/* mklink.c creates startup code and the link command line.

Copyright (C) 2000-2023 Free Software Foundation, Inc.
Contributed by Gaius Mulley <gaius@glam.ac.uk>.

This file is part of GNU Modula-2.

GNU Modula-2 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, or (at your option)
any later version.

GNU Modula-2 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 GNU Modula-2; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */


#include "config.h"
#include "system.h"

#define MAX_FILE_NAME 8192
#define MAXSTACK 4096
#define STDIN 0
#define STDOUT 1
#define ENDOFILE ((char)-1)
#define ERROR(X) \
  (fprintf (stderr, "%s:%d error %s\n", __FILE__, __LINE__, X) \
   && (fflush (stderr)))
#define DEBUG(X) \
  ((Debug) && (fprintf (stderr, "%s\n", X) && (fflush (stderr))))

#if !defined(TRUE)
#define TRUE (1 == 1)
#endif

#if !defined(FALSE)
#define FALSE (1 == 0)
#endif

typedef struct functlist
{
  char *functname;
  struct functlist *next;
} functList;

/* Prototypes.  */

static void ParseFileLinkCommand (void);
static void ParseFileStartup (void);
static void ParseFile (char *Name);
static void ParseComments (void);
static void CopyUntilEof (void);
static void CopyUntilEol (void);
static int IsSym (char *s);
static int SymIs (char *s);
static int FindString (char *String);
static void GetNL (void);
static char GetChar (void);
static void ResetBuffer (void);
static int GetSingleChar (char *ch);
static int InRange (int Element, unsigned int Min, unsigned int Max);
static char PutChar (char ch);
static int IsSpace (char ch);
static void SkipSpaces (void);
static void SkipText (void);
static void SilentSkipSpaces (void);
static void SilentSkipText (void);
static void PushBack (char *s);
static int IsDigit (char ch);
static void GetName (char *Name);
static void OpenOutputFile (void);
static void CloseFile (void);
static void FindSource (char *Name);
static void CopyUntilEolInto (char *Buffer);
static void FindObject (char *Name);
static int IsExists (char *Name);

/* Global variables.  */

static char *NameOfFile = NULL;
static const char *NameOfMain = "main";
static int StackPtr = 0;
static char Stack[MAXSTACK];
static int CurrentFile = STDIN;
static int OutputFile;
static int LinkCommandLine = FALSE;
static int ProfilePCommand = FALSE;
static int ProfilePGCommand = FALSE;
static int ExitNeeded = TRUE;
static char *libraries = NULL;
static char *args = NULL;
static functList *head = NULL;
static functList *tail = NULL;
static int langC = FALSE; /* FALSE = C++, TRUE = C.  */

/* addLibrary - adds libname to the list of libraries to be linked.  */

static void
addLibrary (char *libname)
{
  if (libraries == NULL)
    libraries = strdup (libname);
  else
    {
      char *old = libraries;
      char *newlib
          = (char *)malloc (strlen (libname) + strlen (libraries) + 1 + 1);
      strcpy (newlib, libraries);
      strcat (newlib, " ");
      strcat (newlib, libname);
      libraries = newlib;
      free (old);
    }
}

/* addGccArg - adds arg to the list of gcc arguments.  */

static void
addGccArg (char *arg)
{
  if (args == NULL)
    args = strdup (arg);
  else
    {
      char *old = args;
      char *newarg = (char *)malloc (strlen (old) + strlen (arg) + 1 + 1);
      strcpy (newarg, old);
      strcat (newarg, " ");
      strcat (newarg, arg);
      args = newarg;
      free (old);
    }
}

int
main (int argc, char *argv[])
{
  int i;

