On Friday 28 March 2008 08:55, Michele Sanges wrote:
>
> Il giorno gio, 27/03/2008 alle 17.28 +0100, Denys Vlasenko ha scritto:
> > O_NONBLOCK does not matter one iota if you reached EOF.
> > read() will return 0 immediately, it will not block.
> >
> > Your code is hogging CPU, since your read() sits in a while (1) loop.
>
> + while(1) {
> + int nVal;
> +
> + len = read(fd, buf, 255);
> + printf("after reading\n");
> + if (len == -1) {
> + DEBUG_MESSAGE("error reading the fifo");
> + break;
> + }
> + }
>
> Can you tell me why I see the printf string only when I send a command
> to the applet?
I don't know. You need to give more complete description of what you are doing.
Here is my description:
First, I modify fbsplash.c so that it doesn't really use fb device,
for ease of experiment, and also add a few debug prints.
See modified file in attachment. Basically:
while ((num_buf = xmalloc_fgetline(fp)) != NULL) {
bb_error_msg("got '%s'", num_buf);
if (strncmp(num_buf, "exit", 4) == 0) {
...
}
free(num_buf);
}
// We got EOF/error on fp
if (ferror(fp))
goto exit_cmd;
// TESTING: will read block?
{ static char b; read(fileno(fp), &b, 1); }
bb_error_msg("got EOF");
continue;
We are getting NULL from xmalloc_fgetline() when read() inside it
returns 0. Added "continue" makes it to not exit in this case
(this is what your code does - it doesn't exit on zero bytes read).
Now, I start fbsplash like this:
mkfifo /tmp/fbsplash.fifo
./busybox fbsplash -s qwe -f /tmp/fbsplash.fifo
and then in another xterm I run this sh script:
{
echo 11
sleep 1
echo 22
sleep 1
} >/tmp/fbsplash.fifo
echo 33 >/tmp/fbsplash.fifo
sleep 1
echo 44 >/tmp/fbsplash.fifo
sleep 1
echo exit >/tmp/fbsplash.fifo
In first xterm I see:
./busybox fbsplash -s qwe -f /tmp/fbsplash.fifo
fbsplash: got '11'
fbsplash: got '22'
fbsplash: got EOF
fbsplash: got EOF
fbsplash: got EOF
fbsplash: got EOF <===== repeats forever
...
Same experiment with strace added, so the result of test read
is visible:
strace -tt -o str.log ./busybox fbsplash -s qwe -f /tmp/fbsplash.fifo
str.log contains this:
11:40:03.193114 open("/tmp/fbsplash.fifo", O_RDONLY|O_LARGEFILE) = 3
11:40:05.743811 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xff993954) = -1 EINVAL
(Invalid argument)
11:40:05.743942 read(3, "11\n", 1024) = 3
11:40:05.761084 write(2, "fbsplash: got \'11\'\n", 19) = 19
11:40:05.761209 read(3, "22\n", 1024) = 3
11:40:06.762729 write(2, "fbsplash: got \'22\'\n", 19) = 19
11:40:06.762861 read(3, "33\n", 1024) = 3
11:40:07.763125 write(2, "fbsplash: got \'33\'\n", 19) = 19
11:40:07.763242 read(3, "", 1024) = 0
11:40:07.763334 read(3, "", 1) = 0
11:40:07.763425 write(2, "fbsplash: got EOF\n", 18) = 18
11:40:07.763531 read(3, "", 1) = 0
11:40:07.763622 write(2, "fbsplash: got EOF\n", 18) = 18
11:40:07.763721 read(3, "", 1) = 0
11:40:07.763812 write(2, "fbsplash: got EOF\n", 18) = 18
11:40:07.763915 read(3, "", 1) = 0
11:40:07.764006 write(2, "fbsplash: got EOF\n", 18) = 18
11:40:07.764105 read(3, "", 1) = 0
11:40:07.764196 write(2, "fbsplash: got EOF\n", 18) = 18
11:40:07.764294 read(3, "", 1) = 0
11:40:07.764385 write(2, "fbsplash: got EOF\n", 18) = 18
11:40:07.764483 read(3, "", 1) = 0
11:40:07.764574 write(2, "fbsplash: got EOF\n", 18) = 18
11:40:07.764672 read(3, "", 1) = 0
11:40:07.764763 write(2, "fbsplash: got EOF\n", 18) = 18
....
See? As soon as this block finished:
{
echo 11
sleep 1
echo 22
sleep 1
} >/tmp/fbsplash.fifo
and /tmp/fbsplash.fifo is closed on input side, reads
on output side do not block anymore, they return 0
immediately.
