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egos.c
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egos.c
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#define _GNU_SOURCE
#define _POSIX_C_SOURCE 199309L
#include <fcntl.h>
#include <time.h>
#include <string.h>
#include <sys/types.h>
#include <sys/select.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
typedef struct state {
char *buf;
int capacity;
int pos;
int done;
} state;
int init_state(state *st) {
st->buf = malloc(16301);
if (!st->buf) {
return -1;
}
st->capacity = 16300;
st->pos = 0;
st->done = 0;
return 0;
}
int forward(char stream, int fd, state *st) {
ssize_t bytes_read, remaining;
char *start_search, *start_print;
char *ptr, *next_ptr = NULL;
struct timespec timespec;
struct tm tm;
int time_initialized = 0;
char time_buf[201];
// Position where we start searching for a newline.
// Assume the buffer currently does not contain one.
start_search = st->buf + st->pos;
// Position where we start printing. The beginning of the buffer.
start_print = st->buf;
remaining = st->capacity - st->pos;
if (remaining == 0) {
st->buf = realloc(st->buf, st->capacity * 2 + 1);
if (!st->buf) {
return -1;
}
remaining += st->capacity;
st->capacity = st->capacity * 2;
st->buf[st->capacity] = 0;
}
// Read up to remaining buffer capacity.
// Request up to 100 bytes at a time to avoid buffering of output by
// the kernel.
if (remaining > 100) {
remaining = 100;
}
bytes_read = read(fd, st->buf + st->pos, remaining);
if (bytes_read <= 0) {
st->done = 1;
return 0;
}
// Buffer position indicates the end of the data in the buffer.
st->pos += bytes_read;
for (;;) {
// Look for a newline from search start position.
ptr = (char *) memchr(start_search, '\n', st->pos - (start_search - st->buf));
if (ptr == NULL) {
break;
}
// ptr contains a newline, which is the end of our current output.
// Terminate the string.
*ptr = 0;
// Print the string. We removed the newline from the string.
if (!time_initialized) {
// TODO handle errors
clock_gettime(CLOCK_REALTIME, ×pec);
localtime_r(×pec.tv_sec, &tm);
if (!strftime(time_buf, 200, "%Y-%m-%dT%H:%M:%S", &tm)) {
return -1;
}
time_initialized = 1;
}
printf("[egos:%c %s.%06ld] %s\n", stream, time_buf, timespec.tv_nsec / 1000, start_print);
// Advance starting pointer to the beginning of next line.
start_search = start_print = next_ptr = ptr + 1;
}
if (next_ptr) {
size_t amount_to_move = st->pos - (next_ptr - st->buf);
// We printed something, move the data back in the buffer.
memmove(st->buf, next_ptr, amount_to_move);
st->pos = amount_to_move;
}
}
int main(int argc, char * const argv[]) {
pid_t pid;
va_list ap;
int status;
char *str;
int out_fds[2];
int err_fds[2];
fd_set rfds;
fd_set efds;
int rv;
state out_state, err_state;
if (argc <= 1) {
fputs("Usage: egos program-to-execute ...\n", stderr);
exit(2);
}
if (setvbuf(stdin, NULL, _IONBF, 0)) {
fputs("egos: Failed to unbuffer stdin\n", stderr);
exit(2);
}
if (setvbuf(stdout, NULL, _IONBF, 0)) {
fputs("egos: Failed to unbuffer stdout\n", stderr);
exit(2);
}
if (setvbuf(stderr, NULL, _IONBF, 0)) {
fputs("egos: Failed to unbuffer stderr\n", stderr);
exit(2);
}
if (pipe(out_fds)) {
fputs("egos: Failed to create stdout pipe\n", stderr);
exit(2);
}
if (pipe(err_fds)) {
fputs("egos: Failed to create stdout pipe\n", stderr);
exit(2);
}
pid = fork();
switch (pid) {
case -1:
perror("egos: Failed to fork child");
exit(1);
case 0:
if (dup2(out_fds[1], 1) == -1) {
fputs("egos: Failed to dup stdout\n", stderr);
exit(2);
}
close(out_fds[1]);
if (dup2(err_fds[1], 2) == -1) {
fputs("egos: Failed to dup stdout\n", stderr);
exit(2);
}
close(err_fds[1]);
execvp(argv[1], argv + 1);
puts("ok");
if (asprintf(&str, "egos: Failed to exec child: %s", argv[1]) == -1) {
fputs("egos: Out of memory\n", stderr);
exit(3);
}
perror(str);
free(str);
exit(1);
default:
close(out_fds[1]);
close(err_fds[1]);
fcntl(out_fds[0], F_SETFL, O_NONBLOCK);
fcntl(out_fds[1], F_SETFL, O_NONBLOCK);
if (init_state(&out_state) == -1) {
fputs("egos: Failed to init state\n", stderr);
exit(2);
}
if (init_state(&err_state) == -1) {
fputs("egos: Failed to init state\n", stderr);
exit(2);
}
for (;;) {
FD_ZERO(&rfds);
FD_SET(out_fds[0], &rfds);
FD_SET(err_fds[0], &rfds);
FD_ZERO(&efds);
FD_SET(out_fds[0], &efds);
FD_SET(err_fds[0], &efds);
// Assuming err_fds are larger than out_fds
rv = select(err_fds[0] + 1, &rfds, NULL, &efds, NULL);
if (rv == -1) {
perror("select");
exit(3);
} else if (rv) {
if (FD_ISSET(out_fds[0], &rfds)) {
if (forward('O', out_fds[0], &out_state) == -1) {
fputs("egos: Failed to forward output\n", stderr);
exit(3);
}
}
if (FD_ISSET(err_fds[0], &rfds)) {
if (forward('E', err_fds[0], &err_state) == -1) {
fputs("egos: Failed to forward error\n", stderr);
exit(3);
}
}
if (FD_ISSET(out_fds[0], &efds)) {
out_state.done = 1;
}
if (FD_ISSET(err_fds[0], &efds)) {
err_state.done = 1;
}
if (out_state.done && err_state.done) {
break;
}
}
}
if (out_state.pos > 0) {
out_state.buf[out_state.pos] = 0;
puts(out_state.buf);
}
if (err_state.pos > 0) {
err_state.buf[err_state.pos] = 0;
puts(err_state.buf);
}
waitpid(pid, &status, 0);
// TODO does WIFEXITED also need to be called?
exit(WEXITSTATUS(status));
}
}