diff options
| -rw-r--r-- | doc/info/bus.texinfo | 635 |
1 files changed, 631 insertions, 4 deletions
diff --git a/doc/info/bus.texinfo b/doc/info/bus.texinfo index 4c9bf51..b358ab0 100644 --- a/doc/info/bus.texinfo +++ b/doc/info/bus.texinfo @@ -904,8 +904,6 @@ int main() #include <stdlib.h> #include <string.h> -#define t(stmt) if (stmt) goto fail - static size_t pauser_count = 0; static size_t pausers_size = 0; static char* pausers = NULL; @@ -1119,7 +1117,7 @@ int main() t (bus_open(&bus, "/tmp/example-bus", BUS_RDONLY)); t (bus_poll_start(&bus)); for (;;) @{ - t(clock_gettime(CLOCK_MONOTONIC, &timeout)); + t (clock_gettime(CLOCK_MONOTONIC, &timeout)); timeout.tv_sec += 1; message = bus_poll_timed(&bus, &timeout, CLOCK_MONOTONIC); if (message == NULL) @{ @@ -1419,7 +1417,636 @@ fail: @node Daemon-dependencies @section Daemon-dependencies -TODO +This example shows how bus can be used in an init system +to provide ``aggressivly'' parallel startup of daemons. + +First of, run make to build this example. + +To start the example run @command{./init}. It will print in +red export-statement you may want to run i other terminals. +You will need to select at least one daemon, for example +you can run @code{./init d-ntp}. The available pretend +daemons are: @command{d-network}, @command{d-ntp}, and +@command{d-ssh}. + +When you are done run @command{./cleanup} with @env{BUS_INIT} +exported with the value printed by @command{./init}. + + +@subsubheading @file{./Makefile} +@example +COMMANDS = announce await-ready await-started cleanup \ + init require start-daemon test-daemon + +all: $@{COMMANDS@} +%: %.c + $@{CC@} -Wall -Wextra -pedantic -std=c99 -lbus -o $@@ $< +clean: + -rm $@{COMMANDS@} + -rm -r run + +.PHONY: all clean +@end example + + +@subsubheading @file{./announce.c} +@example +#include <bus.h> +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <unistd.h> + +#define t(stmt) if (stmt) goto fail + +static char arg[4098]; + +int main(int argc, char *argv[]) +@{ + bus_t bus; + if (argc < 3) + return fprintf(stderr, "USAGE: %s state daemon", *argv), 2; + t (bus_open(&bus, getenv("BUS_INIT"), BUS_WRONLY)); + sprintf(arg, "%ji %s %s", (intmax_t)getppid(), argv[1], argv[2]); + t (bus_write(&bus, arg, 0)); + t (bus_close(&bus)); + return 0; + +fail: + perror("announce"); + return 1; +@} +@end example + + +@subsubheading @file{./await-ready.c} +@example +#include <bus.h> +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <unistd.h> +#include <string.h> +#include <sys/wait.h> + +#define t(stmt) if (stmt) goto fail + +static char arg[4098]; +static int argc; +static char **argv; +static int remaining = 0; +static char *started = NULL; +static char msg[BUS_MEMORY_SIZE]; + +static void announce_wait(pid_t pid) +@{ + bus_t bus; + int i; + t (bus_open(&bus, getenv("BUS_INIT"), BUS_WRONLY)); + for (i = 1; i < argc; i++) @{ + if (!started[i]) @{ + sprintf(arg, "%ji awaiting-ready %s", (intmax_t)pid, argv[i]); + t (bus_write(&bus, arg, 0)); + @} + @} + t (bus_close(&bus)); + return; + +fail: + perror("await-ready"); +@} + +static int callback(const char *message, void *user_data) +@{ + int i; + char *arg2; + char *arg3; + pid_t pid; + pid_t ppid; + + if (!message) @{ + ppid = getppid(); + pid = fork(); + if (pid == 0) @{ + if (fork() == 0) + announce_wait(ppid); + exit(0); + @} else @{ + (void) waitpid(pid, NULL, 0); + /* @w{@xrm{}Let's pretend everything will go swimmingly.