caps-printer-process.c File Reference

Process Management to start a printing provider/printer driver. More...

Functions
static void	sanitize_string (char *string)
static char **	create_default_argv (size_t *cnt)
static char **	spread_options (char *options, size_t *cnt)
static void	caps_prn_add_base_options (char **argv, const char *executable, const char *descr_ini, const char *param)
static int	caps_prn_exec (const char *executable, const char *descr_ini, const char *param_dir, const char *options)
int	caps_prn_launch_printer_provider (const char *descr_ini, const char *param_dir)

Detailed Description

Copyright

GNU Lesser General Public License 2.1

Author

Jürgen Borleis

Warning

Use as experimental

Function Documentation

sanitize_string()

static void sanitize_string ( char *  string )

static

Sanitize a string in place

Parameters

[in,out]

string

The string to sanitize

Sanitizing means

• no leading whitespace
• only one whitespace at a time
• no trailing whitespaces

create_default_argv()

static char ** create_default_argv ( size_t *  cnt )

static

Create the default required argv array

Parameters

[out]

cnt

Element count in the returned array

Returns

Pointer to the array

Three elements are required for the executable name and two additional fixed options. The last element in the array must be NULL to terminate the array according to the execv() man page

Note

This function does not return in case of memory failure

spread_options()

static char ** spread_options ( char *  options, size_t *  cnt  )

static

Re-facture the options into an array of string

Parameters

[in]	options	Free options text
[in]	cnt	Count of elements in the returned array

Returns

Array to be used for the printer driver's option list

Additional options are added beginning with element four in the argv array, since the first three elements have a fixed meaning. While at it, already reserved option keywords are sorted out.

Already reserved option keywords are (refer caps_pp_instance_runtime_prepare()):

• –driver-ini=<name> / -s <name>
• –parameter-dir=<name> / -d <name>

Note

The array has at least a size of three for: prog name, the features INI and the parameter directory

Does not return in case or memory failure

Todo:

spread_options() still needs to sort out invalid options for the printer driver

caps_prn_add_base_options()

static void caps_prn_add_base_options ( char **  argv, const char *  executable, const char *  descr_ini, const char *  param  )

static

Insert the base argv options

Parameters

[out]	argv	The string pointer array with at least 4 elements
[in]	executable	The executable string. Name only, no path component!
[in]	descr_ini	The driver INI file name. Name only, no path component! (can be NULL)
[in]	param	The device parameter directory name. Name only, no path component

execv() expects the executable name as argv[0]

Precondition

At least three entries are expected in argv

caps_prn_exec()

static int caps_prn_exec ( const char *  executable, const char *  descr_ini, const char *  param_dir, const char *  options  )

static

Execute a program and forward some fixed and some free options to it

Parameters

[in]	executable	Printer driver executable name (no path!)
[in]	descr_ini	Filename of the driver corresponding driver INI file (no path!)
[in]	param_dir	Directory name of the corresponding device parameter directory (no path!)
[in]	options	Free option text to be forwarded to the printer driver (can be NULL)

Return values

nothing	In case of success it does not return
negative	-errno else

Note

The options text can contain whitespaces (e.g. can contain more than one option)

Terminates the process in case of memory failure

Precondition

The driver expects an open file descriptor "3" for printer access

Todo:

Replace the process's name by the printer driver from the journald point of view. Else, the printer driver is still 'caps-printer' in the journal.

Clean up the environment and use execve() to launch the driver executable

caps_prn_launch_printer_provider()

int caps_prn_launch_printer_provider	(	const char *	descr_ini,
		const char *	param_dir
	)

Launch a printing provider

Parameters

[in]	descr_ini	Printing provider's description INI file (file name only)
[in]	param_dir	Parameter directory for this device (directory name only)

Return values

0	On success
negative	-errno else

File descriptors:

• 0 stdin is closed
• 1 stdout
• 2 stderr
• 3 Line printer device node

Keep stdout and stderr open, the filedescriptor to the printer device node as well.

Calls the printer driver as:

</path/to/caps/exec/dir>/<drivername> --driver-ini=<driverdefault.ini> --parameter-dir=<parameterdir>

These specific options are expected when the printing provider uses libcapsprovider.