  if (argc >= 3)
    {
      if (strcmp (argv[1], "-l") == 0)
	LinkCommandLine = TRUE;
      else if (strcmp (argv[1], "-s") == 0)
	LinkCommandLine = FALSE;
      else
        {
          fprintf (stderr, "Usage: mklink (-l|-s) [--langc|--langc++] [--pg|-p] "
                           "[--lib library] [--main name] [--exit] --name "
                           "filename <modulelistfile>\n");
          fprintf (stderr, "       must supply -l or -s option\n");
          exit (1);
        }
      ProfilePCommand = FALSE;
      ProfilePGCommand = FALSE;
      i = 2;
      while (i < argc - 1)
        {
          if (strcmp (argv[i], "--langc++") == 0)
	    langC = FALSE;
          else if (strcmp (argv[i], "--langc") == 0)
	    langC = TRUE;
          else if (strncmp (argv[i], "-f", 2) == 0)
	    addGccArg (argv[i]);
          else if (strcmp (argv[i], "--pg") == 0)
	    ProfilePGCommand = TRUE;
          else if (strcmp (argv[i], "-p") == 0)
	    ProfilePCommand = TRUE;
          else if (strcmp (argv[i], "--exit") == 0)
	    ExitNeeded = FALSE;
          else if (strcmp (argv[i], "--lib") == 0)
            {
              i++;
              addLibrary (argv[i]);
            }
          else if (strcmp (argv[i], "--main") == 0)
            {
              i++;
              NameOfMain = argv[i];
            }
          else if (strcmp (argv[i], "--name") == 0)
            {
              i++;
              NameOfFile = argv[i];
            }
          i++;
        }
      ParseFile (argv[i]);
    }
  else
    {
      fprintf (stderr, "Usage: mklink (-l|-s) [--gcc|--g++] [--pg|-p] [--lib "
                       "library] [--main name] [--exit] --name filename "
                       "<modulelistfile>\n");
      exit (1);
    }
  if (NameOfFile == NULL)
    {
      fprintf (stderr, "mklink must have a --name argument\n");
      fprintf (stderr, "Usage: mklink (-l|-s) [--gcc|--g++] [--pg|-p] [--lib "
                       "library] [--main name] [--exit] --name filename "
                       "<modulelistfile>\n");
      exit (1);
    }
  exit (0);
}

/* ParseFile - parses the input file and generates the output file.  */

static void
ParseFile (char *Name)
{
  FindSource (Name);
  OpenOutputFile ();
  if (LinkCommandLine)
    ParseFileLinkCommand ();
  else
    ParseFileStartup ();
  CloseFile ();
}

/* ParseFileLinkCommand - generates the link command.  */

static void
ParseFileLinkCommand (void)
{
  char name[MAX_FILE_NAME];
  char *s = NULL;
  char *l = NULL;
  char *c = NULL;

  s = getenv ("CC");
  if (s == NULL)
    {
      if (langC)
        printf ("gcc -g ");
      else
        printf ("g++ -g ");
    }
  else
    printf ("%s -g ", s);

  if (args != NULL)
    printf ("%s ", args);

  l = getenv ("LDFLAGS");
  if (l != NULL)
    printf ("%s ", l);

  c = getenv ("CFLAGS");
  if (c != NULL)
    printf ("%s ", c);

  if (ProfilePGCommand)
    printf (" -pg");
  else if (ProfilePCommand)
    printf (" -p");

  while (PutChar (GetChar ()) != (char)EOF)
    {
      CopyUntilEolInto (name);
      if ((strlen (name) > 0) && (name[0] != '#'))
        FindObject (name);
    }
  printf (" %s\n", libraries);
}

/* FindObject - searches the M2PATH variable to find the object file.
   If it finds the object file it prints it to stdout otherwise it
   writes an error on stderr.  */

static void
FindObject (char *Name)
{
  char m2search[4096];
  char m2path[4096];
  char name[4096];
  char exist[4096];
  int s, p;

  if (getenv ("M2PATH") == NULL)
    strcpy (m2path, ".");
  else
    strcpy (m2path, getenv ("M2PATH"));

  snprintf (name, sizeof (name), "%s.o", Name);
  p = 0;
  while (m2path[p] != (char)0)
    {
      s = 0;
      while ((m2path[p] != (char)0) && (m2path[p] != ' '))
        {
          m2search[s] = m2path[p];
          s++;
          p++;
        }
      if (m2path[p] == ' ')
	p++;
      m2search[s] = (char)0;
      snprintf (exist, sizeof (exist), "%s/%s", m2search, name);
      if (IsExists (exist))
        {
          printf (" %s", exist);
          return;
        }
    }
  fprintf (stderr, "cannot find %s\n", name);
}

/* IsExists - returns true if a file, Name, exists.  It returns false
   otherwise.  */

static int
IsExists (char *Name)
{
  struct stat buf;

  return (stat (Name, &buf) == 0);
}

/* add_function - adds a name to the list of functions, in order.  */

void
add_function (char *name)
{
  functList *p = (functList *)malloc (sizeof (functList));
  p->functname = (char *)malloc (strlen (name) + 1);
  strcpy (p->functname, name);

  if (head == NULL)
    {
      head = p;
      tail = p;
      p->next = NULL;
    }
  else
    {
      tail->next = p;
      tail = p;
      tail->next = NULL;
    }
}

static void
GenerateInitCalls (functList *p)
{
  while (p != NULL)
    {
      printf ("   _M2_%s_init (argc, argv, envp);\n", p->functname);
      p = p->next;
    }
}

static void
GenerateFinishCalls (functList *p)
{
  if (p->next != NULL)
    GenerateFinishCalls (p->next);
  printf ("   _M2_%s_fini (argc, argv, envp);\n", p->functname);
}

