/*
   Copyright (C) 1991-2002, The Numerical Algorithms Group Ltd.
   All rights reserved.

   Copyright (C) 2007-2009, Gabriel Dos Reis.
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are
   met:

       - Redistributions of source code must retain the above copyright
         notice, this list of conditions and the following disclaimer.

       - Redistributions in binary form must reproduce the above copyright
        notice, this list of conditions and the following disclaimer in
         the documentation and/or other materials provided with the
         distribution.

       - Neither the name of The Numerical Algorithms Group Ltd. nor the
         names of its contributors may be used to endorse or promote products
         derived from this software without specific prior written permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
   IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include "openaxiom-c-macros.h"

#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <assert.h>
#include <math.h>
#include <unistd.h>


#ifdef __WIN32__
#  include <windows.h>
#else
#  include <dirent.h>
#  include <fcntl.h>
#endif

#include "cfuns.h"

/* Most versions of Windows don't have the POSIX functions getuid(),
   geteuid(), getgid(), and getegid().  The following definitions are
   approximations, to patch for the deficiencies of Windows
   POSIX interface.  */

#if !HAVE_DECL_GETUID
#  define getuid() 0
#endif

#if !HAVE_DECL_GETGID
#  define getgid() 0
#endif

#if !HAVE_DECL_GETEUID
#  define geteuid() getuid()
#endif

#if !HAVE_DECL_GETEGID
#  define getegid() getgid()
#endif

OPENAXIOM_EXPORT int
addtopath(char *dir)
{
    char *path, *newpath;

    path = oa_getenv("PATH");
    if (path == NULL)
        return -1;

    newpath = (char *) malloc(1 + strlen(path) + strlen(dir) + strlen("PATH=:"));
    if (newpath == NULL)
        return -1;

    sprintf(newpath, "PATH=%s:%s", path, dir);

    return putenv(newpath);
}



/* Returns 1 if `c' designates a path separator, 0 otherwise.  */
static inline int
openaxiom_is_path_separator(char c)
{
#ifdef __WIN32__
   return c == '\\' || c == '/';
#else
   return c == '/';
#endif      
}

/*
  Returns a the dirname of `path'.  If `path' has no separator, then
  returns ".".  The returned value if malloc-allocated.  */

OPENAXIOM_EXPORT char*
oa_dirname(const char* path)
{
   const int n = strlen(path);
   const char* mark = path + n;

   if (n == 0)
      return strdup(".");
   else if (n == 1 &&  openaxiom_is_path_separator(*path))
      return strdup("/");

   /* For "/banana/space/", we want "/banana".  */
   if (openaxiom_is_path_separator(*--mark))
      --mark;
   while (path < mark && !openaxiom_is_path_separator(*mark))
      --mark;

   if (path == mark)
      return strdup(openaxiom_is_path_separator(*path) ? "/" : ".");
   else {
      const int l = mark - path;
      char* dir = (char*) malloc(l + 1);
      memcpy(dir, path, l);
      dir[l] = '\0';
      return dir;
   }
}

/*
 * Test whether the path is the name of a directory.  Returns 1 if so, 0 if
 * not, -1 if it doesn't exist.
 */


OPENAXIOM_EXPORT int
directoryp(char *path)
{
    struct stat buf;
    int code = stat(path, &buf);

    return code == -1 ? -1 : S_ISDIR(buf.st_mode);
}

OPENAXIOM_EXPORT int 
make_path_from_file(char *s, char *t)
{
    char *pos = "";
    char *c;

    /** simply copies the path name from t into s **/
    for (c = t + strlen(t); c != s; c--)
        if (*c == '/') {
            pos = c;
            break;
        }
    /** Check to see if the path was actually present **/
    if (c == t) {               /** No Path, so return the pwd **/
        return (-1);
    }
    /** now just do the copying **/
    strncpy(s, t, pos - t);
    return 1;
}

/* The functions writeablep() and readablep() determine write and
   read access of a file designated by its name.  The function
   axiom_has_write_access is a sub-routine of writeablep.

   The access is determined based on the POSIX semantics; see
   "Advanced Programming in the UNIX Environement", section 4.5.

   1. If the effective user ID of the process is 0 (the superuser),
      access is allowed.  This gives the superuser free rein throughout
      the entire file system.

