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Implement shell style exit status decoding (#754684) 

Command exit status is a 1 byte value between 0 and 255. [1][2]  However
at the Unix API level the value is encoded as documented in the
waitpid(2) manual page.  This is true for the Glib API too. [3]  This is
why, for example, the comment in ext2::check_repair() reported receiving
undocumented exit status 256.  It was actually receiving exit status 1
encoded as per the waitpid(2) method.

Add shell style exit status decoding [2] to execution of all external
commands.   Return value from Utils::execute_command() and
FileSystem::execute_command() functions are now:
    0 - 125 - Exit status from the command
    126     - Error executing the command
    127     - Command not found
    128+N   - Command terminated by signal N
    255     - Unexpected waitpid(2) condition
Also adjust checking of the returned statuses as necessary.

[1] Advanced Bash-Scripting Guide: Appendix D. Exit Codes With Special
    Meanings
    http://www.linuxtopia.org/online_books/advanced_bash_scripting_guide/exitcodes.html

[2] Quote from the bash(1) manual page:

        EXIT STATUS
            ... Exit statuses fall between 0 and 255, though as
            explained below, the shell may use values above 125
            specially.  ...

            ... When a command terminates on a fatal signal N, bash uses
            the value of 128+N as the exit status.

            If a command is not found, the child process created to
            execute it returns a status of 127.  If a command is found
            but is not executable, the return status is 126.

[3] Quote from the Glib Reference Manual, Spawning Processes section,
    for function g_spawn_check_exit_status():
    https://developer.gnome.org/glib/stable/glib-Spawning-Processes.html#g-spawn-check-exit-status

        The g_spawn_sync() and g_child_watch_add() family of APIs return
        an exit status for subprocesses encoded in a platform-specific
        way.  On Unix, this is guaranteed to be in the same format
        waitpid() returns, ...

Bug 754684 - Updates to FileSystem:: and Utils::execute_command()
             functions
This commit is contained in:
Mike Fleetwood 2015-09-06 14:39:07 +01:00 committed by Curtis Gedak
parent a202b4569a
commit 2b57229fc2
8 changed files with 49 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/Utils.h
View File

@ -190,6 +190,8 @@ public:
Glib::ustring & output,
Glib::ustring & error,
bool use_C_locale = false ) ;
static int get_failure_status( Glib::SpawnError & e );
static int decode_wait_status( int wait_status );
static Glib::ustring regexp_label( const Glib::ustring & text
, const Glib::ustring & pattern
) ;

4
src/FileSystem.cc
View File

@ -54,7 +54,7 @@ const Glib::ustring FileSystem::get_generic_text( CUSTOM_TEXT ttype, int index )
void FileSystem::store_exit_status( GPid pid, int status )
{
exit_status = status;
exit_status = Utils::decode_wait_status( status );
running = false;
if (pipecount == 0) // pipes finished first
Gtk::Main::quit();
@ -102,7 +102,7 @@ int FileSystem::execute_command( const Glib::ustring & command, OperationDetail
std::cerr << e.what() << std::endl;
operationdetail.get_last_child().add_child(
OperationDetail( e.what(), STATUS_ERROR, FONT_ITALIC ) );
return 1;
return Utils::get_failure_status( e );
}
fcntl( out, F_SETFL, O_NONBLOCK );
fcntl( err, F_SETFL, O_NONBLOCK );

34
src/Utils.cc
View File

@ -33,6 +33,8 @@
#include <sys/statvfs.h>
#include <gtkmm/main.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/wait.h>
namespace GParted
{
@ -529,7 +531,7 @@ public:
void CommandStatus::store_exit_status( GPid pid, int status )
{
exit_status = status;
exit_status = Utils::decode_wait_status( status );
running = false;
if (pipecount == 0) // pipes finished first
{
@ -596,7 +598,7 @@ int Utils::execute_command( const Glib::ustring & command,
&err );
} catch (Glib::SpawnError &e) {
std::cerr << e.what() << std::endl;
return 1;
return Utils::get_failure_status( e );
}
fcntl( out, F_SETFL, O_NONBLOCK );
fcntl( err, F_SETFL, O_NONBLOCK );
@ -625,6 +627,34 @@ int Utils::execute_command( const Glib::ustring & command,
return status.exit_status;
}
// Return shell style exit status when failing to execute a command. 127 for command not
// found and 126 otherwise.
// NOTE:
// Together get_failure_status() and decode_wait_status() provide complete shell style
// exit status handling. See bash(1) manual page, EXIT STATUS section for details.
int Utils::get_failure_status( Glib::SpawnError & e )
{
if ( e.code() == Glib::SpawnError::NOENT )
return 127;
return 126;
}
// Return shell style decoding of waitpid(2) encoded exit statuses. Return command exit
// status or 128 + signal number when terminated by a signal.
int Utils::decode_wait_status( int wait_status )
{
if ( WIFEXITED( wait_status ) )
return WEXITSTATUS( wait_status );
else if ( WIFSIGNALED( wait_status ) )
return 128 + WTERMSIG( wait_status );
// Other cases of WIFSTOPPED() and WIFCONTINUED() occur when the process is
// stopped or resumed by signals. Should be impossible as this function is only
// called after the process has exited.
std::cerr << "Unexpected wait status " << wait_status << std::endl;
return 255;
}
Glib::ustring Utils::regexp_label( const Glib::ustring & text
, const Glib::ustring & pattern
)

