--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/info/tilde.c	Thu Oct 21 22:39:46 1993 +0000
@@ -0,0 +1,379 @@
+/* tilde.c -- Tilde expansion code (~/foo := $HOME/foo). */
+
+/* This file is part of GNU Info, a program for reading online documentation
+   stored in Info format.
+
+   This file has appeared in prior works by the Free Software Foundation;
+   thus it carries copyright dates from 1988 through 1993.
+
+   Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993 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.
+
+   Written by Brian Fox (bfox@ai.mit.edu). */
+
+#if defined (__GNUC__)
+#  define alloca __builtin_alloca
+#else /* !__GNUC__ */
+#  if defined (_AIX)
+ #pragma alloca
+#  else /* !_AIX */
+#    if defined (HAVE_ALLOCA_H)
+#      include <alloca.h>
+#    endif /* HAVE_ALLOCA_H */
+#  endif /* !AIX */
+#endif /* !__GNUC__ */
+
+#include "tilde.h"
+#include <pwd.h>
+
+#if !defined (savestring)
+#define savestring(x) (char *)strcpy (xmalloc (1 + strlen (x)), (x))
+#endif /* !savestring */
+
+#if !defined (NULL)
+#  define NULL 0x0
+#endif
+
+#if defined (TEST) || defined (STATIC_MALLOC)
+static char *xmalloc (), *xrealloc ();
+#else
+extern char *xmalloc (), *xrealloc ();
+#endif /* TEST || STATIC_MALLOC */
+
+/* The default value of tilde_additional_prefixes.  This is set to
+   whitespace preceding a tilde so that simple programs which do not
+   perform any word separation get desired behaviour. */
+static char *default_prefixes[] =
+  { " ~", "\t~", (char *)NULL };
+
+/* The default value of tilde_additional_suffixes.  This is set to
+   whitespace or newline so that simple programs which do not
+   perform any word separation get desired behaviour. */
+static char *default_suffixes[] =
+  { " ", "\n", (char *)NULL };
+
+/* If non-null, this contains the address of a function to call if the
+   standard meaning for expanding a tilde fails.  The function is called
+   with the text (sans tilde, as in "foo"), and returns a malloc()'ed string
+   which is the expansion, or a NULL pointer if there is no expansion. */
+Function *tilde_expansion_failure_hook = (Function *)NULL;
+
+/* When non-null, this is a NULL terminated array of strings which
+   are duplicates for a tilde prefix.  Bash uses this to expand
+   `=~' and `:~'. */
+char **tilde_additional_prefixes = default_prefixes;
+
+/* When non-null, this is a NULL terminated array of strings which match
+   the end of a username, instead of just "/".  Bash sets this to
+   `:' and `=~'. */
+char **tilde_additional_suffixes = default_suffixes;
+
+/* Find the start of a tilde expansion in STRING, and return the index of
+   the tilde which starts the expansion.  Place the length of the text
+   which identified this tilde starter in LEN, excluding the tilde itself. */
+static int
+tilde_find_prefix (string, len)
+     char *string;
+     int *len;
+{
+  register int i, j, string_len;
+  register char **prefixes = tilde_additional_prefixes;
+
+  string_len = strlen (string);
+  *len = 0;
+
+  if (!*string || *string == '~')
+    return (0);
+
+  if (prefixes)
+    {
+      for (i = 0; i < string_len; i++)
+	{
+	  for (j = 0; prefixes[j]; j++)
+	    {
+	      if (strncmp (string + i, prefixes[j], strlen (prefixes[j])) == 0)
+		{
+		  *len = strlen (prefixes[j]) - 1;
+		  return (i + *len);
+		}
+	    }
+	}
+    }
+  return (string_len);
+}
+
+/* Find the end of a tilde expansion in STRING, and return the index of
+   the character which ends the tilde definition.  */
+static int
+tilde_find_suffix (string)
+     char *string;
+{
+  register int i, j, string_len;
+  register char **suffixes = tilde_additional_suffixes;
+
+  string_len = strlen (string);
+
+  for (i = 0; i < string_len; i++)
+    {
+      if (string[i] == '/' || !string[i])
+	break;
+
+      for (j = 0; suffixes && suffixes[j]; j++)
+	{
+	  if (strncmp (string + i, suffixes[j], strlen (suffixes[j])) == 0)
+	    return (i);
+	}
+    }
+  return (i);
+}
+
+/* Return a new string which is the result of tilde expanding STRING. */
+char *
+tilde_expand (string)
+     char *string;
+{
+  char *result, *tilde_expand_word ();
+  int result_size, result_index;
+
+  result_size = result_index = 0;
+  result = (char *)NULL;
+
+  /* Scan through STRING expanding tildes as we come to them. */
+  while (1)
+    {
+      register int start, end;
+      char *tilde_word, *expansion;
+      int len;
+
+      /* Make START point to the tilde which starts the expansion. */
+      start = tilde_find_prefix (string, &len);
+
+      /* Copy the skipped text into the result. */
+      if ((result_index + start + 1) > result_size)
+	result = (char *)xrealloc (result, 1 + (result_size += (start + 20)));
