Reworked passing of envars to Pinentry.

common/session-env.c

@@ -0,0 +1,384 @@
+/* se4ssiobn-env.c - session environment helper functions.
+ * Copyright (C) 2009 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <ctype.h>
+#include <assert.h>
+#include <unistd.h>
+
+#include "util.h"
+#include "session-env.h"
+
+
+struct variable_s
+{
+  char *value;    /* Pointer into NAME to the Nul terminated value. */
+  int is_default; /* The value is a default one.  */
+  char name[1];   /* Nul terminated Name and space for the value.  */
+};
+
+
+
+/* The session environment object.  */
+struct session_environment_s
+{
+  size_t arraysize;          /* Allocated size or ARRAY.  */
+  size_t arrayused;          /* Used size of ARRAY.  */
+  struct variable_s **array; /* Array of variables.  NULL slots are unused.  */
+};
+
+
+/* A list of environment vribales we pass from the acual user
+  (e.g. gpgme) down to the pinentry.  We do not handle the locale
+  settings because they do not only depend on envvars.  */
+static struct 
+{ 
+  const char *name;
+  const char *assname;  /* Name used by Assuan or NULL.  */
+} stdenvnames[] = {
+  { "GPG_TTY", "ttyname" },      /* GnuPG specific envvar.  */
+  { "TERM",    "ttytype" },      /* Used to set ttytype. */
+  { "DISPLAY", "display" },      /* The X-Display.  */
+  { "XAUTHORITY","xauthority"},  /* Xlib Authentication.  */
+  { "XMODIFIERS" },              /* Used by Xlib to select X input
+                                      modules (eg "@im=SCIM").  */
+  { "GTK_IM_MODULE" },           /* Used by gtk to select gtk input
+                                    modules (eg "scim-bridge").  */
+  { "QT_IM_MODULE" },            /* Used by Qt to select qt input
+                                      modules (eg "xim").  */
+  { "PINENTRY_USER_DATA", "pinentry-user-data"} 
+                                 /* Used for communication with
+                                    non-standard Pinentries.  */
+};
+
+
+/* Track last allocated arraysize of all objects ever created.  If
+   nothing has ever been allocated we use INITIAL_ARRAYSIZE and we
+   will never use more than MAXDEFAULT_ARRAYSIZE for initial
+   allocation.  Note that this is not reentrant if used with a
+   preemptive thread model.  */
+static size_t lastallocatedarraysize;
+#define INITIAL_ARRAYSIZE 8  /* Let's use the number of stdenvnames.  */
+#define CHUNK_ARRAYSIZE 10
+#define MAXDEFAULT_ARRAYSIZE (INITIAL_ARRAYSIZE + CHUNK_ARRAYSIZE * 5)
+
+
+/* Return the names of standard environment variables one after the
+   other.  The caller needs to set the value at the address of
+   ITERATOR initally to 0 and then call this function until it returns
+   NULL.  */
+const char *
+session_env_list_stdenvnames (int *iterator, const char **r_assname)
+{
+  int idx = *iterator;
+
+  if (idx < 0 || idx >= DIM (stdenvnames))
+    return NULL;
+  *iterator = idx + 1;
+  if (r_assname)
+    *r_assname = stdenvnames[idx].assname;
+  return stdenvnames[idx].name;
+}
+
+
+/* Create a new session environment object.  Return NULL and sets
+   ERRNO on failure. */
+session_env_t
+session_env_new (void)
+{
+  session_env_t se;
+
+  se = xtrycalloc (1, sizeof *se);
+  if (se)
+    {
+      se->arraysize = (lastallocatedarraysize? 