@xtt{}} */ + @} + return 1; + @} + + strncpy(msg, message, BUS_MEMORY_SIZE - 1); + msg[BUS_MEMORY_SIZE - 1] = 0; + + arg2 = strchr(msg, ' '); + if (!arg2) + return 1; + arg3 = strchr(++arg2, ' '); + if (!arg3) + return 1; + *arg3++ = 0; + + if (strcmp(arg2, "ready")) + return 1; + + for (i = 1; i < argc; i++) + if (!started[i] && !strcmp(argv[i], arg3)) + started[i] = 1, remaining--; + + return !!remaining; + (void) user_data; +@} + +int main(int argc_, char *argv_[]) +@{ + bus_t bus; + int i; + + argc = argc_; + argv = argv_; + + if (argc < 2) + return fprintf(stderr, "USAGE: %s daemon...", *argv), 2; + t (bus_open(&bus, getenv("BUS_INIT"), BUS_RDONLY)); + started = calloc(argc, sizeof(char)); + t (started == NULL); + + started[0] = 1; + for (i = 1; i < argc; i++) @{ + sprintf(arg, "grep '^%s$'" + " <\"$@{XDG_RUNTIME_DIR@}/ready-daemons\"" + " >/dev/null", + argv[i]); + if (!WEXITSTATUS(system(arg))) + started[i] = 1; + else + remaining++; + @} + + if (remaining) + bus_read(&bus, callback, NULL); + + bus_close(&bus); + free(started); + return 0; + +fail: + perror("await-ready"); + bus_close(&bus); + free(started); + return 1; +@} +@end example + + +@subsubheading @file{./await-started.c} +@example +#include <bus.h> +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <unistd.h> +#include <string.h> +#include <sys/wait.h> + +#define t(stmt) if (stmt) goto fail + +static char arg[4098]; +static int argc; +static char **argv; +static int remaining = 0; +static char *started = NULL; +static char msg[BUS_MEMORY_SIZE]; + +static void announce_wait(pid_t pid) +@{ + bus_t bus; + int i; + t (bus_open(&bus, getenv("BUS_INIT"), BUS_WRONLY)); + for (i = 1; i < argc; i++) @{ + if (!started[i]) @{ + sprintf(arg, "%ji awaiting-started %s", (intmax_t)pid, argv[i]); + t (bus_write(&bus, arg, 0)); + @} + @} + t (bus_close(&bus)); + return; + +fail: + perror("await-started"); +@} + +static int callback(const char *message, void *user_data) +@{ + int i; + char *arg2; + char *arg3; + pid_t pid; + pid_t ppid; + + if (!message) @{ + ppid = getppid(); + pid = fork(); + if (pid == 0) @{ + if (fork() == 0) + announce_wait(ppid); + exit(0); + @} else @{ + (void) waitpid(pid, NULL, 0); + /* @w{@xrm{}Let's pretend everything will go swimmingly.@xtt{}} */ + @} + return 1; + @} + + strncpy(msg, message, BUS_MEMORY_SIZE - 1); + msg[BUS_MEMORY_SIZE - 1] = 0; + + arg2 = strchr(msg, ' '); + if (!arg2) + return 1; + arg3 = strchr(++arg2, ' '); + if (!arg3) + return 1; + *arg3++ = 0; + + if (strcmp(arg2, "started") && strcmp(arg2, "ready")) + return 1; + + for (i = 1; i < argc; i++) + if (!started[i] && !strcmp(argv[i], arg3)) + started[i] = 1, remaining--; + + return !!remaining; + (void) user_data; +@} + +int main(int argc_, char *argv_[]) +@{ + bus_t bus; + int i; + + argc = argc_; + argv = argv_; + + if (argc < 2) + return fprintf(stderr, "USAGE: %s daemon...", *argv), 2; + t (bus_open(&bus, getenv("BUS_INIT"), BUS_RDONLY)); + started = calloc(argc, sizeof(char)); + t (started == NULL); + + started[0] = 1; + for (i = 1; i < argc; i++) @{ + sprintf(arg, "grep '^%s$'" + " <\"$@{XDG_RUNTIME_DIR@}/started-daemons\"" + " >/dev/null", + argv[i]); + if (!WEXITSTATUS(system(arg))) @{ + started[i] = 1; + @} else @{ + sprintf(arg, "grep '^%s$'" + " <\"$@{XDG_RUNTIME_DIR@}/ready-daemons\"" + " >/dev/null", + argv[i]); + if (!WEXITSTATUS(system(arg))) + started[i] = 1; + else + remaining++; + @} + @} + + if (remaining) + bus_read(&bus, callback, NULL); + + bus_close(&bus); + free(started); + return 0; + +fail: + perror("await-started"); + bus_close(&bus); + free(started); + return 1; +@} +@end example + + +@subsubheading @file{./cleanup.c} +@example +#include <bus.h> +#include <stdio.h> +#include <stdlib.h> + +#define t(stmt) if (stmt) goto fail + +int main() +@{ + char *bus_address = getenv("BUS_INIT"); + if (!bus_address || !*bus_address) @{ + fprintf(stderr, "$BUS_INIT has not been set, its export statement " + "should have been printed in bold red by ./init\n"); + return 1; + @} + t (bus_unlink(bus_address)); + return 0; + +fail: + perror("cleanup"); + return 1; +@} +@end example + + +@subsubheading @file{./d-network} +@example +#!/bin/sh +PATH=.:$PATH +d=d-network + +echo $d: starting +sleep 2 +echo $d: ready +announce ready $d +@end example + + +@subsubheading @file{./d-ntp} +@example +#!/bin/sh +PATH=.:$PATH +d=d-ntp + +require d-network +echo $d: started +announce started $d +await-ready d-network +echo $d: ready +announce ready $d +@end example + + +@subsubheading @file{./d-ssh} +@example +#!/bin/sh +PATH=.:$PATH +d=d-ssh + +require d-network +echo $d: starting +sleep 1 +echo $d: started +announce started $d +sleep 1 +echo $d: ready +announce ready $d +@end example + + +@subsubheading @file{./init.c} +@example +#include <bus.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <sys/wait.h> + +#define t(stmt) if (stmt) goto fail +#define _2(...) __VA_ARGS__, __VA_ARGS__ + +static char msg[BUS_MEMORY_SIZE]; +static int argc; +static char **argv; +static char arg[4098]; + +static void start_daemons() +@{ + int i; + for (i = 1; i < argc; i++) + if (fork() == 0) + execl("./start-daemon", "./start-daemon", argv[i], NULL); +@} + +static int callback(const char *message, void *user_data) +@{ + pid_t pid; + char *arg2; + char *arg3; + if (!message) @{ + pid = fork(); + t (pid == -1); + if (pid == 0) @{ + if (fork() == 0) @{ + start_daemons(); + @} + exit(0); + @} else @{ + (void) waitpid(pid, NULL, 0); + /* @w{@xrm{}Let's pretend everything will go swimmingly.@xtt{}} */ + @} + return 1; + @} + + strncpy(msg, message, BUS_MEMORY_SIZE - 1); + msg[BUS_MEMORY_SIZE - 1] = 0; + + pid = fork(); + t (pid == -1); + + if (pid == 0) @{ + if (fork() == 0) @{ + arg2 = strchr(msg, ' '); + if (arg2 == NULL) + exit(0); + arg3 = strchr(++arg2, ' '); + if (arg3 == NULL) + exit(0); + *arg3++ = 0; + if (!strcmp(arg2, "require")) @{ + execl(_2("./start-daemon"), arg3, NULL); + @} else if (!strcmp(arg2, "awaiting-started")) @{ + execl(_2("./test-daemon"), arg3, "started", NULL); + @} else if (!strcmp(arg2, "awaiting-ready") || + !strcmp(arg2, "awaiting")) @{ + execl(_2("./test-daemon"), arg3, "ready", NULL); + @} else if (!strcmp(arg2, "started")) @{ + sprintf(arg, + "grep '^%s\\$' < \"%s\" >/dev/null || echo %s >> \"%s\"", + _2(arg3, "$@{XDG_RUNTIME_DIR@}/started-daemons")); + execlp(_2("sh"), "-c", arg, NULL); + @} else if (!strcmp(arg2, "ready")) @{ + sprintf(arg, + "grep '^%s\\$' < \"%s\" >/dev/null || echo %s >> \"%s\"", + _2(arg3, "$@{XDG_RUNTIME_DIR@}/ready-daemons")); + execlp(_2("sh"), "-c", arg, NULL); + @} + @} + exit(0); + @} else @{ + (void) waitpid(pid, NULL, 0); + /* @w{@xrm{}Let's pretend everything will go swimmingly.