+
+      strncpy (result + result_index, string, start);
+      result_index += start;
+
+      /* Advance STRING to the starting tilde. */
+      string += start;
+
+      /* Make END be the index of one after the last character of the
+	 username. */
+      end = tilde_find_suffix (string);
+
+      /* If both START and END are zero, we are all done. */
+      if (!start && !end)
+	break;
+
+      /* Expand the entire tilde word, and copy it into RESULT. */
+      tilde_word = (char *)xmalloc (1 + end);
+      strncpy (tilde_word, string, end);
+      tilde_word[end] = '\0';
+      string += end;
+
+      expansion = tilde_expand_word (tilde_word);
+      free (tilde_word);
+
+      len = strlen (expansion);
+      if ((result_index + len + 1) > result_size)
+	result = (char *)xrealloc (result, 1 + (result_size += (len + 20)));
+
+      strcpy (result + result_index, expansion);
+      result_index += len;
+      free (expansion);
+    }
+
+  result[result_index] = '\0';
+
+  return (result);
+}
+
+/* Do the work of tilde expansion on FILENAME.  FILENAME starts with a
+   tilde.  If there is no expansion, call tilde_expansion_failure_hook. */
+char *
+tilde_expand_word (filename)
+     char *filename;
+{
+  char *dirname;
+
+  dirname = filename ? savestring (filename) : (char *)NULL;
+
+  if (dirname && *dirname == '~')
+    {
+      char *temp_name;
+      if (!dirname[1] || dirname[1] == '/')
+	{
+	  /* Prepend $HOME to the rest of the string. */
+	  char *temp_home = (char *)getenv ("HOME");
+
+	  /* If there is no HOME variable, look up the directory in
+	     the password database. */
+	  if (!temp_home)
+	    {
+	      extern struct passwd *getpwuid ();
+	      struct passwd *entry;
+
+	      entry = getpwuid (getuid ());
+	      if (entry)
+		temp_home = entry->pw_dir;
+	    }
+
+	  temp_name = (char *)alloca (1 + strlen (&dirname[1])
+				      + (temp_home ? strlen (temp_home) : 0));
+	  temp_name[0] = '\0';
+	  if (temp_home)
+	    strcpy (temp_name, temp_home);
+	  strcat (temp_name, &dirname[1]);
+	  free (dirname);
+	  dirname = savestring (temp_name);
+	}
+      else
+	{
+	  struct passwd *getpwnam (), *user_entry;
+	  char *username = (char *)alloca (257);
+	  int i, c;
+
+	  for (i = 1; c = dirname[i]; i++)
+	    {
+	      if (c == '/')
+		break;
+	      else
+		username[i - 1] = c;
+	    }
+	  username[i - 1] = '\0';
+
+	  if (!(user_entry = getpwnam (username)))
+	    {
+	      /* If the calling program has a special syntax for
+		 expanding tildes, and we couldn't find a standard
+		 expansion, then let them try. */
+	      if (tilde_expansion_failure_hook)
+		{
+		  char *expansion;
+
+		  expansion =
+		    (char *)(*tilde_expansion_failure_hook) (username);
+
+		  if (expansion)
+		    {
+		      temp_name = (char *)alloca (1 + strlen (expansion)
+						  + strlen (&dirname[i]));
+		      strcpy (temp_name, expansion);
+		      strcat (temp_name, &dirname[i]);
+		      free (expansion);
+		      goto return_name;
+		    }
+		}
+	      /* We shouldn't report errors. */
+	    }
+	  else
+	    {
+	      temp_name = (char *)alloca (1 + strlen (user_entry->pw_dir)
+					  + strlen (&dirname[i]));
+	      strcpy (temp_name, user_entry->pw_dir);
+	      strcat (temp_name, &dirname[i]);
+	    return_name:
+	      free (dirname);
+	      dirname = savestring (temp_name);
+	    }
+	    endpwent ();
+	}
+    }
+  return (dirname);
+}
+
+
+#if defined (TEST)
+#undef NULL
+#include <stdio.h>
+
+main (argc, argv)
+     int argc;
+     char **argv;
+{
+  char *result, line[512];
+  int done = 0;
+
+  while (!done)
+    {
+      printf ("~expand: ");
+      fflush (stdout);
+
+      if (!gets (line))
+	strcpy (line, "done");
+
+      if ((strcmp (line, "done") == 0) ||
+	  (strcmp (line, "quit") == 0) ||
+	  (strcmp (line, "exit") == 0))
+	{
+	  done = 1;
+	  break;
+	}
+
+      result = tilde_expand (line);
+      printf ("  --> %s\n", result);
+      free (result);
+    }
+  exit (0);
+}
+
+static void memory_error_and_abort ();
+
+static char *
+xmalloc (bytes)
+     int bytes;
+{
+  char *temp = (char *)malloc (bytes);
+
+  if (!temp)
+    memory_error_and_abort ();
+  return (temp);
+}
+
+static char *
+xrealloc (pointer, bytes)
+     char *pointer;
+     int bytes;
+{
+  char *temp;
+
+  if (!pointer)
+    temp = (char *)malloc (bytes);
+  else
+    temp = (char *)realloc (pointer, bytes);
+
+  if (!temp)
+    memory_error_and_abort ();
+
+  return (temp);
+}
+
+static void
+memory_error_and_abort ()
+{
+  fprintf (stderr, "readline: Out of virtual memory!\n");
+  abort ();
+}
+
+/*
+ * Local variables:
+ * compile-command: "gcc -g -DTEST -o tilde tilde.c"
+ * end:
+ */
+#endif /* TEST */
+