lsof_u.c

/*
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include "lsof.h"
#include <pwd.h>
#include <sys/stat.h>

static void print_header() {
    printf("%-10s %5s %10s %4s %9s %17s %9s %10s %s\n",
            "COMMAND",
            "PID",
            "USER",
            "FD",
            "TYPE",
            "DEVICE",
            "SIZE/OFF",
            "NODE",
            "NAME");
}

static void print_type(const char *type, pid_info_t *info) {
    static ssize_t link_dest_size;
    static char link_dest[PATH_MAX];

    strncat(info->path, type, sizeof info->path);
    info->path[sizeof info->path - 1] = 0;
    if((link_dest_size = readlink(info->path, link_dest, sizeof(link_dest)-1)) < 0) {
        if (errno == ENOENT) goto out;
        snprintf(link_dest, sizeof(link_dest), "%s (readlink: %s)", info->path, strerror(errno));
    } else {
        link_dest[link_dest_size] = 0;
    }

    // Things that are just the root filesystem are uninteresting (we already know)
    if(strcmp(link_dest, "/") == 0) goto out;

    printf("%-10s %5d %10s %4s %9s %17s %9s %10s %s\n",
            info->command, info->pid, info->user, type,
            "???", "???", "???", "???", link_dest);

out:
    info->path[info->parent_length] = 0;
}

// Prints out all file that have been memory mapped
static void print_maps(pid_info_t *info) {
    FILE *maps;
    size_t offset;
    char device[10];
    long int inode;
    char file[PATH_MAX];

    strncat(info->path, "maps", sizeof(info->path));
    maps = fopen(info->path, "r");
    if(!maps) goto out;

    while(fscanf(maps, "%*x-%*x %*s %zx %5s %ld %s\n", &offset, device, &inode, file) == 4) {
        // We don't care about non-file maps
        if(inode == 0 || strcmp(device, "00:00") == 0) continue;
        printf("%-10s %5d %10s %4s %9s %17s %9zd %10ld %s\n",
                info->command, info->pid, info->user, "mem",
                "???", device, offset, inode, file);
    }
    fclose(maps);

out:
    info->path[info->parent_length] = '\0';
}

// Prints out all open file descriptors
static void print_fds(pid_info_t *info) {
    static char *fd_path = "fd/";
    strncat(info->path, fd_path, sizeof(info->path));

    int previous_length = info->parent_length;
    info->parent_length += strlen(fd_path);

    DIR *dir = opendir(info->path);
    if(!dir) {
        char msg[BUF_MAX];
        snprintf(msg, sizeof(msg), "%s (opendir: %s)", info->path, strerror(errno));
        printf("%-10s %5d %10s %4s %9s %17s %9s %10s %s\n",
                info->command, info->pid, info->user, "FDS",
                "", "", "", "", msg);
        goto out;
    }

    struct dirent *de;
    while((de = readdir(dir))) {
        if(strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0) continue;
        print_type(de->d_name, info);
    }
    closedir(dir);

out:
    info->parent_length = previous_length;
    info->path[info->parent_length] = '\0';
}

void lsof_dumpinfo(pid_t pid)
{
    int fd;
    pid_info_t info;
    struct stat pidstat;
    struct passwd *pw;

    info.pid = pid;
    snprintf(info.path, sizeof(info.path), "/proc/%d/", pid);
    info.parent_length = strlen(info.path);

    // Get the UID by calling stat on the proc/pid directory.
    if(stat(info.path, &pidstat) == 0) {
        pw = getpwuid(pidstat.st_uid);
        if(pw) {
            strcpy(info.user, pw->pw_name);
        } else {
            snprintf(info.user, USER_DISPLAY_MAX, "%d", (int)pidstat.st_uid);
        }
    } else {
        strcpy(info.user, "???");
    }

    // Read the command line information; each argument is terminated with NULL.
    strncat(info.path, "cmdline", sizeof info.path);
    fd = open(info.path, O_RDONLY);
    if(fd < 0) {
        fprintf(stderr, "Couldn't read %s\n", info.path);
        return;
    }

    char command[PATH_MAX];
    int numRead = read(fd, command, sizeof(command) - 1);
    close(fd);

    if(numRead < 0) {
        fprintf(stderr, "Error reading command: %s: %s\n", info.path, strerror(errno));
        return;
    }

    command[numRead] = '\0';

    // We only want the basename of the command
    strncpy(info.command, basename(command), COMMAND_DISPLAY_MAX - 1);
    info.command[COMMAND_DISPLAY_MAX - 1] = 0;

    // Read each of these symlinks
    print_type("cwd", &info);
    print_type("exe", &info);
    print_type("root", &info);

    print_fds(&info);
    print_maps(&info);
}

int lsof_main(int argc, char *argv[])
{
    long int pid = 0;
    char *endptr;
    if(argc == 2) {
        pid = strtol(argv[1], &endptr, 10);
    }

    print_header();

    if(pid) {
        lsof_dumpinfo(pid);
    } else {
        DIR *dir = opendir("/proc");
        if(!dir) {
            fprintf(stderr, "Couldn't open /proc\n");
            return -1;
        }

        struct dirent* de;
        while((de = readdir(dir))) {
            if(strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0) continue;

            // Only inspect directories that are PID numbers
            pid = strtol(de->d_name, &endptr, 10);
            if(*endptr) continue;

            lsof_dumpinfo(pid);
        }
        closedir(dir);
    }

    return 0;
}