Hope it's clearer now.
--
vda
/* vi: set sw=4 ts=4: */
/*
* Copyright (C) 2008 Michele Sanges <[EMAIL PROTECTED]>,
* <[EMAIL PROTECTED]>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*
* Usage:
* - use kernel option 'vga=xxx' or otherwise enable framebuffer device.
* - put somewhere fbsplash.cfg file and an image in .ppm format.
* - run applet: $ setsid fbsplash [params] &
* -c: hide cursor
* -d /dev/fbN: framebuffer device (if not /dev/fb0)
* -s path_to_image_file (can be "-" for stdin)
* -i path_to_cfg_file
* -f path_to_fifo (can be "-" for stdin)
* - if you want to run it only in presence of a kernel parameter
* (for example fbsplash=on), use:
* grep -q "fbsplash=on" </proc/cmdline && setsid fbsplash [params]
* - commands for fifo:
* "NN" (ASCII decimal number) - percentage to show on progress bar.
* "exit" (or just close fifo) - well you guessed it.
*/
#include "libbb.h"
#include <linux/fb.h>
/* If you want logging messages on /tmp/fbsplash.log... */
#define DEBUG 0
#define BYTES_PER_PIXEL 2
typedef unsigned short DATA;
struct globals {
#if DEBUG
bool bdebug_messages; // enable/disable logging
FILE *logfile_fd; // log file
#endif
unsigned char *addr; // pointer to framebuffer memory
unsigned nbar_width; // progress bar width
unsigned nbar_height; // progress bar height
unsigned nbar_posx; // progress bar horizontal position
unsigned nbar_posy; // progress bar vertical position
unsigned char nbar_colr; // progress bar color red component
unsigned char nbar_colg; // progress bar color green component
unsigned char nbar_colb; // progress bar color blue component
const char *image_filename;
struct fb_var_screeninfo scr_var;
struct fb_fix_screeninfo scr_fix;
};
#define G (*ptr_to_globals)
#define INIT_G() \
do { \
SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
} while (0)
#if DEBUG
#define DEBUG_MESSAGE(strMessage, args...) \
if (G.bdebug_messages) { \
fprintf(G.logfile_fd, "[%s][%s] - %s\n", \
__FILE__, __FUNCTION__, strMessage); \
}
#else
#define DEBUG_MESSAGE(...) ((void)0)
#endif
/**
* Open and initialize the framebuffer device
* \param *strfb_device pointer to framebuffer device
*/
static void fb_open(const char *strfb_device)
{
int fbfd = xopen(strfb_device, O_RDWR);
// framebuffer properties
xioctl(fbfd, FBIOGET_VSCREENINFO, &G.scr_var);
xioctl(fbfd, FBIOGET_FSCREENINFO, &G.scr_fix);
if (G.scr_var.bits_per_pixel != 16)
bb_error_msg_and_die("only 16 bpp is supported");
// map the device in memory
G.addr = mmap(NULL,
G.scr_var.xres * G.scr_var.yres
* BYTES_PER_PIXEL /*(G.scr_var.bits_per_pixel / 8)*/ ,
PROT_WRITE, MAP_SHARED, fbfd, 0);
if (G.addr == MAP_FAILED)
bb_perror_msg_and_die("can't mmap %s", strfb_device);
close(fbfd);
}
/**
* Draw hollow rectangle on framebuffer
* \param nx1pos,ny1pos upper left position
* \param nx2pos,ny2pos down right position
* \param nred,ngreen,nblue rgb color
*/
static void fb_drawrectangle(int nx1pos, int ny1pos, int nx2pos, int ny2pos,
unsigned char nred, unsigned char ngreen, unsigned char nblue)
{
int cnt;
DATA thispix;
DATA *ptr1, *ptr2;
nred >>= 3; // 5-bit red
ngreen >>= 2; // 6-bit green
nblue >>= 3; // 5-bit blue
thispix = nblue + (ngreen << 5) + (nred << (5+6));
