Context-related functions.

+/* GNU mailutils - a suite of utilities for electronic mail
+   Copyright (C) 1999, 2000, 2001 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 2, 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, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+/* MH context functions. */
+
+#include <mh.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+mh_context_t *
+mh_context_create (char *name, int copy)
+{
+  mh_context_t *ctx;
+  ctx = malloc (sizeof (*ctx));
+  if (!ctx)
+    {
+      mu_error ("not enough memory");
+      abort ();
+    }
+  if (copy)
+    ctx->name = name;
+  else
+    {
+      ctx->name = strdup (name);
+      if (!ctx->name)
+	{
+	  mu_error ("not enough memory");
+	  abort ();
+	}
+    }
+  ctx->header = NULL;
+  return ctx;
+}
+
+int 
+mh_context_read (mh_context_t *ctx)
+{
+  int status;
+  char *blurb;
+  struct stat st;
+  FILE *fp;
+
+  if (stat (ctx->name, &st))
+    return errno;
+
+  blurb = malloc (st.st_size);
+  if (!blurb)
+    return ENOMEM;
+  
+  fp = fopen (ctx->name, "r");
+  if (!fp)
+    {
+      free (blurb);
+      return errno;
+    }
+
+  fread (blurb, st.st_size, 1, fp);
+  fclose (fp);
+  
+  if (status = header_create (&ctx->header, blurb, st.st_size, NULL))
+    free (blurb);
+
+  return status;
+}
+
+int 
+mh_context_write (mh_context_t *ctx)
+{
+  stream_t stream;
+  char buffer[512];
+  size_t off = 0, n;
+  FILE *fp;
+  
+  fp = fopen (ctx->name, "w");
+  if (!fp)
+    {
+      mh_error ("can't write context file %s: %s",
+		ctx->name, strerror (errno));
+      return 1;
+    }
+  
+  header_get_stream (ctx->header, &stream);
+
+  while (stream_read (stream, buffer, sizeof buffer - 1, off, &n) == 0
+	 && n != 0)
+    {
+      buffer[n] = '\0';
+      fprintf (fp, "%s", buffer);
+      off += n;
+    }
+
+  fclose (fp);
+  return 0;
+}
+
+char *
+mh_context_get_value (mh_context_t *ctx, const char *name, char *defval)
+{
+  char *p;
+
+  if (header_aget_value (ctx->header, name, &p))
+    p = defval;
+  return p;
+}
+
+int
+mh_context_set_value (mh_context_t *ctx, const char *name, char *value)
+{
+  if (!ctx->header)
+    {
+      int rc;
+      if ((rc = header_create (&ctx->header, NULL, 0, NULL)) != 0)
+	{
+	  mh_error ("Can't create context %s: %s",
+		    ctx->name,
+		    mu_errstring (rc));
+	  return 1;
+	}
+    }
+  return header_set_value (ctx->header, name, value, 1);
+}