@xtt{}} */ + @} + + return 1; + (void) user_data; + +fail: + perror("init"); + return -1; +@} + +int main(int argc_, char *argv_[]) +@{ + char *bus_address = NULL; + bus_t bus; + argv = argv_; + argc = argc_; + if (argc < 2) @{ + fprintf(stderr, "USAGE: %s daemon...\n", *argv); + return 1; + @} + t (setenv("XDG_RUNTIME_DIR", "./run", 1)); + /* @w{@xrm{}Real init systems with not have the period.@xtt{}} */ + system("mkdir -p -- \"$@{XDG_RUNTIME_DIR@}\""); + system("truncate -s 0 -- \"$@{XDG_RUNTIME_DIR@}/started-daemons\""); + system("truncate -s 0 -- \"$@{XDG_RUNTIME_DIR@}/ready-daemons\""); + t (bus_create(NULL, 1, &bus_address)); + fprintf(stderr, "\033[00;01;31mexport BUS_INIT=%s\033[00m\n", + bus_address); + fprintf(stderr, "\033[00;31mexport XDG_RUNTIME_DIR=./run\033[00m\n"); + t (setenv("BUS_INIT", bus_address, 1)); + t (bus_open(&bus, bus_address, BUS_RDONLY)); + t (bus_read(&bus, callback, NULL)); + bus_close(&bus); + free(bus_address); + return 0; + +fail: + perror("init"); + bus_close(&bus); + free(bus_address); + return 1; +@} +@end example + + +@subsubheading @file{./require.c} +@example +#include <bus.h> +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <unistd.h> + +#define t(stmt) if (stmt) goto fail + +static char arg[4098]; + +int main(int argc, char *argv[]) +@{ + bus_t bus; + int i; + if (argc < 2) + return fprintf(stderr, "USAGE: %s daemon...", *argv), 2; + t (bus_open(&bus, getenv("BUS_INIT"), BUS_WRONLY)); + + for (i = 1; i < argc; i++) @{ + sprintf(arg, "grep '^%s$' <\"%s\" >/dev/null", + argv[i], "$@{XDG_RUNTIME_DIR@}/started-daemons"); + if (WEXITSTATUS(system(arg))) @{ + sprintf(arg, "%ji require %s", (intmax_t)getppid(), argv[i]); + t (bus_write(&bus, arg, 0)); + @} + @} + + bus_close(&bus); + return 0; + +fail: + perror("require"); + bus_close(&bus); + return 1; +@} +@end example + + +@subsubheading @file{./start-daemon.c} +@example +#include <bus.h> +#include <stdio.h> +#include <stdlib.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +static char arg[4098]; + +int main(int argc, char *argv[]) +@{ + if (argc != 2) @{ + fprintf(stderr, "This program should be called from ./init\n"); + return 2; + @} + + sprintf(arg, "grep '^%s$' <\"%s\" >/dev/null", + argv[1], "$@{XDG_RUNTIME_DIR@}/started-daemons"); + if (!WEXITSTATUS(system(arg))) + return 0; + sprintf(arg, "grep '^%s$' <\"%s\" >/dev/null", + argv[1], "$@{XDG_RUNTIME_DIR@}/ready-daemons"); + if (!WEXITSTATUS(system(arg))) + return 0; + + sprintf(arg, "./%s", argv[1]); + execlp(arg, arg, NULL); + perror("start-daemon"); + return 1; +@} +@end example + + +@subsubheading @file{./test-daemon.c} +@example +#include <bus.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#define t(stmt) if (stmt) goto fail + +static char arg[4098]; + +int main(int argc, char *argv[]) +@{ + bus_t bus; + if (argc != 3) @{ + fprintf(stderr, "This program should be called from ./init\n"); + return 2; + @} + +retry: + sprintf(arg, "grep '^%s$'" + " <\"$@{XDG_RUNTIME_DIR@}/%s-daemons\"" + " >/dev/null", + argv[1], argv[2]); + if (!WEXITSTATUS(system(arg))) @{ + t (bus_open(&bus, getenv("BUS_INIT"), BUS_WRONLY)); + sprintf(arg, "0 %s %s", argv[2], argv[1]); + t (bus_write(&bus, arg, 0)); + bus_close(&bus); + @} else if (!strcmp(argv[2], "started")) @{ + argv[2] = "ready"; + goto retry; + @} + return 0; + +fail: + perror("test-daemon"); + return 1; +@} +@end example |