// horizontal lines
ptr1 = (DATA*)(G.addr + (ny1pos * G.scr_var.xres + nx1pos) * BYTES_PER_PIXEL);
ptr2 = (DATA*)(G.addr + (ny2pos * G.scr_var.xres + nx1pos) * BYTES_PER_PIXEL);
cnt = nx2pos - nx1pos;
do {
*ptr1++ = thispix;
*ptr2++ = thispix;
} while (--cnt >= 0);
// vertical lines
ptr1 = (DATA*)(G.addr + (ny1pos * G.scr_var.xres + nx1pos) * BYTES_PER_PIXEL);
ptr2 = (DATA*)(G.addr + (ny1pos * G.scr_var.xres + nx2pos) * BYTES_PER_PIXEL);
cnt = ny2pos - ny1pos;
do {
*ptr1 = thispix; ptr1 += G.scr_var.xres;
*ptr2 = thispix; ptr2 += G.scr_var.xres;
} while (--cnt >= 0);
}
/**
* Draw filled rectangle on framebuffer
* \param nx1pos,ny1pos upper left position
* \param nx2pos,ny2pos down right position
* \param nred,ngreen,nblue rgb color
*/
static void fb_drawfullrectangle(int nx1pos, int ny1pos, int nx2pos, int ny2pos,
unsigned char nred, unsigned char ngreen, unsigned char nblue)
{
int cnt1, cnt2, nypos;
DATA thispix;
DATA *ptr;
nred >>= 3; // 5-bit red
ngreen >>= 2; // 6-bit green
nblue >>= 3; // 5-bit blue
thispix = nblue + (ngreen << 5) + (nred << (5+6));
cnt1 = ny2pos - ny1pos;
nypos = ny1pos;
do {
ptr = (DATA*)(G.addr + (nypos * G.scr_var.xres + nx1pos) * BYTES_PER_PIXEL);
cnt2 = nx2pos - nx1pos;
do {
*ptr++ = thispix;
} while (--cnt2 >= 0);
nypos++;
} while (--cnt1 >= 0);
}
/**
* Draw a progress bar on framebuffer
* \param percent percentage of loading
*/
static void fb_drawprogressbar(unsigned percent)
{
int i, left_x, top_y, width, height;
// outer box
left_x = G.nbar_posx;
top_y = G.nbar_posy;
width = G.nbar_width - 1;
height = G.nbar_height - 1;
if ((height | width) < 0)
return;
// NB: "width" of 1 actually makes rect with width of 2!
fb_drawrectangle(
left_x, top_y,
left_x + width, top_y + height,
G.nbar_colr/2, G.nbar_colg/2, G.nbar_colb/2);
// inner "empty" rectangle
left_x++;
top_y++;
width -= 2;
height -= 2;
if ((height | width) < 0)
return;
fb_drawfullrectangle(
left_x, top_y,
left_x + width, top_y + height,
G.nbar_colr, G.nbar_colg, G.nbar_colb);
if (percent > 0) {
// actual progress bar
width = width * percent / 100;
i = height;
if (height == 0)
height++; // divide by 0 is bad
while (i >= 0) {
// draw one-line thick "rectangle"
// top line will have gray lvl 200, bottom one 100
unsigned gray_level = 100 + i*100/height;
fb_drawfullrectangle(
left_x, top_y, left_x + width, top_y,
gray_level, gray_level, gray_level);
top_y++;
i--;
}
}
}
/**
* Draw image from PPM file
*/
static void fb_drawimage(void)
{
char head[256];
char s[80];
FILE *theme_file;
unsigned char *pixline;
unsigned i, j, width, height, line_size;
memset(head, 0, sizeof(head));
theme_file = xfopen_stdin(G.image_filename);
// parse ppm header
while (1) {
if (fgets(s, sizeof(s), theme_file) == NULL)
bb_error_msg_and_die("bad PPM file '%s'", G.image_filename);
if (s[0] == '#')
continue;
if (strlen(head) + strlen(s) >= sizeof(head))
bb_error_msg_and_die("bad PPM file '%s'", G.image_filename);
strcat(head, s);
if (head[0] != 'P' || head[1] != '6')
bb_error_msg_and_die("bad PPM file '%s'", G.image_filename);
// width, height, max_color_val
if (sscanf(head, "P6 %u %u %u", &width, &height, &i) == 3)
break;
// TODO: i must be <= 255!
