Add process_environment_make and related utilities

This commit is contained in:
Robert Ransom 2012-02-12 20:14:48 -08:00 committed by Nick Mathewson
parent 806e0f7e19
commit 98cec14982
2 changed files with 126 additions and 0 deletions

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@ -3721,6 +3721,117 @@ tor_get_exit_code(const process_handle_t *process_handle,
return PROCESS_EXIT_EXITED;
}
/** Return non-zero iff getenv would consider <b>s1</b> and <b>s2</b>
* to have the same name as strings in a process's environment. */
int
environment_variable_names_equal(const char *s1, const char *s2)
{
size_t s1_name_len = strcspn(s1, "=");
size_t s2_name_len = strcspn(s2, "=");
return (s1_name_len == s2_name_len &&
tor_memeq(s1, s2, s1_name_len));
}
/** Free <b>env</b> (assuming it was produced by
* process_environment_make). */
void
process_environment_free(process_environment_t *env)
{
if (env == NULL) return;
/* As both an optimization hack to reduce consing on Unixoid systems
* and a nice way to ensure that some otherwise-Windows-specific
* code will always get tested before changes to it get merged, the
* strings which env->unixoid_environment_block points to are packed
* into env->windows_environment_block. */
tor_free(env->unixoid_environment_block);
tor_free(env->windows_environment_block);
tor_free(env);
}
/** Make a process_environment_t containing the environment variables
* specified in <b>env_vars</b> (as C strings of the form
* "NAME=VALUE"). */
process_environment_t *
process_environment_make(struct smartlist_t *env_vars)
{
process_environment_t *env = tor_malloc_zero(sizeof(process_environment_t));
size_t n_env_vars = smartlist_len(env_vars);
size_t i;
size_t total_env_length;
smartlist_t *env_vars_sorted;
tor_assert(n_env_vars + 1 != 0);
env->unixoid_environment_block = tor_calloc(n_env_vars + 1, sizeof(char *));
/* env->unixoid_environment_block is already NULL-terminated,
* because we assume that NULL == 0 (and check that during compilation). */
total_env_length = 1; /* terminating NUL of terminating empty string */
for (i = 0; i < n_env_vars; ++i) {
const char *s = smartlist_get(env_vars, i);
size_t slen = strlen(s);
tor_assert(slen + 1 != 0);
tor_assert(slen + 1 < SIZE_MAX - total_env_length);
total_env_length += slen + 1;
}
env->windows_environment_block = tor_malloc_zero(total_env_length);
/* env->windows_environment_block is already
* (NUL-terminated-empty-string)-terminated. */
/* Some versions of Windows supposedly require that environment
* blocks be sorted. Or maybe some Windows programs (or their
* runtime libraries) fail to look up strings in non-sorted
* environment blocks.
*
* Also, sorting strings makes it easy to find duplicate environment
* variables and environment-variable strings without an '=' on all
* OSes, and they can cause badness. Let's complain about those. */
env_vars_sorted = smartlist_new();
smartlist_add_all(env_vars_sorted, env_vars);
smartlist_sort_strings(env_vars_sorted);
/* Now copy the strings into the environment blocks. */
{
char *cp = env->windows_environment_block;
const char *prev_env_var = NULL;
for (i = 0; i < n_env_vars; ++i) {
const char *s = smartlist_get(env_vars_sorted, i);
size_t slen = strlen(s);
size_t s_name_len = strcspn(s, "=");
if (s_name_len == slen) {
log_warn(LD_GENERAL,
"Preparing an environment containing a variable "
"without a value: %s",
s);
}
if (prev_env_var != NULL &&
environment_variable_names_equal(s, prev_env_var)) {
log_warn(LD_GENERAL,
"Preparing an environment containing two variables "
"with the same name: %s and %s",
prev_env_var, s);
}
prev_env_var = s;
/* Actually copy the string into the environment. */
memcpy(cp, s, slen+1);
env->unixoid_environment_block[i] = cp;
cp += slen+1;
}
tor_assert(cp == env->windows_environment_block + total_env_length - 1);
}
return env;
}
#ifdef _WIN32
/** Read from a handle <b>h</b> into <b>buf</b>, up to <b>count</b> bytes. If
* <b>hProcess</b> is NULL, the function will return immediately if there is

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@ -379,6 +379,21 @@ int tor_spawn_background(const char *const filename, const char **argv,
HANDLE load_windows_system_library(const TCHAR *library_name);
#endif
int environment_variable_names_equal(const char *s1, const char *s2);
struct process_environment_t {
/** A pointer to a sorted empty-string-terminated sequence of
* NUL-terminated strings of the form "NAME=VALUE". */
char *windows_environment_block;
/** A pointer to a NULL-terminated array of pointers to
* NUL-terminated strings of the form "NAME=VALUE". */
char **unixoid_environment_block;
};
typedef struct process_environment_t process_environment_t;
process_environment_t *process_environment_make(struct smartlist_t *env_vars);
void process_environment_free(process_environment_t *env);
/* Values of process_handle_t.status. PROCESS_STATUS_NOTRUNNING must be
* 0 because tor_check_port_forwarding depends on this being the initial
* statue of the static instance of process_handle_t */