fpmake.c

#!/usr/bin/tcc -run
/*
 * ^^ If you don't know tcc, you should.
 *
 * This program is a wrapper around make(1), it parses recursive make
 * output and try to generate valid pathnames for errors generated by
 * the compiler for relative pathnames.
 * It keep tracks (well it tries to) of parallel make jobs and try to
 * look in the directory for all the running jobs for a matching
 * pathnames, then doctor the error message with the 'real' pathname.
 *
 * This was made to go around stuff like Visual Studio Code
 * and KDE's Kate not being able to parse recursive make messages.
 *
 * (C) 2020 Michel Pollet <buserror@gmail.com>
 * MIT Licence
 */
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <unistd.h>
#include <strings.h>
#include <string.h>
#include <poll.h>
#include <regex.h>

struct stream_t {
	uint8_t buf[128 * 1024];
	size_t len;
};
#define AS(__a) ((sizeof(__a) / sizeof((__a)[0])))

struct {
	char dir[4096];
	int idx;
} current_pwd[32];
int max_pwd = -1;
int debug = 0;

/*
 * Use make(1) 'Entering/leaving' directory messages to populate a
 * table of running sub-makes; that's pretty much it really
 */
static void
process_stdout(
	const char * line)
{
	static bool init = false;
	static regex_t r_make, r_emake;

	// we don't doctor the normal output, might as well plonk it out now
	fprintf(stdout, "%s\n", line);
	if (!init) {
		if (regcomp(&r_make,
				"^make\\[([0-9]+)\\]: Entering directory '(.*)'",
				REG_EXTENDED))
			perror("r_make");
		if (regcomp(&r_emake,
				"^make\\[([0-9]+)\\]: Leaving directory '(.*)'",
				REG_EXTENDED))
			perror("r_emake");
		init = true;
	}
	regmatch_t m[4];
	if (regexec(&r_make, line, AS(m), m, 0) == 0) {	// add  entry
		int idx = atoi(line + m[1].rm_so);
		if (idx < 0 || idx >= AS(current_pwd)) {
			printf("fpmake: make directory index overflow: %d!!\n", idx);
			return;
		}
		current_pwd[idx].idx = idx;
		snprintf(current_pwd[idx].dir, sizeof(current_pwd[idx].dir),
					"%.*s", m[2].rm_eo - m[2].rm_so, line + m[2].rm_so);
		if (idx > max_pwd)
			max_pwd = idx;
		if (debug)
			printf(" >> Entering IDX = %d/%d, '%s'\n",
				idx, max_pwd, current_pwd[idx].dir);
	} else if (regexec(&r_emake, line, AS(m), m, 0) == 0) { // clear it
		int idx = atoi(line + m[1].rm_so);
		current_pwd[idx].idx = -1;
		if (debug)
			printf("    << Leaving %d/%d '%s'\n", idx, max_pwd,
					current_pwd[idx].dir);
		// update max_pwd if appropriate
		if (idx == max_pwd) {
			while (current_pwd[max_pwd].idx == -1)
				max_pwd--;
		}
	}
}

/*
 * If an error line arrives, try to find some sort of
 * <relative pathname>:<line number> pattern in there.
 * If found, look in all the open sub-make jobs directory for an
 * existing file, and doctor the line with THAT path before output.
 * Of course, there's lots of potential issues in there, like similarly
 * named files in multiple directories etc but hey. Better that than
 * nothing at all.
 */
static void
process_stderr(
	const char * line)
{
	static bool init = false;
	static regex_t r_info, r_error;

//	fprintf(stderr, "ERR: %s\n", line);
	if (!init) {
		if (regcomp(&r_info, "from ([^/][^:]+):[0-9]+", REG_EXTENDED))
			perror("r_info");
		if (regcomp(&r_error, "^([^/][^:]+):[0-9]+", REG_EXTENDED))
			perror("r_emake");
		init = true;
	}
	regmatch_t m[4];
	if (regexec(&r_info, line, AS(m), m, 0) &&
		regexec(&r_error, line, AS(m), m, 0)) {
		fprintf(stderr, "%s\n", line);
		return;
	}

	int rell = m[1].rm_eo - m[1].rm_so;
	const char * rel = strndup(line + m[1].rm_so, rell);
	if (debug)
		printf("   ERROR RELATIVE PATH: '%s'\n", rel);

