DPV(3) FreeBSD Library Functions Manual DPV(3)
NAME
dpv - dialog progress view library
LIBRARY
library "libdpv"
SYNOPSIS
#include <dpv.h>
int
dpv(struct dpv_config *config, struct dpv_file_node *file_list);
void
dpv_free(void);
DESCRIPTION
The dpv library provides an interface for creating complex "gauge"
widgets for displaying progress on various actions. The dpv library can
display progress with one of dialog(3), dialog(1), or Xdialog(1)
(x11/xdialog from the ports tree).
The dpv() config argument properties for configuring global display
features:
struct dpv_config {
uint8_t keep_tite; /* Cleaner exit for scripts */
enum dpv_display display_type; /* Def. DPV_DISPLAY_LIBDIALOG */
enum dpv_output output_type; /* Default DPV_OUTPUT_NONE */
int debug; /* Enable debug on stderr */
int display_limit; /* Files/page. Default -1 */
int label_size; /* Label size. Default 28 */
int pbar_size; /* Mini-progress size */
int dialog_updates_per_second; /* Default 16 */
int status_updates_per_second; /* Default 2 */
uint16_t options; /* Default 0 (none) */
char *title; /* Widget title */
char *backtitle; /* Widget backtitle */
char *aprompt; /* Append. Default NULL */
char *pprompt; /* Prefix. Default NULL */
char *msg_done; /* Default `Done' */
char *msg_fail; /* Default `Fail' */
char *msg_pending; /* Default `Pending' */
char *output; /* Output format string */
const char *status_solo; /* dialog(3) solo-status format.
* Default DPV_STATUS_SOLO */
const char *status_many; /* dialog(3) many-status format.
* Default DPV_STATUS_MANY */
/*
* Function pointer; action to perform data transfer
*/
int (*action)(struct dpv_file_node *file, int out);)(struct dpv_file_node *file, int out);
};
enum dpv_display {
DPV_DISPLAY_LIBDIALOG = 0, /* Use dialog(3) (default) */
DPV_DISPLAY_STDOUT, /* Use stdout */
DPV_DISPLAY_DIALOG, /* Use spawned dialog(1) */
DPV_DISPLAY_XDIALOG, /* Use spawned Xdialog(1) */
};
enum dpv_output {
DPV_OUTPUT_NONE = 0, /* No output (default) */
DPV_OUTPUT_FILE, /* Read `output' member as file path */
DPV_OUTPUT_SHELL, /* Read `output' member as shell cmd */
};
The options member of the dpv() config argument is a mask of bit fields
indicating various processing options. Possible flags are:
DPV_TEST_MODE Enable test mode. In test mode, the action() callback of
the config argument is not called but instead simulated-
data is used to drive progress. Appends "[TEST MODE]" to
the status line (to override, set the status_format
member of the dpv() config argument; for example, to
DPV_STATUS_DEFAULT).
DPV_WIDE_MODE Enable wide mode. In wide mode, the length of the
aprompt and pprompt members of the dpv() config argument
will bump the width of the gauge widget. Prompts wider
than the maximum width will wrap (unless using
Xdialog(1); see BUGS section below).
DPV_NO_LABELS Disables the display of labels associated with each
transfer (label_size member of dpv() config argument is
ignored).
DPV_USE_COLOR Force the use of color even if the display_type does not
support color (USE_COLOR environment variable is
ignored).
DPV_NO_OVERRUN When enabled, callbacks for the current dpv_file_node are
terminated when action() returns 100 or greater
(alleviates the need to change the status of the current
dpv_file_node but may also cause file truncation if the
stream exceeds expected length).
The file_list argument to dpv() is a pointer to a "linked-list",
described in <dpv.h>:
struct dpv_file_node {
enum dpv_status status; /* status of read operation */
char *msg; /* display instead of "Done/Fail" */
char *name; /* name of file to read */
char *path; /* path to file */
long long length; /* expected size */
long long read; /* number units read (e.g., bytes) */
struct dpv_file_node *next;/* pointer to next (end with NULL) */
};
For each of the items in the file_list "linked-list" argument, the
action() callback member of the dpv() config argument is called. The
action() function performs a "nominal" action on the file and return.
The return value of int represents the current progress percentage
(0-100) for the current file.
The action() callback provides two variables for each call. file
provides a reference to the current dpv_file_node being processed. out
provides a file descriptor where the data goes.
If the output member of the dpv() config argument was set to
DPV_OUTPUT_NONE (default; when invoking dpv()), the out file descriptor
of action() will be zero and can be ignored. If output was set to
DPV_OUTPUT_FILE, out will be an open file descriptor to a file. If
output was set to DPV_OUTPUT_SHELL, out will be an open file descriptor
to a pipe for a spawned shell program. When out is greater than zero,
write data that has been read back to out.