+                       lastallocatedarraysize : INITIAL_ARRAYSIZE);
+      se->array = xtrycalloc (se->arraysize, sizeof *se->array);
+      if (!se->array)
+        {
+          xfree (se);
+          se = NULL;
+        }
+    }
+
+  return se;
+}
+
+
+/* Release a session environment object.  */
+void
+session_env_release (session_env_t se)
+{
+  int idx;
+
+  if (!se)
+    return;
+
+  if (se->arraysize > INITIAL_ARRAYSIZE 
+      && se->arraysize <= MAXDEFAULT_ARRAYSIZE
+      && se->arraysize > lastallocatedarraysize)
+    lastallocatedarraysize = se->arraysize;
+
+  for (idx=0; idx < se->arrayused; idx++)
+    if (se->array[idx])
+      xfree (se->array[idx]);
+  xfree (se->array);
+  xfree (se);
+}
+
+
+static gpg_error_t
+delete_var (session_env_t se, const char *name)
+{
+  int idx;
+
+  for (idx=0; idx < se->arrayused; idx++)
+    if (se->array[idx] && !strcmp (se->array[idx]->name, name))
+      {
+        xfree (se->array[idx]);
+        se->array[idx] = NULL;
+      }
+  return 0;
+}
+
+
+static gpg_error_t
+update_var (session_env_t se, const char *string, size_t namelen,
+            const char *explicit_value, int set_default)
+{
+  int idx;
+  int freeidx = -1;
+  const char *value;
+  size_t valuelen;
+  struct variable_s *var;
+
+  if (explicit_value)
+    value = explicit_value;
+  else
+    value = string + namelen + 1;
+  valuelen = strlen (value);
+
+  for (idx=0; idx < se->arrayused; idx++)
+    {
+      if (!se->array[idx])
+        freeidx = idx;
+      else if (!strncmp (se->array[idx]->name, string, namelen)
+               && strlen (se->array[idx]->name) == namelen)
+        {
+          /* Check if the value is the same; no need to update it,
+             except for updating the default flag.  */
+          if (strlen (se->array[idx]->value) == valuelen)
+            {
+              se->array[idx]->is_default = !!set_default;
+              return 0;
+            }
+          /* Prepare for update.  */
+          freeidx = idx;
+        }
+    }
+
+  if (freeidx == -1)
+    {
+      if (se->arrayused == se->arraysize)
+        {
+          /* Reallocate the array. */
+          size_t newsize;
+          struct variable_s **newarray;
+
+          newsize = se->arraysize + CHUNK_ARRAYSIZE;
+          newarray = xtrycalloc (newsize, sizeof *newarray);
+          if (!newarray)
+            return gpg_error_from_syserror ();
+          for (idx=0; idx < se->arrayused; idx++)
+            newarray[idx] = se->array[idx];
+          se->arraysize = newsize;
+          xfree (se->array);
+          se->array = newarray;
+        }
+      freeidx = se->arrayused++;
+    }
+
+  /* Allocate new memory and return an error if that didn't worked.
+     Allocating it first allows us to keep the old value; it doesn't
+     matter that arrayused has already been incremented in case of a
+     new entry - it will then pint to a NULL slot.  */
+  var = xtrymalloc (sizeof *var + namelen + 1 + valuelen);
+  if (!var)
+    return gpg_error_from_syserror ();
+  var->is_default = !!set_default;
+  memcpy (var->name, string, namelen);
+  var->name[namelen] = '\0';
+  var->value = var->name + namelen + 1;
+  strcpy (var->value, value);
+
+  xfree (se->array[freeidx]);
+  se->array[freeidx] = var;
+  return 0;
+}
+
+
+/* Set or update an environment variable of the session environment.
