Extract process-management functionality into a new lib/process

Note that procmon does *not* go here, since procmon needs to
integrate with the event loop.

1 files changed, 215 insertions, 0 deletions

diff --git a/src/lib/process/env.c b/src/lib/process/env.c
new file mode 100644
index 0000000000..95e1e515d4
--- /dev/null
+++ b/src/lib/process/env.c
@@ -0,0 +1,215 @@
+/* Copyright (c) 2003-2004, Roger Dingledine
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#include "orconfig.h"
+#include "lib/process/env.h"
+
+#include "lib/malloc/util_malloc.h"
+#include "lib/ctime/di_ops.h"
+#include "lib/container/smartlist.h"
+#include "lib/log/util_bug.h"
+#include "lib/log/torlog.h"
+#include "lib/malloc/util_malloc.h"
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#include <stdlib.h>
+#include <string.h>
+
+#ifndef HAVE__NSGETENVIRON
+#ifndef HAVE_EXTERN_ENVIRON_DECLARED
+/* Some platforms declare environ under some circumstances, others don't. */
+#ifndef RUNNING_DOXYGEN
+extern char **environ;
+#endif
+#endif /* !defined(HAVE_EXTERN_ENVIRON_DECLARED) */
+#endif /* !defined(HAVE__NSGETENVIRON) */
+
+/** Return the current environment. This is a portable replacement for
+ * 'environ'. */
+char **
+get_environment(void)
+{
+#ifdef HAVE__NSGETENVIRON
+  /* This is for compatibility between OSX versions.  Otherwise (for example)
+   * when we do a mostly-static build on OSX 10.7, the resulting binary won't
+   * work on OSX 10.6. */
+  return *_NSGetEnviron();
+#else /* !(defined(HAVE__NSGETENVIRON)) */
+  return environ;
+#endif /* defined(HAVE__NSGETENVIRON) */
+}
+
+/** Helper: return the number of characters in <b>s</b> preceding the first
+ * occurrence of <b>ch</b>. If <b>ch</b> does not occur in <b>s</b>, return
+ * the length of <b>s</b>. Should be equivalent to strspn(s, "ch"). */
+static inline size_t
+str_num_before(const char *s, char ch)
+{
+  const char *cp = strchr(s, ch);
+  if (cp)
+    return cp - s;
+  else
+    return strlen(s);
+}
+
+/** 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 = str_num_before(s1, '=');
+  size_t s2_name_len = str_num_before(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));
+  int n_env_vars = smartlist_len(env_vars);
+  int 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, (int)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, (int)i);
+      size_t slen = strlen(s);
+      size_t s_name_len = str_num_before(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);
+  }
+
+  smartlist_free(env_vars_sorted);
+
+  return env;
+}
+
+/** Return a newly allocated smartlist containing every variable in
+ * this process's environment, as a NUL-terminated string of the form
+ * "NAME=VALUE".  Note that on some/many/most/all OSes, the parent
+ * process can put strings not of that form in our environment;
+ * callers should try to not get crashed by that.
+ *
+ * The returned strings are heap-allocated, and must be freed by the
+ * caller. */
+struct smartlist_t *
+get_current_process_environment_variables(void)
+{
+  smartlist_t *sl = smartlist_new();
+
+  char **environ_tmp; /* Not const char ** ? Really? */
+  for (environ_tmp = get_environment(); *environ_tmp; ++environ_tmp) {
+    smartlist_add_strdup(sl, *environ_tmp);
+  }
+
+  return sl;
+}
+
+/** For each string s in <b>env_vars</b> such that
+ * environment_variable_names_equal(s, <b>new_var</b>), remove it; if
+ * <b>free_p</b> is non-zero, call <b>free_old</b>(s).  If
+ * <b>new_var</b> contains '=', insert it into <b>env_vars</b>. */
+void
+set_environment_variable_in_smartlist(struct smartlist_t *env_vars,
+                                      const char *new_var,
+                                      void (*free_old)(void*),
+                                      int free_p)
+{
+  SMARTLIST_FOREACH_BEGIN(env_vars, const char *, s) {
+    if (environment_variable_names_equal(s, new_var)) {
+      SMARTLIST_DEL_CURRENT(env_vars, s);
+      if (free_p) {
+        free_old((void *)s);
+      }
+    }
+  } SMARTLIST_FOREACH_END(s);
+
+  if (strchr(new_var, '=') != NULL) {
+    smartlist_add(env_vars, (void *)new_var);
+  }
+}