static void
GeneratePrototypes (functList *p)
{
  while (p != NULL)
    {
      if (langC)
        {
          printf ("extern void _M2_%s_init (int argc, char *argv[], char *envp[]);\n",
                  p->functname);
          printf ("extern void _M2_%s_fini (int argc, char *argv[], char *envp[]);\n",
                  p->functname);
        }
      else
        {
          printf ("extern \"C\" void _M2_%s_init (int argc, char *argv[], char *envp[]);\n",
                  p->functname);
          printf ("extern \"C\" void _M2_%s_fini (int argc, char *argv[], char *envp[]);\n",
                  p->functname);
        }
      p = p->next;
    }
}

/* ParseFileStartup - generates the startup code.  */

static void
ParseFileStartup (void)
{
  char name[MAX_FILE_NAME];
  functList *p;

  while (PutChar (GetChar ()) != (char)EOF)
    {
      CopyUntilEolInto (name);
      if ((strlen (name) > 0) && (strcmp (name, "mod_init") != 0)
          && (name[0] != '#'))
	add_function (name);
    }
  GeneratePrototypes (head);
  printf ("extern");
  if (!langC)
    printf (" \"C\"");
  printf (" void _exit(int);\n");

  printf ("\n\nint %s(int argc, char *argv[], char *envp[])\n", NameOfMain);
  printf ("{\n");
  GenerateInitCalls (head);
  GenerateFinishCalls (head);
  if (ExitNeeded)
    printf ("   _exit(0);\n");
  printf ("   return(0);\n");
  printf ("}\n");
}

/* OpenOutputFile - shut down stdout and open the new mod_init.c */

static void
OpenOutputFile (void)
{
  if (strcmp (NameOfFile, "-") != 0)
    {
      if (close (STDOUT) != 0)
        {
          ERROR ("Unable to close stdout");
          exit (1);
        }
      OutputFile = creat (NameOfFile, 0666);
      if (OutputFile != STDOUT)
        {
          ERROR ("Expected that the file descriptor should be 1");
        }
    }
}

/* CloseFile - flush and close the file.  */

static void
CloseFile (void)
{
#if 0
  fflush(stdout);
  if (close(STDOUT) != 0) {
    ERROR("Unable to close our output file"); exit(1);
  }
#endif
}

/* CopyUntilEof - copies from the current input marker until ENDOFILE
   is reached.  */

static void
CopyUntilEof (void)
{
  char ch;

  while ((ch = GetChar ()) != ENDOFILE)
    putchar (ch);
}

/* CopyUntilEol - copies from the current input marker until '\n' is
   reached.  */

static void
CopyUntilEol (void)
{
  char ch;

  while (((ch = GetChar ()) != '\n') && (ch != (char)EOF))
    putchar (ch);
  if (ch == '\n')
    putchar (ch);
}

/* CopyUntilEolInto - copies from the current input marker until '\n'
   is reached into a Buffer.  */

static void
CopyUntilEolInto (char *Buffer)
{
  char ch;
  int i = 0;

  while (((ch = GetChar ()) != '\n') && (ch != (char)EOF))
    {
      Buffer[i] = ch;
      i++;
    }
  if ((ch == '\n') || (ch == (char)EOF))
    Buffer[i] = (char)0;
}

/* IsSym - returns true if string, s, was found in the input stream.
   The input stream is uneffected.  */

static int
IsSym (char *s)
{
  int i = 0;

  while ((s[i] != (char)0) && (s[i] == PutChar (GetChar ())))
    {
      GetChar ();
      i++;
    }
  if (s[i] == (char)0)
    {
      PushBack (s);
      /* found s in input string.  */
      return (TRUE);
    }
  else
    {
      /* push back the characters we have scanned.  */
      if (i > 0)
        {
          do
            {
              i--;
              PutChar (s[i]);
            }
          while (i > 0);
        }
      return (FALSE);
    }
}

/* SymIs - returns true if string, s, was found in the input stream.
   The token s is consumed from the input stream.  */

static int
SymIs (char *s)
{
  int i = 0;

  while ((s[i] != (char)0) && (s[i] == PutChar (GetChar ())))
    {
      GetChar ();
      i++;
    }
  if (s[i] == (char)0)
    {
      /* found s in input string.  */
      return (TRUE);
    }
  else
    {
      /* push back the characters we have scanned.  */
      if (i > 0)
        {
          do
            {
              i--;
              PutChar (s[i]);
            }
          while (i > 0);
        }
      return (FALSE);
    }
}