}
line_size = width*3;
if (width > G.scr_var.xres)
width = G.scr_var.xres;
if (height > G.scr_var.yres)
height = G.scr_var.yres;
pixline = xmalloc(line_size);
for (j = 0; j < height; j++) {
unsigned char *pixel = pixline;
DATA *src = (DATA *)(G.addr + j * G.scr_fix.line_length);
if (fread(pixline, 1, line_size, theme_file) != line_size)
bb_error_msg_and_die("bad PPM file '%s'", G.image_filename);
for (i = 0; i < width; i++) {
unsigned thispix;
thispix = (((unsigned)pixel[0] << 8) & 0xf800)
| (((unsigned)pixel[1] << 3) & 0x07e0)
| (((unsigned)pixel[2] >> 3));
*src++ = thispix;
pixel += 3;
}
}
free(pixline);
fclose(theme_file);
}
/**
* Parse configuration file
*/
static void init(const char *ini_filename)
{
static const char const param_names[] ALIGN1 =
"BAR_LEFT\0" "BAR_TOP\0"
"BAR_WIDTH\0" "BAR_HEIGHT\0"
"BAR_R\0" "BAR_G\0" "BAR_B\0"
#if DEBUG
"DEBUG\0"
#endif
;
FILE *inifile;
char *buf;
inifile = xfopen_stdin(ini_filename);
while ((buf = xmalloc_fgetline(inifile)) != NULL) {
char *value_str;
int val;
if (*buf == '#') { // it's a comment
free(buf);
continue;
}
value_str = strchr(buf, '=');
if (!value_str)
goto err;
*value_str++ = '\0';
val = xatoi_u(value_str);
switch (index_in_strings(param_names, buf)) {
case 0:
// progress bar horizontal position
G.nbar_posx = val;
break;
case 1:
// progress bar vertical position
G.nbar_posy = val;
break;
case 2:
// progress bar width
G.nbar_width = val;
break;
case 3:
// progress bar height
G.nbar_height = val;
break;
case 4:
// progress bar color - red component
G.nbar_colr = val;
break;
case 5:
// progress bar color - green component
G.nbar_colg = val;
break;
case 6:
// progress bar color - blue component
G.nbar_colb = val;
break;
#if DEBUG
case 7:
G.bdebug_messages = val;
if (G.bdebug_messages)
G.logfile_fd = xfopen("/tmp/fbsplash.log", "w");
break;
#endif
err:
default:
bb_error_msg_and_die("syntax error: '%s'", buf);
}
free(buf);
}
fclose(inifile);
}
int fbsplash_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int fbsplash_main(int argc ATTRIBUTE_UNUSED, char **argv)
{
const char *fb_device, *ini_filename, *fifo_filename;
FILE *fp = fp; // for compiler
bool bCursorOff;
INIT_G();
// parse command line options
fb_device = "/dev/fb0";
ini_filename = NULL;
fifo_filename = NULL;
bCursorOff = 1 & getopt32(argv, "cs:d:i:f:",
&G.image_filename, &fb_device, &ini_filename, &fifo_filename);
// parse configuration file
if (ini_filename)
init(ini_filename);
// We must have -s IMG
if (!G.image_filename)
bb_show_usage();
if (fifo_filename)
fp = xfopen_stdin(fifo_filename);
if(0) fb_open(fb_device);
if (fifo_filename && bCursorOff) {
// hide cursor (BEFORE any fb ops)
full_write(STDOUT_FILENO, "\x1b" "[?25l", 6);
}
if(0) fb_drawimage();
if (fifo_filename) while (1) {
struct stat statbuf;
unsigned num;
char *num_buf;
if(0) fb_drawprogressbar(0);
// Block on read, waiting for some input.
// Use of <stdio.h> style I/O allows to correctly
// handle a case when we have many buffered lines
// already in the pipe
while ((num_buf = xmalloc_fgetline(fp)) != NULL) {
bb_error_msg("got '%s'", num_buf);
if (strncmp(num_buf, "exit", 4) == 0) {
DEBUG_MESSAGE("exit");
exit_cmd:
if (bCursorOff) {
// restore cursor
full_write(STDOUT_FILENO, "\x1b" "[?25h", 6);
}
return EXIT_SUCCESS;
}
num = atoi(num_buf);
if (isdigit(num_buf[0]) && (num <= 100)) {
#if DEBUG
char strVal[10];
sprintf(strVal, "%d", num);
DEBUG_MESSAGE(strVal);
#endif
if(0) fb_drawprogressbar(num);
}
free(num_buf);
}
// We got EOF/error on fp
if (ferror(fp))
goto exit_cmd;
// TESTING: will read block?
{ static char b; read(fileno(fp), &b, 1); }
bb_error_msg("got EOF");
continue;
fclose(fp);
if (LONE_DASH(fifo_filename)
|| stat(fifo_filename, &statbuf) != 0
|| !S_ISFIFO(statbuf.st_mode)
) {
goto exit_cmd;
}
// It's really a named pipe!
// For named pipes, we want to support this:
// mkfifo cmd_pipe
// fbsplash -f cmd_pipe .... &
// ...
// echo 33 >cmd_pipe
// ...
// echo 66 >cmd_pipe
// This means that on EOF, we need to close/open cmd_pipe
// (just reading again works too, but it hogs CPU)
fp = xfopen_stdin(fifo_filename); // blocks on open
} // end of while (1)
return EXIT_SUCCESS;
}
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