   2. If the effective user ID of the process equals the owner ID of
      the file (i.e., the process owns the file), access is allowed
      if the appropriate user access permission bit is set. [...]

   3. If the effective group ID of the process or one of the
      supplementary group IDs of the process equals the group ID
      of the file, access is allowed if the appropriate
      group access permission bit is set.  Otherwise, permission
      is denied.

   4. If the appropriate other access permission bit is set, access is
      allowed.  Otherwise, permission is defined.   */


/* Return 1 if the process has write access of file as explained above.
   Otherwise, return 0.  */

static inline int
axiom_has_write_access(const struct stat* file_info)
{
   int effetive_uid = geteuid();

   if (effetive_uid == 0)
      return 1;

   if (effetive_uid == file_info->st_uid)
      return (file_info->st_mode & S_IWUSR) ? 1 : 0;

#ifdef S_IWGRP
   if (getegid() == file_info->st_gid)
      return (file_info->st_mode & S_IWGRP) ? 1 : 0;
#endif

#ifdef S_IWOTH
   return (file_info->st_mode & S_IWOTH) ? 1 : 0;
#else
   return 0;
#endif   
}


/* Return
     -1 if the file designated by PATH is inexistent.
      0 if the file exists but write access is denied.
      1 if the file exists and process has write access.
      2 if the file does not exists but process has write
        has write access to the dirname of path.  */

OPENAXIOM_EXPORT int
writeablep(char *path)
{
    struct stat buf;
    int code;

    code = stat(path, &buf);
    if (code == -1) {
       /* The file does not exist, so check to see if the directory
          is writable.  */
       char* dir = oa_dirname(path);
       code = stat(dir, &buf);
       /* FIXME: Work around MinGW/MSYS bug.
            The string pointed to by `dir' was strdup'd.  According to
            the C standard, that means the the string was allocated
            by `malloc', therefore can be disposed of by `free'.  However,
            the MinGW/MSYS port appears to use MS' StrDup as the real
            worker.  Consequently, the guarantee that the the string can
            free'd no longer holds.  We have to use MS's LocalFree.  */
#ifdef __WIN32__
       LocalFree(dir);
#else
       free(dir);
#endif
       return (code == 0) && axiom_has_write_access(&buf) ? 2 : -1;
    }

    return axiom_has_write_access(&buf);
}


/* Return
     -1 if the file designated by PATH is inexistent.
      0 if the file exists but process has no read access.
      1 if the file exists and read access is granted.  */

OPENAXIOM_EXPORT int
readablep(char *path)
{
    struct stat buf;
    int code;

    code = stat(path, &buf);
    if (code == -1)
        return -1;

    if (geteuid() == buf.st_uid) 
        return ((buf.st_mode & S_IREAD) != 0);

#ifdef S_IRGRP    
     if (getegid() == buf.st_gid) 
        return ((buf.st_mode & S_IRGRP) != 0);
#endif

#ifdef S_IROTH
     return ((buf.st_mode & S_IROTH) != 0);
#else
     return 0;
#endif
}



OPENAXIOM_EXPORT long
findString(char *file, char *string)
{
    int nstring, charpos;
    FILE *fn;
    char buffer[1024];

    if ((fn = fopen(file, "r")) == NULL)
        return -1;

    for (charpos = 0, nstring = strlen(string);
         fgets(buffer, sizeof buffer, fn) != NULL;
         charpos += strlen(buffer)
        )
        if (!strncmp(buffer, string, nstring))
            return charpos;
    return -1;

}

OPENAXIOM_EXPORT int
copyEnvValue(char *varName, char *buffer)
{
    char *s;

    s = oa_getenv(varName);
    if (s == NULL)
        return 0;
    strcpy(buffer, s);
    return strlen(s);
}

/* Return 1 if the file descriptor FD, as viewed by the Core Executable,
   is attached to a terminal.  */
OPENAXIOM_EXPORT int
std_stream_is_terminal(int fd)
{
   assert(fd > -1 && fd < 3);
#ifdef __WIN32__
   DWORD handle;
   switch (fd) {
   case 0: handle = STD_INPUT_HANDLE; break;
   case 1: handle = STD_OUTPUT_HANDLE; break;
   case 2: handle = STD_ERROR_HANDLE; break;
   /* Next code is never executed but it makes the compiler happy.  */
   default: return 0;
   }
   /* The MS documentation suggests `GetFileType' for determining
      the nature of the file handle.  The return value, in our case,
      is an over approximation of what we are interested in:  Are we
      dealing with a stream connected to a terminal?  The constant
      FILE_TYPE_CHAR characterises character files; in particular
      a console terminal, or a printer.  There is an undocumented
      function `VerifyConsoleIoHandle' to deal precisely with the case
      we are interested in.  However, while availale in Wine, it is
      not available in the MinGW headers.  Consequently, we cannot
      rely on it for the moment.  
      So, we may still get garbage out of this function on MS platforms.  */
   return GetFileType(GetStdHandle(handle)) == FILE_TYPE_CHAR;
#else
   return isatty(fd);
#endif
}

