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#define _POSIX_C_SOURCE 200809L
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include "collector.h"
#include "scrape.h"
#include "util.h"
#ifndef XCOLLECTORS
#define XCOLLECTORS \
X(cpu) X(diskstats) X(filesystem) X(hwmon) \
X(meminfo) X(network) X(textfile) X(uname)
#endif
#define X(c) extern const struct collector c##_collector;
XCOLLECTORS
#undef X
#define X(c) &c##_collector,
static const struct collector *collectors[] = {
XCOLLECTORS
};
#undef X
#define NCOLLECTORS (sizeof collectors / sizeof *collectors)
enum tristate { flag_off = -1, flag_undef = 0, flag_on = 1 };
struct config {
const char *port;
bool daemonize;
const char *pidfile;
};
const struct config default_config = {
.port = "9100",
.daemonize = true,
.pidfile = 0,
};
struct handler_ctx {
struct {
enum tristate enabled;
struct slist *args;
struct slist **next_arg;
void *ctx;
} collectors[NCOLLECTORS];
};
static bool parse_args(int argc, char *argv[], struct config *cfg, struct handler_ctx *ctx);
static bool initialize(struct handler_ctx *ctx, int max_args);
static bool daemonize(struct config *cfg);
static void handler(scrape_req *req, void *ctx_ptr);
int main(int argc, char *argv[]) {
struct config cfg = default_config;
struct handler_ctx ctx;
if (!parse_args(argc, argv, &cfg, &ctx))
return 1;
if (!initialize(&ctx, argc > 0 ? argc - 1 : 0))
return 1;
scrape_server *server = scrape_listen(cfg.port);
if (!server)
return 1;
if (cfg.daemonize)
if (!daemonize(&cfg))
return 1;
scrape_serve(server, handler, &ctx);
scrape_close(server);
return 0;
}
static bool parse_args(int argc, char *argv[], struct config *cfg, struct handler_ctx *ctx) {
for (size_t i = 0; i < NCOLLECTORS; i++) {
ctx->collectors[i].args = 0;
ctx->collectors[i].next_arg = &ctx->collectors[i].args;
ctx->collectors[i].enabled = flag_undef;
}
enum tristate enabled_default = flag_on;
for (int arg = 1; arg < argc; arg++) {
// check for collector arguments
for (size_t i = 0; i < NCOLLECTORS; i++) {
size_t name_len = strlen(collectors[i]->name);
if (strncmp(argv[arg], "--", 2) == 0
&& strncmp(argv[arg] + 2, collectors[i]->name, name_len) == 0
&& argv[arg][2 + name_len] == '-') {
char *carg = argv[arg] + 2 + name_len + 1;
if (strcmp(carg, "on") == 0) {
ctx->collectors[i].enabled = flag_on;
enabled_default = flag_off;
} else if (strcmp(carg, "off") == 0) {
ctx->collectors[i].enabled = flag_off;
} else if (collectors[i]->init && collectors[i]->has_args) {
ctx->collectors[i].next_arg = slist_append(ctx->collectors[i].next_arg, carg);
} else {
fprintf(stderr, "unknown argument: %s (collector %s takes no arguments)\n", argv[arg], collectors[i]->name);
return false;
}
goto next_arg;
}
}
// parse any non-collector arguments
// TODO --help
if (strncmp(argv[arg], "--port=", 7) == 0) {
cfg->port = &argv[arg][7];
goto next_arg;
} else if (strcmp(argv[arg], "--foreground") == 0) {
cfg->daemonize = false;
goto next_arg;
} else if (strncmp(argv[arg], "--pidfile=", 10) == 0) {
cfg->pidfile = &argv[arg][10];
goto next_arg;
}
fprintf(stderr, "unknown argument: %s\n", argv[arg]);
return false;
next_arg: ;
}
for (size_t i = 0; i < NCOLLECTORS; i++)
if (ctx->collectors[i].enabled == flag_undef)
ctx->collectors[i].enabled = enabled_default;
return true;
}
static bool initialize(struct handler_ctx *ctx, int max_args) {
int argc;
char *argv[max_args + 1];
for (size_t i = 0; i < NCOLLECTORS; i++) {
if (ctx->collectors[i].enabled == flag_on && collectors[i]->init) {
argc = 0;
for (struct slist *arg = ctx->collectors[i].args; arg && argc < max_args; arg = arg->next)
argv[argc++] = arg->data;
argv[argc] = 0;
ctx->collectors[i].ctx = collectors[i]->init(argc, argv);
if (!ctx->collectors[i].ctx) {
fprintf(stderr, "failed to initialize collector %s\n", collectors[i]->name);
return false;
}
}
}
return true;
}
static bool daemonize(struct config *cfg) {
pid_t pid;
pid = fork();
if (pid == -1) {
perror("fork");
return false;
}
if (pid > 0) {
// in the parent, verify the intermediate process exits successfully
int status;
if (waitpid(pid, &status, 0) == -1) {
perror("waitpid(daemon)");
exit(1);
}
if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
fprintf(stderr, "daemonized process exited unexpectedly: %x\n", status);
exit(1);
}
exit(0);
}
// in the intermediate process, prepare for daemon life and fork again
if (setsid() == -1) {
perror("setsid");
exit(1);
}
close(0);
close(1);
close(2);
pid = fork();
if (pid == -1)
exit(2);
else if (pid > 0)
exit(0); // lets the parent know all is well
// attempt to record the grandchild PID, if asked to
if (cfg->pidfile) {
FILE *f = fopen(cfg->pidfile, "w");
if (f) {
fprintf(f, "%ld\n", (long) getpid());
fclose(f);
}
}
return true;
}
static void handler(scrape_req *req, void *ctx_ptr) {
struct handler_ctx *ctx = ctx_ptr;
for (size_t c = 0; c < NCOLLECTORS; c++) {
if (ctx->collectors[c].enabled == flag_on)
collectors[c]->collect(req, ctx->collectors[c].ctx);
}
}
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