed++; if (putenv_bss_count != __bss_count) { putenv_bss_count = __bss_count; prev_environ = environ; /* it's malloced by crt1.c */ } } for (eindex=0; environ[eindex]; eindex++) if (strncmp(environ[eindex], val, nlen) == 0 && (epos || environ[eindex][nlen] == '=')) { char *oval = environ[eindex]; int olen = strlen(oval); if (val[nlen] == 0 && !epos) /* delete the entry */ { free(oval); environ[eindex] = environ[ecount-1]; environ[ecount-1] = 0; ecount--; __environ_changed++; return 0; } /* change existing entry */ if (strcmp(environ[eindex]+nlen, val+nlen) == 0) return 0; /* they're the same */ /* If new is the same length as old, reuse the same storage. If new is shorter, call realloc to shrink the allocated block: this causes less memory fragmentation. */ if (vlen != olen) { if (vlen > olen) environ[eindex] = (char *)malloc(vlen+1); else /* vlen < olen */ environ[eindex] = (char *)realloc(oval, vlen+1); if (environ[eindex] == 0) { environ[eindex] = oval; return -1; } if (vlen > olen) free(oval); } strcpy(environ[eindex], val); __environ_changed++; return 0; } /* delete nonexisting entry? */ if (val[nlen] == 0 && !epos) return 0; /* create new entry */ if (ecount >= emax) { char **enew; emax += 10; enew = (char **)malloc((emax+1) * sizeof(char *)); if (enew == 0) return -1; memcpy(enew, environ, ecount * sizeof(char *)); /* If somebody set environ to another array, we can't safely free it. Better leak memory than crash. */ if (environ == prev_environ) free(environ); environ = enew; prev_environ = environ; } environ[ecount] = (char *)malloc(vlen+1); if (environ[ecount] == 0) return -1; strcpy(environ[ecount], val); ecount++; environ[ecount] = 0; __environ_changed++; return 0; }