index/maildir/maildir-filename.c

/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "ioloop.h"
#include "time-util.h"
#include "hostpid.h"
#include "maildir-storage.h"
#include "maildir-filename.h"

const char *maildir_filename_generate(void)
{
    static struct timeval last_tv = { 0, 0 };
    struct timeval tv;

    /* use secs + usecs to guarantee uniqueness within this process. */
    if (timeval_cmp(&ioloop_timeval, &last_tv) > 0)
        tv = ioloop_timeval;
    else {
        tv = last_tv;
        if (++tv.tv_usec == 1000000) {
            tv.tv_sec++;
            tv.tv_usec = 0;
        }
    }
    last_tv = tv;

    return t_strdup_printf("%s.M%sP%s.%s",
                   dec2str(tv.tv_sec), dec2str(tv.tv_usec),
                   my_pid, my_hostname);
}

bool maildir_filename_get_size(const char *fname, char type, uoff_t *size_r)
{
    uoff_t size = 0;

    for (; *fname != '\0'; fname++) {
        i_assert(*fname != '/');
        if (*fname == ',' && fname[1] == type && fname[2] == '=') {
            fname += 3;
            break;
        }
    }

    if (*fname == '\0')
        return FALSE;

    while (*fname >= '0' && *fname <= '9') {
        size = size * 10 + (*fname - '0');
        fname++;
    }

    if (*fname != MAILDIR_INFO_SEP &&
        *fname != MAILDIR_EXTRA_SEP &&
        *fname != '\0')
        return FALSE;

    *size_r = size;
    return TRUE;
}

/* a char* hash function from ASU -- from glib */
unsigned int maildir_filename_base_hash(const char *s)
{
    unsigned int g, h = 0;

    while (*s != MAILDIR_INFO_SEP && *s != '\0') {
        i_assert(*s != '/');
        h = (h << 4) + *s;
        if ((g = h & 0xf0000000UL) != 0) {
            h = h ^ (g >> 24);
            h = h ^ g;
        }

        s++;
    }

    return h;
}

int maildir_filename_base_cmp(const char *fname1, const char *fname2)
{
    while (*fname1 == *fname2 && *fname1 != MAILDIR_INFO_SEP &&
           *fname1 != '\0') {
        i_assert(*fname1 != '/');
        fname1++; fname2++;
    }

    if ((*fname1 == '\0' || *fname1 == MAILDIR_INFO_SEP) &&
        (*fname2 == '\0' || *fname2 == MAILDIR_INFO_SEP))
        return 0;
    return *fname1 - *fname2;
}

static bool maildir_fname_get_usecs(const char *fname, int *usecs_r)
{
    int usecs = 0;

    /* Assume we already read the timestamp. Next up is
       ".<uniqueness>.<host>". Find usecs inside the uniqueness. */
    if (*fname != '.')
        return FALSE;

    fname++;
    while (*fname != '\0' && *fname != '.' && *fname != MAILDIR_INFO_SEP) {
        if (*fname++ == 'M') {
            while (*fname >= '0' && *fname <= '9') {
                usecs = usecs * 10 + (*fname - '0');
                fname++;
            }
            *usecs_r = usecs;
            return TRUE;
        }
    }
    return FALSE;
}

int maildir_filename_sort_cmp(const char *fname1, const char *fname2)
{
    const char *s1, *s2;
    time_t secs1 = 0, secs2 = 0;
    int ret, usecs1, usecs2;

    /* sort primarily by the timestamp in file name */
    for (s1 = fname1; *s1 >= '0' && *s1 <= '9'; s1++)
        secs1 = secs1 * 10 + (*s1 - '0');
    for (s2 = fname2; *s2 >= '0' && *s2 <= '9'; s2++)
        secs2 = secs2 * 10 + (*s2 - '0');

    ret = (int)((long)secs1 - (long)secs2);
    if (ret == 0) {
        /* sort secondarily by microseconds, if they exist */
        if (maildir_fname_get_usecs(s1, &usecs1) &&
            maildir_fname_get_usecs(s2, &usecs2))
            ret = usecs1 - usecs2;

        if (ret == 0) {
            /* fallback to comparing the base file name */
            ret = maildir_filename_base_cmp(s1, s2);
        }
    }
    return ret;
}