+   String is similar to the putval(3) function but it is reentrant and
+   takes a copy.  In particular it exhibits this behaviour:
+
+          <NAME>            Delete envvar NAME
+          <KEY>=            Set envvar NAME to the empty string
+          <KEY>=<VALUE>     Set envvar NAME to VALUE
+
+   On success 0 is returned; on error an gpg-error code.  */
+gpg_error_t
+session_env_putenv (session_env_t se, const char *string)
+{
+  const char *s;
+  
+  if (!string || !*string)
+    return gpg_error (GPG_ERR_INV_VALUE);
+  s = strchr (string, '=');
+  if (s == string)
+    return gpg_error (GPG_ERR_INV_VALUE);
+  if (!s)
+    return delete_var (se, string);
+  else
+    return update_var (se, string, s - string, NULL, 0);
+}
+
+
+/* Same as session_env_putenv but with name and value given as distict
+   values.  */
+gpg_error_t
+session_env_setenv (session_env_t se, const char *name, const char *value)
+{
+  if (!name || !*name)
+    return gpg_error (GPG_ERR_INV_VALUE);
+  if (!value)
+    return delete_var (se, name);
+  else
+    return update_var (se, name, strlen (name), value, 0);
+}
+
+
+
+
+/* Return the value of the environment variable NAME from the SE
+   object.  If the variable does not exist, NULL is returned.  The
+   returned value is valid as long as SE is valid and as long it has
+   not been removed or updated by a call to session_env_putenv.  The
+   caller MUST not change the returned value. */
+char *
+session_env_getenv (session_env_t se, const char *name)
+{
+  int idx;
+
+  if (!se || !name || !*name)
+    return NULL;
+
+  for (idx=0; idx < se->arrayused; idx++)
+    if (se->array[idx] && !strcmp (se->array[idx]->name, name))
+      return se->array[idx]->is_default? NULL : se->array[idx]->value;
+  return NULL;
+}
+
+
+/* Return the value of the environment variable NAME from the SE
+   object.  The returned value is valid as long as SE is valid and as
+   long it has not been removed or updated by a call to
+   session_env_putenv.  If the variable does not exist, the fucntion
+   tries to return the value trough a call to getenv; if that returns
+   a value, this value is recorded and and used.  If no value could be
+   found, returns NULL.  The caller must not change the returned
+   value. */
+char *
+session_env_getenv_or_default (session_env_t se, const char *name,
+                               int *r_default)
+{
+  int idx;
+  char *defvalue;
+
+  if (r_default)
+    *r_default = 0;
+  if (!se || !name || !*name)
+    return NULL;
+
+  for (idx=0; idx < se->arrayused; idx++)
+    if (se->array[idx] && !strcmp (se->array[idx]->name, name))
+      {
+        if (r_default && se->array[idx]->is_default)
+          *r_default = 1;
+        return se->array[idx]->value;
+      }
+  
+  /* Get the default value with and additional fallback for GPG_TTY.  */
+  defvalue = getenv (name);
+  if ((!defvalue || !*defvalue) && !strcmp (name, "GPG_TTY") && ttyname (0))
+    defvalue = ttyname (0);
+  if (defvalue)
+    {
+      /* Record the default value for later use so that we are safe
+         from later modifications of the environment.  We need to take
+         a copy to better cope with the rules of putenv(3).  We ignore
+         the error of the update function because we can't return an
+         explicit error anyway and the following scan would then fail
+         anyway. */
+      update_var (se, name, strlen (name), defvalue, 1);
+      
+      for (idx=0; idx < se->arrayused; idx++)
+        if (se->array[idx] && !strcmp (se->array[idx]->name, name))
+          {
+            if (r_default && se->array[idx]->is_default)
+              *r_default = 1;
+            return se->array[idx]->value;
+          }
+    }
+
+  return NULL;
+}
+
+
+/* List the entire environment stored in SE.  The caller initially
+   needs to set the value of ITERATOR to 0 and then call this function
+   until it returns NULL.  The value is retruned at R_VALUE.  If
+   R_DEFAULT is not NULL, the default flag is stored on return.  The
+   default flag indicates that the value has been taken from the
+   process' environment.  The caller must not change the returned
+   name or value.  */ 
+char *
+session_env_listenv (session_env_t se, int *iterator,
+                     const char **r_value, int *r_default)
+{
+  int idx = *iterator;
+
+  if (!se || idx < 0)
+    return NULL;
+
+  for (; idx < se->arrayused; idx++)
+    if (se->array[idx])
+      {
+        *iterator = idx+1;
+        if (r_default)
+          *r_default = se->array[idx]->is_default;
+        if (r_value)
+          *r_value = se->array[idx]->value;
+        return se->array[idx]->name;
+      }
+  return NULL;
+}
+
+