4
src/btrfs.cc
View File

@ -356,8 +356,8 @@ bool btrfs::resize( const Partition & partition_new, OperationDetail & operation
// but not ignoring them will cause resizing to the
// same size as part of check operation to fail.
resize_succeeded = ( exit_status == 0
|| ( btrfs_found && exit_status == 30<<8 )
|| ( ! btrfs_found && exit_status == 1<<8 )
|| ( btrfs_found && exit_status == 30 )
|| ( ! btrfs_found && exit_status == 1 )
) ;
}
set_status( operationdetail, resize_succeeded );

5
src/ext2.cc
View File

@ -240,10 +240,7 @@ bool ext2::check_repair( const Partition & partition, OperationDetail & operatio
{
exit_status = execute_command( fsck_cmd + " -f -y -v -C 0 " + partition.get_path(), operationdetail,
EXEC_CANCEL_SAFE );
//exitstatus 256 isn't documented, but it's returned when the 'FILE SYSTEM IS MODIFIED'
//this is quite normal (especially after a copy) so we let the function return true...
bool success = ( exit_status == 0 || exit_status == 1 || exit_status == 2 || exit_status == 256 );
bool success = ( exit_status == 0 || exit_status == 1 || exit_status == 2 );
set_status( operationdetail, success );
return success;
}

4
src/fat16.cc
View File

@ -128,7 +128,7 @@ FS fat16::get_filesystem_support()
void fat16::set_used_sectors( Partition & partition )
{
exit_status = Utils::execute_command( check_cmd + " -n -v " + partition .get_path(), output, error, true ) ;
if ( exit_status == 0 || exit_status == 1 || exit_status == 256 )
if ( exit_status == 0 || exit_status == 1 )
{
//total file system size in logical sectors
index = output .rfind( "\n", output .find( "sectors total" ) ) +1 ;
@ -239,7 +239,7 @@ bool fat16::check_repair( const Partition & partition, OperationDetail & operati
{
exit_status = execute_command( check_cmd + " -a -w -v " + partition .get_path(), operationdetail,
EXEC_CANCEL_SAFE );
bool success = ( exit_status == 0 || exit_status == 1 || exit_status == 256 );
bool success = ( exit_status == 0 || exit_status == 1 );
set_status( operationdetail, success );
return success;
}

2
src/ntfs.cc
View File

@ -121,7 +121,7 @@ void ntfs::set_used_sectors( Partition & partition )
{
exit_status = Utils::execute_command(
"ntfsresize --info --force --no-progress-bar " + partition .get_path(), output, error, true ) ;
if ( exit_status == 0 || exit_status == 1<<8 )
if ( exit_status == 0 || exit_status == 1 )
{
index = output .find( "Current volume size:" ) ;
if ( index >= output .length() ||

9
src/reiserfs.cc
View File

@ -176,7 +176,12 @@ bool reiserfs::resize( const Partition & partition_new, OperationDetail & operat
Glib::ustring cmd = "sh -c 'echo y | resize_reiserfs" + size + " " + partition_new .get_path() + "'" ;
exit_status = execute_command( cmd, operationdetail ) ;
bool success = ( exit_status == 0 || exit_status == 256 );
// NOTE: Neither resize_reiserfs manual page nor the following commit, which first
// added this check, indicate why exit status 1 also indicates success. Commit
// from 2006-05-23:
// 7bb7e8a84f164cd913384509a6adc3739a9d8b78
// Use ped_device_read and ped_device_write instead of 'dd' to copy
bool success = ( exit_status == 0 || exit_status == 1 );
set_status( operationdetail, success );
return success;
}
@ -185,7 +190,7 @@ bool reiserfs::check_repair( const Partition & partition, OperationDetail & oper
{
exit_status = execute_command( "reiserfsck --yes --fix-fixable --quiet " + partition.get_path(),
operationdetail, EXEC_CANCEL_SAFE );
bool success = ( exit_status == 0 || exit_status == 1 || exit_status == 256 );
bool success = ( exit_status == 0 || exit_status == 1 );
set_status( operationdetail, success );
return success;
}