Share gdb/environ.[ch] with gdbserver

We will need access to the environment functions when we share
fork_inferior between GDB and gdbserver, therefore we simply make the
API on gdb/environ.[ch] available on common/.  No extra adjustments
are needed to make it compile on gdbserver.

gdb/ChangeLog:
2017-03-07  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (SFILES): Replace "environ.c" with
	"common/environ.c".
	(HFILES_NO_SRCDIR): Likewise, for "environ.h".
	* environ.c: Include "common-defs.h" instead of "defs.h.  Moved
	to...
	* common/environ.c: ... here.
	* environ.h: Moved to...
	* common/environ.h: ... here.

gdb/gdbserver/ChangeLog:
2017-03-07  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (SFILES): Add "common/environ.c".
	(OBJS): Add "common/environ.h".

2 files changed, 231 insertions, 0 deletions

diff --git a/gdb/common/environ.c b/gdb/common/environ.c
new file mode 100644
index 0000000..3145d01
--- /dev/null
+++ b/gdb/common/environ.c
@@ -0,0 +1,182 @@
+/* environ.c -- library for manipulating environments for GNU.
+
+   Copyright (C) 1986-2017 Free Software Foundation, Inc.
+
+   This program 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.
+
+   This program 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 "common-defs.h"
+#include "environ.h"
+#include <algorithm>
+
+
+/* Return a new environment object.  */
+
+struct gdb_environ *
+make_environ (void)
+{
+  struct gdb_environ *e;
+
+  e = XNEW (struct gdb_environ);
+
+  e->allocated = 10;
+  e->vector = (char **) xmalloc ((e->allocated + 1) * sizeof (char *));
+  e->vector[0] = 0;
+  return e;
+}
+
+/* Free an environment and all the strings in it.  */
+
+void
+free_environ (struct gdb_environ *e)
+{
+  char **vector = e->vector;
+
+  while (*vector)
+    xfree (*vector++);
+
+  xfree (e->vector);
+  xfree (e);
+}
+
+/* Copy the environment given to this process into E.
+   Also copies all the strings in it, so we can be sure
+   that all strings in these environments are safe to free.  */
+
+void
+init_environ (struct gdb_environ *e)
+{
+  extern char **environ;
+  int i;
+
+  if (environ == NULL)
+    return;
+
+  for (i = 0; environ[i]; i++) /*EMPTY */ ;
+
+  if (e->allocated < i)
+    {
+      e->allocated = std::max (i, e->allocated + 10);
+      e->vector = (char **) xrealloc ((char *) e->vector,
+				      (e->allocated + 1) * sizeof (char *));
+    }
+
+  memcpy (e->vector, environ, (i + 1) * sizeof (char *));
+
+  while (--i >= 0)
+    {
+      int len = strlen (e->vector[i]);
+      char *newobj = (char *) xmalloc (len + 1);
+
+      memcpy (newobj, e->vector[i], len + 1);
+      e->vector[i] = newobj;
+    }
+}
+
+/* Return the vector of environment E.
+   This is used to get something to pass to execve.  */
+
+char **
+environ_vector (struct gdb_environ *e)
+{
+  return e->vector;
+}
+
+/* Return the value in environment E of variable VAR.  */
+
+char *
+get_in_environ (const struct gdb_environ *e, const char *var)
+{
+  int len = strlen (var);
+  char **vector = e->vector;
+  char *s;
+
+  for (; (s = *vector) != NULL; vector++)
+    if (strncmp (s, var, len) == 0 && s[len] == '=')
+      return &s[len + 1];
+
+  return 0;
+}
+
+/* Store the value in E of VAR as VALUE.  */
+
+void
+set_in_environ (struct gdb_environ *e, const char *var, const char *value)
+{
+  int i;
+  int len = strlen (var);
+  char **vector = e->vector;
+  char *s;
+
+  for (i = 0; (s = vector[i]) != NULL; i++)
+    if (strncmp (s, var, len) == 0 && s[len] == '=')
+      break;
+
+  if (s == 0)
+    {
+      if (i == e->allocated)
+	{
+	  e->allocated += 10;
+	  vector = (char **) xrealloc ((char *) vector,
+				       (e->allocated + 1) * sizeof (char *));
+	  e->vector = vector;
+	}
+      vector[i + 1] = 0;
+    }
+  else
+    xfree (s);
+
+  s = (char *) xmalloc (len + strlen (value) + 2);
+  strcpy (s, var);
+  strcat (s, "=");
+  strcat (s, value);
+  vector[i] = s;
+
+  /* This used to handle setting the PATH and GNUTARGET variables
+     specially.  The latter has been replaced by "set gnutarget"
+     (which has worked since GDB 4.11).  The former affects searching
+     the PATH to find SHELL, and searching the PATH to find the
+     argument of "symbol-file" or "exec-file".  Maybe we should have
+     some kind of "set exec-path" for that.  But in any event, having
+     "set env" affect anything besides the inferior is a bad idea.
+     What if we want to change the environment we pass to the program
+     without afecting GDB's behavior?  */
+
+  return;
+}
+
+/* Remove the setting for variable VAR from environment E.  */
+
+void
+unset_in_environ (struct gdb_environ *e, const char *var)
+{
+  int len = strlen (var);
+  char **vector = e->vector;
+  char *s;
+
+  for (; (s = *vector) != NULL; vector++)
+    {
+      if (strncmp (s, var, len) == 0 && s[len] == '=')
+	{
+	  xfree (s);
+	  /* Walk through the vector, shuffling args down by one, including
+	     the NULL terminator.  Can't use memcpy() here since the regions
+	     overlap, and memmove() might not be available.  */
+	  while ((vector[0] = vector[1]) != NULL)
+	    {
+	      vector++;
+	    }
+	  break;
+	}
+    }
+}
diff --git a/gdb/common/environ.h b/gdb/common/environ.h
new file mode 100644
index 0000000..3ace69e
--- /dev/null
+++ b/gdb/common/environ.h
@@ -0,0 +1,49 @@
+/* Header for environment manipulation library.
+   Copyright (C) 1989-2017 Free Software Foundation, Inc.
+
+   This program 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.
+
+   This program 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/>.  */
+
+#if !defined (ENVIRON_H)
+#define ENVIRON_H 1
+
+/* We manipulate environments represented as these structures.  */
+
+struct gdb_environ
+  {
+    /* Number of usable slots allocated in VECTOR.
+       VECTOR always has one slot not counted here,
+       to hold the terminating zero.  */
+    int allocated;
+    /* A vector of slots, ALLOCATED + 1 of them.
+       The first few slots contain strings "VAR=VALUE"
+       and the next one contains zero.
+       Then come some unused slots.  */
+    char **vector;
+  };
+
+extern struct gdb_environ *make_environ (void);
+
+extern void free_environ (struct gdb_environ *);
+
+extern void init_environ (struct gdb_environ *);
+
+extern char *get_in_environ (const struct gdb_environ *, const char *);
+
+extern void set_in_environ (struct gdb_environ *, const char *, const char *);
+
+extern void unset_in_environ (struct gdb_environ *, const char *);
+
+extern char **environ_vector (struct gdb_environ *);
+
+#endif /* defined (ENVIRON_H) */