fltk/src/fl_open_uri.cxx

//
// "$Id$"
//
// fl_open_uri() code for FLTK.
//
// Test with:
//
//    gcc -I/fltk/dir -I/fltk/dir/src -DTEST -o fl_open_uri fl_open_uri.cxx -lfltk
//
// Copyright 2003-2010 by Michael R Sweet
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file.  If this
// file is missing or damaged, see the license at:
//
//     http://www.fltk.org/COPYING.php
//
// Please report all bugs and problems on the following page:
//
//     http://www.fltk.org/str.php
//

//
// Include necessary headers...
//

#include "config_lib.h"
#include <FL/filename.H>
#include <FL/Fl.H>
#include <FL/Fl_System_Driver.H>
#include <stdio.h>
#include <stdlib.h>
#include "flstring.h"

/** \addtogroup filenames
 @{ */

/**
 * Opens the specified Uniform Resource Identifier (URI).
 * Uses an operating-system dependent program or interface. For URIs
 * using the "ftp", "http", or "https" schemes, the system default web
 * browser is used to open the URI, while "mailto" and "news" URIs are
 * typically opened using the system default mail reader and "file" URIs
 * are opened using the file system navigator.
 *
 * On success, the (optional) msg buffer is filled with the command that
 * was run to open the URI; on Windows, this will always be "open uri".
 *
 * On failure, the msg buffer is filled with an English error message.
 *
 * \note
 * \b Platform \b Specific \b Issues: \b Windows \n
 * With "file:" based URIs on Windows, you may encounter issues with
 * anchors being ignored. Example: "file:///c:/some/index.html#anchor"
 * may open in the browser without the "#anchor" suffix. The behavior
 * seems to vary across different Windows versions. Workaround: open a link
 * to a separate html file that redirects to the desired "file:" URI.
 *
 * \b Example
 * \code
 * #include <FL/filename.H>
 * [..]
 * char errmsg[512];
 * if ( !fl_open_uri("http://google.com/", errmsg, sizeof(errmsg)) ) {
 *     char warnmsg[768];
 *     sprintf(warnmsg, "Error: %s", errmsg);
 *     fl_alert(warnmsg);
 * }
 * \endcode
 *
 * @param uri The URI to open
 * @param msg Optional buffer which contains the command or error message
 * @param msglen Length of optional buffer
 * @return 1 on success, 0 on failure
 */
int fl_open_uri(const char *uri, char *msg, int msglen) {
  // Supported URI schemes...
  static const char * const schemes[] = {
    "file://",
    "ftp://",
    "http://",
    "https://",
    "mailto:",
    "news://",
    NULL
  };

  // Validate the URI scheme...
  int i;
  for (i = 0; schemes[i]; i ++)
    if (!strncmp(uri, schemes[i], strlen(schemes[i])))
      break;

  if (!schemes[i]) {
    if (msg) {
      char scheme[255];
      if (sscanf(uri, "%254[^:]", scheme) == 1) {
        snprintf(msg, msglen, "URI scheme \"%s\" not supported.", scheme);
      } else {
        snprintf(msg, msglen, "Bad URI \"%s\"", uri);
      }
    }

    return 0;
  }
  return Fl::system_driver()->open_uri(uri, msg, msglen);
}

/** Decodes a URL-encoded string.
 
 In a Uniform Resource Identifier (URI), all non-ASCII bytes and several others (e.g., '<', '%', ' ')
 are URL-encoded using 3 bytes by "%XY" where XY is the hexadecimal value of the byte. This function
 decodes the URI restoring its original UTF-8 encoded content. Decoding is done in-place.
 */
void fl_decode_uri(char *uri)
{
  char *last = uri + strlen(uri);
  while (uri < last-2) {
    if (*uri == '%') {
      int h;
      if ( sscanf(uri+1, "%2X", &h) != 1 ) break;
      *uri = h;
      memmove(uri+1, uri+3, last - (uri+2));
      last -= 2;
    }
    uri++;
  }
}

/**   @} */


#if defined(FL_CFG_SYS_POSIX) && !defined(FL_DOXYGEN)
// code shared by the Mac OS and USE_X11 platforms
#  include "drivers/Posix/Fl_Posix_System_Driver.H"
#  include <unistd.h>
#  include <sys/wait.h>
#  include <signal.h>
#  include <fcntl.h>
#  include <errno.h>

// Run the specified program, returning 1 on success and 0 on failure
int Fl_Posix_System_Driver::run_program(const char *program, char **argv, char *msg, int msglen) {
  pid_t	pid;				// Process ID of first child
  int status;				// Exit status from first child
  sigset_t set, oldset;			// Signal masks


  // Block SIGCHLD while we run the program...
  //
  // Note that I only use the POSIX signal APIs, however older operating
  // systems may either not support POSIX signals or have side effects.
  // IRIX, for example, provides three separate and incompatible signal
  // APIs, so it is possible that an application setting a signal handler
  // via signal() or sigset() will not have its SIGCHLD signals blocked...

  sigemptyset(&set);
  sigaddset(&set, SIGCHLD);
  sigprocmask(SIG_BLOCK, &set, &oldset);

  // Create child processes that actually run the program for us...
  if ((pid = fork()) == 0) {
    // First child comes here, fork a second child and exit...
    if (!fork()) {
      // Second child comes here, redirect stdin/out/err to /dev/null...
      close(0);
      ::open("/dev/null", O_RDONLY);

      close(1);
      ::open("/dev/null", O_WRONLY);

      close(2);
      ::open("/dev/null", O_WRONLY);

      // Detach from the current process group...
      setsid();

      // Run the program...
      execv(program, argv);
      _exit(0);
    } else {
      // First child gets here, exit immediately...
      _exit(0);
    }
  } else if (pid < 0) {
    // Restore signal handling...
    sigprocmask(SIG_SETMASK, &oldset, NULL);

    // Return indicating failure...
    return 0;
  }

  // Wait for the first child to exit...
  while (waitpid(pid, &status, 0) < 0) {
    if (errno != EINTR) {
      // Someone else grabbed the child status...
      if (msg) snprintf(msg, msglen, "waitpid(%ld) failed: %s", (long)pid,
                        strerror(errno));

      // Restore signal handling...
      sigprocmask(SIG_SETMASK, &oldset, NULL);

      // Return indicating failure...
      return 0;
    }
  }

  // Restore signal handling...
  sigprocmask(SIG_SETMASK, &oldset, NULL);

  // Return indicating success...
  return 1;
}
#endif // FL_CFG_SYS_POSIX


#ifdef TEST
//
// Test code...
//

// Open the URI on the command-line...
int main(int argc, char **argv) {
  char msg[1024];


  if (argc != 2) {
    puts("Usage: fl_open_uri URI");
    return 1;
  }

  if (!fl_open_uri(argv[1], msg, sizeof(msg))) {
    puts(msg);
    return 1;
  } else return 0;
}
#endif // TEST

//
// End of "$Id$".
//