To abort dpv(), either from the action() callback or asynchronously from
a signal handler, two globals are provided via <dpv.h>:
extern int dpv_interrupt; /* Set to TRUE in interrupt handler */
extern int dpv_abort; /* Set to true in callback to abort */
These globals are not automatically reset and must be manually
maintained. Do not forget to reset these globals before subsequent
invocations of dpv() when making multiple calls from the same program.
In addition, the status member of the action() file argument can be used
to control callbacks for the current file. The status member can be set
to any of the below from <dpv.h>:
enum dpv_status {
DPV_STATUS_RUNNING = 0, /* Running (default) */
DPV_STATUS_DONE, /* Completed */
DPV_STATUS_FAILED, /* Oops, something went wrong */
};
The default status is zero, DPV_STATUS_RUNNING, which keeps the callbacks
coming for the current file(). Setting `file->status' to anything other
than DPV_STATUS_RUNNING will cause dpv() to loop to the next file,
effecting the next callback, if any.
The action() callback is responsible for calculating percentages and
(recommended) maintaining a dpv global counter so dpv() can display
throughput statistics. Percentages are reported through the int return
value of the action() callback. Throughput statistics are calculated
from the below global int in <dpv.h>:
extern int dpv_overall_read;
Set this to the number of bytes that have been read for all files.
Throughput information is displayed in the status line (only available
when using dialog(3)) at the bottom of the screen. See
DPV_DISPLAY_LIBDIALOG above.
Note that dpv_overall_read does not have to represent bytes. For
example, the status_format can be changed to display something other than
"bytes" and increment dpv_overall_read accordingly (for example, counting
lines).
When dpv() is processing the current file, the length and read members of
the action() file argument are used for calculating the display of mini
progress bars (if enabled; see pbar_size above). If the length member of
the current file is less than zero (indicating an unknown file length), a
humanize_number(3) version of the read member is used instead of a
traditional progress bar. Otherwise a progress bar is calculated as
percentage read to file length. action() callback must maintain these
member values for mini-progress bars.
The dpv_free() function performs free(3) on private global variables
initialized by dpv().
ENVIRONMENT
The below environment variables are referenced by dpv:
DIALOG Override command string used to launch dialog(1) (requires
DPV_DISPLAY_DIALOG) or Xdialog(1) (requires
DPV_DISPLAY_XDIALOG); default is either `dialog' (for
DPV_DISPLAY_DIALOG) or `Xdialog' (for
DPV_DISPLAY_XDIALOG).
DIALOGRC If set and non-NULL, path to `.dialogrc' file.
HOME If `$DIALOGRC' is either not set or NULL, used as a prefix
to `.dialogrc' (that is, `$HOME/.dialogrc').
USE_COLOR If set and NULL, disables the use of color when using
dialog(1) (does not apply to Xdialog(1)).
msg_done msg_fail msg_pending
Internationalization strings for overriding the default
English strings `Done', `Fail', and `Pending'
respectively. To prevent their usage, explicitly set the
msg_done, msg_fail, and msg_pending members of dpv()
config argument to default macros (DPV_DONE_DEFAULT,
DPV_FAIL_DEFAULT, and DPV_PENDING_DEFAULT) or desired
values.
FILES
$HOME/.dialogrc
SEE ALSO
dialog(1), Xdialog(1), dialog(3)
HISTORY
The dpv library first appeared in FreeBSD 10.2.
AUTHORS
Devin Teske <dteske@FreeBSD.org>
BUGS
Xdialog(1), when given both `--title title' (see above `title' member of
struct dpv_config) and `--backtitle backtitle' (see above `backtitle'
member of struct dpv_config), displays the backtitle in place of the
title and vice-versa.
Xdialog(1) does not wrap long prompt texts received after initial launch.
This is a known issue with the `--gauge' widget in Xdialog(1). Embed
escaped newlines within prompt text to force line breaks.
dialog(1) does not display the first character after a series of escaped
escape-sequences (for example, ``\\n'' produces ``\'' instead of ``\n'').
This is a known issue with dialog(1) and does not affect dialog(3) or
Xdialog(1).
If an application ignores USE_COLOR when set and NULL before calling
dpv() with color escape sequences anyway, dialog(3) and dialog(1) may not
render properly. Workaround is to detect when USE_COLOR is set and NULL
and either not use color escape sequences at that time or use unsetenv(3)
to unset USE_COLOR, forcing interpretation of color sequences. This does
not effect Xdialog(1), which renders the color escape sequences as plain
text. See "embedded "\Z" sequences" in dialog(1) for additional
information.
FreeBSD 13.1-RELEASE-p6 March 13, 2018 FreeBSD 13.1-RELEASE-p6
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