/* Change the process' curretnt directory.  Return zero on success,
   and -1 on failure.  */
OPENAXIOM_EXPORT int
oa_chdir(const char* path)
{
#ifdef __WIN32__
   return SetCurrentDirectory(path) ? 0 : -1;
#else
   return chdir(path);
#endif /* __WIN32__ */
}


/* return true if path is `.' or `..'.  */
static inline int
is_dot_or_dotdot(const char* path)
{
   return strcmp(path, ".") == 0 || strcmp(path, "..") == 0;
}

/* Remove a directory entry.  Files are removed, directories are
   recursively walked and removed.
   Return 0 on success, and -1 on falure.
   In practice, OpenAxiom does not remove directories with
   non-trivial recursive structues.  */
OPENAXIOM_EXPORT int
oa_unlink(const char* path)
{
   const char* curdir;
   int status = -1;
#ifdef __WIN32__
   WIN32_FIND_DATA findData;
   HANDLE walkHandle;

   if (is_dot_or_dotdot(path))
      return -1;

   walkHandle = FindFirstFile(path, &findData);
   if (walkHandle == INVALID_HANDLE_VALUE) 
      return -1;

   /* Remember where we are so we can return back properly.  */
   curdir = oa_getcwd();

   do {
      if (is_dot_or_dotdot(findData.cFileName))
         continue;
      if (findData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
         if ((status = oa_chdir(findData.cFileName)) < 0)
            goto sortie;
         if ((status = oa_unlink("*")) < 0)
            goto sortie;
         if ((status = oa_chdir("..")) < 0)
            goto sortie;
         if(!RemoveDirectory(findData.cFileName)) {
            status = -1;
            goto sortie;
         }
      }
      else if (!DeleteFile(findData.cFileName)) {
         status = -1;
         goto sortie;
      }
      status = 0;
   } while (FindNextFile(walkHandle, &findData));
   if (!FindClose(walkHandle)) {
      status = -1;
      goto sortie;
   }
#else
   struct stat pathstat;
   DIR* dir;
   struct dirent* entry;

   /* Don't ever try to remove `.' or `..'.  */
   if (is_dot_or_dotdot(path))
      return -1;

   if (stat(path, &pathstat) < 0)
      return -1;

   /* handle non directories first.  */
   if (!S_ISDIR(pathstat.st_mode))
      return unlink(path);

   /* change into the path so that we don't have to form full
      pathnames. */
   curdir = oa_getcwd();
   if ((dir = opendir(path)) == NULL || oa_chdir(path) < 0)
      goto sortie;

   while (errno = 0, (entry = readdir(dir)) != NULL) {
      struct stat s;
      if (is_dot_or_dotdot(entry->d_name))
         continue;
      if ((status = stat(entry->d_name, &s)) < 0)
         goto sortie;
      if (S_ISDIR(s.st_mode)) {
         if ((status = oa_unlink(entry->d_name)) < 0)
            goto sortie;
      }
      else if ((status = unlink(entry->d_name)) < 0)
         goto sortie;
   }
   if (errno != 0) {
      status = -1;
      goto sortie;
   }

   /* Now, get one level up, and remove the empty directory.  */
   if (oa_chdir("..") < 0 || closedir(dir) < 0 || rmdir(path) < 0) 
      status = -1;
   else
      status = 0;
#endif /* __WIN32__ */

  sortie:
   oa_chdir(curdir);
   free((char*) curdir);
   return status;
}

/* Rename a file or directory.  */
OPENAXIOM_EXPORT int
oa_rename(const char* old_path, const char* new_path)
{
#ifdef __WIN32__
   return MoveFile(old_path, new_path) ? 0 : -1;
#else
   return rename(old_path, new_path);
#endif
}