	char path[4096];
	int done = 0;
	for (int pi = max_pwd; pi >= 0; pi--) {
		if (current_pwd[pi].idx == -1)
			continue;
		snprintf(path, sizeof(path), "%s/%s",
					current_pwd[pi].dir, rel);
		int pl = strlen(path);
		if (debug)
			printf("  Trying[%d]: '%s'\n", pi, path);

		struct stat stb;
		if (stat(path, &stb) == 0) {
			if (debug)
				printf("     Exists!!\n");
			int nll = strlen(line) - rell + pl + 1;
			char * newline = malloc(nll);

			snprintf(newline, nll, "%.*s%s%.*s",
					m[1].rm_so, line, path,
					strlen(line) - m[1].rm_eo, line + m[1].rm_eo);
			fprintf(stderr, "%s\n", newline);
			free(newline);
			done++;
			break;
		}
	}
	/* don't drop the error if we didn't doctor it */
	if (!done) {
		if (debug)
			printf("fmake: Unable to find a valid '%s', sorry\n", rel);
		fprintf(stderr, "%s\n", line);
	}
	free((void*)rel);
}

/* read some data into running buffer, split into lines, call callback.
 * this deal with fragmented lines, altho in reality, I don't think to
 * get them. Oh well. */
static int
st_read(
	struct stream_t * s,
	int fd,
	void (*line)(const char *))
{
	ssize_t rd = read(fd, s->buf + s->len, AS(s->buf) - s->len - 1);

	if (rd <= 0)
		return -1;
	s->len += rd;
	s->buf[s->len] = 0;
	char *b = s->buf;
	do {
		char * r = index(b, '\n');
		if (!r)
			break;
		*r = 0;
		line(b);
		b = r + 1;
	} while ((b - s->buf) < s->len);

	size_t remains = s->len - (b - s->buf);
	if (remains) {
		if (debug)
			printf("***** %d remains\n", (int)remains);
		memmove(s->buf, b, remains);
	}
	s->len = remains;

	return 0;
}

int
main(
	int argc,
	char *argv[])
{
	static struct {
		int pipe[2];
		struct stream_t st;
		void (*line)(const char *);
	} fd[2] = {
		[0].line = process_stdout,
		[1].line = process_stderr,
	};

	for (int i = 0; i < AS(fd); i++)
		if (pipe(fd[i].pipe)) {
			perror(argv[0]);
			exit(1);
		}
	// prep concurent make directory table
	for (int i = 0; i < AS(current_pwd); i++)
		current_pwd[i].idx = -1;
	// pre fill current directory
	getcwd(current_pwd[0].dir, sizeof(current_pwd[0].dir));
	current_pwd[0].idx = 0;

	pid_t child = fork();
	if (child == 0) {
		close(1); close(2);
		if (dup2(fd[0].pipe[1], 1) == -1 ||
			dup2(fd[1].pipe[1], 2) == -1) {
				printf("%s failed to dup2 descriptor\n", argv[0]);
				exit(1);
		}
		argv[0] = "make";
		execvp("make", argv);
		perror("execvp");
		exit(1);
	}

	int exited_status = 0;
	pid_t exited = 0;
	do {
		struct pollfd fds[2] = {
			[0] = { .fd = fd[0].pipe[0], .events = POLLIN, },
			[1] = { .fd = fd[1].pipe[0], .events = POLLIN, },
		};
		exited = waitpid(child, &exited_status, WNOHANG);
		if (exited == child)
			break;
		int r = poll(fds, AS(fds), 200);
		if (r == 0)
			continue;
		if (r == -1) {
			perror("poll");
			break;
		}
		for (int i = 0; i < AS(fd); i++) {
			if (fds[i].revents) {
				if (fds[i].revents & POLLIN) {
					if (st_read(&fd[i].st, fd[i].pipe[0], fd[i].line))
						break;
				} else
					break;
			}
		}
	} while (1);

	// kill kiddy if it wasn't dead already.
	if (!exited) {
		kill(child, SIGHUP);
		/*exited = */waitpid(child, &exited_status, WNOHANG);
	}
	if (debug)
		printf("%s exits with %d\n", argv[0],
				WEXITSTATUS(exited_status));
	// exit like the kid make did
	exit(WEXITSTATUS(exited_status));
}