/* FindString - keeps on reading input until a string, String, is
   matched.  If end of file is reached then FALSE is returned, otherwise
   TRUE is returned.  */

static int
FindString (char *String)
{
  int StringIndex = 0;
  int Found = FALSE;
  int eof = FALSE;
  char ch;

  while ((!Found) && (!eof))
    {
      if (String[StringIndex] == (char)0)
	/* must have found string.  */
	Found = TRUE;
      else
        {
          ch = GetChar ();
          eof = (ch == ENDOFILE);
          if (ch == String[StringIndex])
	    StringIndex++;
          else
	    StringIndex = 0;
        }
    }
  return (Found);
}

/* GetNL - keeps on reading input from until a new line is found.  */

static void
GetNL (void)
{
  char ch;

  while ((ch = GetChar ()) != '\n')
    putchar (ch);
  putchar ('\n');
}

/* GetChar - returns the current character in input.  */

static char
GetChar (void)
{
  char ch;

  if (StackPtr > 0)
    {
      StackPtr--;
      return (Stack[StackPtr]);
    }
  else
    {
      if (GetSingleChar (&ch))
	return (ch);
      else
	return (ENDOFILE);
    }
}

#define MAXBUF 0x1000
static int Pointer = 0;
static int AmountRead = 0;
static char Buffer[MAXBUF];

/* ResetBuffer - resets the buffer information to an initial state.  */

static void
ResetBuffer (void)
{
  StackPtr = 0;
  Pointer = 0;
  AmountRead = 0;
}

/* GetSingleChar - gets a single character from input.  TRUE is
   returned upon success.  */

static int
GetSingleChar (char *ch)
{
  if (Pointer == AmountRead)
    {
      AmountRead = read (CurrentFile, &Buffer, MAXBUF);
      if (AmountRead < 0)
	AmountRead = 0;
      Pointer = 0;
    }
  if (Pointer == AmountRead)
    {
      *ch = ENDOFILE;
      return (FALSE);
    }
  else
    {
      *ch = Buffer[Pointer];
      Pointer++;
      return (TRUE);
    }
}

/* InRange - returns true if Element is within the range Min..Max.  */

static int
InRange (int Element, unsigned int Min, unsigned int Max)
{
  return ((Element >= Min) && (Element <= Max));
}

/* PutChar - pushes a character back onto input.  This character is
   also returned.  */

static char
PutChar (char ch)
{
  if (StackPtr < MAXSTACK)
    {
      Stack[StackPtr] = ch;
      StackPtr++;
    }
  else
    {
      ERROR ("Stack overflow in PutChar");
    }
  return (ch);
}

/* IsSpace - returns true if character, ch, is a space.  */

static int
IsSpace (char ch)
{
  return ((ch == ' ') || (ch == '\t'));
}

/* SkipSpaces - eats up spaces in input.  */

static void
SkipSpaces (void)
{
  while (IsSpace (PutChar (GetChar ())))
    putchar (GetChar ());
}

/* SilentSkipSpaces - eats up spaces in input.  */

static void
SilentSkipSpaces (void)
{
  char ch;

  while (IsSpace (PutChar (GetChar ())))
    ch = GetChar (); /* throw away character.  */
}

/* SkipText - skips ascii text, it does not skip white spaces.  */

static void
SkipText (void)
{
  while (!IsSpace (PutChar (GetChar ())))
    putchar (GetChar ());
}

/* SilentSkipText - skips ascii text, it does not skip white spaces.  */

static void
SilentSkipText (void)
{
  char ch;

  while (!IsSpace (PutChar (GetChar ())))
    ch = GetChar (); /* throw away character.  */
}

/* PushBack - pushes a string, backwards onto the input stack.  */

static void
PushBack (char *s)
{
  int i;

  i = strlen (s);
  while (i > 0)
    {
      i--;
      PutChar (s[i]);
    }
}

/* IsDigit - returns true if a character, ch, is a decimal digit.  */

static int
IsDigit (char ch)
{
  return (((ch >= '0') && (ch <= '9')));
}

/* GetName - returns the next name found.  */

static void
GetName (char *Name)
{
  int i;
  char ch;

  SkipSpaces ();
  ch = GetChar ();
  i = 0;
  while (!IsSpace (ch))
    {
      Name[i] = ch;
      i++;
      ch = GetChar ();
    }
  Name[i] = '\0';
}

/* FindSource - open source file on StdIn.  */

static void
FindSource (char *Name)
{
  if (close (STDIN) != 0)
    {
      ERROR ("close on STDIN failed");
    }
  CurrentFile = open (Name, O_RDONLY);
  if (CurrentFile < 0)
    {
      perror ("failed to open file");
      exit (1);
    }
  if (CurrentFile != STDIN)
    {
      ERROR ("Expecting file descriptor value of 1");
    }
}