/* Create a new directory named `path'.  Return 0 on success,
   and -1 on failure.  */
OPENAXIOM_EXPORT int
oa_mkdir(const char* path)
{
#ifdef __WIN32__
   return CreateDirectory(path, NULL) ? 0 : -1;
#else
#  define DIRECTORY_PERM ((S_IRWXU|S_IRWXG|S_IRWXO) & ~(S_IWGRP|S_IWOTH))
   return mkdir (path, DIRECTORY_PERM);
#  undef DIRECTORY_PERM   
#endif   
}

/* Run a shell command.  Effectively forward to C's system().  */
OPENAXIOM_EXPORT int
oa_system(const char* cmd)
{
   return system(cmd);
}

OPENAXIOM_EXPORT int 
oa_getpid(void) 
{
#ifdef __WIN32__
   return GetCurrentProcessId();
#else
   return getpid();
#endif
}

/* Return the value of an environment variable.  */
OPENAXIOM_EXPORT char*
oa_getenv(const char* var)
{
#ifdef __WIN32__   
#define BUFSIZE 128
   char* buf = (char*) malloc(BUFSIZE);
   int len = GetEnvironmentVariable(var, buf, BUFSIZE);
   if (len == 0) {
      free(buf);
      return NULL;
   }
   else if (len > BUFSIZE) {
     buf = (char*) realloc(buf,len);
      len = GetEnvironmentVariable(var, buf, len);
      if (len == 0) {
         free(buf);
         return NULL;
      }
   }
   return buf;
#else
   return getenv(var);
#endif   
}

/* Set the value of environment variable VAR to VAL.
   Return 1 on success, and 0 otherwise.  */
OPENAXIOM_EXPORT int
oa_setenv(const char* var, const char* val)
{
#ifdef __WIN32__
   return SetEnvironmentVariable(var, val);
#else
   const int var_length = strlen(var);
   const int val_length = strlen(val);
   char* str = (char*) malloc(var_length + 1 + val_length + 1);
   strcpy(str, var);
   str[var_length] = '=';
   strcpy(str + var_length + 1, val);
   str[var_length + 1 + val_length] = '\0';
   return !putenv(str);
#endif   
}


OPENAXIOM_EXPORT char*
oa_getcwd(void)
{
   int bufsz = 256;
   char* buf = (char*) malloc(bufsz);
#ifdef __WIN32__
   int n = GetCurrentDirectory(bufsz, buf);
   if (n == 0) {
      perror("oa_getcwd");
      exit(-1);
   }
   else if (n > bufsz) {
      buf = realloc(buf,n);
      if (GetCurrentDirectory(n, buf) != n) {
         perror("oa_getcwd");
         exit(-1);
      }
   }
   return buf;
#else /* __WIN32__ */
   errno = 0;
   while (getcwd(buf,bufsz) == 0) {
      if (errno == ERANGE) {
         errno = 0;
         bufsz *= 2;
         buf = realloc(buf, bufsz);
      }
      else {
         perror("oa_getcwd");
         exit(-1);
      }
   }
   return buf;
#endif
}

OPENAXIOM_EXPORT int
oa_access_file_for_read(const char* path)
{
#ifdef __WIN32__
  return GetFileAttributes(path) == INVALID_FILE_ATTRIBUTES ? -1 : 1;
#else
   return access(path, R_OK);
#endif   
}


OPENAXIOM_EXPORT const char*
oa_get_tmpdir(void)
{
#ifdef __WIN32__
   char* buf;
   /* First, probe.  */
   int bufsz = GetTempPath(0, NULL);
   if (bufsz == 0) {
      perror("oa_get_tmpdir");
      exit(1);
   }
   else {
      int new_size;
      buf = (char*) malloc(bufsz + 1);
      new_size = GetTempPath(bufsz, buf);
      if(new_size == 0 || new_size >= bufsz) {
         perror("oa_get_tmpdir");
         free(buf);
         exit(1);
      }
      buf[new_size] = '\0';
   }
   return buf;
#else
   return "/tmp";
#endif   
}


