#include <stdlib.h>
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>

#include "procfs.h"

int procfs_open(pid_t pid) {
	char path[2048];
	sprintf(path, "/proc/%d/mem", pid);
	return open(path, O_RDWR);
}

ssize_t procfs_maps(pid_t pid, struct procfs_map **maps) {
	char path[2048];
	sprintf(path, "/proc/%d/maps", pid);
	FILE *f = fopen(path, "r");
	if (!f) return -1;

	int n = 0;
	int capacity = 2;
	if (*maps) {
		free(*maps);
	}
	*maps = calloc(capacity, sizeof(**maps));
	if (!*maps) return -1;
	while (1) {
		void *base, *max;
		char prot_str[4];
		char name[4096] = {0};
		void *unused;
		int matches = fscanf(
			f, "%p-%p %4c %p %p:%p %d",
			&base, &max, &prot_str, &unused, &unused, &unused, &unused
		);
		if (matches == EOF) goto eof;
		if (matches < 7) goto err;

		int c = ' ';
		while (c == ' ') {
			c = fgetc(f);
		}
		if (c == EOF) goto err;
		ungetc(c, f);
		if (fgets(name, 4096, f) == NULL) goto err;
		name[strlen(name) - 1] = '\0'; // remove newline

		int prot = 0;
		for (int i = 0; i < 4; i++) {
			switch (prot_str[i]) {
				case 'r':
					prot |= PROT_READ;
					break;
				case 'w':
					prot |= PROT_WRITE;
					break;
				case 'x':
					prot |= PROT_EXEC;
					break;
				default:
					break;
			}
		}
		if (prot == 0) prot = PROT_NONE;

		if (n > 0) {
			procfs_map *prev = *maps + (n - 1);
			if ((strlen(name) == 0 || strncmp(prev->name, name, 1024) == 0) &&
					prev->max == (uintptr_t)base) {
				prev->max = (uintptr_t)max;
				continue;
			}
		}

		n++;
		if (n > capacity) {
			capacity <<= 1;
			struct procfs_map *r = reallocarray(*maps, capacity, sizeof(*r));
			if (!r) goto err;
			*maps = r;
		}
		procfs_map *new = *maps + (n - 1);
		new->base = (uintptr_t)base;
		new->max = (uintptr_t)max;
		new->prot = prot;
		strncpy(new->name, name, sizeof(new->name) - 1);
	}
eof:
	if (ferror(f)) goto err;
	fclose(f);
	if (n == 0) {
		free(*maps);
		*maps = NULL;
	}
	return n;
err:
	fclose(f);
	free(*maps);
	*maps = NULL;
	return -1;
}

// mmap does not work on /proc/pid/mem, so we issue reads/writes instead
int read_mem(int fd, uintptr_t addr, uint8_t *data, size_t size) {
	if (lseek(fd, addr, SEEK_SET) == -1) return -1;
	size_t n = 0;
	while (n < size) {
		ssize_t result = read(fd, data + n, size - n);
		if (result <= 0) return -1;
		n += result;
	}
	return 0;
}

int write_mem(int fd, uintptr_t addr, uint8_t *data, size_t size) {
	if (lseek(fd, addr, SEEK_SET) == -1) return -1;
	size_t n = 0;
	while (n < size) {
		ssize_t result = write(fd, data + n, size - n);
		if (result <= 0) return -1;
		n += result;
	}
	return 0;
}