OPENAXIOM_EXPORT int
oa_copy_file(const char* src, const char* dst)
{
#ifdef __WIN32__
   return CopyFile(src,dst, /* bFailIfExists = */ 0) ? 0 : -1;
#else
#define OA_BUFSZ 512
#define OA_DEFAULT_MODE (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
   char buf[OA_BUFSZ];
   int src_fd;
   int dst_fd;
   int count;
   if((src_fd = open(src, O_RDONLY)) < 0)
      return -1;
   if ((dst_fd = creat(dst, OA_DEFAULT_MODE)) < 0) {
      close(src_fd);
      return -1;
   }

   while ((count = read(src_fd, buf, OA_BUFSZ)) > 0) 
      if (write(dst_fd, buf, count) != count)
         break;

#undef OA_DEFAULT_MODE
#undef OA_BUFSZ
   return (close(dst_fd) < 0 || close(src_fd) < 0 || count < 0) ? -1 : 0;
#endif   
}


OPENAXIOM_EXPORT double 
plus_infinity(void )
{
#ifdef INFINITY   
   return INFINITY;
#else
   /* This must be a curious platform.  */
   volatile double zero = 0.0;
   return 1.0 / zero;           /* If it traps, well, it traps.  */
#endif   
}

OPENAXIOM_EXPORT double 
minus_infinity(void)
{
   return -plus_infinity();
}

OPENAXIOM_EXPORT double 
quiet_double_NaN(void)
{
#ifdef NAN
   return NAN;
#else
   return sqrt(-1.0);            /* Just pick one.  */
#endif
}


OPENAXIOM_EXPORT openaxiom_byteorder
oa_get_host_byteorder(void)
{
#ifdef WORDS_BIGENDIAN
   return oa_big_endian;
#else
   return oa_little_endian;
#endif   
}


OPENAXIOM_EXPORT void
oa_allocate_process_argv(openaxiom_process* proc, int argc)
{
   proc->argc = argc;
   proc->argv = (char**) malloc((1 + argc) * sizeof (char*));
   proc->argv[argc] = NULL;
}

OPENAXIOM_EXPORT int
oa_spawn(openaxiom_process* proc, openaxiom_spawn_flags flags)
{
#ifdef __WIN32__
   const char* path = NULL;
   char* cmd_line = NULL;
   int curpos = strlen(proc->argv[0]);
   int cmd_line_length = curpos;
   int i;
   PROCESS_INFORMATION proc_info;
   STARTUPINFO startup_info = { 0 };
   DWORD status;

   for (i = 0; i < proc->argc; ++i)
      cmd_line_length += 1 + strlen(proc->argv[i]);

   cmd_line = (char*) malloc(cmd_line_length + 1);
   strcpy(cmd_line, proc->argv[0]);
   for (i = 0; i < proc->argc; ++i) {
      cmd_line[curpos++] = ' ';
      strcpy(cmd_line + curpos, proc->argv[i]);
      curpos += strlen(proc->argv[i]);
   }
   cmd_line[curpos] = '\0';

   if ((flags & openaxiom_spawn_search_path) == 0)
      path = proc->argv[0];

   if(CreateProcess(/* lpApplicationName */ path,
                    /* lpCommandLine */ cmd_line,
                    /* lpProcessAttributes */ NULL,
                    /* lpThreadAttributes */ NULL,
                    /* bInheritHandles */ TRUE,
                    /* dwCreationFlags */ 0,
                    /* lpEnvironment */ NULL,
                    /* lpCurrentDirectory */ NULL,
                    /* lpstartupInfo */ &startup_info,
                    /* lpProcessInformation */ &proc_info) == 0) {
      fprintf(stderr, "oa_spawn: error %d\n", GetLastError());
      return proc->id = -1;
   }
   proc->id = proc_info.dwProcessId;
   if ((flags & openaxiom_spawn_replace) == 0)
      return proc->id;
   WaitForSingleObject(proc_info.hProcess, INFINITE);
   GetExitCodeProcess(proc_info.hProcess, &status);
   CloseHandle(proc_info.hThread);
   CloseHandle(proc_info.hProcess);
   return 0;

#else
   proc->id = 0;
   if ((flags & openaxiom_spawn_replace) == 0)
      proc->id = fork();
   if (proc->id == 0) {
      if (flags & openaxiom_spawn_search_path)
         execvp(proc->argv[0], proc->argv);
      else
         execv(proc->argv[0], proc->argv);
      perror(strerror(errno));
      /* Don't keep useless clones around.  */
      if ((flags & openaxiom_spawn_replace) == 0)
         exit(-1);
   }
   return proc->id;
#endif   
}